JPS5972434A - Exposure display device - Google Patents

Abstract

PURPOSE:To detect quantitatively a desired exposure value by relating a film latitude to a photometric value. CONSTITUTION:In a photometric circuit 1, photodiodes P1-P25 connected in parallel are placed like a matrix in a prescirbed area 11 corresponding to a photographic picture, and send out successively voltage being proportional to logarithm of brightness of an object to be photographed, to an information arithmetic circuit 2. In the circuit 2, an information signal of sensitivity of a film and an aperture is calculated, the maximum value and the minimum value are detected 3, 4, respectively, and also, basing on these detected values, an intermediate value is detected 5. The intermediate value is supplied to an exposure time controlling circuit P of a camera. Also, each detected value is decoded 6-8, repectively, is given to a display part 10 through an OR gate 9, and a difference of a bright part and a dark part of the object to be photographed is displayed by each LEDL1-L15. Accordingly, latitude of a film and a photometric value are displayed correspondingly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device in a light meter for photographing.

Conventionally, single exposure R1 or a light meter built into a camera measures a certain subject's light and measures the brightness of the subject, and then measures the subject area corresponding to that measured value or the intermediate or average density on the film. Just display it as information to be reproduced.

Generally, there is the following relationship between a photographic film that records the intensity of light and the luminance distribution of the subject to be recorded. In other words, the difference or ratio of light intensity that a photographic film can record is specified according to each type of photographic film.
This is sometimes called the latitude of photographic film.

With respect to this latitude, for some objects, the brightness ratio between the maximum brightness and the minimum brightness of that object is smaller than the latitude. On the other hand, for other objects, the brightness ratio may exceed the latitude. For objects whose brightness ratio does not exceed the latitude, if the camera exposure is set based on the average value of the maximum brightness and minimum brightness, all the brightness information of the object is recorded on the film. In the case of such an exposure, information that the photographer considers unnecessary for expressing the intention of the image can be removed at various processing stages after the exposure is completed. However, if the luminance ratio of the subject exceeds the latitude, it is impossible to record all the subject's luminance information on the film no matter how the exposure is set. Therefore, exposure settings become a matter of choice. Of course, for ordinary photographers, such exposure setting problems are troublesome, and one way to solve this problem is to adjust the average brightness of the shooting screen even when the brightness ratio exceeds the latitude of the film. A photometry system has been provided that measures the brightness of an object to determine exposure.

However, in such a photometry system, the key point is to find an exposure value suitable for obtaining the photographic result intended by the photographer. In order to obtain a film with an exposure suitable for expressing the intention of the image, it is necessary to select and set the exposure value, that is, the combination of exposure time and aperture value. For a subject whose luminance ratio exceeds the latitude, there may be cases where it is determined that information on the high luminance side is necessary even if information on the low luminance side is sacrificed, or vice versa. Furthermore, there may be cases where it is determined that information on the inner side is necessary at the expense of information on both the altitude side and the low brightness side.

The present invention has been made in view of the above-mentioned circumstances, and provides a useful exposure meter for finding an exposure value suitable for expressing the photographer's drawing intention, and expresses the photographer's drawing intention. You can determine the appropriate exposure value without relying on empirical intuition, etc.
The purpose is to make it possible to discover quantitatively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments shown in the drawings.

First, the configuration of an embodiment of a light meter according to the present invention will be described with reference to the block diagram shown in FIG. In FIG. 1, block 1 is a photometry circuit, and this photometry circuit has a plurality of light-receiving units composed of photodiodes (photocells) within a certain area corresponding to the photographing screen, that is, the film focal plane of the camera, as shown in FIG. Elements P1 to 25 are arranged in series to obtain a series of photoelectric conversion outputs corresponding to the intensity of light incident on each of the customer light receiving elements.Specific circuit of this photometric circuit 1 An example is shown in FIG. 3, and the details will be described later. From the output terminal 16 of the photometric circuit 1, a voltage signal proportional to the logarithm of the intensity of light incident on each of the light receiving elements P1 to P25 is transmitted in time series. Output.

