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X-ray
Film Viewer, X ray Film Viewer
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 X-ray Film Viewer,
X ray Film Viewer，X-ray viewer,X ray viewer |
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X-ray viewer with automatic compensation for changes
in light intensity |
A fluorescent X-ray
viewer includes a photosensor within the housing
proximate to the fluorescent lamps for detecting the
intensity of the light prior to transmission through the
X-rays or other transparencies to be viewed. A dimming
circuit is used to adjust the intensity of the
fluorescent lamps to less than the nominal value, and
feedback through the photosensor is used to maintain the
light intensity output at a substantially uniform level
to compensate for line and load variations and aging and
changes of the efficiency of the fluorescent lamps. The
X-ray viewer is provided with an LED warning indicator
which is energized when the lamps have deteriorated to
an extent which requires replacement.
1. X-ray viewer comprising a housing, at least one
fluorescent lamp within said housing, and a light
transmissive screen forming a wall of said housing for
passage of light from said at least one fluorescent lamp
to allow viewing of an X-ray or other transparency
placed outside said housing adjacent said screen;
photo-detector means arranged within said housing
proximate to said at least one fluorescent lamp for
detecting the intensity of the direct light output
emitted by said at least one fluorescent lamp prior to
transmission through said screen; and electrical circuit
control means for dimming said at least one fluorescent
lamp to a desired predetermined level below the nominal
light intensity level and automatically adjusting the
light intensity to maintain a substantially uniform
light intensity output from said at least one
fluorescent lamp corresponding to said desired
predetermined light intensity level thereby compensating
for factors influencing the light intensity output of
said at least one fluorescent lamp, including line and
load variations and aging of said at least one
fluorescent lamp.
2. X-ray viewer as defined in claim 1, wherein said
photo-detector comprises a silicon cell.
3. X-ray viewer as defined in claim 1, wherein said
electrical control means comprises feedback means
cooperating with said photo-detector means for comparing
a reference signal with a signal which is a function of
the light output intensity of said at least one
fluorescent lamp and for generating a control voltage
which adjusts light intensity until it attains said
desired predetermined level.
4. X-ray viewer as defined in claim 1, wherein said
electrical circuit control means includes pre-setting
means for pre-setting the dimming level of said at least
one fluorescent lamp to said desired predetermined
level.
5. X-ray viewer as defined in claim 4, wherein said
pre-setting means is arranged to be generally
inaccessible from the outside of said housing.
6. X-ray viewer as defined in claim 5, wherein said
pre-setting means is disposed within said housing,
whereby initial adjustments can be made by the
manufacturer but not by the user.
7. X-ray viewer as defined in claim 4, wherein said
pre-setting means is set to provide a light output less
than approximately 75% of the nominal light output of
said at least one fluorescent lamp.
8. X-ray viewer as defined in claim 7, wherein said
electrical circuit control means provides relative
changes in output light intensity as a percent of full
or nominal light intensity equal to approximately 0.8%
per change in one volt of applied A.C. input voltage.
9. X-ray viewer as defined in claim 4, wherein said
pre-setting means is set to provide a light output less
than approximately 65% of the nominal light output of
said at least one fluorescent lamp.
10. X-ray viewer as defined in claim 9, wherein said
electrical circuit control means provides relative
changes in output light intensity as a percent of full
or nominal light intensity equal to approximately 0.35%
per change in one volt of applied A.C. input voltage.
11. X-ray viewer as defined in claim 4, wherein said
electrical circuit control means provides relative
changes in output light intensity as a percent of full
or nominal light intensity equal to approximately 50%
per change in one volt of applied A.C. input voltage.
12. X-ray viewer as defined in claim 11 wherein said
electrical circuit control means provides relative
changes in output light intensity as a percent of full
or nominal light intensity equal to approximately 0.2%
per change in one volt of applied A.C. input voltage.
13. X-ray viewer as defined in claim 4, wherein said
electrical circuit control means provides relative
changes in output light intensity as a percent of full
or nominal light intensity equal to approximately 13%
per change in one volt of applied A.C. input voltage.
14. X-ray viewer as defined in claim 13, wherein said
electrical circuit control means provides relative
changes in output light intensity as a percent of full
or nominal light intensity equal to approximately 0.16%
per change in one volt of applied A.C. input voltage.
15. X-ray viewer as defined in claim 1, wherein said
electrical circuit control means provides increasingly
smaller changes in output light intensity as a percent
of full or nominal light intensity per volt of applied
input A.C. voltage with increased amounts of initial
dimming of said at least one fluorescent lamp, whereby
the lower said desired predetermined level of intensity
is selected relative to the nominal level of intensity,
the more uniform the level of intensity maintained with
line and load changes and aging of said at least one
fluorescent lamps.
16. X-ray viewer as defined in claim 1, further
comprising warning means for providing a signal when
said electrical circuit control means is no longer
capable of adjusting said at least one fluorescent lamp
to provide said desired predetermined level of light
intensity.
17. X-ray viewer as defined in claim 16, wherein said
warning means includes an LED for providing a visible
flag.
18. X-ray viewer as defined in claim 16, where said
warning means includes comparator means for comparing a
first signal which is a function of the actual light
intensity of said at least fluorescent lamp and a
reference signal which is indicative of the nominal
light intensity achievable by said fluorescent lamp.
19. X-ray viewer comprising a housing, at least one
light source within said housing, and a light
transmissive screen forming a wall of said housing for
passage of light from said at least one light source to
allow viewing of an X-ray or other transparency placed
outside said housing adjacent said screen;
photo-detector means arranged within said housing
proximate to said at least one light source for
detecting the intensity of the light emitted by said at
least one light source prior to transmission through
said screen; and electrical circuit control means for
dimming said at least one light source to a desired
predetermined level below the nominal light intensity
level and automatically adjusting the light intensity to
maintain a substantially uniform light intensity output
from said at least one light source corresponding to
said desired predetermined light intensity level thereby
compensating for factors influencing the light intensity
output of said at least one light source, including line
and load variations and aging of said at least one light
source.
Description:BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention generally relates to X-ray film viewers,
and more specifically to such a device with automatic
light intensity compensation for changes in load and
line voltage and aging of the source of illumination.
