JPS6045228A - Detecting device of information on object to be photographed - Google Patents

Abstract

PURPOSE:To eliminate an influence of an object to be photographed of high luminance, which is entered into a part of a picture, by providing an amplitude compressing circuit which inputs a photoelectric converting output and has a characteristic set in advance. CONSTITUTION:A luminance of each part of a picture of light of an object to be photographed, which has passed through a diaphragm 2 is brought to photometry 3a-3d, each photometric value is brought to amplitude compression 4a-4d and added, and basing on this added value, the diaphragm is servo-controlled. In case when a part of a picture is in high luminance, when each photoelectric converting output is added as it is, it is feared that a main object to be photographed becomes underexposure by being influenced by a high luminance part, but photographing within an allowable exposure range can be executed by setting a characteristic of the amplitude compressing circuit so as to intensify a degree of compression at the time of high luminance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a subject information detection device that has a plurality of photoelectric conversion means and detects subject information by spatially dividing a photographic screen and measuring light.

[Prior art]

Conventionally, in this type of apparatus, various weights have been applied in order to accurately control the exposure of a target object in a subject. However, there was a problem with exposure accuracy when each screen was spatially divided for weighting or when there were smaller dark spots or bright spots in addition to the main subject. In other words, it is difficult to obtain accurate photometric data even if there is a small part of the spatially divided picture of each element or the main subject whose brightness deviates significantly from the average value. It was extremely difficult.

For example, when the deviation from the average value is large, the effect of high brightness is greater than that of low brightness. If a specific value is given, the brightness of the subject is compared to the average, i.e. 21°g20.901'-2-0. ”' (-0,1
5EV)・・・・・・・・・■It is judged that it is extremely low, and this much error occurs.

On the other hand, the brightness of the area of the corner is 100 times the average brightness, i.e. 210g210゛9-23°45 (+3.45EV)
(4) It is judged to be very high, and an error of +-1 will occur.

Comparing Equation (2) and (4), it is clear that when there is a minute dark or bright spot, the error caused by the bright spot is much larger.

If a high-brightness subject enters a part of the screen in this way, the exposure data will be drastically distorted. Such drawbacks could not be sufficiently removed even if the signals of each part of the screen were weighted.

〔the purpose〕

The object of the present invention is to provide a subject information detection bag that can largely eliminate the influence of high-brightness areas that have entered a part of the screen.
The goal is to provide U.

〔Example〕

The present invention will be described in detail below with reference to the attached drawings. Addition diagram in FIG. 1 (j is a diagram showing the first embodiment of the present invention.

FIG. 1 is an electrical system block diagram of the first embodiment of the present invention, where 1 is a photometric optical system 2 is an aperture, and 1 and 2 are photometric systems.
It may be shared with the imaging system, or may be kept separately. A, b, c, and d are light receiving elements as photoelectric conversion means, which spatially divide the subject image as shown in FIG. 2, for example. Ro a, 3b, Ro C9 rod d is photoelectric conversion circuit, 4a, 4
b, 4c, and 4d are amplitude compression circuits as amplitude compression means;
5 is an adder circuit as a mixing means, and 10 is an amplifier that supplies current for error amplification and driving the aperture drive coil.

Reference numeral 11 denotes an aperture drive coil, which is configured to close the aperture 2 when a positive voltage is applied to the terminal 11a and open the aperture 2 when a negative voltage is applied.

Here, the photoelectric conversion circuits 3a, 3b, 3c, and 3d have a configuration as shown in FIG. 6, for example, and in this circuit, the current of the light receiving element 102, that is, the output voltage of the amplifier 101 is proportional to the amount of incident light. Also, amplitude compression circuit 4 a + 4
b+4'+4d has a circuit configuration as shown in FIG. 4 or FIG. 5, for example.

! (First of all, referring to FIG. 4, 201 and 202 are resistors, 203 is a transistor, and 204 is a reference voltage generation circuit.
Assuming that the voltage is ■2o4, when the input voltage V1 is lower than V2o4, the base and emitter of the transistor 203 are reverse biased, the transistor 203 is cut off, no current flows through the transistor 206, and the output voltage becomes ■. is equal to the input voltage.

■-V・ (5) l On the other hand, when the input voltage V is sufficiently higher than ■2o4, a current flows through the resistor 202 according to the resistor 203.

Ignoring the base-emitter voltage of transistor 20, the resistance values of resistors 201 and 202 are R2o□, R2o2
Then, the output voltage is ■. The relationship between and input voltage ■i is as follows.

