JPS5844319A - Scanning type weighing photometer for camera - Google Patents

Abstract

PURPOSE:To achieve the purpose by a single collecting element and to obtain an appropriate sensitivity distribution, by a method wherein a relative position relation between the collecting element and an optical member for photometry is caused to change during the photometry, and a weighting photometry takes place as a given part of an object to be photogaphed is scanned. CONSTITUTION:At least a part of light from an object to be photographed is led to a collecting element by an optical member 1 for photometry. A relative position relation between a collecting element 5 and the optical member 1 for photometry is caused to change by a motor MT. A frequency of a control input to the motor MT is caused to change coresponding to a given weighing function to perform a weighing on a photometry output. This performs a weighing photometry as a scanning is made on a given part of the object to be photographed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a photometry device for 11TTL photometry in which photometry is performed using a light flux transmitted through a photographic lens, and in particular, it is possible to select a vertical photometric sensitivity distribution and obtain an appropriate photometric sensitivity distribution. This invention relates to a weighted photometry device for cameras that allows for

2. Description of the Related Art Various devices have been known for switching the photometric sensitivity distribution of incident light from a photographic lens. However, it is generally necessary to arrange multiple sets of photometric optical systems and switch the optical systems mechanically or electrically, which requires multiple lens systems and light receiving elements, and the measurement electrical circuit is also complicated. It has some drawbacks. In addition, the photometric sensitivity distribution also has the problem that a portion of the screen is biased and determined due to longitudinal positional relationships.

SUMMARY OF THE INVENTION An object of the present invention is to provide a camera weighting photometry device that can change the photometric sensitivity distribution using the same photometric optical system and optimize the photometric sensitivity distribution, in order to solve the problems of the conventional example described above. KIS Ru to do. For this reason, in the embodiment of the present invention, a light-receiving element that measures the brightness of a subject, a photometric optical member that guides a part of the incident light into the camera to the light-receiving element, and a light-receiving element and a photometric reflecting member are combined. These problems are solved by providing a drive mechanism that scans the field by changing the relative positional relationship during photometry, and means for weighting the photometry output in accordance with the scanning position. As a means for weighting the photometric output, for example, weighting may be performed by changing the scanning speed f by driving the photometric optical member with an eccentric or deformed cam.
The embodiments of the present invention mainly provide a scanning weighting photometry device in which the weighting function can be easily changed by electrically arbitrarily weighting the photometric sensitivity distribution.

The present invention will be explained in detail below based on illustrated embodiments.

Figure 1 shows, for example, TTL in a σ-eye flex camera.
1 is a configuration diagram of a photometric device for photometry, in which 1 is a reflecting member as an optical member for photometry, a photographing lens 2,
The photometric reflecting member 1, which receives the light beam transmitted through the quick return mirror 6 which has a light transmitting part in the center and guides it to the element 5, is driven by a drive mechanism such as a small motor to reduce the amount of light in the secondary light as shown by the arrow. Can be driven. In this embodiment, the reflecting member l is scanned in the vertical direction via a stepping motor MMT.

CPD is a code plate for co-rotation position detection disposed on the rotating shaft of the stepping motor MT, and has an Al gA hole, and when the reflecting member 1 is at the reference (center) position shown in the figure, the photocoupler The photocoupler PC2 is configured to detect a bird when the PCI is detected and l is at a position removed from the photographing optical path. FS is a focusing plate, CL is a condenser lens, PR is a pentaprism, ELFi7 (piece lens % M 1 a) is a current needle for displaying exposure value, SH is a focal plane shutter.The light incident on the light receiving element 5 performs one scan. Therefore, the instantaneous value of the amount of light differs, so a photometering basket for determining exposure is created by dividing the electrical output of the light-receiving element 5 into a predetermined period of time using an integrating circuit.
It will be done.

Further, the reflecting member 1 can be driven as required, and the reflecting member 1 is configured so as to be able to be photometered while standing still.