2. Description of the Prior Art
In many applications, transparencies or negatives are
not used to print positive pictures, but are viewed
directly by transmission of light through them. One very
common such application is the viewing of X-rays by
doctors and other medical personnel. Industrial X-ray
pictures are also viewed in this manner to examine
mechanical parts and the like and illuminated viewing
boxes are used in photography to examine negatives for
selection for printing of pictures.
Typically, X-rays and other transparencies are viewed by
placing same against a light transmissive screen, such
as a light diffusion plate, which forms one wall of a
film viewer which houses a source of illumination such
as incandescent, halogen, or fluorescent light sources.
A detailed observation of the X-rays is facilitated by
transmission through the film of adequate intensity
light. However, the brightness of the light source
cannot be excessive since that would make extended
examinations of the films difficult and the viewer would
be exposed to substantial levels of light intensity when
the film is removed. The viewing of a large number of
such negatives in succession would require that the
viewer's eyes continuously adjust between very high
intensity light levels and significantly lower light
intensity levels, and this could make the viewing
uncomfortable and tedious.
U.S. Pat. No. 4,118,654, issued on Oct. 3, 1978 to Ohta
et al. discloses an automatic light intensity control
for an X-ray film viewer. Ohta et al. teach the use of a
photo-detector mounted externally of the film viewer so
that it receives the same light that passes through the
X-ray film which is viewed by the observer. The
photo-detector is intended to only detect the intensity
of light which penetrates through the film. While Ohta
et al. intend to shield the photosensor from ambient
light and only respond to light which passes through the
film, it is possible that ambient light will modify the
results since the photo-detector is mounted outside of
the X-ray film viewer.
Ohta et al. also teach the use of a control knob for
manually setting the intensity level of the light.
Therefore, the user can presumably adjust the light
intensity output level at or near the maximum or nominal
light level intensity, or at a level substantially below
the nominal value. Although Ohta et al. describe a
circuit for automatically controlling the light source
to maintain a constant level of intensity, it is
improbable that the circuit can fully compensate for
line and load variations and aging of the sources of
light under all circumstances, particularly when the
user has already manually adjusted the units for maximum
light intensity. Ohta et al. are primarily concerned
with maintaining a constant light level at the output of
the X-ray film, irrespective of the transmissivity of
such film. The patent is not directed to the solution of
the problem of maintaining the output of the source of
illumination at a substantially constant level prior to
passage through the X-ray film as a result of line and
load variations and aging of the light source.
Another X-ray viewer provides two levels of
illumination. The first level provides a lower standard
intensity of illumination and is intended for
preliminary viewing and general use. A second high
brightness level of illumination is provided which is
approximately 50% higher than the first level, and is
intended for viewing of darker films or those that are
less light transmissive. However, the device does not
appear to provide automatic light intensity
compensation, but only provides one of two selected
levels of such light intensity.
SUMMARY OF THE INVENTION
It is one of object of the present invention to provide
an X-ray viewer with automatic compensation for changes
in light intensity which does not have the problems and
disadvantages inherent in the prior art or known X-ray
viewers.
It is another object of the present invention to provide
an X-ray viewer of the type under discussion which is
simple in construction and economical to manufacture.
It is yet another object of the present invention to
provide an X-ray viewer of the type above suggested
which monitors the light output at the light source
prior to transmission through the X-ray or other
transparency to be viewed, and which automatically
compensates for changes in light intensity output for
line and load variations and aging of the light source.
It is a further object of the present invention to
provide an X-ray viewer of the type described in the
last object, wherein the sources of light are
fluorescent bulbs or lamps.
It is still a further object of the present invention to
provide an X-ray viewer with a pre-setting control which
can be set to a preselected or preset level of light
intensity which cannot be easily modified or changed by
the user.
It is yet a further object of the present invention to
provide an X-ray viewer of the type under discussion
which includes a warning signal to alert the user when
the light source has attained a condition when it must
be replaced since it can no longer be automatically
adjusted to maintain a desired predetermined level of
light intensity.
In order to achieve the above objects, as well as others
which will become apparent hereafter, an X-ray viewer in
accordance with the present invention comprises a
housing and at least one fluorescent lamp within said
housing. A light transmissive screen forms a wall of
said housing for passage of light from said at least one
fluorescent lamp to allow viewing of an X-ray or other
transparency placed outside said housing adjacent to
said screen. Photo-detector means is arranged within
said housing proximate to said at least one fluorescent
lamp for detecting the intensity of the light emitted by
said at least one fluorescent lamp prior to transmission
through said screen. Electrical circuit control means is
provided for dimming said at least one fluorescent lamp
to a desired predetermined level below the nominal light
intensity level and automatically adjusting the light
intensity to maintain a substantially uniform light
intensity output from said at least one fluorescent lamp
corresponding to said desired predetermined light
intensity level, thereby compensating for factors
influencing the light intensity output of said at least
one fluorescent lamp, including line and load variations
and aging of said at least one fluorescent lamp.
Advantageously, said electrical circuit control means
includes pre-setting means for pre-setting the dimming
level of said at least one fluorescent lamp to said
desired predetermined level, and said pre-setting means
is arranged so as to be generally inaccessible from the
outside of said housing. In this manner, initial
adjustments can be made by the manufacturer and not
modified by the user.
According to a further feature of the present invention,
warning means are provided for providing a signal when
said electrical circuit control means is no longer
capable of adjusting said at least one fluorescent lamp
to provide said desired predetermined level of light
intensity. In accordance with the presently preferred
embodiment, such warning means include an LED for
providing a visible flag when the intensity of the
fluorescent lamp can no longer be adjusted or increased.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features of the present
invention will be more readily apparent from the
following detailed description and drawings of an
illustrative embodiment of the invention in which:
FIG. 1 is a schematic diagram illustrating a typical
conventional o prior art dimmer;
FIG. 2 is a cross-sectional view of a typical X-ray
viewer, showing the fluorescent lamps and one internal
arrangement of the photosensor for monitoring or
detecting the intensity of the light emitted by the
fluorescent lamps;
FIG. 3 is an electrical circuit schematic showing a
regulating dimmer in accordance with the present
invention used in conjunction with the X-ray viewer
shown in FIG. 2;
FIG. 4 is a plot or chart quantitatively indicating the
typical functional relationship of fluorescent light
intensity to its AC supply voltage;
FIG. 5 is similar to FIG. 4, and illustrates the
response of light intensity to variations in line
voltage for a conventional dimmer as contrasted to the
equivalent response for the regulating dimmer in
accordance with the present invention; and
FIG. 6 indicates in synoptic format the responses of
both conventional and the regulating dimmer in
accordance with the present invention to changes in
supply line voltage for several arbitrary intensity
levels.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now specifically to the FIGS., in which
identical or similar parts are designated by the same
reference numerals throughout, and first referring to
FIG. 1, there is illustated a typical conventional or
prior art dimmer generally designated by the reference
numeral 10.