FIG. 5 illustrates this. For example, R201
” ”202 = 9 ” If 1, then '201''2
02 So11 'ILJ and the differential gain a is ■i>V
In 2o4, ■1 <■ is compressed to 1/10 of 2o4. 8 Next, FIG. 6 will be explained. 301 is a resistor, 302 is a diode, and 603 is a reference voltage generation circuit.

The reference voltage generated by the reference voltage generation circuit 606 is
Then, when the input voltage Vi is lower than 3o3, the diode 602 is cut off and 3o3 and 2i are cut off, so the input/output voltage is high.

■・=V (8)! 〇On the other hand, when the input voltage Vi becomes higher than ■3o3, the diode 602 turns on, and if the voltage drop in the j111 direction of the diode 302 is ignored, the output 11j becomes voltage ■. is■3o3
is equal to

V-V (9) 0 303 FIG. 7 illustrates this.

The adder circuit 5 in FIG. 1 is composed of 1Mj of circuits as shown in FIG. In the figure, 401 to 405 are resistors, and 406 is an operational amplifier. In this way, the input/output characteristics are Vo−−(Via+V, b+V, o+Vid) (10
).

However, the values of resistors 401 to 405 are all equal to resistor 201.
, 202, and 301.

The first embodiment of the present invention has the configuration as described above, and its operation will be explained below. The subject image passes through the photographic optical system 1 and the aperture 2 to the light receiving elements al b, c,
The image is formed on d. The photoelectric conversion circuits 3a, 3b, 3
The signal is converted into a voltage proportional to the brightness of each part by c and 3d, and the amplitude is compressed by amplitude compression circuits 4a, 4b, 4c and 4d. By driving the light receiving elements a, b, c, and d, the incident light is made constant.

To simplify the explanation, it is assumed that the subject has a uniform brightness surface, that is, the light incident on the light receiving elements a, b, c, and d is equal.

First, if the intensity of light incident on each light receiving element is too high, the outputs of the photoelectric conversion circuits 3a, 3b, 3c, 3d and therefore the amplitude compression circuits 4a, 4b, 4c, 4d will be higher than the equilibrium value, and their inverted sum value The output of the adder circuit 5 becomes lower than the reference voltage of the reference voltage generating circuit 90. Therefore, the output of the error amplifier 10 is positive, and the terminal 11 of the aperture drive coil 11
Since a is driven positively, the aperture 2 is closed and the light receiving elements a,
Reduce the amount of light incident on b, c, and d.

Conversely, if the intensity of the light incident on the light receiving elements a, b, c, and d is too low, the output of the adder circuit 5 is applied to the reference voltage generating circuit 9.
higher than the reference voltage. Therefore, the output of the error amplifier 10 becomes negative and the terminal 11a of the aperture drive coil 11 is driven negatively, so the aperture 2 is opened and the light receiving elements al b, c,
Increase the amount of light incident on d. Hiddenly, whether the amount of incident light is higher or lower than the reference value, there is a function that always tries to return it to the reference value by driving the aperture 2, and if the gain of 10 is high enough, the output voltage of the adder 5 remains at a constant value. (a value equal to the reference voltage generated by the reference voltage generating circuit 9). In other words, for a 1-degree subject, the amplitude compression circuit 4 a + 4 b + 4 c +
4 Appropriate exposure control is always performed by 1° regardless of the characteristics of d. 1. Next, consider a case where the intensity of light incident on one of the light receiving elements a, b, c, and d, a, is 10 times stronger than the other G elements. First, amplitude compression circuits 4a and 4b.

When 4c and 4d are hot, the overall brightness is felt to be 3 1 l3 - control so that the output is constant. In this case, maybe.

If c and d are the main subjects (for example, a person), and a is a bright spot in the background (the sky, a lighting device, etc.), the exposure amount for the main subject is only 60% of the desired value (evil mind). Otherwise, the shooting will fail.

On the other hand, the amplitude compression circuit 4a for the same subject condition.

Set the characteristics of 4b, 4c, and 4d as shown in Figure 5, and
4 is the balanced output of a subject with uniform brightness, and R2o1 and R20
When the ratio of Compared to the case of a subject, the output of the adding circuit 5 is controlled to be constant as a plate. In this case, the exposure amount of the main subjects A, C, and D is 0 (-2 iV2) 82% of the desired value, and the photographing is not a failure.

If the brightness difference with the main subject is even larger, the degree of compression will be increased step by step as shown in Figure 9, or even the 10th
As shown in the figure, the influence of high-intensity bright spots can be removed by clipping the output above a certain level. Figures 9 and 10
The input/output characteristics shown in the figure can be easily realized by combining the circuits shown in FIGS. 4 and 5.

