JPH0448372B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic exposure device, and particularly to an automatic exposure device for an endoscopic photographing system.

In an endoscopic imaging system, since the subject is inside a body cavity, it is difficult to know the imaging distance, and it is difficult to know the limit of the amount of light, such as the guide number of a general strobe. The only way to determine whether a photograph was successful or not was to check the automatic flash control after taking a photo, just like with a regular strobe, to see if the light intensity limit was exceeded. On the other hand, Japanese Patent Application Laid-Open No. 10127/1983 discloses a device that calculates exposure before photographing and informs the user of the limit of the amount of light, but this device has a problem with accuracy. The reason for this is that the device calculates the pre-photographing exposure using the illumination light of the subject and a constant photographing light, so if a constant photographic light cannot be obtained, the calculation accuracy will decrease. However, the photographing light is not constant due to variations in the lamp, misalignment of the lamp, reduction in light intensity due to long-term use, etc., and therefore there is a drawback that calculation accuracy deteriorates. In addition, there are strobes disclosed in Utility Model Publication No. 53-32595 that calculate the exposure by emitting one burst of light before taking a picture, but this method cannot be used continuously, so there is a lot of movement like inside a body cavity. When photographing a subject, past exposure values do not provide sufficient accuracy.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an automatic exposure device for an endoscope system that accurately calculates exposure before photographing based on the amount of light before photographing and the amount of illumination light of the object.

Embodiments of the present invention will be described below with reference to the drawings. According to FIG. 1, an endoscope 1, a light source unit 2
The endoscope camera 3 constitutes an endoscope photographing system. The endoscope 1 is provided with an image guide 5 and a light guide 6, and a subject 4 is illuminated by light guided through the light guide 6.
An objective lens 7 is provided at the front end of the image guide 5, and an eyepiece lens 8 is provided at the rear end. A camera 3 is attached to an eyepiece 9, and a beam splitter 10 of the camera 3 faces an eyepiece 8. A film 11 is placed opposite a beam splitter 10 with a mirror shutter 12 in between. The camera control circuit 13 is connected to a light receiving element 14 and a release switch 15 provided on the side surface of the beam splitter 10. A signal end of the camera control circuit 13 is connected to a connection pin 16. The light source unit 2 is provided with a xenon (Xe) discharge lamp 18.
The connector portion 20 is connected to the light source unit 2 such that the light guide end 19 is located on the optical axis of the light source unit 2.
The connection pin 21 of the connector part 20 is connected to the light source unit 2.
The light source control unit 17 is connected to the light source control unit 17 through the socket. The Xe discharge lamp 18 is composed of a cathode 22 and an anode 23 facing each other, and a reflecting surface 24. Xe discharge lamp 18 and light guide end 1
A condenser lens 25, a shutter blade 26, and an aperture blade 28 are sequentially arranged between the lens 9 and the shutter blade 9. The shutter blades 26 are driven by a shutter solenoid 27, and the aperture blades 28 are driven by an aperture motor 29. A light guide member 3 made of, for example, an acrylic rod between the light guide end 19 and the aperture blade 28
1 is arranged. The tip of the light guiding member 31 has an inclined surface facing the lamp 18, and the light receiving element 32 is disposed at the rear end. In FIG. 2, the shutter blade 26, the aperture blade 28, the light guide member 31, etc. are shown in perspective.