This disclosure describes a technique for dimming and
regulating the intensity of fluorescent light and its
application in X-ray film (radiograph) illumination and
reading. Many radiologists prefer to view or to "read"
X-ray films at various light intensities to better suit
the range of film densities encountered to visual
sensitivities and individual preferences. The vast
majority of film reading is performed with fluorescent
lighting. For several technical reasons, fluorescent
lighting does not lend itself as readily to dimming as
does incandescent lighting. A dimmer circuit such as
that shown in FIG. 1 can be used to alter or modify the
light level intensity output from fluorescent lamps.
In FIG. 1, the dimmer 10 utilizes an RC
(resistance-capacitance) network consisting of
adjustable resistor 12, resistor 14, capacitor 16,
resistor 18, capacitor 20, resistor 22 and capacitor 24.
A diac 26 is shown connected to a triac 28 to achieve
phase control of the current flowing through fluorescent
lamp ballasts 32. The resistor 12 provides a limited
range of adjustment of light intensity. The ballasts 32
are connected and supply the fluorescent lamps 34. The
dimmer is connected across AC power lines 36, 38. The
circuit 10 characteristically provides no line or load
regulation and consequently the brightness of the
fluorescent lamps 38 will vary directly with changes in
line voltage, and will not compensate for normal
reduction in light intensity caused by aging or other
losses in lamp efficiency.
Referring to FIG. 2, an X-ray viewer is shown in
cross-section and generally designated by the reference
numeral 39. The specific shape or configuration of the
viewer housing is not critical. The viewer 39 is shown
to have a light transmissive glass screen or panel 39a
through which internally generated light from the
fluorescent bulbs 34 pass and continue through an X-ray
film or other transparency T which may be held in the
position shown by clip 39b or other conventional
devices.
The viewer 39 includes electrical circuit control means,
generally designated by the box 40, which will be more
fully described in connection with FIG. 3. Also
illustrated is one possible position for a photosensor
or photodetector 41 inside the viewer 39 and proximate
to at least one of the fluorescent lamps 34 for
monitoring the output light intensity thereof.
Referring to FIG. 3, there is illustrated the electrical
schematic in accordance with the presently preferred
embodiment for the regulating dimmer. The control
circuit 40 includes, as above noted, a photodetector 41
which may be a silicon cell and is arranged within the
housing of the viewer 39 for monitoring and detecting
the output light intensity of the fluorescent lamps 34.
The photocell 41 is connected across the differential
inputs of amplifier 48, with capacitor 50 and resistor
52 being connected between the negative differential
input and the output of the amplifier. The output of the
amplifier 48 is connected to common potential through
resistors 54, 56 and 58, resistor 56 being an adjustable
potentiometer.
The sliding contact of the potentiometer 56 is connected
to the negative differential input of a comparator 62,
with the positive differential input of the comparator
being connected to the output of a sawtooth wave
generator 64. The sawtooth generator 64 is provided with
timing elements including capacitor 66 and resistor 68.
A further resistor 70 connects the sawtooth wave
generator to the AC power line.
The output of the comparator 62 is connected to a driver
72, another input of which is connected to the output of
comparator 74. A resistor 76 is connected between the
positive differential inputs of the comparators 62 and
64. The positive differential input of the comparator 74
is also connected to the common D.C, potential through
resistor 78. A resistor 80 and, capacitor 82, forming a
low frequency filtering circuit, are connected to the
negative differential input of the comparator 74 and and
connected to a source 84 of reference potential through
resistor 86.
A triac 88, connected between one of the A.C. power
lines 38 and the fluorescent ballasts 32, has its gate
connected to the triac driver 72 through resistor 90.
The A.C. power line 38 is filtered to the common
potential by means of capacitor 92, a Zener diode 94
being connected across the capacitor 92 to produce the
desired levels of D.C. voltage at the output of the
power supply 96. The power supply 96, in the circuit
being described, generates +14 volts of D.C. which is a
nominal voltage for operating the various electrical
components such as amplifiers, comparators, etc., and a
reference voltage of +2 volts. The reference voltage is
used at the terminal 84 as well as at the positive
differential input of the comparator 99, to be more
fully decribed below.
A series connected diode 98 and resistor 100 connect the
A.C. power line 86 to the power supply 96 as shown.
A switch 101 is advantageously provided which can turn
the dimmer on and off by applying or removing AC power,
although any other switch or control may be used for
this purpose.
All of the items which have been marked with an asterisk
in FIG. 3 are available on an integrated circuit which
has been used to construct the circuit shown. The
integrated circuit which has been used for this purpose
is the Siemens' device TLE 3101 described in the Siemens
Consumer IC Data Book--1985, pages 735-745. The Siemens'
TLE 3101 is a phase control IC with independent on-chip
op amp 48 and comparator 99. However, any other
integrated circuit or discrete components may be used,
and the Siemen device is mentioned only by way of
example since it has been satisfactorily functioned in
the circuit shown.
The dimmer shown in FIG. 3 accomplishes phase control of
the fluorescent lamp ballasts 32 and its resultant light
dimming by using the line synchronized sawtooth wave
generator 64 and comparator 62 in conjunction with the
light or photosensor 41 and the resultant feedback loop
of which these elements form a part. The silicon
photocell 41 samples an averaged level of fluorescent
light and produces a current which is proportional to
the intensity of the incident light λ. The current is
converted to an analog voltage by amplifier 48, and
filtered to remove the A.C. fluctuations associated with
fluorescent light sources. The smoothed D.C. voltages
apply to one input of the comparator 62 while the
sawtooth wave generator 64 output is applied to the
other input. The output of the comparator 62 is applied
to triac driver circuitry 72 triggers the triac 88 into
latched conduction once each half period of the A.C.
line of frequency.
A sample of the dimmed light from the fluorescent lamps
34 is coupled to the silicon photocell 41 completing the
feedback loop. Thus, for variations in fluorescent light
intensity caused by changes in line voltage or by aging
characteristics of the fluorescent lamp 34, a correction
signal is automatically produced and applied to the
control circuitry causing the level of fluorescent light
to remain relatively constant.
The adjustable potentiometer 56 comprises a pre-setting
adjustable element used to preset the dimming level of
the fluorescent lamps 34 to a desired predetermined
level. The potentiometer 56, however, is advantageously
made inaccessible or inconvenient to be reached by the
user. Preferably, the potentiometer 56 is preset at the
factory to provide the desired predetermined level of
light intensity. The specific level of light intensity
which is preselected is not critical for purposes of the
present invention. However, the initial setting of the
potentiometer 56 should be such that the fluorescent
lamps 34 operate at a level below their nominal light
intensity values so that the control circuit 40 can
boost the light intensity levels over time to compensate
for losses associated with such fluorescent lamps,
including line and voltage variations, aging, losses of
efficiency, etc. The circuit 40, therefore, initially
dims or reduces the potentially available output from
the fluorescent lamps so that such lamps can be
increasingly energized or otherwise appropriately
adjusted to maintain a substantially constant level of
light intensity output.
In accordance with another feature of the present
invention, there is advantageously provided a warning
mechanism for providing a signal when the electrical
circuit 40 is no longer capable of adjusting the
fluorescent lamps 34 to provide the desired
predetermined level of light intensity. In FIG. 3, such
warning element is an LED 102 for providing a visible
flag to the user when the circuit is no longer capable
of making the necessary adjustments for further
fluctuations in the external conditions or the
deteriorating conditions of the fluorescent lamps 34. To
accomplish this, the negative potential input of the
comparator 99 is connected to the sliding output of the
potentiometer 56 by means of a voltage divider including
resistors 104 and 106. The positive potential input of
the comparator 99 is connected to a source of positive
reference potential which, as suggested above, can be
the reference potential output of the power supply 96.
The output of the comparator 99 is connected to the LED
102 by means of a resistor 110. In the specific
embodiment illustrated and described, the comparator 99
is used to signal when conditions are such that the loop
is no longer able to compensate adequately for low line
voltage excursions (typically below 110 volts), or for
lamps which through aging and use have lost efficiency
and should be replaced. The light emitting diode 102 is
driven directly by the comparator circuitry and provides
a clear visual indication of such conditions. It is
pointed out, however, that other warning devices or
elements may be used in place of or in addition to an
LED visible indicator. Audible sound emitters and other
warning elements are well known to those skilled in the
art and can be used individually or in any combination.
To illustrate the benefits of the disclosed apparatus
and method of fluorescent dimming, reference will be
made to FIGS. 4, 5 and 6. FIG. 4 indicates
quantitatively the typical functional relationship of
the fluorescent light intensity to its A.C. supply
voltage. Considering 120 volts A.C. to be nominal line
voltage, the slope of the response curve of FIG. 3
reflects an average of 1.55% change in brilliance per
volt change of applied voltage. This slope increases at
lower line voltages and illumination levels. FIG. 4
illustrates the slope to be measured at A o , at the
nominal or applied voltage of 120 volts, the average
slope being measured between A 1 and A 2 .
FIG. 5 illustrates the response of light intensity to
variations in line voltage for a conventional dimmer
(curve B') as contrasted to the equivalent response for
the regulating dimmer in accordance with the present
invention (curve B"). Here, the nominal operating point
B o is again taken at 120 volts A.C., and each dimmer is
set for 50% dimming. The curve B' for the conventional
dimmer, taken between B 1 and B 2 , exhibits an average
slope of 2.4% light intensity per volt at the operating
point B o or 120 volts A.C. The corresponding average
slope for the regulating dimmer in accordance with the
present invention, taken between B 3 and B 4 of curve B"
exhibits an average slope of 0.2% light intensity per
volt. As can be seen, therefore, the conventional dimmer
is far more sensitive to changes in applied voltage, in
this instance by a factor of approximately 12.
FIG. 5 indicates in synoptic format the responses of
both the conventional and the regulating dimmer in
accordance with the pesent invention to changes in
supply line voltage for several arbitrary intensity
levels. The intensity levels of the dimmer is set by
adjustment of the potentiometer 56 in FIG. 3. The curves
C', D', E' and F' are those associated with the
conventional dimmer, while curves C", D", E" and F" are
for the regulating dimmer in accordance with the present
invention.
The curves C' and C" have been shown for a 78% nominal
setting of measured relative light intensity, curves D'
and D" at 63% setting, E' and E" at 50% setting and F'
and F" at 41% setting. The average slopes have been
measured for each of the curves at the initially preset
operating conditions C o , D o , E o and F o , each of
which represents operation at 120 volts applied A.C.
At a setting of 78% of nominal light value, there is an
average of 1.94% change in brilliance per volt change of
applied voltage for the conventional dimmer as compared
to an average of 0.8% change in brilliance per volt
change of applied voltage. At 63% setting of nominal
light value, the conventional dimmer exhibits 2.1%
change in brilliance per volt of change of applied
voltage as compared to 0.35% change in brilliance per
volt change of applied voltage for the subject dimmer.
At 50% of nominal light value, the conventional dimmer
exhibits a 2.4% average change in brilliance per volt
change of applied voltage as compared with only 0.2% for
the dimmer of the present invention. In the remaining
curves, representing a 41% setting of nominal light
value, the conventional dimmer exhibits 2.5% average
change in brilliance per volt change of applied voltage
as compared with 0.16% such average change per volt
change of applied voltage for the described subject
dimmer.
The curves of FIG. 6 illustrate that there is an
improvement in operating characteristics at almost all
preset levels of dimming. However, the greater the
initial dimming, the greater the improvement in
operating characteristics. Thus, the electrical circuit
in accordance with the invention provides increasingly
smaller changes in output light intensity as a percent
of full or nominal light intensity per volt of applied
input A.C. voltage with increased amounts of initial
dimming of the fluorescent lamps. In this manner, the
lower the desired predetermined levels of intensity that
are selected relative to the nominal level of intensity,
the more uniform the level of intensity that is
maintained with line and load changes and aging of the
fluorescent lamps. The opposite result is exhibited by
the conventional dimmers.
