JPS62180340A - Daylight synchronizing flash control method - Google Patents

Abstract

PURPOSE:To perform proper daylight synchronized flash photography by controlling the quantity of lighting of an electric flash to a value set according to the relation between an elapsed time and information on distance to a subject, and starting shutter closing operation when the integrated quantity of light reaches or almost reaches proper exposure. CONSTITUTION:Information obtained by converting light into an electric signal by a light measuring circuit 6 is inputted to an integration circuit 7, whose integral output 8 is inputted to the 1st and the 2nd comparators 9 and 10. The 1st comparator 9 compares the integral output 8 with the 1st specific value 12 below the proper quantity 11 of exposure and the 2nd comparator 10 compares the integral output 8 with the 2nd specific value 13 set to or almost to the proper quantity of exposure; and the 1st and the 2nd detection outputs 14 and 15 are inputted to a CPU 16 which controls the whole. A shutter driving circuit 17 opens and closes a shutter 3 according to an opening command 18 and a closing command 19 from the CPU 16. A distance measuring circuit 20 receives a distance measurement command 21 from the CPU 16 to measure the distance to a subject 1 and outputs distance information 23 together with a distance measurement end pulse 22 when the measurement is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a daytime synchronization control method for a camera using a lens shutter.

Conventional technology Cameras that use a lens shutter use a daytime synchronization control method that starts the shutter opening operation, then starts the shutter closing operation when the integrated amount of light transmitted through the lens reaches the appropriate exposure amount, and simultaneously fires the strobe at full capacity. It is used.

Problems to be Solved by the Invention However, in the above-mentioned method, processing is not performed in accordance with the distance to the subject, so the exposure of the subject image is not appropriate.

Also, since the strobe is always firing at full capacity, the battery is consumed rapidly, and there is a lot of wasted time in charging the flash capacitor.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method in which the integral amount of light transmitted through the lens and shutter after the start of the shutter opening operation, or the equivalent amount of light that changes, is less than the appropriate exposure. 1st
When the strobe reaches a predetermined value, the strobe starts emitting light, and the amount of light emitted is controlled to a value set as a function of the elapsed time and distance information to the subject, and the integrated amount is determined to be appropriate exposure, Alternatively, control is performed so that the shutter closing operation is started when the temperature reaches that vicinity.

By using these means, proper daytime synchronization is possible regardless of the distance to the subject.

Furthermore, since the amount of light emitted at that time is suppressed to the minimum necessary, there is less power consumption and less time lost in charging the light emitting capacitor.

Embodiment FIG. 1 is a block diagram for explaining a daytime synchronization control method according to an embodiment of the present invention.

The reflected light from the subject 1 passes through a lens 2, a shutter that also serves as an aperture (lens shutter) 3, and a half mirror 4, and then reaches an imaging unit 6.
image is formed. Further, a part of the reflected light from the noof mirror 4 enters a photometry circuit 6, and the light that changes equivalently to the amount of light incident on the imaging section 6 is photometered.

The information converted from light into electrical signals by the photometric circuit 6 is input to the integrating circuit 7, and its integrated output 8 is sent to the first . The first comparison circuit 9 receives the first predetermined value 12 which is less than or equal to the appropriate exposure amount 11 and the integral output 8, and the second comparison circuit 1o receives the appropriate exposure amount, Alternatively, the second predetermined value 13 set near the second predetermined value 13 and the integral output 8 are compared, and the first.
The second detection output 14.15 is sent to the CPU 1 which controls the entire control.
Enter e.

The shutter drive circuit 17 receives an opening command 18 from the CPU 1e.
, the shutter 3 is opened and closed according to the closing command 19.

The distance measurement circuit 2o receives a distance measurement command 21 from the CPU 16, measures the distance to the subject 1, and outputs distance information 23 together with a distance measurement completion pulse 22 when the distance measurement is completed.

The reset pulse 24 resets the integral output 8 of the integral circuit 7 and also resets the timer 25.

Further, the timer 26 measures until the first detection output 14 is obtained from the reset operation, and is addressed by the timer output 26 and the A-D output 28 obtained by converting the distance information 23 by the A-D conversion circuit 27. The output of the ROM table 29 is input to the strobe light emission control circuit 31 as light emission time information 3o. The strobe light emission control circuit 31 receives a light emission ON pulse 32 from the CPU 16 and outputs a light emission pulse 33 having a width corresponding to the light emission time information 30, and the strobe light 34 emits light toward the subject 1.

The mode selector switch 36 is a switch for switching between a daytime synchro mode 36 and a normal mode 37, and its mode signal 38 is input to the CPU 16, and a release pulse 39 requesting exposure is similarly input from the release switch 40. Ru.

FIG. 2 is a waveform diagram showing waveforms of various parts of the block diagram shown in FIG. This waveform diagram shows the mode selector switch 36.
shows the case where the daytime synchronization mode 36 is selected, and the normal mode 37 is omitted because it has no direct relation to the present invention.

When the release pulse 39 is input to the CPU 16, the CP
U outputs a distance measurement command 21, and after measuring the distance, the distance measurement circuit 20 outputs a distance measurement completion pulse 22 and also outputs distance information 23 to the CPU 16.

Next, the CPU outputs the reset pulse 24 and integrates the output 8.
, and after resetting the timer 26, an opening command 18 is output to start an opening operation in which the opening amount 41 of the shutter 3 increases as shown in the figure. Therefore, the integral output 8 also increases as shown in the figure,
When the first predetermined value 12, which is less than the appropriate exposure amount, is reached, the first detection output 14 is obtained, the timer 26 stops measuring, and at the same time, the light emission is turned on. . Further, the amount of light emitted is controlled according to the light emitting time information 30 from the ROM table 29 addressed by the timer output 26 and the A-D output 28 obtained by converting the distance information 23.

During this light emission period, the increase in the exposure amount of the imaging section 6 becomes large, so the integral output 8 changes as shown in the figure, and when it reaches the second predetermined value 13 set at or near the appropriate exposure, the second A detection output 16 is obtained.

Upon receiving this output, the CPU 1e outputs a close command 19 to close the shutter 3 and complete the exposure in the daytime synchro mode.

Generally, the shutter 3 that also serves as an aperture is a governor (not shown).
etc. to control the opening operation and obtain a stable opening operation as shown in the figure, the timer output 26 is controlled by the strobe 34.
0 indicates the aperture value of the shutter 3 when it starts firing. Also, in order to obtain proper exposure with a strobe when the brightness is very low, the amount of light emitted by the strobe = aperture value x distance...・(1
), but since the strobe light emission period is less than 1m5ec at the maximum compared to the time it takes for the shutter 3 to reach its maximum aperture from the closed state (several tens of milliseconds), the light emission period Changes in the aperture value during shooting are small, and there is little error even if the required light emission amount is calculated assuming that the aperture value is constant during the flash period of the strobe 34 in any photographing.

FIG. 3 shows a ROM table 290 that is addressed by the timer output 26 that indicates the aperture value of the shutter 3 when the strobe 34 fires, and the distance information 23 to the subject.
0 indicates 0 As shown above, the amount of light emitted according to the distance to the subject is obtained,
Furthermore, since the shutter 3 is configured to close when the second detection output 16 is obtained, appropriate exposure of the peripheral area can be obtained.

In the above description, the light passing through the lens 2 and shutter 3 is photometered, but the same operation can be performed even if the light that changes equivalently is photometered.

Effects of the Invention With the following configuration, proper daytime synchronization is possible regardless of the distance to the subject, and since the strobe light emission is kept to the minimum necessary, power consumption is low and the capacitor for light emission is easily charged. There is also less loss time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram of each part thereof, and FIG. 3 is an explanatory diagram of the contents of a ROM table. 1...Subject, 3...Shutter, 6.
...Photometering circuit, Complete...Integrator circuit, 8...
...Integral output, 9...First comparison circuit, 1
o...Second comparison circuit, 12...First
predetermined value, 13... second predetermined value, 14...
...First detection output, 16...Second detection output, 16...CPU, 17...Shutter drive circuit, 18...Opening Directive, 19...
...Close command, 2o... Distance measurement circuit, 23...
...Distance information, 24...Reset pulse, 2
6...Timer, 26...Timer output,
28...A-D output, 29...ROM
Table, 3o... Light emission time information, 31...-
... Strobe light emission control circuit, 32 ... Light emission O
N pulse, 34... Strobe, 36...
・Daytime sync mode, 3B...Mode signal,
39...Release pulse.

Claims (1)

[Claims] When the integral amount of light transmitted through the lens and shutter after the start of the shutter opening operation, or equivalently changing light, reaches a first predetermined value that is less than the appropriate exposure, the strobe starts emitting light, and The amount is controlled to a value set as a function of the elapsed time and distance information to the subject,
A daytime synchronization control method, characterized in that a shutter closing operation is started when the integral amount reaches appropriate exposure or its vicinity.