FIG. 3 shows the circuit configuration of the camera control circuit 13. According to this circuit, the light receiving element 14 is connected to an operational amplifier 36 of an integrator/current/voltage converter 37. An integral capacitor 34 and a current-voltage conversion resistor 35 are connected in series between the inverting input terminal and the output terminal of the operational amplifier 36. Short-circuit analog switches 38 and 39 are connected to the integral capacitor 38 and the resistor 35, respectively. The output terminal of the integrator and current-voltage converter 37 is connected to the operational amplifier 4 of the comparator 40.
It is connected to the non-inverting input terminal of 1. operational amplifier 41
The inverting input terminal of
It is connected to the chip CPU 33. operational amplifier 41
The output terminal of is connected to the non-inverting input terminal of an operational amplifier 47 of the buffer circuit 43 via an analog switch 44. Further, the non-inverting input terminal of this operational amplifier 47 is connected to the output terminal of the operational amplifier 36 via an analog switch 45. analog switch 4
4 and 45 are opened and closed by the output signal of the CPU 33, and the analog switch 45 is controlled by a signal via an inverter gate 46. The inverting input terminal of the operational amplifier 47 is grounded via a resistor 48 and connected to an output terminal via a resistor 49. The output end of this buffer circuit 43 is connected to terminal e. Terminal f is grounded, terminals a and b are
Connected to Vcc and GND respectively. terminals c and d
is the CPU via serial interface 50
33. CPU33 is inverter 51,
It is connected to Vcc via a light emitting diode (LED) 52 and a resistor 53.

FIG. 4 shows the light source control circuit 1 of the light source unit 2.
7 circuit configurations are shown. In this circuit, terminals c and d are serial interface 5
Connected to 4. serial interface 54
is the CPU55, ROM56, RAM5 via the bus.
7, A/D converter 58, D/A converter 5
9, connected to a condition setting display unit 60 and a parallel interface 61. Terminal e is connected to non-inverting input terminals of operational amplifiers 64 and 67 of low amplification amplifier circuit 62 and high amplification amplifier circuit 63. The inverting input terminal of the operational amplifier 64 is grounded via a resistor 65 and connected to the output terminal via a feedback resistor 66. Similarly, resistors 68 and 69 are connected to the inverting input terminal of operational amplifier 67. The output terminal of the amplifier circuit 62 is connected to the non-inverting input terminal of the comparator 70. The output end of the comparator 70 is connected to the parallel I/F 61. The non-inverting input terminal of the operational amplifier 72 of the potentiometer amplifier circuit 71 is connected to the aperture potentiometer 30, and the inverting input terminal thereof is connected to resistors 73 and 74. Light receiving element 32
The current-voltage converter 75 connected to the operational amplifier 7
6 and a resistor 77. The output terminal of the D/A converter 59 is connected to the inverting input terminal of the operational amplifier 79 of the aperture driver 78, and the resistor 8
0 to the emitter of the transistor 82 and the aperture motor 29. The collector of the transistor 82 is connected to Vs via the resistor 81, and the base is connected to the output terminal of the operational amplifier 79.

FIG. 5 shows the power circuit of the light source unit 2. As shown in FIG. The Xe discharge lamp 18 is connected to a high voltage generation source consisting of a high voltage generation circuit 83 and a high voltage generation coil 84. This high voltage generation source is connected to a rectifier circuit 89 via an Xe lamp current control section composed of an Xe lamp current control circuit 85, a current detection resistor 86, and a current control transistor 87, and a chiyoke coil 90. A power terminal of this rectifier circuit 89 is connected to a secondary winding of a transformer 88 . The flash capacitor 91 is connected to a rectifier circuit 93 via a resistor 92. A power terminal of the rectifier circuit 93 is connected to a secondary winding of a transformer 94. The primary winding of the transformer 94 is connected via the triax 95.
Connected to AC current line. Triack 95
is connected to a capacitor charging voltage control circuit 96 that generates a control signal according to the charging voltage of the capacitor 91. One end of the capacitor 91 is connected to the transistor 9
7 emitter and a transistor drive circuit 98 . The collector of the transistor 97 is connected to the cathode of the Xe lamp 18, and the base is connected to the drive circuit. Power supply circuit 99 is connected to the AC line via transformer 100. The “CHARGE” signal from which the capacitor 91 is “CHARGE” UP from the capacitor charging voltage control circuit 96 is connected to the “CHARGE” terminal of the parallel I/F 61 . “FLASH” and “STOP” signals input to the transistor drive circuit 98 are connected to the parallel I/F 6
Input from 1.