Block 2 is an information calculation circuit that calculates an exposure time signal by photographically calculating a voltage signal obtained by sequentially converting, for example, the film sensitivity and the aperture value of the photographing lens into one electric signal from the voltage signal of the photometry circuit 1. If the exposure time is determined in advance and the aperture is to be calculated in accordance with the exposure time, a voltage signal in accordance with the exposure time is applied to the information calculation circuit instead of the aperture value signal. A specific circuit example of the information calculation circuit 2 is shown in a broken line block 12 in FIG. 3, and details thereof will be described later.

Blocks 3 and 4 are the maximum value Emax and the minimum value among the series of exposure time signals corresponding to the light intensity incident on each of the light receiving elements P1 to P25 that is output in time series from the information calculation circuit 2. This circuit detects Emin and Emin, respectively. A specific circuit example of the maximum value and minimum value detection circuit is shown in FIG. 4, and as described later, these circuits 3,
In step 4, the detected maximum and minimum values are digitized and output to decoder circuits 6 and 7 at the next stage.

The block 5 is an intermediate value calculating circuit which outputs an arbitrary value between the E+nax and Emin detected by the maximum value and minimum value detection circuits 3 and 4, respectively. The output Ern1d of the circuit 5 is expressed by equation (1).

E, mid = (Jimax-Emin) k 10Emin-... (1) In equation (1), k is 0≦≦1
arbitrarily determined by the photographer within the range of For example k
The intermediate value calculating circuit 5 is configured so that any one of the five numerical values of =0, 0.25°0.5, and 0.75.1 can be freely selected. Now, when k-0 is selected, the output is 1', mId=Emin, and when k=0.5, Emid=(Emax-F, m1n)/2. ni=1+
near), Emi d = Emax.

To explain more specifically, if Emax and Etnin represent exposure times of 1/250 seconds and 1/15 seconds, if k = 0.5, the intermediate value calculation circuit 5
A signal corresponding to l,/60 seconds is output. This output signal can be manually applied to an exposure time control circuit P provided in the camera to automatically control the exposure time. Blocks 6 , 7 , '8 are each pre-stage circuit 3 , 4 .
This is a decoder that converts the binary code in 5 into a signal suitable for display. The output of the decoder 6.7 is input to the 01 (gate) via the switches SW1 and SW2. is displayed manually.

When the switches SW1 and SW2 are closed, the output signals of the maximum value and minimum value detection circuits 3 and 4 are also input to the display section 0, and the maximum and minimum values of the circuits 3 and 4.5 are input together with the contents of the intermediate value calculation circuit 5. Values and intermediate values are displayed simultaneously. As shown in FIG. 2, the display section 10 includes a plurality of display elements L1 to L1, such as light emitting diodes, each of which sequentially displays values within a certain range of the exposure time signal, respectively, in response to the exposure time signal.
5.5 are lined up in at least one or two rows within the field of view 11 of the object image observation finder.

In FIG. 2, the operating ranges of these plurality of display elements are provided corresponding to the respective shutter speeds. For example, the display element L6 that is currently lit corresponds to a shutter speed of 1/250 seconds with the maximum value Emax. , and I-8 corresponds to a shutter speed of 1/60 seconds as the intermediate value, F, n1id, and Llo corresponds to the minimum value Emi
The opening corresponds to a shutter speed of 1/15 seconds, respectively. These multiple displays simultaneously show a plurality of pieces of exposure information about the subject to be photographed, that is, information about the light intensity of the bright and dark parts of the subject, and the difference in brightness between the bright and dark parts can be easily confirmed. Therefore, the photographer can set the exposure taking into account the latitude of the film, and the exposure can be shown in accordance with the photographer's intention.

The embodiments of each block shown in FIG. 1 will be explained in more detail below.

First, in the photometry circuit 1 shown in FIG. 3, a plurality of parallel-connected photodiodes P1 to P25 are arranged in a matrix within a predetermined area corresponding to the photographic screen as shown in FIG. The anode of the photodiode Pi is a pair of field effect transistors connected in parallel.
l-1a, -r ib(i = l.

2, . . . , 25) via two transistors LT.

r, - connected to the collector of r 2 . The gate of one field effect transistor l"ia is directly connected to the output terminal 12-1.12-2. of the shift register 12.
....

12-25, the gates of the other field effect transistors are connected to inverters N0T1.12-25, respectively. No 0 2. ..., No
Output terminal 12- of shift register 12 via I'25
1, 12-2, . . . , 12-25. The shift register 12 sequentially outputs a high level "1" pulse from its output terminal as a scanning command, and one of the field effect transistors 1a, 21, .

``'25a are switched one after another to make them conductive, so when the shift register 12 is outputting a pulse from the output terminal of 1J\, the field effect transistor □2
+2a+...,'r25a, only the field transistor whose gate is connected to the output terminal is in a conductive state. In addition, since the other field effect transistor Tib is connected to each inverter N0Ti, the state is opposite to that of the above one field effect transistor Tia, and when the shift register 12 is outputting a pulse from its output terminal, the output terminal is Only one connected field effect transistor 'T'ib is in a cut-off state and the others are in a conductive state. Due to the scanning operation of the shift register, one of the transistors L1-1 has a photodiode P.
1, P2. ....

The photocurrents generated by P25 are sequentially applied. The high input impedance amplifier circuit A, whose input and output are connected to the collector and base of the transistor LT1, respectively, constitutes a negative feedback amplifier 11 circuit together with the transistor LT. The circuit A2 connected to the collector and base of the other transistor LT2 may be constructed in the same manner as the circuit Δ1 described above. 1] Due to the action of the circuit A1, the potential of the collector of the transistor LT1 is kept almost constant, and a voltage proportional to the logarithm of the collector current of the transistor LT1 is generated between the base and emitter of the transistor LT1, that is, from the output terminal 11). In other words, a voltage signal proportional to the logarithm of the brightness of the subject light that enters each photodiode PL, P2, . ]
, I).

The output of the photometry circuit 1 obtained in this way is outputted as exposure time information by the information calculation circuit 2 shown by the broken line block in FIG. To the arithmetic intensifier□, constant current circuit 1
, and a potentiometer PM1.in which film sensitivity and aperture information are set. PM2 is provided, and the output terminal 2a of the information calculation circuit 2 outputs film sensitivity information to the output voltage of the photometric circuit 1 between the slider W1 of the potentiometer PM1 and the connection point a) according to the film sensitivity. A voltage is applied, and a voltage obtained by subtracting the voltage between the slider W2 of the potentiometer PM2 and the connection point a1 is output as the aperture information. In addition,
In this case, if it is desired to obtain the aperture for the set exposure time, information on the exposure time may be provided in place of the aperture information by the information calculation circuit shown in "-". Next, the maximum value and minimum value detection circuits 3.4 are each a well-known feedback comparison type A-D converter using an up counter 13 or a down counter 18 as a binary counter, as shown in FIG. In the maximum value detection circuit 3, the count contents of the up counter 13 are cleared by resetting, but in this state, the voltage level of the output terminal 14a of the 1)-A conversion circuit 14 connected to the up counter 13 is output by the circuit 14. This is the lowest level ever. The comparison circuit 15 receives an input 15a from the information calculation circuit 2 and the D-A conversion circuit 14.
The voltage level of both inputs is compared, and when the level of one input 15a is higher than the other input 151), a high level, that is, "1'' signal is applied to allow the clock pulse from the pulse generator G to pass and is inputted to the up counter 13 as a digital value, while the input 15b from the other side, in other words, the output level from the D-A converter circuit 14. When becomes higher than one input 15a, it outputs "0" and closes the AN/D gate 16 to prevent passage of the clock pulse. In this way, the Δ-reverse converter 3 receives the input 1.5 from the information calculation circuit 2. When the analog voltage applied to H changes, the maximum value thereof is constantly converted to a digital value via the up counter 13. Therefore, during photometry, after the up counter 13 is reset, i
'1lll) photodiionide I't of u circuit 1,
I'2.

..., P2. During the period when AN is scanned by the scanning circuit 13,
+) 1" is manually applied from the measurement start circuit S to the end 'f-16a of the gate J6, and during this time η from the information calculation circuit 2
The maximum value in the i pressure signal is converted to A-1), and the count contents of the up counter 13 are transferred to the storage register 17 after the scanning is completed.

In FIG. 4, the minimum value detection circuit 4 converts the up counter 13 in the maximum value detection circuit 3 into a down counter 1.
This is a replacement for 8. When the down counter 18 is reset, the voltage level at the output terminals T-1 and 9a of the I)-A conversion circuit 19 connected to the down counter 18 is the highest level that the circuit 19 can output. , when the down counter 18 counts pulses from this state, the voltage in a predetermined unit is I), - to the conversion circuit 19.
The output level of will continue to decrease. When the level of the input 20H from the information calculation circuit 2 is lower than the input 20b from the A conversion circuit 19, the comparator circuit 20 gives a signal of "1" to the gate 21, while If the relationship is reversed, it will give a signal of 0゛.

Therefore, like the maximum value detection circuit 3, when the minimum value detection circuit 4 receives a voltage signal from the information calculation circuit 2 during the scanning period using the scanning circuit 1a, the lowest level signal among the signals is converted into a digital value. After the scanning is completed, the digital signal of the down counter 18 is transferred to the storage register 22.

Further, the intermediate value calculation circuit 5 includes a value setting circuit 23 and an arithmetic circuit 24, and the k value setting circuit 23 sets the value of k to, for example, 0, 0.25, 0.5.0.75.
1 can be set, and these numerical values are converted into codes suitable for digital calculation in the arithmetic circuit 24, and the arithmetic circuit 24 receives the digital signals from the storage registers 17 and 22 as input, and inputs the digital signals from the storage registers 17 and 22. The operation shown in equation (1) is performed 1'J. This calculation result is input to the exposure time system 4111 circuit P provided in the camera and is simultaneously sent to the decoder 8. The maximum value and minimum value detection circuits 3.4 and intermediate value calculation circuit 5 are respectively connected to a display unit 10 as shown in FIG. 5 via decoders 6, 7, and 8. Now, FIG. 5 shows a display circuit in which the digital signal from the maximum value and minimum value detection circuits 3 and 4 and the intermediate value calculation circuit 5 is manually input as a 4-bit information signal. There are 16 states for a 4-bit input, but for example, the output for an input indicated by ``(] 000°'' is meaningless, so it is omitted and the remaining 00
Each decoder 6, 7.8 is provided with 15 output terminals so as to take display outputs for 15 states such as 01'', etc., and each decoder 6, 7.8 is provided with 15 output terminals, and each person can select one of the 15 terminals according to his or her ability. The configuration is such that only the output car Mizuko is set to high health "1".In addition, in FIG. 5, the switch SW □ shown in FIG.
As SW2, AND gates A N l to AND8 are used on the input side of each decoder 6.7.8. Normally, if a '0゛ signal is applied to one terminal 3a of each AND gate, the AND gates ANDl~A, N
Since D8 is closed, the inputs to decoders 6 and 7 are "
oooo", so no output appears from the decoders 6, 7, but if there is no "0" signal at the terminal 3a, an output appears from the decoder 6.7. Each decoder 6.7.
8 are configured in the same circuit and have the same response for the same input signal.
A signal of "1" is output from the - output terminal. The corresponding identical output terminals of each of the three decoders 6.7.8 are connected to the input of one OR gate,
Further, one light emitting element to L circuit 5, such as a light emitting diode, is connected to each of the outputs of the OR gates 1-OR1 to 0R15. Therefore, each decoder 6,
Even if signals are input to 7.8 at the same time, displays corresponding to the inputs can be simultaneously performed via respective OR gates. In this way, the difference between the bright and dark areas of the subject measured by the photometry circuit 1 is displayed on each of the light emitting elements L1 to L□5 of the display section 10.

The above examples are for bright areas and dark areas;! l
By simultaneously displaying the ILE exposure times on a dot-type display device as shown in FIG. 2, the difference between them can be visually displayed. Apart from such an embodiment, a maximum value detection circuit 3 and a minimum value detection circuit 4 are provided.
It is also possible to calculate the difference between the outputs of , and perform a display according to this difference. Various other arrangements of the circuit for such display are possible. In addition, in photometry circuit 1, 25
Although the implementation using the number of light receiving elements r is shown, the present invention is not limited to this number. Furthermore, the light receiving element f of the photometric circuit 1 is set to 1
Spot light metering may be performed individually, and information on each part of the subject may be obtained by manually scanning the subject with the exposure meter. For example, in the circuit shown in FIG.
By adding a circuit, it is also possible to select and use any one receiver.