Therefore, for example, if photometry is performed with the #1 light reflecting member 1 stationary, the distribution of the 111 Jft input to the light receiving element 5 will be at the center of only the circular portion 10 at the center of the screen 3 in FIG. Partial side light. However, when the reflecting member 1 is rotated during side light, the vertical band-shaped portion 11 shown in FIG. 2 becomes a side light beam. The photometric sensitivity distribution can be weighted by scanning while changing the rotational speed of the photometric reflecting member l.

Further, it is also possible to weight the photometric sensitivity distribution by setting the rotating speed of the reflecting member 10 constant and multiplying it by an appropriate weighting function. Figure 3 shows the rotational speed f? of the photometric reflecting member l? FIG. 3 is a diagram illustrating an embodiment of a drive mechanism and a photometric circuit that perform weighting of photometric sensitivity distribution by scanning with different values.

08C1 is a quasi-clock generation circuit, CNTl, CNT
2 is a counter, MCPI, MCP2 is Magnichi-o-
44-Comparator, reduced T ti photometry part setting circuit,
RFI to RF3 are RS 7 Q-tube flops, DPI.

DF2 is a D flip full tube, 5T1ti rising synchronization one-shot circuit, 5T2Fi falling synchronization one-shot circuit, OR1 to OR5 are orage, -do, ANI to AN
8 is an AND gate, NDI, ND2 is a Nandt gate, INI and IN2 are inverters, R4-R18 are resistors, Ct-C'r are capacitors, and LDI.

LD2 is a logarithmic conversion diode, MPl is a temperature compensation resistor with a temperature coefficient proportional to high input input, BHI is a buffer amplifier, CTI is a constant current source, and EcK is an exposure amount control for controlling the camera exposure amount by the output of B stage 1. It is a circuit. M.I.
C is a motor control circuit for rotating the stepping motor MT in the direction corresponding to the direction pulse DR using the clock pulse CPIC♂, and the first clamping magnet, SW1, SW2 is the shutter of the camera, which controls the starting of the Mg1ti camera. Release 1. The switch El, which is turned on by the second push, is a power source battery. LEI and LE2 are light emitting diodes Tri and Tr that constitute a photocoupler.
2 Fi receiving transistors, Tr2 to Tr5 Fi) transistors. Mamo BR is a terminal for setting a weighting function,
vFC is a voltage frequency conversion circuit for converting the voltage generated by the weighting function into a frequency, DFM is a differential amplifier circuit,
DIv is a division circuit, and MLTi1 is a multiplication circuit.

FIG. 4 is a timing chart of the main parts of FIG. 3. Based on FIG. 4, the specific operation of FIG. 3 will be explained in detail. The photographer sets the desired weighting function and photometry section using the weighting function setting terminal BR and the photometry section setting circuit MSTK.
First, set it up. A according to the set value (QO, -Q10)
RTM, RTI ~ RTn, C1 via GO~AGn
, ODI is corrected.

That is, the ratio of the resistance values of RTM, RTO, RTI, etc. is set as 1:2:4, and in this example, when the photometry range is doubled, the photometry integration time is doubled. The integrated current becomes 1/! It is corrected so that

When the camera release button is pressed at time t1, SWI
is turned on, power is supplied to the fI11 circuit system, and 03. R6t-via RFI~RF3. %DFI.

DF2. Since CNT is initially cleared, the reflecting member 1 is always retracted downward after shooting, so when photometry starts, the DR terminal, which is the output of ORI, goes to a low level, and the 4-pulse generated from O8C1 continues until RF2 is set. Compatible with CP.

and quickly rotate upward in FIG. Reflective member 1 at time
When reaches the reference position as shown in the first diagram, the output of the photocoupler PCI becomes a high level and RFI is set, but when the output of OR2 is rotated, the output of PCI becomes a low level and the output of the counter CNT1 becomes a low level. starts counting. Time t.

1 is rotated to the set pulse value set in MST, the magnitude comparator MCPI produces a matching pulse. Simultaneously with the rising edge of the match pulse, STI generates a one-shot pulse via AND gate AN6, and synchronously with the falling edge of STI, ST2 generates a one-shot pulse.