In the above-described circuit, the A/D converter 58 has a built-in multiplexer and can output an 8-bit digital output, and specifically, ADC0808 manufactured by NS is used. This ADC0808 has 8 channels of analog inputs and 8 bits of digital output, but in the embodiment, 4 channels of analog inputs _A0 to _A3 are used. These inputs A to ₀
A ₃ is connected to the outputs of amplifier circuits 62, 63, 71 and current-voltage converter 75, respectively. The serial interface 54 and the CPU 55 are made by Intel.
If you are using 8085, you are part of that family.
Connected to camera 3 as UART using 8251A. The ROM 56 is selected according to the program capacity, and if the capacity is 2K bytes, the family 2716 is used. Further, 2114 is used for the RAM 57. The D/A converter 59 is used to convert 8-bit digital data into analog output, and specifically uses NS's DAC1008. This has the advantage of being directly connected to the data bus of the CPU 55. Note that since the analog output of this D/A converter 59 is a current output, it is converted into a voltage by the aperture driver 78. In addition, the A/D converter 5
The 8-bit resolution is effectively treated as 16-bit. The condition setting/display unit 60 controls shooting still film sensitivity, cine (TV) film sensitivity, still/cine correction during auto shooting, still auto/manual switching, cine auto/manual switching, and cine manual, that is, manual light intensity setting. I'm starting to be able to do it. The parallel interface 61 uses Intel's Family 8255A.

Next, the operation of the endoscopic imaging system described above will be explained. When the power supply circuit (Fig. 5) of the light source unit 2 is turned on, the Xe lamp 18 automatically lights up.
After this, the light source signal processing circuit (FIG. 4) goes into initial operation, and preprocessing for pre-photographing exposure calculation is performed according to the flowchart of FIG. 6. That is, when the ASA sensitivity etc. are set in the condition setting/display unit 60, only the setting data is output and stored in the RAM.
57. Flush capacitor 91
(Fig. 5) is determined to be "CHARGE" UP. If the determination is "YES", the multiplexer of the A/D converter 58 is set to _A3 . At this time, the parallel interface 61 outputs a "FLASH" signal. In response to this "FLASH" signal, the transistor drive circuit 98 of FIG.
turns on transistor 97. As a result, the charge stored in the capacitor 91 flows into the Xe lamp 18, causing the lamp to emit a high-intensity flash. At this time, the shutter blade 26 and the aperture blade 28
is open, and part of the flash light from the Xe lamp 18 is guided to the light receiving element 32 by the light guide member 31. The light receiving element 32 detects flash light as photographing light. The output of the light receiving element 32 is amplified by the current/voltage converter 75, converted into a voltage signal, and inputted to the terminal _A3 of the A/D converter 58. From the start of the flash
It is determined whether 100ms has passed and this determination is “NO”
If so, the A/D converter 58 takes in the light reception data of the light receiving element 32. If the judgment is “YES”, “STOP” is sent from the parallel interface 61.
A signal is output. In response to this "STOP" signal, the transistor 97 turns off and the Xe lamp 18
The flash of light stops and becomes normal light emission. The received light data taken into the A/D converter 58 is integrated and stored in the RAM 5 as the total flash light amount value L・t (lux・second).
7 is stored. It is determined whether or not this total flash light amount value L·t is equal to or greater than a specified value, and if this determination is "NO", an alarm for insufficient light amount is generated. The determination result at this time indicates a lack of light amount due to the lamp life, etc., and it is understood from this that the lamp needs to be replaced. If the determination is "YES", the multiplexer of the A/D converter 58 is set to _A2 ,
The aperture 28 is opened. The aperture opening data at this time is read out from the A/D converter 58. Next, the aperture 28 is set to the minimum aperture, and the minimum aperture data is read from the A/D converter 58. The aperture dynamic range is calculated from the minimum aperture data and the maximum aperture data. It is determined whether or not the aperture dynamic range is within the specified value range, and if the determination is "NO", an aperture abnormality alarm is generated and a malfunction of the aperture mechanism is notified. If the determination is "YES", the preprocessing for pre-shooting exposure calculation ends. This pre-photographing exposure calculation pre-processing is automatically performed when the power is turned on, but a separate manual switch may be provided and the pre-photographing exposure calculation pre-processing may be started when this switch is activated. Further, the operation of the diaphragm 28 can be checked by a potentiometer 30 used for servoing the manual illumination light.

