JPS58142323A - Display of exposure controlled value - Google Patents

Abstract

PURPOSE:To make the time measuring device necessary for a long time photographing unnecessary, by providing a function to display the second time for exposure and a timer function after apex-operating a photometric output and other information digitally. CONSTITUTION:A mode changing-over switch 13b is set at a photometric mode, and the film sensitivity and an F value are set by switches 13c, d, and when a photometric switch 12 is turned on, an output of a photometric circuit 1 and the film sensitivity and the F value are apex-operated digitally to display 14 the second time for exposure. When a timer mode is set, the subtraction is repeated by output pulses of generation circuits 16, 17 of reference time from the measuring second time or the set second time to display 14 at the same time, and when the second time comes to 0, a signal is outputted to an alarm circuit 7 to alarm. An automatic control is also possible by outputting an alarm signal to an outer controlling circuit 18.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exposure control value display device for a light meter, a camera, etc.

Conventionally, when setting a shutter speed for a long time on a camera, the longest shutter speed of the camera is generally about 1 second, so it was necessary to set the shutter speed to Pulp and manually release the shutter while measuring the time with a stopwatch etc. was cutting.

However, this method has the disadvantage that it requires a device for measuring time, such as a stopwatch, and is cumbersome to operate.

In view of the above points, the present invention has a built-in timer function to display the real time of exposure time relative to brightness information and to set the shutter opening time when photographing a low-brightness scene. The purpose of this invention is to provide an exposure control value display device that makes it possible to display the exposure control value and eliminates the need for a time measurement device.This will be explained below based on an embodiment shown in the drawings. In the block diagram showing the circuit, 1 is a photometric circuit, 2
is the apex value Bv1 of the brightness information from the photometric circuit 1'')
: A/D conversion circuit that converts the electrical signal corresponding to the digital signal into a digital signal; 3 is a central processing unit that performs digital calculations on the digital signal to make it suitable for display; 4 is a digital display device that displays exposure information; 5 is a digital display device that displays exposure information; A reference time generating circuit, 6 a switch circuit for setting various exposure information, and 7 an alarm circuit.

The operation of this embodiment configured as above will be described next. First, a signal corresponding to the brightness information in terms of apex value from the photometry circuit 1 is converted into a digital signal D (Bv) by the A/D conversion circuit 2. The relationship between the apex value Bv of the luminance information at this time and the digital signal D (Bv) output from the A/D conversion circuit 2 is as shown in the table of FIG. The digital signal D (Bv) is manually inputted to the central control device 3, and digital signals D (Sv) and D (Av) corresponding to the set film sensitivity and the set F value are inputted by the switch circuit 6 (third (See Figure and Figure 4).

Thus in the central control unit 3 D(Tv) = D(''v) + D(Sv) + K-
A digital calculation D(Av) (K=80) is performed, and a digital signal D ('r5□) corresponding to the exposure time is obtained. Next, the side light seconds are determined from the calculated digital signal D (Tv), but first, from the table shown in FIG.
The maximum X value that does not exceed (Tv) is determined, and the corresponding multiple series shutter speed is digitally displayed on the display device 4. This completes the photometry mode, but when used as a timer, the switch circuit 6 switches to the timer mode. As a result, the actual time Tx at this time is obtained from the X value, and further, Y=D(TV)-X is calculated to obtain the magnification α from the table shown in FIG. From Tx and α thus obtained, TI=Tx·α is calculated to obtain the real time T of exposure time for the luminance information, and this is displayed on the display device 4 in minutes and seconds. In addition, D(Tv) of the real time T of the calculation result
The error with respect to the theoretical value T' calculated from is as shown in the table shown in FIG. 6, and does not pose a problem in practice. Here, time is counted by the pulse output from the reference time generating circuit 5, and when the actual time T is reached, the alarm circuit 7 is activated and an alarm is issued.

FIG. 7 shows a light meter according to the present invention, where 10 is the entire light meter, 11 is a light receiving section, 12 is a photometry switch, and 13 corresponds to the switch circuit 6 in FIG. 1. FF switch 13a.

Mode selection switch 13b, film sensitivity switch 13
It has a C9F value switch 13d, a start switch 1361, and a stop switch 13f. 14 is the film sensitivity set in photometry mode.

This is a digital display device that can display the set F value and shutter speed, and can also display the actual shutter speed time in timer mode.

FIG. 8 is a block diagram showing the electrical circuit of the exposure meter of FIG. 7, and the same elements as in FIGS. 1 and 7 are given the same reference numerals. 15 is a light-receiving element disposed in the light-receiving section ll;
16 is a crystal oscillation circuit, 17 is a frequency dividing circuit that outputs a 10 Hz pulse, and 18 is an external control circuit.

Next, the operation will be explained according to FIG. First, use the film sensitivity switch 13C and F value switch 13d of the keyboard 13 to set the film sensitivity to, for example, ASA.
When the F value of IQQ is initialized to, for example, 5.6, these numerical values are displayed on the digital display device 14. When the switch is turned on here, the 0N10FF switch 13a
, film g degree X (border 13c, F value switch 13
(When either l or mode selector switch 13e is turned on, the power can be turned off, the setting film sensitivity can be changed, and the setting F
Value changes and mode switching are activated. If each of the above switches is not turned on or after changing the set value,
When the photometry switch 12 is turned on, the signal output from the photometry circuit 1 is converted into a digital signal D (Bv) based on the brightness information (Bv) from the light receiving element 15, and the set film sensitivity and F value that have already been input are converted into a digital signal D (Bv). Using digital signals D(Sv) and D(Av) corresponding to DC(v) = D(
Bv) +D (Sv) 10K -D CAV)
(K=80), a digital signal D (Tv) corresponding to the exposure time is calculated, and is further converted into a multiple series shutter speed and digitally displayed on the display device 14. Note that the contents of the tables shown in FIGS. 2 to 6 are stored in the central processing unit 3. Here, for example, Bv = −
3,5, film sensitivity A S A 100 s F value 2
Considering case 2, from Figure 2 to Figure 4, D (Bv)
-15s D(”v) = 40, D(Av) =
90 and D(Tv) = 45 is calculated. Therefore, the shutter speed am is obtained from FIG. 5(A) and displayed on the display device 14 as shown in FIG. 9 (A+).After this, the state after the initial setting is return.

When using it as a timer, it is sufficient to turn on the start switch 138 again from this state and then turn on the mode changeover switch 13b.

The case of timer mode will be explained below with reference to FIG. When photometry is performed in the above photometry mode, first find the integer part X' of (D(Tv)÷10), then Y'=
Find the decimal part Y' which is D(TV)-10-X'. Here, X' and Y' have a relationship of x=10.x' and .Y=τ, respectively.

Further, the real time Tx in exposure seconds is read from the integer part 7, that is, the X value, and the correction magnification α is read from the decimal part Y', that is, the Y value. In this way, 'r='rx・α is calculated, converted into minutes and seconds, and displayed digitally on the display device 14. At the same time, the set film sensitivity and set F value that were previously displayed are changed to OF.
Make it F. In the case of the above example, from D(Tv) = 45, " = 4 t " = 0-5 is obtained, and Tx = 256
seconds), α = 0.71, and from fixed-point calculation T
x・α = 181.76 C seconds) is obtained, but after rounding down, T = 181.7 (seconds) is obtained. This is converted into minutes and seconds and displayed on the display device 14 as shown in FIG. 9 fb). If photometry is not performed in the photometry mode, T-0 is set and displayed in the same way.

When the switch is turned on here, 0N10F'? When the switch 13a is turned on, the power is turned off, and when the timer set switch is turned on, T, ..., T+
1 is performed and the photometric value and ' can be set to an arbitrary time different from each other. Next, when the start switch 13e is turned on, T is saved as BT=T, and when there is a division output from the frequency dividing circuit 17, T = T -0,1 (seconds) is calculated, which is converted into minutes and seconds and displayed on the display device. 14 is displayed. If the stop switch 13f is turned on here, the state returns to the state before QNing the switch, but if the switch 13f is not turned on and T is not 0, the state returns to the state after T was saved, and this operation is resumed. repeated i.e. T=T −0
*i is calculated, the result is displayed, and when 4°T=0, a signal is output to the alarm circuit 7 to activate it and issue a warning through a speaker or the like. After a certain period of time, for example 3 seconds, T
=BT, restore T to the above-mentioned saved T, and return to the initial state C of the timer mode.

Here, by outputting the output to the above-mentioned alarm circuit also to the external control circuit shown in FIG. 8, automatic control of external equipment, electromagnetic release, etc. becomes possible.

As described above, according to the present invention, by incorporating a timer function in the exposure control value display device, when photographing a low-luminance scene, it is possible to obtain a display of the real time of 1 light second for luminance information and to open the shutter. Since the time can be set and an alarm is issued when a predetermined exposure time has elapsed, there is no need for a time measurement device such as a stopwatch under the above shooting conditions, and there is no need to continue monitoring in order to issue an alarm. Moreover, since it can be set to any time, it has the advantage that it can also be used simply as a timer.

Although the above description has been made regarding the case where the present invention is applied to a light meter, the present invention is not limited to this, and can be incorporated into an automatic exposure camera, for example, to perform long-term automatic exposure.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of an exposure control value display device according to the present invention, and FIGS. 2 to 4 show digital signals D (Bv), pD (Sv), and A table showing the relationship between D(Av), brightness information Bv, film sensitivity and F value, and FIG. FIG. 6 is a table showing the difference between the exposure time Tx obtained by the present invention and the theoretical value T'. FIG. 7 is an external view of the light meter according to the present invention. A block diagram showing the electric circuit of the exposure meter in Figure 9. Figure 9 is a display example of the exposure meter in Figure 7. (A) is a diagram showing the light metering mode, (B) is a diagram showing the timer mode. Figure 10 is a diagram showing the light metering mode. Flowchart showing operation in mode. FIG. 11 is a flowchart showing operation in timer mode. 1...Photometering circuit, 2...A/D conversion circuit,
3...Central processing unit, 4.14...Display device, 5
・・Reference time generation circuit, 6・Medium switch circuit, 7・・・
Information circuit, 10... Exposure meter, 11. Instep light receiving section, 12
...Metering switch, 13...Keyboard.・S941・ Agent Yasushi Shinohara: λj° Former 11th Portrait,' 1 Figure 51P2 Figure 5j'3 Figure 4 Figure 5 (A) (B) Procedural Amendment (Method) June 1982 July 23rd, Commissioner of the Japan Patent Office, Mr. 1, Indication of the case, Patent Application No. 1982-24336, Publication No. λ, Name of the invention, Exposure control value display device, person who makes the amendment, Patent applicant 5, Date of amendment order, 1980, 5th son. 25th, 6, column for detailed explanation of the invention and column for brief explanation of drawings of the specification to be amended. 7. Contents of amendment (1) “Table of Figure 2” on page 4, line 10 of the specification letter has been changed to “Table 2”.
"Fig." is corrected. (2) "Table J" on page 4, line 20 of the specification letter is corrected as r-charts J. (8) "Table" on page 5, lines 7 and 12 of the specification is corrected as "figures and tables." (4) "Table" on page 7, line 15 of the specification is corrected to "figures and tables." (6) "Table" in lines 9, 11, and 13 of page 11 of the specification is corrected to "r-diagram." 115

Claims (1)

[Scope of Claims] (1) A photometric circuit that converts field brightness information into an electrical signal, a MU/D conversion circuit that converts the electrical signal from the photometric circuit into a digital signal, and photographic engineering information are set. a central processing unit that performs digital calculations suitable for display from the digital signal and information input to the switch circuit; a digital display device that displays exposure information; a reference time generation circuit; It includes an alarm device that notifies the end of the shutter open time, and inputs a signal corresponding to the apex value of the brightness information and a signal corresponding to the apex value of the set exposure value, and sends a signal corresponding to the apex value of the exposure control value to the center. A processing device digitally calculates the shutter open time data at the address specified by the data corresponding to the integer part of the apex value, and the correction magnification at the address specified by the data corresponding to the decimal part of the apex value. An exposure control value display device, characterized in that the shutter opening time is determined as the product of the time specified by the integer part and the magnification specified by the decimal part by storing the information. (2) It is characterized by having a timer function configured to repeatedly subtract from the obtained shutter opening time by the output pulse of the reference time generation circuit, and when this becomes 0, an alarm is issued by the alarm circuit. The device according to claim (1). (8) The device according to claim (2), characterized in that the timer function is made independent by allowing the timer one hour to be set independently of the shutter open time. (4) The device according to any one of claims (1) to (8), characterized in that the alarm circuit outputs a signal to the outside to control an external device at the same time as the alarm circuit issues the alarm.