JPS62270929A - Photometric device for camera - Google Patents

Abstract

PURPOSE:To output a photometric value by which a main part of a screen always becomes a correct exposure, irrespective of a position of a camera, and also, by a simple constitution, by providing a light receiving means, a lower part discriminating means for discriminating the lower part of the camera at the time of photographing, and an arithmetic means. CONSTITUTION:An image of an object is brought to photometry by a photodetecting means 6 through a pentaprism 4 and an image forming lens 5. The light receiving means 6 is provided with a center part photometric area A for executing a photometry to the center part of a field to be photographed, and peripheral part photometric areas B-D for executing a photometry by dividing its peripheral part into four. As for a lower part discriminating means 9, when the peripheral part photometric area B becomes the lower part, mercury 10 and an electrode 12a contact and an output voltage VCC1 is generated, when the peripheral part photometric area C becomes the lower part, the mercury 10 and an electrode 12b contact and an output voltage VCC2 is generated, when the peripheral part photometric area D becomes the lower part, the mercury 10 and an electrode 12c contact and an output voltage VCC3 is generated, and when the peripheral part photometric area E becomes the lower part, the mercury 10 and an electrode 12d contact and an output voltage VCC4 is generated.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Application of the Invention) The present invention provides a camera that divides the field into 411 lights and outputs a Jilt light value so that the main part is properly exposed. This paper relates to improvements to photometric devices.

(Background of the Invention) Conventionally, a photographic field is divided into a plurality of regions, the light is measured for each region, and the light metering information is used to output the light metering value so that the main part of the photographic screen is properly exposed. Various photometric devices have been proposed.

For example, Japanese Utility Model Publication No. 51-9271 proposes a photometry device that uses the arithmetic average value of the maximum and minimum values of outputs from a plurality of photoelectric elements to obtain an appropriate photometric value.
Publication No. 4-123030 proposes a photometric device that outputs a photometric value that provides appropriate exposure for the main subject by appropriately combining output signals from light-receiving elements corresponding to each area divided into a plurality of areas. .

However, with the former device, there is a problem that the main subject may be underexposed or overexposed when the background is particularly bright or, conversely, when the background is particularly dark. There was a problem that the circuit configuration for performing the processing became complicated.

Furthermore, in Japanese Utility Model Application Publication No. 60-161321, when the posture of the camera is changed from the horizontal position to the vertical position when photographing,
A photometering device that automatically switches the metering range from the bottom to the center to give the subject the proper exposure has been proposed, but in devices like the one proposed, the metering range is limited depending on the camera's posture. This poses a problem in that it tends to depend on the pattern of the subject.

(Objective of the Invention) The object of the present invention is to solve the above-mentioned problems, and to produce a camera capable of outputting a photometric value such that the main part of the screen is always properly exposed regardless of the posture of the camera and with a simple configuration. An object of the present invention is to provide a photometric device.

(Features of the Invention) In order to achieve the above object, the present invention provides four
a light-receiving means having a central photometry area that emits 16 lights; and at least four peripheral photometry areas that divide the peripheral area of the screen into upper, lower, left, and right directions with respect to the central photometry area; and a lower part of the camera when shooting. and a calculation for calculating a photometric value based on information from the peripheral photometric area and information from the central photometric area that are weighted according to the signal obtained by the lower discrimination unit. The present invention is characterized in that, in addition to the photometric information at the center of the screen, 1tll light information at the bottom of the periphery of the screen is multiplexed.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 shows an example of a photometric optical system for implementing the present invention in a single-lens reflex camera. Photography lens 1
The object image that is reflected by the quick return mirror 2 and formed on the focusing plate 3 is photometered by the light receiving means 6 via the pentaprism 4 and the imaging lens 5. In the figure, 7 is an eyepiece lens, and 8 is a film.

FIG. 2 is a diagram illustrating the light-receiving surface of the light-receiving means 6 shown in FIG. 1, which corresponds to the screen size. , and a peripheral photometry area B- in which the surrounding area is divided into four parts and photometered.
It is equipped with D.