Also, in the above example, to simplify the discussion, we explained the case of 4 Utsu C base, but in reality, it would be easy to increase the number of divisions or add weights to them. Can be done. In particular, if weighting is desired, the values of the input resistors 401 to 404 of the adder circuit shown in FIG. 8 may be changed.

FIG. 11 is a diagram showing a second embodiment of the present invention.
This is applied to movie or still cameras that use imaging devices such as cameras and image pickup tubes. In such a camera, the imaging device itself can be regarded as an assembly of a plurality of light-receiving elements that spatially divide the subject into finely divided areas and measure the light, thereby enabling more precise light measurement.

In the figure, 501 is an optical system, 502 is an aperture, 50 is an imaging device such as COD as a photoelectric conversion means, 504
is a signal processing circuit that processes the photoelectric conversion output of the CCD and extracts the luminance component. Reference numeral 505 denotes an amplitude compression circuit as an amplitude compression means, which has the configuration shown in FIG. 4, the configuration shown in FIG. 6, or a combination thereof. Reference numeral 506 is an integrating circuit as a mixing means, which calculates an integral value as a time-added mixed output of time-series luminance (after amplitude compression) signals for the entire screen, and most fftj is simply as shown in FIG. It can be configured by a series circuit of a resistor 601 and a capacitor 602. Reference numeral 507 denotes an error multiplier 1iIiIi and a frizz driving circuit, which can be realized, for example, with exactly the same configuration as 10 in FIG. Reference numeral 50B is an aperture drive coil, and the aperture of the aperture 502 is changed by driving this coil.

The second embodiment shown in FIG. 11 has the configuration described above. 1st
Comparing the figure and No. 11 LA, 3 1 Figure 11 Optical system 1←-→Optical system 501 Aperture 2
502 light receiving elements a, b, c, d ('-ra image sensor 503
Since the error amplifier 10 (-÷error amplifier 507 aperture drive coil 11% aperture drive fJ11 coil 51, )8 corresponds to each other, FIG. 11 operates in the same way as FIG. The adder circuit 5 in FIG. 1 has an inversion characteristic, and the integrator circuit 506 in FIG.
does not have an inverted q-mo property, so when the terminal 5osa of the diaphragm drive coil 508 is driven with a negative voltage, the diaphragm 502 is closed, and when it is driven with a positive voltage, , 4□, 5o2□8. 6 o i, 1. ￥, B 7io.・Jl, ・[Effect] As is clear from the above explanation, according to the present invention, by adding a simple amplitude compression circuit, the influence of bright spots in the object space can be eliminated, and the accuracy of object information can be improved. can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a 1u air circuit block diagram of the first embodiment of the present invention,
FIG. 2 is a diagram showing an example of the spatial arrangement of light receiving elements a to d, FIG. 6 is a diagram showing a specific configuration example of photoelectric conversion circuits 3--d, and
Figure 6 is a diagram showing an embodiment of the amplitude compression circuit, and Figure 5 shows an embodiment of the amplitude compression circuit, respectively.
Figures 7 and 7 are respectively Figure 4. 6 is an input/output amplitude characteristic diagram of the illustrated circuit, FIG. 8 is a configuration example diagram of an adder circuit, FIGS. 9 and 10 are input/output characteristic diagrams of other embodiments of the amplitude compression circuit, and FIG. 11 is a diagram of the present invention. A block diagram of the second embodiment of the invention, FIG. 12 is a specific circuit diagram of the integrating circuit in FIG. 11. 1... Optical system 2... Aperture a-d... Light-receiving elements 6a to d... as photoelectric conversion means ...Photoelectric conversion circuits 4a to 4d...Amplitude compression circuit 5 as amplitude compression means...Addition circuit 1 as mixing means
0...Error amplifier and aperture drive coil drive circuit 11...Aperture drive circuit 501...Optical system 502...Aperture 5
06...Imaging device 504 such as a CCD as an imaging means...Signal processing circuit 506...Amplitude compression circuit 507 as an amplitude compression means...・Integrator circuit 508 as mixing means・
...Error amplifier

Claims (1)

[Claims] A plurality of photoelectric conversion means that divides a subject image into a plurality of parts and photoelectrically converts them, amplitude compression means that amplitude compresses the outputs of the photoelectric conversion means, and mixing means that mixes the outputs of the amplitude compression means. A subject information detection device comprising: