JPH0545665U - Inappropriate exposure amount detection device. - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize automatic light control of electronic flash device with a wide range of film sensitivity. [Structure] A photometric integration unit 1 that measures and integrates a subject irradiation light of an electronic flash device S with reflected light on a film surface, an integration amount measurement unit 2 that measures a photometric integration amount of the photometric integration unit 1, and an automatic light adjustment Reference level setting means 7 for setting the reference level
And a communication unit 4 for transmitting the difference between the reference level and the integrated photometric value, and a communication unit 4 for transmitting the output of the calculation unit 3. After the exposure of the electronic flash device S is completed, the integrated amount is measured. The means 2 measures the photometric integration amount, the computing means 3 computes the difference between the reference level and the photometric integrated value, and outputs the result from the communication means 4.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a method for detecting an inappropriate exposure amount generated by automatic light control of an electronic flash device.

[0002]

[Prior Art]

 Conventionally, there has been TTL automatic light control as a method of automatic light control of an electronic flash device. The TTL automatic light control is to measure the irradiation of an object by an electronic flash device from the reflection on the film surface during exposure, and stop the emission of the speedlight at an appropriate light amount. In this TTL automatic light control, if the full exposure does not reach the proper exposure yet, the exposure under- put is estimated, so a warning display is displayed (hereinafter referred to as “post-warning”) or before the full flash. When the dimming operation was performed, the display was made assuming that the proper exposure amount was obtained. With conventional TTL automatic light control, it was possible to know underexposure by a post-warning. However, it was not possible to know how much underexposure. In other words, since underexposure occurred, it is impossible to know how much more aperture to open the taking lens to prevent underexposure when taking another picture. In addition, if the amount of underexposure is very small, it may not be necessary to take another picture because the latitude of the film can compensate. Nonetheless, it was possible to repeat useless shooting because it was not clear how underexposed. The same applies to overexposure.

As a solution to such a problem, a display device of an inappropriate exposure amount in stroboscopic photography is proposed in Japanese Utility Model Laid-Open No. 61-182533. This is to measure the amount of reflected light from the object and display the improper exposure amount from the difference from the set value of the proper exposure amount. The display device for the inappropriate exposure amount in the stroboscopic photography thus configured sets the proper exposure amount based on the film sensitivity value and the like. The value that represents this proper exposure amount is specifically replaced by a voltage, and this voltage is compared with a voltage that indicates the result of photometric measurement and integration of the reflected light amount of the subject to display the over or under inappropriate exposure amount. It was

[0004]

[Problems to be solved by the device]

However, the device for displaying an inappropriate exposure amount in stroboscopic photography having such a structure has a problem that the amplification factor of the photometric amplifier of the photodetector that detects the reflected light amount of the subject is fixed. That is, the fact that the amplification factor is fixed means that the voltage representing the proper exposure amount is switched depending on the film sensitivity value or the like. If the amplification factor of the photometric amplifier of the light receiver is fixed, the voltage indicating the result of photometric measurement of the reflected light amount and integration will have an extremely wide value. Specifically, there is a difference of 128 times (2 ⁷ ) just by comparing the appropriate exposure amounts of a commercially available ISO 25 speed film and an ISO 3200 speed film. If the amount of reflected light to be actually measured is within ± 3 steps of the proper amount of normal light, the photometric value must be output over a wide range of 8192 times (2 ¹³ ). If exposure compensation is added, the range will be further expanded. It is extremely difficult to accurately generate such a voltage within the circuit of a camera or electronic flash device with a limited power supply voltage, and the result of photometric integration with a small amount of light becomes unreliable due to the influence of noise. Will end up. Therefore, there is a problem in the metering method of the display device having an inappropriate exposure amount according to the above-mentioned configuration, and there is a problem that it can be used only with a limited film sensitivity.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object thereof is to provide an apparatus for detecting an inappropriate exposure amount that can be used in a wide range of film sensitivities.

[0006]

[Means for Solving the Problems]

 In order to achieve such an object, the apparatus for detecting an inappropriate exposure amount according to the present invention comprises a photometric integration means for photometrically integrating the subject irradiation light of an electronic flash device with the reflected light of the film surface, and a photometric integration of the photometric integration means. Integral amount measuring means for measuring the amount, reference level setting means for setting the reference level of automatic light control, calculating means for calculating the difference between the reference level and the integrated photometric value, and communication means for transmitting the output of the calculating means After the exposure of the electronic flash device is completed, the integrated amount measuring means measures the photometric integrated value, the computing means computes the difference between the reference level and the photometric integrated value, and the result is sent from the communication means. It is designed to be output. Further, in the above configuration, gain setting means for setting the gain of the amplifier of the photometric integration means is provided.

[0007]

[Action]

 In the present invention, immediately after the TTL automatic light control is performed, the amount of integration of the photometric integration means of the camera is measured by the integrated amount measuring means to know the overshooting of the exposure separately from the dimming operation, and the result is reported. It is transmitted to the electronic flash device by communication means. Further, the gain of the light receiving amplifier is variable depending on the film sensitivity and the exposure correction value, and the calculation means always compares the fixed reference level with the output of the photometric integration value.

[0008]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram for explaining the configuration of an improper exposure amount detection device according to the present invention. This improper exposure amount detection device is basically a combination of a camera C and an electronic flash device S. .. In the figure, the camera C is provided with a photometric integration means 1, an integral quantity measurement means 2, a calculation means 3, a communication means 4, a gain setting means 5, a comparison means 6, and a reference level setting means 7. The photometric integrating means 1 is composed of an optical system for photometrically measuring the irradiation of the subject of the electronic flash device S by reflection on the film surface, a light receiving element, a light receiving amplifier, an integrating capacitor, etc., and is a component of TTL automatic light control. The gain of the light receiving amplifier is set by the gain setting means 5 according to the film sensitivity and the exposure correction value. The integration amount measuring means 2 measures the output of the photometric integration means 1, calculates the difference from the reference level 7 (fixed) of automatic light adjustment by the operation means 3, and outputs it from the communication means 4 to the electronic flash device S. .. The principle of this gain setting means 5 is the same as that disclosed in Japanese Patent Laid-Open No. 1-297635 (amplification factor switching circuit of automatic light control device). In Japanese Patent Laid-Open No. 1-297635, automatic dimming on the electronic flash device side is described as an example, but this circuit may be applied to a camera. Therefore, D2 shown in FIG. 1 of Japanese Patent Laid-Open No. 1-297635 can be replaced with the light receiving element of this embodiment, and C3 and C4 can be replaced with an integrating capacitor. Therefore, by combining the constituent elements of the present invention with FIG. 1 of Japanese Patent Laid-Open No. 1-297635, the constitution shown in FIG. 2 is obtained. In FIG. 2, the difference from Japanese Patent Laid-Open No. 1-297635 is that the integration capacitors C3 and C4 are first reset from the IC 103. The output of the comparator COM can be transmitted to the electronic flash device as a light emission stop signal. Then, the voltage of the integrating capacitors C3 and C4 can be read into the IC 103 by the A / D converter 20 for A / D converting the outputs of the integrating capacitors C3 and C4. The IC 103 is, for example, a microcomputer, which calculates an inappropriate exposure amount from the voltage of the reference voltage E2 and the voltage of the integrating capacitors C3 and C4 which are known in advance, and transmits the data to the electronic flash device by the communication means 21 to display it. Is to do.

Hereinafter, the processing procedure will be described centering on the IC 103 which is a microcomputer. The IC 103 has the arithmetic means 3, the communication means 4, the gain setting means 5, and other control functions of the electronic flash device shown in FIG. First, prior to the light emission of the electronic flash device S, the gain corresponding to the film sensitivity and the exposure correction amount set by the photographer's intention is given to the photometric circuit by the output ports E to I, J of the IC 103. The principle of this operation is described in detail in Japanese Patent Application Laid-Open No. 1-297635, and therefore its explanation is omitted.

Next, TTL automatic light control proceeds in the following procedure. First, immediately before the light emission start signal S1 (not shown) is given from the IC 103 to the electronic flash device S and the light emission is started, the transistor TR6 is turned off, and photometry and integration are performed from the light emission start. On the other hand, the reference voltage E2 is, for example, 0.5 V and the power supply voltage Vcc is 5 V. When the voltage of the inverting input of the comparator COM becomes Vcc-E2, that is, 4.5 V, the output of the comparator COM is inverted. Then, the light emission stop signal S2 is output, and the TTL automatic light control ends. Of course, the gain of the photometry circuit is set so that the light emission is stopped under the above conditions and an appropriate amount of light is obtained. By the way, to explain how overexposure or underexposure is observed in such a photometric system, the appropriate light amount is Vcc-E 2, that is, 4.5V, 4V for 1-step over, and 3V for 2-step over. , 3 steps over is 1V. On the contrary, 1-stage under is 4.75V, 2-stage under is 4.875V, and 3-stage under is 4.9375V. Therefore, in this voltage range, the resolution of the 8-bit A / D converter is about 0.02V with a full scale of 5V, so it can be read sufficiently.

Next, the operation of the IC 103 will be described with reference to the flowchart of FIG. This subroutine is started from step # 100 (hereinafter abbreviated as # 100) triggered by the output of the light emission start signal. First clear timer 1 at # 101. The timer 1 is a timer that overflows at the maximum flash time of the electronic flash device S, and it is usually sufficient to set about 2 mS. In step # 102, it is checked whether the light emission stop signal S2 is output. If it is output, the process proceeds to step # 104. On the other hand, if it is not output, proceed to # 103 and return to # 102 until timer 1 overflows. However, if the light emission stop signal S2 is output during the repetition of the loop from # 103 to # 102 or the timer 1 overflows, the process proceeds to # 104. Since light emission has already stopped in # 104, the voltages of the integrating capacitors C3 and C4 are immediately A / D converted by the A / D converter 20, and the result is read into IC103. Then calculating the improper exposure amount E _B from the result value and the A / D conversion of the reference voltage E2 that is known in advance at # 105. The calculation method is expressed by E _B = log ₂ [{Vcc- (A / D)} / E2]. However, (A / D) is a photometric integration value after A / D conversion. Further, if the data is converted into data for each 1/3 stage, the right side may be tripled and rounded off. Then, in # 107, the above value is transmitted to the electronic flash unit S, and the process is terminated.

Although the embodiment has been developed for the TTL automatic light control performed by combining the camera C and the electronic flash device S, these elements may be incorporated in the electronic flash device S to be implemented.

[0013]

[Effect of the device]

 As described above, according to the present invention, it is possible to accurately obtain the improper exposure amount, and it is possible to obtain an extremely excellent effect that it is possible to deal with a wide range of film sensitivity and correction.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration according to an embodiment of a device for detecting an inappropriate exposure amount according to the present invention.

FIG. 2 is a circuit diagram showing a device for detecting an inappropriate exposure amount according to the present invention.

FIG. 3 is a flowchart illustrating the operation of the apparatus for detecting an inappropriate exposure amount according to the present invention.

[Explanation of symbols]

 C camera S electronic flash device 1 photometric integration means 2 integration amount measurement means 3 computing means 4 communication means 5 gain setting means 6 comparing means 7 reference level setting means 103 IC

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideki Matsui 1-6-3 Nishioi, Shinagawa-ku, Tokyo Inside Nikon Oi Manufacturing Co., Ltd. (72) Noriichi Yokonuma 1-3-6 Nishioi, Shinagawa-ku, Tokyo Nikon Oi Manufacturing Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A photometric integration unit that measures and integrates a subject irradiation light of an electronic flash device by reflected light on a film surface, an integration amount measuring unit that measures a photometric integration amount of the photometric integration unit, and a reference for automatic light adjustment. And a reference level setting unit for setting a level, a calculation unit for calculating a difference between the reference level and the photometric integrated value, and a communication unit for transmitting an output of the calculation unit. After that, the integration amount measuring means measures the photometric integration amount, the computing means computes a difference between the reference level and the photometric integration value, and outputs the result from the communication means. Appropriate exposure amount detection device. 2. The apparatus for detecting an inappropriate exposure amount according to claim 1, further comprising gain setting means for setting a gain of an amplifier of the photometric integration means.