In addition to the obvious and measureable advantages of
the regulating dimmer in compensating for varations in
line voltage, tests were conducted to determine its
efficacy in load regulation. In these tests, the applied
line voltage was held constant at a nominal 120 volts
A.C. To simulate lamps which have aged and are producing
reduced levels of brilliance, tubular translucent
filters of several optical densities were configured to
slide easily on and off the fluorescent lamps. As a
point of reference, the unfiltered lamps were installed
and two dimmer types were set to 50% dimming as measured
at several random points on the surface of an X-ray film
illuminator. An average illumination level was
calculated from the samples. Next, filters were
installed on the lamps which reduced the emitted light
from the lamps by 60%. Measurements were again taken of
the light levels at the same sample points used in the
reference condition. When the readings were averaged,
the illumination level of the lamps driven by the
conventional dimmer was reduced by approximately 60%,
which is consistent with the optical density of the
filter. The illumination levels recorded and averaged
for the regulating dimmer of the present invention under
like conditions were reduced by approximately 5% from
the unfiltered light levels. Several densities of
filters were tested with similar results. Thus, the
circuitry configured by the subject regulating dimmer
provides excellent compensation for normally encountered
line voltage variations of from below 110 A.C. to more
than 130 volts A.C., and for reductions of up to 60% in
light output associated with losses of lamp efficiency.
Additionally, the visual device signaling device in the
form of the LED 102 and associated circuitry proved to
be an effective visual warning to help determine when
lamp replacement should be made or considered.
While the invention is described with reference to
specific embodiments thereof and with respect to the
incorporation therein of certain combinations of
features, it is to be understood that the invention may
be embodied in other forms, many of which do not
incorporate all of the features present in this specific
embodiment of this invention which has been described.
Thus, while one specific circuit has been described for
controlling the light intensity output of fluorescent
lamp may be used. Additionally, many of the advantages
of the present invention can also be achieved if other
light sources are used other than fluorescent lamps.
Thus, halogen and incandescent lamps can also be used
with varying degrees of advantage. Further, while it is
presently desired to conceal the pre-setting
potentiometer 56 from the user, it may be desirable, in
some instances, to make such potentiometer readily
accessible. For this reason, the invention is to be
taken and limited only as defined by the claims that
follow. |
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Combination unit doubles as slide or X-ray viewer |
Lester A. Dine
introduces a simple-to-use combination unit that doubles
as a slide or X-ray viewer for desk-top presentations or
a small-screen projection. Standard cardboard, plastic
or glass-mounted slides may be used. A single-slide
adapter and a six-slide strip holder are included. The
36-slide semi-automatic slide changer is available as an
optional accessory.
For additional information on this combination unit,
circle the number below on the reader service card
located at the back of the magazine. |
| Article Source: |
| http://www.dentaleconomics.com/index/display/article-display/122549/articles/dental-economics/volume-86/issue-7/departments/new-products/combination-unit-doubles-as-slide-or-x-ray-viewer.html |
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Portable x-ray
film viewer |
A portable x-ray viewer
is configured as a clipboard. The clipboard
configuration makes the portable x-ray viewer easy to
handle by doctors and other medical personnel. Since the
viewer is portable, the number of required x-ray viewers
in a doctor's office or a medical facility is greatly
reduced, thus reducing the overall cost. In addition,
the portable x-ray viewer is provided with an automatic
control for controlling the viewer. In particular, in
accordance with an important aspect of the invention,
the viewer is automatically turned on when an x-ray is
inserted and is automatically turned off when the x-ray
is removed. As such, use of the x-ray viewer is
facilitated for medical personnel and also eliminates
the problem of premature burnout of the display or lamp
when the x-ray viewer is left on for extended periods of
time.
1. A film viewer comprising: a portable housing formed
with a base and a viewing window for receiving films to
be viewed; a handle formed in the base of said housing
for facilitating handling of said portable housing, said
housing being configured so that said handle is
concealed when said film viewer is resting on a flat
surface; a film grip assembly mounted on said portable
housing adjacent said viewing window for holding films,
wherein said film grip assembly includes a top plate is
pivotally connected to the housing in a cantilever
configuration defining a film receiving slot, said film
grip assembly further including a biasing spring for
biasing said top plate toward said housing, said film
grip assembly including an actuator in communication
with said film receiving slot and responsive to films
placed within the film grip assembly, said actuator
having a first position when no film is in said film
receiving slot and a second position when a film is in
said film receiving slot; a lamp disposed beneath said
viewing window for illuminating said viewing window; an
electrical power source for providing electrical power
to said lamp; and an automatic control circuit which
includes a microswitch, said microswitch being
responsive to said actuator, said microswitch having a
first position when there no films in the film grip
assembly and a second position when a film is disposed
in said film grip assembly, said automatic control
circuit causing said electrical power source to
automatically turn on said electrical power source when
said microswitch is in a first position, and
automatically turn off said electrical power source when
said microswitch is in said second position, wherein
said housing and said clipboard are configured as a
clipboard.
2. The film viewer as recited in claim 1, wherein said
electrical power source is DC.
3. The film viewer as recited in claim 1, wherein said
electrical power source is AC.
4. The film viewer as recited in claim 1, wherein said
housing is a molded plastic housing. assembly includes a
top plate connected to the housing in a cantilever
configuration defining a film receiving slot.
5. The film viewer as recited in claim 1 wherein said
top plate includes one or more bosses and said film grip
assembly includes one or more balls and one or more
springs, said one or more balls received in said one or
more bosses with said one or more springs and configured
such that said one or more balls are biased toward said
housing.
6. A film viewer comprising: a housing formed with a
base and a viewing window for receiving films to be
viewed, said housing configured to rest on a flat
surface; a film grip assembly mounted on said housing
adjacent said viewing window for holding films, said
housing and said film grip assembly configured as a
clipboard; a lamp disposed beneath said viewing window
for illuminating said viewing window; an electrical
power source for providing electrical power to said
lamp; an automatic control circuit which includes an
optical sensor for switching said source of electrical
power on whenever a film is disposed on said viewing
surface and turning off said source of electrical power
when said film is removed; and a knob for handling said
film viewer, wherein said knob is formed in said base of
said housing being configured so that said knob is
concealed when said film viewer is resting on a flat
surface.
Description:BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a film viewer and more
particularly to a portable film viewer configured as a
clipboard with an automatic control circuit which
automatically turns the viewer on when a hard copy film
is inserted and automatically turns the viewer off when
the film is removed.