These one-shot pulses are sent to counters CNT2 and R
11t ops, as analog control of the time integration circuit for correction consisting of analog control (AGP) for storing photometric information) AGM and analog control (AGM) for resetting photometric information.

RF2 is set by a one-shot pulse generated from 8T2, and photometry information is stored in accordance with the pulse from STI after setting RF2. In the figure, a warning is displayed by the pointer of the ammeter MT for displaying the cod value.

Control of the photometric reflection member is started by a pulse generated by a voltage frequency conversion circuit VFC controlled by the output of a weighting function generation circuit composed of an AGT. AGT of the weighting function generation circuit is reset at time t by the output of AN6, and AGR GS is reset at time -e Ls e j4 *
It is controlled by the output of DF2 which is inverted at t. OF
In this embodiment, the output of No. 2 decreases as the photometric reflection member 1 approaches the reference position (center) f*, ta, as shown in the fourth figure.

When the output of OF2 decreases, the oscillation frequency of vFC decreases, so the rotation speed of the photometric reflection member 1 slows down, making it possible to perform center-weighted photometry.

The degree of center emphasis can also be adjusted by adjusting the weighting function setting terminal BR.

Also, at time t, DP
Since I is inverted, the I)R terminal of MIC becomes high level, and the stepping motor MTilt begins to rotate downward in FIG.

When the reflective member 1 reaches the reference position at time t, the output of the PCI becomes high level and the counter CNTl is reset.6 Next, the reflective member 1 is rotated downward to the set pulse value determined by MSTKS. At time t, the MCP generates a matching pulse, and the temperature-compensated object brightness information detected moment by moment is transferred to the resistors RTO to RTn by the light receiving element 5, the operational amplifiers MPI and OP2, and the logarithmic conversion elements CDI and CD2.
, RThl *The first appropriate scanning photometric output is integrated in an integrating circuit consisting of a condenser C1 operational amplifier OPI, and after correcting the photometric output in a correction circuit described below, it is stored in a capacitor C21C via an analog converter (AGMt). Retains until next scan.

The correction circuit is for correcting errors in the photometry output due to fluctuations in the photometry integration time in accordance with the set weighting function and the photometry portion. A after the pulse from ST2
It is reset via the GP and starts integration, and when the counter CNT2 counts the pulses corresponding to the nine photometric portions, which are preset in the MST at the time, the magniche is activated. The MCP2 generates a matching pulse, the output of O20 is stored in the capacitor tc6 via AGQ, and the reference output signal a(t) corresponding to the photometric part is detected and held. When one cycle of photometry ends at time t, time 1
．． The ratio of b(t) and a(t) which is the OP3 output at is D
IV, the product of the DFM output 111J'yt and the output m(t) is taken at ML1%, and the corrected side light information is stored and held in the capacitor C2 via the AGM.

Also, since RF3 is set in accordance with the pulse from STI at *#ti, for example, when the camera's shooting start switch SW2 is turned on at time -, the output of AND gate AN4 becomes high level, and the output of the camera is transmitted through transistor Tr5. 1 tension Mgl is excited and the camera exposure 5t, ii control sequence is started. On the other hand, since the output of AN2 becomes high level, the DR terminal of MIC also becomes high level through ogit-, and the output of OR4 also becomes high level, and the pulse from O201 causes reflection member 1 to be activated through MICU stepper motor MTt-. Rotates quickly in the direction of downward rotation. When the reflective member 1 is completely retracted from the photographing optical path, the output of the photocoupler PC2 becomes high level9.
Since the output of the AND gate NDI becomes a low level, the output of the AND gate also becomes a low level, and the rotation of the motor MT is stopped and the shutter SH is activated. Further, the shooting start switch 8W2 is activated at the time 1. when the first appropriate scanning photometry output is obtained. K if previously turned on
ti,, Since RF3 is not set, the storage of subject brightness information and the start of the camera's exposure control sequence are stopped via AGM and AN4 until RF3 is set and an appropriate scanning photometry output is obtained. .