If it is confirmed that the Xe lamp 18 and the aperture 28 are normal through the above pre-processing, endoscopic observation and endoscopic photography can be performed. When performing endoscopic observation, the amount of light is appropriately narrowed down by the diaphragm 28 and the object 4 is
to illuminate. The diaphragm 28 is controlled by a servo mechanism so that the diaphragm 28 is narrowed down accurately to the set amount of light. This servomechanism is controlled by the CPU 55 according to a program. That is, the signal from the potentiometer 30 is transferred to the A/D converter 58.
It is input to the _A2 channel of , and is compared with the value already set by the CPU 55, and the D/A converter 59 outputs a signal such that the signal of the potentiometer 30 matches the set value. The output of the D/A converter 59 is input to the aperture driver 78, whereby the aperture motor 29 operates in accordance with the input signal to move the aperture 28 to an appropriate position. Since the aperture 28 is thus servo-controlled by the control loop via the CPU 55, accurate aperture position control is achieved and no inconveniences such as hysteresis are imposed on the user.

Next, when performing endoscopic photography, the camera 3 is attached to the eyepiece 9 of the endoscope 1. At this time camera 3
The light receiving element 14 receives the reflected light from the subject via the image guide 5, the eyepiece 8 and the beam splitter 10. Also, at this time, the serial interface 54 indicates that the camera 3 is connected to the endoscope 1.
When detected by , pre-photographing exposure calculation begins according to the flowchart of FIG. That is, first, the multiplexer of the A/D converter 58 is set to the _A3 channel, and the photometric data corresponding to the light receiving element 32 is taken into the A/D converter 58. This photometric data is data corresponding to illumination light, and is stored in the RAM 57 as an Lsend value. The multiplexer of the A/D converter is set to _A1 and takes in reflected light data corresponding to the object reflected light from the camera 3. When the A/D converter 58 A/D converts this reflected light data, it is determined whether the output of the high amplification amplifier 63 exceeds the conversion capability of the A/D converter 58. If this judgment is “NO”, the data in channel _A1 is A/D converted and converted to Lrcv.
It is stored in RAM57. Then, if the brightness of the reflected light is large and the judgment result is “YES”,
The multiplexer of A/D converter 58 is set to A ₀ and A/D converter 58 takes in the output of low gain amplifier 62 . The reflected light data A/D converted by the A/D converter 58 is G ₁
It is multiplied by -G ₀ and stored in the RAM 57 as Lrcv. (Here, G ₁ is the gain of the high amplification amplifier 63, and G ₀ is the gain of the low amplification amplifier 62.) Further, the following equation is calculated.

K/ASA×Lsend/Lrcv However, ASA: film illuminance Lsend: light guide incident light amount K: constant, also includes exchange coefficient for light receiving element illuminance (Lux).

Lrcv: amount of reflected light The value resulting from this calculation corresponds to the ratio of the light irradiated to the subject and the light reflected from the subject, and represents subject information that is mainly determined by the distance to the subject. Then, it is determined whether this calculated exposure value is smaller than the total flash light amount L·t value obtained in the pre-processing of the pre-photographing exposure calculation. If this determination is YES, then it is determined whether this calculated exposure value is greater than L·t/10. If this calculated exposure value falls within the range between the L.t value and L.t/10, the subject is within the flashable range, and an appropriate display is made. Further, if it is not within this range, that is, if the calculated exposure value is greater than the L.t value or smaller than L.t/10, a warning is displayed on the camera 3.