In another embodiment of the present invention, the brightness information of the part intended by the photographer is measured and stored in two or more areas according to the photographer's command, and the information is displayed on the dot display section. The device may be configured to display the information simultaneously.

FIG. 6 shows still another embodiment of the present invention.

That is, in the circuit shown in FIG. 6, a plurality of light emitting elements are arranged in two rows, two dot display sections 30 and 32 are provided, and one of the display sections 30 has a maximum and minimum value detection circuit as shown in FIG. while displaying the respective outputs of the other display section 32.
In order to display the latitude L of the film used for shooting, the exposure range in which the density of the exposure meter and the film have a proportional relationship is displayed in correspondence with the display of the maximum and minimum values, and the maximum and minimum brightness of the subject is displayed. To easily check whether or not the film is within the latitude of the film. The analog output of the information calculation circuit 2 in FIG.
, -D conversion circuit 25 inputs one photoelectric element of the photometric circuit 1 to be scanned and converts it into a digital signal.
It is connected to maximum value and minimum value detection circuits 3' and 4' as shown in the figure. A value setting circuit 23 and an arithmetic circuit 24 connected to the maximum value and minimum value detection circuits 3 and 4 are the same as those shown in FIG. The film latitude code setting circuit 26, which is constituted by an encoder, determines the latitude of the film used in the camera.In other words, it is expressed in the same unit as the apex index, for example, the latitude l of negative color film.

When is set as 5 E v (levels), a value corresponding to 1/'21-, which is half the film latitude, is encoded into a signal suitable for calculation. This 1//2H- encoded signal is input to the adder circuit 27 and the arithmetic circuit 2
At the same time, the output signal of the arithmetic circuit 24 is added to the output signal of 17. L
subtract the signal. Therefore, the difference between the outputs of these circuits 27 and 28 corresponds to the film latitude, and each of the outputs is centered on the output of the arithmetic circuit 24, that is, the signal corresponding to the aperture value or shutter speed to be set in the camera. This corresponds to the point /2L. The dot display devices 29, 3 which display the outputs of the circuits 3', 4' and the circuits 27 and 28 are circuits for simultaneously lighting up two signals on the display sections 30 and 32, respectively, and are similar to the circuit shown in FIG. similarly configured. Also,
The maximum value detection circuit 3' in FIG. 6 consists of a conventionally known comparator 34 and a latch circuit 35 connected to a register 33 included in the A/D conversion circuit 25, as shown in FIG. The register 33 is composed of a latch circuit, and the A-D converted contents are temporarily transferred.The contents of this register 33 and the contents of the latch circuit 35 are compared by a comparator 34, and the contents of the latch circuit 35 are larger. If they are equal, the latch circuit 35 outputs a signal I-1" to the output terminal 34a. When the signal tr" is lowered from the comparator 34, the latch circuit 35 reads the contents of the register 33. The maximum value of is taken into the latch circuit 35. In addition, the minimum value detection circuit 4'' has an inverter (NOT circuit) connected to the output terminal 34a of the comparator 34 in FIG.
is connected so that when the output of the comparator 34 is L°, a latch signal of "H" is given to the latch circuit, so that the minimum value given to the register 33 is taken into the launch circuit 35.

The arithmetic circuit 24 that performs photographic arithmetic operations is well known, but to explain its original form in FIG. 8, a closed circuit consisting of a power source (I et al. This is a photoelectric conversion circuit that obtains a voltage signal proportional to the logarithm of the brightness of the light incident on PD2) from between the terminals of the diode (D Index (B v
) is proportional to A circuit in which potentiometers (2M3) and (P M4 ) are connected in parallel to another power supply (E',) produces voltage signals VS, VA proportional to the film sensitivity and the apex index Sv, Av of the lens aperture.
At the same time, a predetermined calculation is performed to obtain a voltage signal proportional to an apex index of 1.0 V of exposure time.

As is well known, the conditional expression for the appropriate exposure time in Apex is -I''v=Rv1Sv-Av=----(
l]. Therefore, in Fig. 8, the voltage between the sliding terminal (W3) of the potentiometer (1゛ to 43) and the connection point (P3) between the power supply (1゛・2) and the potentiometer (2M3) is determined by filter sensitivity. The sliding terminal (W4) of the potentiometer (PM4) and the power supply (E2)/potentiometer (I) are connected to the value Vs corresponding to the apex index.
'M4) and the connection point (P3) to a value corresponding to the apex index of the aperture value\, then the ground wire (P
The voltage between □) and terminal (P4) ■1 is V −I−=
V B 1s ”A, and the voltage V]- is
) corresponds to the apex index TV of the shutter speed obtained by the calculation shown in the equation.

Note that the potentiometers (PM) and (PM4) are connected to the power supply (
The point (P3) connected to the negative pole of E2) and the sliding terminal (W3) of the potentiometer (2M3), (PM4) (W
4) Voltage y5/, ■A/ corresponds to the apex index of film sensitivity and aperture value, respectively, the voltage, V-r
is v −r' == v 8− v5. ' + v A'
In this case too, electrical calculations corresponding to photographic calculations are carried out, and the voltage -F corresponds to the apex index of the correct shutter speed. In Figure 8, the sliding terminal (W3) of the potentiometer (1'M3) and the power supply (1+, 2)
, connection point between potentiometer and ri (PN43) (1>3)
The voltage between the value corresponding to the apex index of film sensitivity vs. the 1st auxiliary terminal of the potentiometer (PM4) (
W4), power supply (E2), potentiometer (1) M4)
When the voltage between the connection point (P3) and the connection point (P3) is set to a value VA corresponding to the apex index of the aperture value, the
The potential VT at the point (P4) is VT=VI, -t,
V S -V A-song (2) and l5, voltage \l・I
It can be seen that .corresponds to the apex index of the shutter speed obtained by the calculation shown in equation (1).

As is clear from the following, the present invention includes a large number of display parts arranged in a row to display the output of a photometric circuit, and an edge of the latitude of the film along the column direction of the row display parts. The present invention provides an exposure display device that has a display section that displays the position corresponding to the exposure value, and expresses the photographer's shooting intention by consciously relating film latitude, which has not been exposed in the past, to the photometric value. This makes it possible to make more appropriate exposure decisions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an exposure device according to the present invention;
FIG. 2 is a diagram showing the configuration of a display device in a light meter according to the present invention, FIG. 3 is a circuit diagram showing a specific configuration of a photometric circuit and an information calculation circuit, and FIG. 4 is a specific diagram of a maximum value and minimum value detection circuit. 5 is a circuit diagram showing the connection between the decoder and the display section, FIG. 6 is a block diagram showing the configuration of the light meter with two display sections according to the present invention, and FIG. 7 is a circuit diagram showing the connection between the decoder and the display section. FIG. 8 is a circuit diagram showing the configuration of the maximum value detection circuit, and is a diagram explaining the principle of the arithmetic circuit. DESCRIPTION OF SYMBOLS 1... Photometry circuit, 2... Information calculation circuit, 3... Maximum value detection circuit, 5... Intermediate value calculation circuit, 4... Minimum value detection circuit, 10... Display section, P□~ P25... Light receiving element, L□~r-15... Display element. Patent Applicant: Minolta Camera Co., Ltd. Representative Patent Attorney Aoyama Aoyama and 2 others

Claims (1)

[Claims] 1. A large number of display sections arranged in a row to display the output of a photometric circuit, and a position corresponding to the latitude edge of the film along the column direction of the row display sections. An exposure display device having a display section for displaying images. 2. A circuit is provided that adds or subtracts approximately half the value of the film latitude rl+ to the output based on the photometric circuit, and the output of this addition or subtraction circuit displays the position corresponding to the edge of the film latitude described in 2. Claim fI+J characterized by controlling the display position of the display unit
The exposure display device according to item 1.