2. Description of the Prior Art
Film viewers, such as x-ray viewers, are generally known
in the art. Such x-ray viewers are known to be used in
the medical industry by medical personnel to view x-ray
films. Examples of such x-ray viewers are disclosed in
U.S. Pat. Nos. 4,118,654; 4,510,708; 4,908,876;
6,031,516; 6,088,941; 6,208,437; 6,462,868; and
6,548,823. X-ray viewers are also known for viewing
digital x-rays. U.S. Pat. Nos. 6,031,516 and 6,462,868
disclose dual-function x-ray viewers that are configured
to view both hard copy x-ray films as well as digital
x-rays.
In the medical industry, hard copy x-ray films are
predominately used. Such x-ray film viewers are normally
wall-mounted and include a lightbox. One known
conventional viewer includes a light source or lamp, a
reflector plate, and a diffuser plate. The lamp and the
reflector plate are disposed adjacent a rear wall of the
light box. The diffuser plate forms the front wall of
the lightbox. The diffuser plate causes relatively
uniform light to be distributed across its surface to
allow relatively accurate reading of the x-ray film. An
example of such an x-ray viewer is disclosed in U.S.
Pat. Nos. 4,118,654 and 4,510,708.
There are several problems with such known x-ray
viewers. First, in many medical applications, such as
doctors' offices, such x-ray viewers are required in
each of the patient examination rooms—especially in
patient examination rooms of orthopedic surgeons. By
having an x-ray viewer in the patient examination rooms,
the orthopedic surgeon is able to show patients the
exact nature of their problem. However, such x-ray
viewers are relatively expensive. Thus, separate x-ray
viewers in each patient examination room can be costly
for a doctor.
Another problem with known x-ray viewers is that the
light or display must be controlled manually by the
medical personnel, which is cumbersome. Additionally,
medical personnel are known to leave the lamp or display
on for extended periods of time. Accordingly, the lamps
and displays are known to burn out prematurely, thus
increasing the cost to the medical facility. Thus, there
is a need to reduce the cost of such x-ray viewers.
SUMMARY OF THE INVENTION
Briefly, the present invention relates to a portable
film viewer configured as a tabletop clipboard device
with a handle. The handle and the clipboard
configuration make the portable film viewer easy to
handle by doctors and other medical personnel. Since the
viewer is portable, the number of required film viewers
in a doctor's office or a medical facility is greatly
reduced, thus reducing the overall cost. In addition,
the portable film viewer is provided with an automatic
control circuit for controlling the light source in the
viewer. In particular, the automatic control circuit
automatically turns the film viewer on when a hard copy
film is inserted and automatically turns off the film
viewer when the film is removed. As such, use of the
film viewer is facilitated for medical personnel and
also eliminates the problem of premature burnout of the
display or lamp.
DESCRIPTION OF THE DRAWINGS
These and other advantages of the present invention will
be readily understood with reference to the following
drawings and attached specification wherein:
FIG. 1 is a perspective view of a portable film viewer
in accordance with the present invention.
FIG. 2 is another perspective view, illustrating a top
portion of the portable film viewer, formed with a slot
for carrying a marking pencil.
FIG. 3 is an exploded perspective view of the film
viewer in accordance with the present invention.
FIG. 4A is a front view of the film viewer in accordance
with the present invention.
FIG. 4B is a bottom view of the film viewer in
accordance with the present invention.
FIG. 4C is a left side view of the film viewer in
accordance with the present invention.
FIG. 4D is a top view of the film viewer in accordance
with the present invention.
FIG. 4E is a right side view of the film viewer in
accordance with the present invention.
FIG. 5A is a back view of the film viewer in accordance
with the present invention.
FIG. 5B is a sectional view of the right side of the
film viewer in accordance with the present invention.
FIG. 5C is a detailed view of a portion of the film
viewer, illustrating a contact switch and film grip in
accordance with the present invention.
FIG. 6 is a perspective view of a front portion of the
film viewer in accordance with the present invention.
FIG. 7 is a perspective view of the back of the film
viewer in accordance with the present invention.
FIG. 8 is a block diagram, illustrating the electrical
connections for the film viewer in accordance with the
present invention.
DETAILED DESCRIPTION
The present invention relates to a portable film viewer,
for example, an x-ray viewer. In order to facilitate
handling of the portable film viewer, the device
includes a handle and is configured as a clipboard. In
addition, a slot for carrying a marking pencil commonly
known as a so-called “China marker”. In order to further
facilitate use of the film viewer in accordance with the
present invention, the film viewer is provided with a
control circuit, which automatically turns on the film
viewer when an x-ray film or other hard copy film is
inserted into a film grip. The automatic control circuit
also automatically turns off the film viewer when the
hard copy film is removed from the film grip.
The portable film viewer is described and illustrated
herein for use in medical applications for viewing x-ray
films in the medical industry. It is to be understood
that the principles of the present invention are also
applicable to other applications, such as dental x-rays
and industrial x-rays. Furthermore, it is to be further
understood that the portable film viewer in accordance
with the present invention can also be used with other
hard copy films, other than x-ray films.
Referring to the drawings, the portable film viewer in
accordance with the present invention is generally
identified with the reference numeral 20 . As shown in
FIG. 1, the portable film viewer 20 in accordance with
the present invention includes a front panel 22 , a
viewing window 24 , and a film grip assembly 26 . The
film grip assembly 26 includes a notch 28 for receiving
hard copy films (not shown), such as x-ray films. As
will be discussed in more detail below, the film grip
assembly 26 includes an automatic control circuit for
automatically turning on the viewer when hard copy film
is inserted therein and shutting the viewer 20 off when
the hard copy film is removed.
As shown best in FIGS. 5A and 7, a handle or knob 27 may
be provided to facilitate handling of the device 20 . An
exemplary oval knob is illustrated. However, other types
of handles are contemplated, such as a circular knob, as
well as non-circular knobs or handles of virtually any
configuration. The portable film viewer 20 is configured
to rest on a flat surface, such as a tabletop, as shown
in FIGS. 1 and 2. The knob 27 facilitates handling of
the viewer 20 when it is not resting on a flat surface.
In particular, the knob 27 facilitates a user holding
the viewer 20 in one hand and while marking on the film
with the other hand. The knob 27 may be configured to
either be concealed from view when the film viewer 20 is
resting on a flat surface or alternatively exposed.
In order to further facilitate the use of the portable
film viewer 20 , a transverse slot 30 (FIG. 2) is
provided along a top portion of the portable film viewer
20 . The width of the slot 30 is configured to receive a
conventional marking pencil 32 , known as a so-called
“China marker”. Such marking pencils 32 are often used
by medical personnel to highlight portions of an x-ray
film.
As shown in the Figures, the portable film viewer 20 is
configured as a clipboard and is rather compact in size.
For example, with reference to FIGS. 4A through 4E, the
portable film viewer 20 may be configured with a length
L 1 of around 400 mm and a width W 1 of about 230 mm.
With such a configuration, the viewing window 24 may be
configured with a length L 2 of about 230 mm and a width
of about 190 mm. The overall depth W 3 of the portable
viewer 20 may be about 40 mm and have an overall weight
of around 18 ounces.
The portable viewer 20 may be configured in the shape of
a clipboard and formed with a molded plastic housing 34
(FIG. 3). The molded housing 34 includes a front panel
22 configured with the viewing window 24 and a rear
panel 36 , as generally shown in FIGS. 3, 5 A, and 7 .
The front panel 22 includes a viewing window 24 . A
flange 48 is formed on the top of the front panel 22 . A
separate top plate 50 forms a portion of the film grip
assembly 26 . The top plate 50 is connected in a
cantilever configuration to the front panel 22 as shown
defining a film receiving slot 51 (FIG. 1). In
particular, the top plate 50 is formed with a one or
more bosses 38 , 40 , and 42 on its underside. The
bosses 38 , 40 , and 42 are formed as cylindrical
members and project outwardly toward the front panel 22
after assembly. The bosses 38 , 40 , and 42 are for
receiving metal balls 44 and biasing springs 46 . In a
normal position, the metal balls 46 are urged against
the front panel 22 under the influence of the biasing
springs 46 .
A microswitch actuator 54 is formed on one end of a
lever arm 55 that is coupled to a momentary action
microswitch 56 configured as an automatic control
circuit. When a hard copy film 60 is inserted into the
film grip assembly 26 , the microswitch actuator 54 is
depressed which causes the lever arm 55 to change the
state of a momentary contact 57 (FIG. 8) within the
microswitch 56 to a state opposite to that shown in FIG.
8. In a normal position (i.e. when no film inserted into
the film grip assembly 26 ) and when the film 60 has
been removed from the film grip assembly 26 , the
momentary contact 57 returns to a normally open state as
shown in FIG. 8. Other automatic control circuits can
also be used. For example, an optical sensor can
alternatively be used and configured to interrupt a
light beam when a film is inserted.
The back panel 36 forms the base of the portable film
viewer 20 and includes a generally C-shaped surface 62
that is configured to enable the portable viewer 20 to
rest on a table, cabinet, or the like. A battery
compartment 64 may be provided for carrying a battery 66
. An access door 68 may also be provided to allow the
battery 66 to be replaced from the bottom of the
portable viewer 20 . An on-off switch 70 may also be
provided. The on-off switch 70 is located on a side wall
76 of the rear panel 36 .
Various types of illumination devices or lamps may be
used for the portable film viewer 20 . As shown, and as
illustrated herein, an electroluminescent lamp, for
example, a model number SH-200-BE, as manufactured by
Ping Po Lighting Electronics Factory of TungKuan City,
Guangdong, China, may be used for viewing hard copy
film, such as x-ray film. Referring to FIG. 8, the
electroluminescent display 72 may be powered by an
inverter 74 , for example, a model no. SH-12-200
manufactured by Shang Hong Factory GuangZhou City,
Guangdong, China, and a battery 66 , for example, a
nine-volt battery. In one exemplary embodiment, the
on-off switch 70 is connected in parallel with the
momentary contact 57 . As shown in FIG. 8, the position
of the momentary contact 57 is in a state as shown in
FIG. 5C (i.e., an x-ray 60 has been inserted into the
film grip assembly 26 , tripping the microswitch
actuator 54 and closing the momentary contact 57 of the
microswitch 56 ), defining a view mode. When the film 60
is removed from the film grip assembly 26 , the
microswitch actuator 54 and thus the momentary contact
57 returns to its normal position. As such, assuming the
on-off switch 70 is open as shown in FIG. 8, insertion
of a film 60 into the film grip assembly 26 causes the
momentary contact 57 of the microswitch 56 to close, as
shown in FIG. 8, thus providing a closed-current path
between the battery 66 and the inverter 74 . The
inverter 74 converts the nine-volt DC output from the
battery 66 to a 120-volt AC output for use with the
electroluminescent display 72 . When the film 60 is
removed from the film grip assembly 26 , the momentary
contact 57 in the microswitch 56 opens, thus
disconnecting the positive terminal of the battery 66
from the inverter 74 , which, in turn, turns off the
electroluminescent display 72 .
The on-off switch 70 may be connected in parallel with
the microswitch 56 , as shown in FIG. 8. In such a
configuration, the on-off switch 70 may be used to
connect the battery 66 directly to the inverter 74 ,
irrespective of the state of the momentary contact 57 of
the microswitch 56 . Assuming the momentary contact 57
is open as shown in FIG. 8, when the on-off switch 70 is
open or off, as shown in FIG. 8, the battery 66 is
disconnected from the inverter 74 , causing the
electroluminescent display 72 to be off. During such a
condition, when the on-off switch 70 is closed, the
positive terminal of the battery 66 is connected to the
inverter 74 , which, in turn, causes the
electroluminescent display 72 to be turned on.
In alternate embodiments of the invention, the portable
film viewer 20 may be provided with an electrical cord
(not shown) and an electrical plug for direct connection
to a 120-volt AC receptacle. In this embodiment, the
battery 66 and the inverter 74 would be eliminated.
However, the parallel combination of the microswitch 56
and the on-off switch 70 may be connected in series with
a line 1 terminal L 1 of the 120-volt plug, so that the
automatic control of the electroluminescent display 72
operates in the same manner as discussed above.
Obviously, many modifications and variations of the
present invention are possible in light of the above
teachings. Thus, it is to be understood that, within the
scope of the appended claims, the invention may be
practiced otherwise than as specifically described
above. |
| Article Source: |
| http://www.freepatentsonline.com/7404266.html |
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Motorized X-ray
viewer |
Specification: X-ray
vewing is the uniquely, versatile, extremly reliable and
easy to operate viewing system holding an amazing
quantity of films. With 2 viewing pa nels
, rapid belt-driven film transport, operation via touch
keys and foot switch, 6° angulation of the viewing
panels, homogeneous illumination, flicker-free lighting,
high luminance - can be continously reduced to approx.