The alarm display is performed by lighting or blinking a light emitting diode (LED) 52 provided in the camera 3, and upon recognizing this alarm display, the user can automatically control the exposure of the distance between the endoscope 1 and the subject 4. Adjust accordingly. In such usage conditions, if the exposure limit is reached, that is, at the critical point of the automatic exposure controllable limit, the situation may not be determined between proper exposure and an alarm. In this case, when issuing a warning, processing is performed such as issuing a warning for a certain period of time depending on how many times the calculation result falls within the limit range. This makes it possible to stabilize the display in an unstable state. Such a display method can be easily executed by calculations of the CPU 55, and other methods can also be executed by programming. By sequentially performing the above pre-photographing exposure calculation flow, it is possible to always know whether or not proper exposure control is possible when emitting flash light for the object being observed.

Next, the operation after the release switch 15 is closed for photographing will be explained. If it is determined in the pre-photographing exposure calculation that the photographing limit is under, photographing is performed according to the time chart shown in FIG. That is, when the release switch 15 is closed, the light source aperture 28 begins to open, the signals at the camera contact pins e to f become low level, the light source shutter 26 begins to close, and the light incident on the light guide end 19 is blocked. Then, the output of the integrator/current-voltage converter 37 becomes 0 value. When the mirror shutter 12 of the camera 3 opens after a predetermined time and the light source shutter 26 opens, light enters the light guide end 19, and the output of the integrator and current-voltage converter 37 operates as an integrator, and a received light signal corresponding to the reflected light from the object is generated. Integrate. The Xe lamp 18 flashes, and the flash light illuminates the subject 4 via the light guide 6 as photographing light. When the Xe lamp 18 stops flashing in 100ms with the light source shutter fully open, the Xe lamp 18 enters normal lighting. After a predetermined time, the shutter mirror 12 is closed and the photographing is completed.

If it is determined in the pre-photographing exposure calculation that photographing can be performed properly, a photographing operation is performed according to the time chart shown in FIG. In this case, the integrator and current-voltage converter 3 is connected until the camera shutter opens.
7 does not start the exposure calculation, but when the camera shutter opens, the light source shutter 26 starts to open, and the integrator/current-voltage converter 37 starts the exposure calculation. When the light source shutter 26 is fully opened, the Xe lamp 18 flashes. When the calculated exposure value reaches the proper exposure value, a "STOP" signal is generated, the Xe lamp 18 stops emitting light, and after a certain period of time, the mirror shutter 12 closes and the photographing ends. After this, Xe lamp 1
8 normally lights up and returns to the observation state. Note that Vref in exposure calculation is determined by the ASA setting provided on the camera, and since the light source is also set to the same ASA, exposure calculation before shooting is possible.

Another embodiment is shown in FIG. 10, and according to this embodiment, a light guide member 31 is provided between the Xe lamp 18 and the condenser lens 25. Therefore, since the light is focused by the condensing lens 25 at the light guide entrance end 19, there were many variations due to positional deviation, but with the state of parallel light output from the Xe lamp 18, such possibility is reduced and production is improved. Easy to assemble.

Next, still another embodiment of the present invention will be described using FIGS. 11 to 16. FIG. 11 is a schematic configuration diagram of the endoscope system. In the first embodiment, illumination light for observation and flash light for photography were irradiated from a single xenon discharge lamp, but in this embodiment, separate lamps are provided for flash and observation, and a strobe lamp is used. 101 and halogen lamp 1
02 is used as a light source. in this case,
The light receiving element 32 is arranged to receive the light from the halogen lamp 102 that passes through an opening provided at the center of the mirror 103. Furthermore, the mirror 103 serves as a rear mirror to direct the light from the strobe lamp 101 to the light receiving element 3.
It is designed to lead to 2. However, since the strobe light is extremely strong, the reflectance of the back mirror is not made very high, and for example, a precisely finished metal surface may be used. With such a configuration, the light incident on the light guide end 19 can be measured by the light receiving element 32. FIG. 12 shows a light guide end 19, a light receiving element 32, a halogen lamp 102,
The arrangement of mirrors 103 is shown perspectively. The mirror 103 is a solenoid 105 for switching the optical path.
Moved by

