JPS60125526A - Photoelectric transducer for photometry of camera - Google Patents

Abstract

PURPOSE:To minimize a division number of a photodiode by reducing effective photosensitive parts of a photoelectric converting means, which measures the light in the center part of a screen, and plural photoelectric converting means, which measures the light in the peripheral part of the screen, according as going from the center to the edge of the screen. CONSTITUTION:Elements A, B, C, and D are arranged around an element K in the center, and a photoelectric converting part is so constituted that the effective photosensitive part is reduced according as going from the center to the edge. A bias voltage is applied to the non-inverted input terminal of an operational amplifier OP1 of a high input impedance for photometry by a constant current source CS and a resistance R1 to operate elements K and A-D in the current mode. Currents of elements K and A-D are compressed logarithmically by a logarithmic compressing element LD and are operated together with exposure information VR in an operating circuit consisting of resistances R2 and R3 and an operational amplifier OP2 to output shutter seconds, and they are displayed on a display means MT, and a camera is controlled through an exposure control circuit CKT.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoelectric conversion element for photometry for controlling the exposure lid of a camera.

Conventionally, a single photodiode has often been used as a photometric element for cameras, but a 7-E diode that is divided into multiple parts is used to obtain the best possible exposure even for subjects under poor conditions. It's starting to happen.

If the photodiode is divided into many parts and each output is subjected to arithmetic processing, the circuit configuration will become complicated and the cost will increase.

The present invention has been made in view of the above circumstances, and includes a photoelectric conversion element that measures light at the center of the screen and a plurality of photoelectric conversion elements that measure light at the periphery of the screen. The present invention aims to provide a photoelectric conversion element for photometry in a camera that performs highly accurate photometry by dividing the photodiode into the minimum necessary number by decreasing the number of photodiodes from the center to the edges.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows the optical characteristics of a single-lens reflex camera! L8 is a photographing lens, QM is a quick return mirror, PG is a focusing plate, CL is a condenser lens, PM is a pentaprism, EL is an eyepiece lens, ML is a condensing lens for photometry, and SP is for photometry. In the photoelectric conversion section, SH is a shutter.

It is configured such that an image of the subject is focused on the photoelectric conversion unit SP via the photometric condensing lens ML.

FIG. 2 shows the photometric system configured as shown in FIG. 1, and FIG. 3 specifically shows the photoelectric conversion section 81) shown in FIG. 1.
The photoelectric conversion section SP is divided into five parts.

Elements A and B are arranged around element K in the center of the screen.

C and D are arranged. A and B for each of these elements.

By configuring C and D so that the effective photosensitive area decreases from the center to the edge, photometry is weighted inside each element, and the outputs of these elements are further calculated to obtain highly accurate photometry information. Yes, I also set the camera horizontally. In order to guarantee exposure accuracy even when placed in the vertical position and in the vertical position, each element is provided with A.

The effective photosensitive areas B, C, and D are formed symmetrically with respect to the center as shown in FIG.

FIG. 4 is an example of the horizontal side when the photoelectric conversion element shown in FIG. 3 is cut at PIP2.

8B is a high resistance substrate, 8I is an element isolation region, N region and P
The junction of the areas is the effective photosensitive area, and this photosensitive area is I
With the C process, it can be formed in any way.

The configuration is such that the photocurrent generated in the photosensitive portion of each element is collected and output via electrodes (not shown).

Fig. 5 shows a photometric circuit using A to A to each photoelectric conversion element shown in Fig. 6, OPl is an operational amplifier, and the non-inverting input terminal of this operational amplifier OPI is connected in series. A connection point between constant current source C8 and resistor & is connected. Between the input terminals of this operational amplifier OP1, a series circuit of elements A and B, and C and D, which are arranged symmetrically with respect to the element K in the center of the screen, is connected in parallel, and the central element is also connected in parallel. LD is a logarithmic compression element connected between the input and output terminals of the operational amplifier OPI, OF2 is an operational operational amplifier with a return resistor connected between the input and output terminals, and the inverting input terminal of this operational amplifier. The output terminal of the operational term rlJ unit OPI is connected via a resistor, and the exposed information resistor VB is also connected to the output terminal.

The output of this operational amplifier OP2 is transmitted to a display means MT such as an ammeter.
It can also be added to the light amount control circuit.

To explain the operation of such a photometric circuit, the constant current source C
8 and resistor R1, a bias voltage is applied to the non-inverting input terminal of the photometric high input impedance operational amplifier OPI, and the high current conversion elements A and D operate in current mode.

The current generated from these photoelectric conversion elements is the logarithmic compression element L.
Logarithmically compressed by D, resistors R2, R3, operational amplifier OP2
The exposure information V tt is calculated by the arithmetic circuit consisting of O
Shutter time or aperture information is output as the output of F2 and displayed on display means MT such as an ammeter, and the camera is controlled via a known exposure gate control circuit CKT.

Each element is structured so that the effective photosensitive area of A, B, N', and D decreases from the center to the edge, so the measurements are weighted inside each element and the outputs of these elements are further calculated. It is possible to obtain highly accurate photometric information.

FIG. 6 shows another example of the photometric circuit shown in FIG. 5, in which operational amplifiers OPK, OPA, OPB, OPO, OP are provided for each photoelectric conversion element ', λ nl , CI, D/.
D, and the same parts as in FIG. 5 are denoted by the same reference numerals. That is, photoelectric conversion elements x', A', .
The photocurrents from ... are operational amplifiers OPx and OP, respectively.
A,... and logarithmic compression elements LDK, LDA,...
It is logarithmically compressed and calculated by the information calculation circuit cpuB, and information on shutter speed I or aperture is output.

FIG. 7 shows another example of the photoelectric conversion section SP divided into five parts. That is, FIG. 3 shows an example in which effective photosensitive areas are formed concentrically, and FIG. 5 shows an example in which effective photosensitive areas are formed in a star shape.

Alternatively, an equivalent element can be formed by forming a photosensitive portion by creating a PN junction in the entirety of each separated photoelectric conversion region, and blocking light with M or the like except for the necessary photosensitive portions.

As described above, according to the present invention, it is possible to locate subject information within each photoelectric conversion element, so that a small number of

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of the optical system of a single-lens reflex camera, Fig. 2 is a sensitivity distribution diagram of the optical conversion element shown in Fig. 1, and Figs. 6, 4, and 5 show an example of the present invention. 6 is a detailed diagram of the photoelectric conversion unit shown in FIG. 1, FIG. 4 is a PL-P2 cutaway diagram of FIG. 1, and FIG. 5 is a photometric circuit using the photoelectric conversion element shown in FIG. 3. 6 is a circuit diagram showing another example of the photometric circuit shown in FIG. 5, and FIG. 7 is a diagram showing another example of the photoelectric conversion section shown in FIG. 1. L8・■Photographing lens, PGll・・Focus board, PM・・
・Penta prism, BL...Eyepiece lens, ML
...Condensing lens for photometry, sp...Photoelectric conversion unit, A to D, ni'...Photoelectric conversion element.

Claims (1)

[Claims] (1) A photoelectric conversion means for measuring light at the center of the screen and a plurality of photoelectric conversion means for measuring light at the periphery of the screen are provided, and the effective photosensitive area of each of the photoelectric conversion means is adjusted from the center to the edge of the screen. A photoelectric conversion element for photometry of a camera, characterized in that it is configured to reduce the amount of light. (2) A photoelectric conversion element for photometry of a five-camera according to claim (1), characterized in that a P-N junction for photosensing is formed only in the effective photosensitive area. 6) A photoelectric conversion element for photometry in a camera as set forth in claim (1), wherein the photoelectric conversion means has an effective photosensitive portion that is approximately symmetrical with respect to the center of the screen.