20% of it's max. value, the lower panel with 4 motorized
shutters, flat film holders, top and bottom antistatic
protection, extremely silent operation, excellent
dependable operation, mobile and easy to service.
- capacity 220 radiographs (of 17" - 35x43 format)
- fluorescent lamps 8x58W
- density app. 4800 cd/m²
- power intput 740W
- net weight 475 kg
- transport speed 1 segment 3-5sec.
Remark: Optional accessories: 4 viewing panels
Other models available. |
| Article Source: |
| http://www.medproducts.com/A/Ab/Ab50099.html |
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Slim X-Ray Film
Viewers |
We offer a superior
quality range of Slim X-Ray Film Viewers which is easy
to use and maintain. These are available in the market
at highly competitive prices. Our range of products is
in great demand in the domestic market because of its
excellent performance and longer service life.
Ultra Thin X-Ray Film Viewers
Our range of Ultra Thin X-Ray Film Viewers posses
brightness control, automatic film sensor & power saving
mode. These are the luxury model x-ray viewers with
ultra-thin design and the thickness of only 35mm. Our
range of products is professional in outlook and use
space effectively.
Features:
■Ultra-thin
design and the thickness is only 35mm, professional
outlook and effective use of space
■Defend
ultraviolet radiation panel, never be yellow
■CCFL
lamp, can be used for more than 30,000 hours, which is 8
times than traditional lamp
■Low
heat on the window surface
■Easy
use and easy maintenance
■Film
sensor and power saver, power is auto on when film in
and off when film off
■Now
also available with LED Technology |
| Article Source: |
| http://www.indiamart.com/merinointernational/medical-equipment.html |
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X-Ray Film
Viewer Summary |
Product
Description
Terms of Payment: L/C, T/T
Supply Ability:
20,00pcs/month
Minimum Order: 100pcs
Delivery Lead Time: 35 days
Detailed Product Description
Features:
1) PD series X-ray viewer is applicable to view various sizes of X-ray films, CT
films and other imaging films; it absorbs the advantages of similar products in
aboard and domestic; with its elaborately designed, it is novel in structure, beautiful
in shape, steadily lighting and equal illumination in the screen; it is an
ideal viewer with its clearly viewing effect and easy operation
2) The frame of screen is made of special high-intensity aluminum-alloy, four corners
are connected with steel plates and decorated with ABS, the screen is composed
of import white polymethyl methacrylate plate; with its reasonable structure
and high-intensity in whole, it never distorts
3) The case is wholly shaped with special high-intensity aluminum-alloy, it never
distorts with its excellent rigidity; the inside and outside of the case are coated
by static-electricity spraying powder; therefore, it is attractive, novel, safe
and durable
4) Adopted with the most advanced clipping device (patented) in domestic, films are
easy to be inserted taken out and clipping firmly
5) It is very easy to check, maintain the circuit or replace the fluorescent lamp
tube just following the arrow to pull out the screen
6) Dimensions: 50 x 50 x 5.5cm
7) Voltage: AC 100V - 230V
8) Power: 24W, 0.5A
9) The range of applied working voltage is wide, it can be normally operating at
voltage is 150V; it will light immediately while turning on
10) We produce a variety of sizes and models X-ray viewers, there are desk-top type
and wall-mounted type X-ray viewer; the desk-top type X-ray viewer may be
equipped with desk to different requirements; at the same time, special X-ray
viewer also can be made according to the clients' requirements
|
| Article Source: |
| http://www.tootoo.com/d-rp24083096-X_Ray_Film_Viewer/ |
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X-RAY
FILM VIEWERS AND ILLUMINATORS |
Model 185 and 185I
High Intensity Illuminator
A six inch diameter super-bright, superior high
intensity, viewing area for reading industrial films
with densities up to 5.0. These viewers come with an
on/off foot switch and a set of steel masks to reduce
the size of the viewing area. A variable intensity
electronic control allows you to adjust the brightness
of the 500-watt photoflood bulb. These illuminators are
power air-cooled.
The model 185I, in addition to the above, has an
adjustable iris which cones down the viewer’s light
source for reading smaller film areas.
Model 186 High Intensity Fluorescent Illuminator
Ten 15-watt fluorescent bulbs mounted in a special
reflector system produce an extremely bright even
illumination for viewing industrial films. The tree
position toggle switch allows you to choose full
brightness, activate the electronic intensity control,
or turn the unit off. The step-less electronic variable
intensity control gives full range of illumination. A
stainless steel gravity grip extending the full width of
the 14”W x 17”H Plexiglass viewing panel holds film
firmly in place
Model 189 High Intensity Photoflood Illuminator
Three number-two 500-watt photoflood bulbs provide
extremely bright even illumination for viewing
industrial films. Heat is dissipated by a powerful
blower, with removable fiberglass dust filter, and a
heat absorbing glass filter. An on/off toggle switch and
a continuous step-less electronic control provide
variable intensity lighting. The 14”W x 17”H viewing
surface is white translucent Plexiglass. Four lift up
film clips across the top edge of the viewer hold film
firmly in place
Model 187A High Intensity 4.5" x 17" Illuminator
Four number-one photoflood bulbs provide 1000 watts of
brightness. An internal heat absorbing glass protects
film from heat damage. The cooling system uses a power
driven air supply with replaceable air filters. The
electronic brightness control and low light level
‘writing light’ are mounted at the front of the viewer.
This illuminator comes with an on/off foot-switch, and a
set of four steel masks for reading 4.5”x10”, 3.5”x17”,
3.5”x10”, or 70mm films
Model 65-C1 Twin Deluxe Illuminator
Designed for industrial radiography.
Full 14”x17” viewing panel, plus a 4” round
high-intensity spot all in one unit.
Light intensity controlled by a rugged variable
transformer on both viewing surfaces.
The 4” viewing surface is equipped with a 50,000
candlepower incandescent light source.
Fan cooled heat absorber protects valuable radiographs.
Illuminator comes complete, ready to operate, with lamps
and foot-switch |
| Article Source: |
| http://www.tsgxray.com/FilmViewers.htm |
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