FIG. 13 shows the signal processing circuit 17 of the light source unit 2 of FIG. 11. In this circuit,
A current-voltage converter 75 is provided after the light receiving element 32, and its output is input to the _A3 channel of the A/D converter 58, and is also input to the integrator/sample hold circuit 107 via a signal inverting amplifier and a resistor 109. be done. The output of the integrator/sample hold circuit 107 is output from the A/D converter 58.
Input to A ₂ channel. Analog switch 111 is used to reset the integrator, and analog switch 112 is used to sample and hold after integration. The integral constant is resistor 109 and capacitor 1
10. The counter 113 is a timer interface and is called PIC. this
PIC is 8253A in Intel's 8085 family
use. Clock CLK is supplied from the clock of CPU55, and “GATE” is supplied with “ZERO-
"CROSS" signal is supplied, and "BRIGHT" signal is input/output to "OUT".

FIG. 14 shows a power supply circuit, and according to this circuit, a lighting circuit for a strobe lamp 101 and a halogen lamp 102 is provided. Main capacitor 114 is connected to voltage doubler rectifier circuit 125 . The charging control circuit 126 is connected to the main capacitor 11
It controls the charging pressure of 4 to be constant, and generates a "CHARGE" signal when charging is completed. A triax 129 provided in series and a phase control circuit 128 for controlling the triax 129 are connected to the halogen lamp 102 .

In the above device, the “BRIGHT” signal is output by the CPU 55 from the “ZERO CROSS” signal detection.
Only the data set in the PIC 113 is counted and output after a predetermined time. As shown in the flowchart of FIG. 15, the ASA sensitivity etc. are set in the initial operation, and the setting data is read out and stored in the RAM 57. “CHARGE”
If it is UP, the halogen lamp is turned off and the sample hold analog switch 112 is activated to the sample state. The reset of integrating capacitor 110 is released and the multiplexer of A/D converter 58 is set to _A2 . A "FLASH" signal is generated and the strobe lamp 101 is flashed for 20ms. After the 20ms flash, the sample and hold analog switch 112 is placed in the hold state. Data is read from the A/D converter 58, and this data is stored in the RAM 57 as an Lt value. If the L.t value is greater than or equal to the specified value, the integral capacitor 110 is reset, and if it is less than the specified value, a warning of insufficient light quantity is issued. When the integrating capacitor 110 is reset, the halogen lamp is turned on and the multiplexer of the A/D converter 58 is turned on.
A is set to ₃ . When the halogen lamp 102 is turned on to the maximum, data is read from the A/D converter 58. Based on this data, it is determined whether the total amount of light emitted by the halogen lamp 102 is within the specified light amount, and if "NO", a decrease in the amount of light from the halogen lamp is displayed. If the determination is "YES", the pre-shooting exposure calculation preprocessing ends.

The light intensity adjustment of the halogen lamp 102 is done using PIC113.
This is done using the 8253A in mode 5. The timing of the phase angle is down-counted from the "ZERO CROSS" signal, and when the count reaches 0, only one cycle of the clock is output to "OUT". The count amount is
The CPU 55 loads the count register with the number of clock cycles of the phase angle. The count is
It is performed when the CPU 55 is reset, and is counted down by the clock. By doing this, the amount of light from the halogen lamp 102 is arbitrarily adjusted by the CPU 58. halogen lamp 1
Since the light intensity of 02 can be adjusted as described above, automatic collimation or manual setting is possible. However, the halogen lamp 102 is not suitable for cine photography because the color temperature changes greatly when the light amount is adjusted by electric current. Furthermore, because the halogen lamp itself does not have enough light intensity, it is not suitable for cinema. Regarding the manual light intensity setting, the count register of the PIC 113 is loaded according to the set light intensity using a predetermined light intensity-phase angle (count value) table. This allows the CPU 55 to arbitrarily change the amount of light from the halogen lamp 102.

Pre-photographing exposure calculation is performed in the same manner as in the first embodiment. However, Lsend is the amount of light sent out from the halogen lamp 102, and Lrcv is the amount of light sent out from the halogen lamp 10.
2 is the amount of reflected light from the subject. The minimum shooting limit for L・t is 100 minutes L・t. This indicates that the range that can be photographed has expanded, and the flash control range has become wider. halogen lamp 102
When determining Lsend and Lrcv, the light receiving element 14
It is necessary that the spectral sensitivities of and 32 match.