Furthermore, when photometry is performed with the photometric reflection member 1 stationary, MS
By setting Q, *a*, Q to Qo, ..., Qn of T, when l reaches the reference position, the output of AN8 and P
The output of CI becomes high level, the output of ND2 becomes low level, and the clock pulse does not enter the MIC, so 1
The drive motor MT stops. 1MCP output is 08C
Since it is ANDed with the output of I, photometric information storage and resetting are performed alternately.

Next, FIG. 5 shows an embodiment of a drive mechanism and a side light circuit that weights the photometric sensitivity distribution by keeping the rotational speed of the reflecting member l constant and multiplying it by an appropriate weighting function. The output of OF2, which is the output of the weighting function generation circuit, is the photometric output.The output of the differential amplifier circuit DFM is multiplied by the multiplier circuit MAT, and the weighted photometric output is R21, OF2°C1,
In order to correct the error in the photometric output due to the shape of the six weighting functions integrated by the integrating circuit consisting of AGN, the weighting functions and the reference signal are integrated over one cycle of photometry, and the signals b(t) and &(t ) dividing circuit DIV
By multiplying the output of DIV and the output of OF2 by the multiplier circuit MLT, corrected and accurate side light information can be obtained no matter how the photometry part and weighting function are set. Furthermore, in order to perform photometry over almost the entire range on the screen, two sets of photometric reflecting members, drive mechanisms, and weighting means are provided, one for scanning horizontally and the other for vertical scanning, while one reflecting member By guiding the diffused light from the reflective member to the other reflecting member and then to the light receiving element, it is possible to perform cross-shaped photometry on the screen and to apply weighting both horizontally and vertically.

As explained above, the weighted photometry device for a camera according to the present invention uses only one light receiving element, and can perform at least partial photometry and average photometry without increasing the number of photometers.
It has the advantage that an arbitrary a11 photosensitivity distribution of l1ljt can be selected while being weighted, and an appropriate sensitivity distribution can be obtained.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view showing one embodiment of the photometric device of the present invention, Fig. 2 is a diagram showing an example of the photometric range of the present invention, and Fig. 3 is a diagram showing an example of the photometric range of the present invention. FIG. 4 is a diagram showing an example of the electric circuit. FIG. 4 is a diagram showing the drive timing of the circuit shown in @3. FIG. 5 is a diagram showing another example of the electric circuit of the weighted photometry device of the present invention. 2...-Photographing optical system, 6... Quick return mirror, 1... Optical member for photometry, 5... Light receiving element, MT.
...Drive source, SH...Shutter, CT1...Constant current source, VFC...Voltage frequency conversion circuit, DIv...
Division circuit, MLT...multiplication circuit.

Claims (2)

[Claims] (1) A photometric optical member for guiding at least a portion of light from a subject to a light-receiving element, a driving means for changing the relative positional relationship between the light-receiving element and the photometric optical member during photometry, and a cocoon weight Weighting of photometric output according to relative position by 4
1. A scanning weighting photometry device for a camera, characterized in that it is configured to perform weighted photometry while scanning a predetermined portion of a photographic object. (2) The photometric optical member is configured to be driven via a motor controlled by a periodic input, and changes the frequency of the control input to the motor in accordance with a predetermined weighting function. 2. A scanning weighted photometry device for a camera according to claim 1, wherein the photometry output is weighted depending on the situation. (s) comprising an integrating circuit that integrates the scanned weighted light output, and a ratio detection circuit that detects a ratio between an integration time for integrating the scanning weighted photometric output and a reference integration time;
A multiplier circuit that multiplies the output of the multiplier circuit according to claim (2), and an integrator circuit that integrates the output of the multiplier circuit. , a correction ratio detection circuit for detecting a ratio between an integral value of a weighting function and a reference value, and the output of the integration circuit is corrected by the output of the correction ratio detection circuit. A scanning type weighted photometry device for a camera according to item (1).