FIG. 3 is a diagram showing an example of the lower part discriminating means disposed in the photometry device of the present invention. Here, the lower part discriminating means whether the camera is in the horizontal position or in the vertical position when taking pictures. This refers to determining the shooting state. The lower discrimination means 9 consists of mercury 10 that flows according to the attitude of the camera, a container 11 that seals the mercury 10, electrodes 12a-12b, and pull-down resistors 13a-13b, and includes a peripheral photometry area shown in FIG. Since B is at the bottom, the mercury 10 and the electrode 12a come into contact and the output voltage VCOL is increased, and because the peripheral photometry area C is at the bottom, the water filO and the electrode 12b are brought into contact with each other.
When the mercury lO and the electrode 12c come into contact, the output voltage Vcc2 is increased, and the peripheral photometric area E is at the bottom, and the mercury lO and the electrode 12c are in contact, resulting in an output voltage VCC3, and the peripheral photometric area E is at the bottom. When the mercury lO and the electrode 12d come into contact with each other, an output voltage Vcc is generated.

That is, the output voltages Vccl to Vcc correspond to each photometry region BE.

For example, if the camera is held horizontally, mercury lO
Since the state is as shown in FIG. 3, the lower discriminating means 9
As the output of Vcc3=Vcc.

Vccl= Vcc2 = Vcc, = Otonari,
It can be seen that this was taken in a horizontal position with the peripheral photometry area at the bottom. Further, when the camera is held in the vertical position, the output of the lower discriminating means 9 is Vcc2=Vcc,
Vcc, =Vcc3 =Vcca =o Aluminum is V
CCa=Vcc, Vccl=Vcc2=Vcc3
It can be seen that this is vertical photographing with peripheral photometry area C or E at the bottom. Note that Vcc is a positive power supply voltage.

FIG. 4 is a circuit diagram showing an embodiment of the present invention including the lower discriminating means 9. As shown in FIG. In FIG. 4, 14 to 18 are silicon photodiodes (spc) corresponding to each region A to H of the light receiving means 6, and generate a photocurrent iA"iE according to the brightness of each region. 19 to 23 is photocurrent 1A-
This is a logarithmic compression circuit that logarithmically compresses iE and outputs a voltage of VA-VE. Here, the voltage VA-VE is constants a1 to a5 (a, ≧o), b (>o) and photocurrent i
If expressed using A''iE, it will be as follows.

VA =al +blniA VB=a2+blniB VC=a3+blniC VD =a4+b l n 1DVE=a5+
However, it is assumed that the constants a1 to a5 are set in advance in the logarithmic compression circuits 19 to 23 so that when the brightness of each photometric area is equal, VA = VB = VC = VD = VE.

24 to 28 are resistors having the same resistance value, and 29 to 32 are analog switches that are selectively turned on when the output voltages Vccl to VCC4 are generated, and the output voltages VB-VE and VA are
33 is an operational amplifier which has the function of arithmetic averaging.The output terminal and the inverting input terminal are connected here and used as a voltage follower. Regardless of the current circuit state, the value is equal to the voltage value input to the non-inverting input terminal.

Next, the photometry output Vout in each shooting state
We will explain the state of . First, a normal horizontal photographing time as shown in FIG. 5 will be described. In this case, since the mercury 10 is in a state as shown in FIG. 3, a signal (output voltage Vcc3) indicating that horizontal photography is being performed with the peripheral photometry area at the bottom is output from the lower discrimination means 9. Analog switch 31 is turned on. As a result 2 op amps 33
The photometric output V after the calculation is (VA+Vll)/2
out will be output. In this case, the main subject is metering area A! -D is considered.

Further, when photographing is performed in a vertical position with the peripheral photometry area C at the bottom, the output voltage Vcc2 is outputted from the lower discriminating means 9, so the analog switch 30 is turned on. the result,
The operational amplifier 33 outputs a photometric output Vout after calculation of (VA+VC)/2. This takes into account that the main subject is mainly located in the J11 light areas A and C.

When photographing in a vertical position with the peripheral part fl11 light area E at the bottom, the output voltage VCC4 is output from the lower discrimination means 9, so the analog switch 32 is turned on.

Sono result, from operation 77bu 33 (VA, VE) /2
The photometric output V out after the calculation is output. This takes into consideration that the main subject is mainly located in the photometric areas A and E.

By setting the photometry output V out in accordance with the calculation result as described above, for example, even when shooting in a so-called backlit scene where the main subject is darker than the background as shown in FIG.
By determining the top and bottom (bottom), it is possible to perform photometry that focuses on the area where the main subject is located. The present invention is particularly effective when applied to a camera such as an AF camera that assumes that the main subject exists in the center.

FIG. 6 is a circuit diagram showing another embodiment of the present invention. In this embodiment, the photometric information of the surrounding areas other than the bottom of the field is weighted weakly, and the value calculated by taking into account the brightness around the object is used as the photometric output. , resistors 34 to 37 . are added to the circuit of the embodiment shown in FIG. The circuit configuration includes analog switches 38 to 41 and inverters 42 to 45.

For example, if the resistance values of the resistors 34 to 37 are set to three times the resistance value of the resistors 25 to 28, then during normal horizontal shooting as shown in FIG. .41 is turned on. Therefore, the weighting of the voltages VB, VC, and VE is 1/3 of the voltages VA, V[), and as a result, the photometric output Vout is Vout = (VA +VD + 1/3 (VB
+VC+VE))/3 The value is obtained from the formula.

(Correspondence between the invention and the embodiment) In this embodiment, from the resistor 24 to the operational amplifier 33,
The components from the resistor 34 to the inverter 45 correspond to the calculation means of the present invention.

(Modification) In this embodiment, the light receiving surface of the light receiving means 6 has one photometric area in the center and four Jllll light areas in the peripheral area, but it may have more than this. In other words, the central portion may be further divided concentrically, or the peripheral portion may be further divided in the vertical and horizontal directions with respect to the central gR, 111 light area.

In addition, as a means for determining the lower part of the camera during shooting, mercury lO is used, but the present invention is not limited to this, and the lower part of the camera may be determined mechanically using a weight such as a pendulum. It is also useful to have various configurations.

(Effects of the Invention) As explained above, according to the present invention, the center part of the screen is
A light receiving means having a central photometric area that emits 1llll light, and at least four peripheral photometric areas that divide the screen peripheral area vertically and horizontally with respect to the central photometric area and measure the light;
a lower part discriminating means for discriminating the lower part of the camera at the time of photographing, and information from the peripheral photometric area and information from the central photometric area weighted according to the signal obtained by the lower discriminating means; It is equipped with a calculation means for calculating photometric values, so that in addition to the photometric information at the center of the screen, the photometric information at the bottom of the periphery of the screen is respected, so it is easy to use regardless of the camera posture. With this configuration, it is possible to output photometric values such that the main part of the screen is always properly exposed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a photometric optical system for realizing the present invention,
Figure 2 is a diagram explaining the light-receiving surface of the light-receiving means in Figure 1;
The figure shows an example of the lower discriminating means arranged in the present invention,
FIG. 4 is a circuit diagram showing one embodiment of the present invention, FIG. 5 is a diagram showing an example of a commonly photographed scene, and FIG. 6 is a circuit diagram showing another embodiment of the present invention. 6... Light receiving means, 9... Lower discriminating means, 14-18... Silicon photodiode,
19-23... Logarithmic compression circuit, 29-32...
...Analog switch, 33...Operational amplifier, 38~41...Analog switch, 42~
45...Inverter. Patent Applicant Canon Co., Ltd. Representative Minoru Nakamura Figure 1 Figure 2 Figure 3 (corresponds to the di optical area) Figure 5 Figure 6

Claims (1)

[Claims] 1. A light receiving means having a central photometric area for metering the center of the screen, and at least four peripheral photometric areas for dividing the peripheral area of the screen vertically and horizontally with respect to the central photometric area, and photographing. photometry based on information from the peripheral photometry area and information from the center photometry area that are weighted according to the signal obtained by the bottom discrimination means; A photometry device for a camera, comprising a calculation means for calculating a value.