The still photographing operation operates according to the time chart shown in FIG. In this photographing operation, "FLASH" and "STOP" of the strobe lamp 101 are performed from the time of light emission to the stop by well-known DC control and commutation. Of course, when taking still photos, it is necessary to check that the exposure calculations are appropriate before taking the photo. Since the subject is inside the body cavity, the stomach and other parts move repeatedly, so even if there is a shift due to movement between the time when the exposure is calculated before the shot is taken, it will only take a small amount of time, so the distance will be significantly increased. movement is impossible. Therefore, the exposure is calculated while the film is being exposed in real time, rather than being controlled based on the exposure value calculated in the exposure calculation before photographing, so that the film will not be overexposed or underexposed.

FIG. 14 is a diagram showing another embodiment of the camera used in the present invention, and in this embodiment, the camera 3
Display light emitting diodes 140, 141 and 14
2 is provided. These light emitting diodes 14
0, 141 and 142 are as shown in FIG.
For example, overexposure, proper exposure, and underexposure are displayed respectively. Note that these displays are performed according to the results of pre-shooting exposure calculation. Further, it is preferable that these displays be displayed to the extent that they do not flicker to the eye, so it is sufficient to perform exposure calculations several times per second. However, the aperture has to be faster (at least 24
times/sec) can also be calculated in conjunction with that routine.

In this embodiment, the pre-photographing exposure calculation is also performed using the first method.
This is done in the same way as in the example.

The second embodiment is also substantially the same.

L・t/10<K/ASA<Lsend/Lrcv<L・t Lsend/Lrcv is the reflection coefficient of the subject. Changes in the reflection coefficient can be expressed as the loss of the endoscope's light guide and image guide, and the coefficient of distance. there was.

Using this reflection coefficient as a parameter, the energy required for exposing the film (Lux sec) is converted to the light emitting side and compared with L·t (Lux sec) to determine the photographing limit. However, it goes without saying that there are other methods other than this one. For example, there are the following methods.

t=K/ASA×L×1/S×F [msec] L: Light reception signal S: Refinement amount F: Flash magnification t: Exposure time Judgment is made when 10<t<100msec.

L determines the brightness during observation, 1/S determines the brightness when the aperture is open, and F (flash)
Multiplying this will give you the brightness (Lux) at the time of shooting.
However, since the film surface illuminance cannot be calculated from simply measured L, it is necessary to calculate K by including its conversion coefficient in addition to the so-called K value. Once t is determined, the photographing limit can be easily determined. The value of S can be found by reading the output of the potentiometer with an A/D converter, and the flash magnification is determined by measuring the observation light and photographing light at the initial stage. However, since the measurement results in L·t, t must be deleted. In the first embodiment, only the calculation method can be changed without changing the configuration. The same applies to the second embodiment, and the brightness of the halogen lamp is controlled by
Since it is a CPU, the current brightness and maximum brightness are configured so that you can easily see them. Therefore L×1/S
is required immediately.

Although the embodiment describes a camera, the present invention can also be applied to a cine camera. The circuit configuration of a cine camera is the first
As shown in Figure 9, according to this circuit, CPU1
43 is connected to terminals c and d of the terminal group 16 via a serial interface 144. The light receiving element 145 is connected to a photocurrent voltage converter 148 consisting of an operational amplifier 146 and a resistor 147. The output of this photocurrent voltage converter 148 is connected to terminal e. CPU 143 is connected to light emitting diode 150 via inverter 149. This light emitting diode 150 displays whether the exposure calculation result is appropriate or not. This circuit can also be used for automatic light intensity adjustment of a TV camera, but since the cine film sensitivity is set for the light source, the output of the photocurrent-voltage converter 48 is sent directly to the light source unit. In light source unit 2, the amount of light is adjusted to match the film sensitivity.
The CPU 55 sets the D/A converter 59 to an appropriate aperture. The CPU 55 reads the signals outputted to terminals e and f by the A/D converter 58 as digital values. The serial interface 144 is for receiving an inappropriate signal from the light source even in the case of cine (TV) when there is insufficient light at a long distance or when there is a possibility of overshoot at a short distance. Alternatively, the film sensitivity can be sent from the cine camera to the light source. In the case of a TV camera, this is the sensitivity of the image pickup tube. Also, when a cine camera is connected, a light reception signal from the cine camera is input to terminals e and f of the contact point 21, and this light reception signal is input to the A/D converter.
By digitizing with converter 58
The CPU 55 controls the cine set by the light reception signal.
It is also possible to control the amount of light to be constant according to the ASA sensitivity. Since it is sufficient to control the diaphragm so that the received light signal remains constant according to the ASA, automatic light intensity adjustment becomes possible by adjusting the diaphragm from the D/A converter. In particular, the manual illuminator and cine auto can be used without using a special circuit.
It has the advantage of being controlled by the CPU 55.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an endoscope system using an automatic exposure device according to an embodiment of the present invention, and FIG.
The figure is a perspective view of the aperture mechanism and shutter mechanism, Figure 3 is a circuit diagram of the camera, Figure 4 is a circuit diagram of the signal processing circuit of the light source unit, Figure 5 is a circuit diagram of the power supply circuit, and Figure 6 is a photographing circuit diagram. A flowchart diagram explaining the preprocessing of pre-exposure calculation, FIG. 7 is a flowchart diagram explaining the operation of pre-exposure calculation, and FIG. 8 explains the photographing operation when the pre-exposure calculation result is inappropriate. Figure 9 is a time chart explaining the photographing operation in appropriate judgment, Figure 1.
FIG. 0 is a schematic configuration diagram of an endoscope system using an automatic exposure device according to another embodiment, and FIG. 11 is a schematic configuration diagram of an endoscope system using an automatic exposure device according to another embodiment. 12 is a perspective view of the light source section of FIG. 11, FIG. 13 is a circuit diagram of the signal processing circuit of the light source unit shown in FIG. 11, and FIG. 14 is a diagram of the power supply circuit of the light source unit used in FIG. circuit diagram,
FIG. 15 is a flowchart explaining the operation of the pre-photographing exposure calculation preprocessing according to the embodiment of FIG. 11, FIG. 16 is a time chart showing the photographing operation according to the embodiment of FIG. 11, and FIG. 17 is a further Circuit diagram of a camera circuit of an automatic exposure device according to another embodiment, No. 18
The figure is a plan view of the display section, and FIG. 19 is a circuit configuration diagram of the cine camera. 1... Endoscope, 2... Light source unit, 3... Camera, 4... Subject, 13... Camera control circuit,
14... Light receiving element, 15... Release switch,
17... Light source control circuit, 18... Xe discharge lamp (irradiation means), 26... Shutter blade, 28... Aperture blade, 31... Light guiding member, 32... Light receiving element.

Claims (1)

[Scope of Claims] 1. An endoscopic photographing system comprising an endoscope, a camera connected to the endoscope to photograph endoscopic images, and a light source connected to the endoscope and supplying illumination light. , an irradiation means that is provided in the light source and irradiates illumination light toward the subject with a constant amount of light and flash emission; and a control means that controls the irradiation means to emit a constant amount of light when observing and controls the flash emission when shooting. , a first light receiving element provided in the light source near the irradiation means to receive the irradiation light from the irradiation means; and a first light receiving element provided in the camera to receive the reflected light of the irradiation light from the subject. 2 light-receiving elements, and a pre-photographing exposure value is calculated based on the output ratio from the first and second light-receiving elements during observation prior to photographing, and this calculated exposure value is used for exposure control during flash emission of the irradiation means. a determining means for determining whether or not it is within a limit; a display means for displaying the determination result of the determining means; and a light control means for stopping flash light emission based on the output of the second light receiving element during flash photography. An automatic exposure device for an endoscopic imaging system, comprising: