JPH04256934A - camera - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a lens shutter camera that is capable of photographing with strobe light even during the day.

0002

[Prior Art] A programmable shutter that also serves as an aperture blade whose aperture gradually opens over time is popular for compact cameras because of its small size, simple mechanism, and low manufacturing cost. Widely used as a shutter. Furthermore, in recent years, electronic control of cameras using microprocessors and the like has progressed significantly, and it has become possible to control them with high precision.

[0003] With this electronic control, compact cameras have become highly automated. For example, the brightness of the subject to be photographed may be detected, and if the brightness does not reach a predetermined level, the electronic flash device built into the camera will be automatically activated to control the subject to the appropriate exposure. On the other hand, when the brightness exceeds a predetermined level, the electronic flash device is prohibited from operating, and proper exposure is achieved using only natural light.

Furthermore, even when the brightness exceeds a predetermined level, so-called daytime synchronized photography involves manually or automatically driving an electronic flash device and using it as an auxiliary light source when the subject is backlit. It is also becoming easier to do so. This has traditionally been a very difficult photographing method for beginners.

A conventional example in which daytime synchronized photography is possible is shown in FIG. 6, and will be explained based on this figure. Here, to simplify the explanation, we will use the central processing unit (hereinafter simply CPU).
The explanation will be given using an example in which a system (hereinafter referred to as "sequence control system") is used as a sequence control device.

[0006] Normally, the shutter is controlled by the energization time determined according to the brightness of the subject, film sensitivity information, exposure compensation information, and the like. For example, SW1 in the figure is closed in response to pressing of the photographing button, and when this is detected by the CPU, predetermined photometry/distance measurement operations are started. When this predetermined photometry/distance measurement operation is completed, the CPU determines the shutter control time and the control information for the electronic flash device according to these results. In response to further pressing of the shooting button, SW2 in the figure
is further closed. The CPU detects this, performs a predetermined lens drive operation, and then enters a shutter control sequence. Many of the program shutter control methods are
It is as follows.

For example, in control when the subject is bright and auxiliary illumination by an electronic flash device is not required (hereinafter referred to as AE control), the CPU energizes a means (for example, a photointerrupter) that detects the opening operation of the shutter, and then and an electromagnetic drive means (for example,
(stepping motor, moving coil, etc.). This energization causes the shutter to begin to open, and in response to the movement of the shutter, a predetermined signal is output from a detection means such as a photointerrupter. The CPU monitors this output signal and starts a delay timer after counting the pulse signal a predetermined number of times according to the shutter control time. When this timer finishes counting, the CPU stops energizing the shutter. As shown in FIG. 8, the shutter continues to move in the opening direction due to inertia for a while even after the power supply is stopped, but at a certain point the maximum aperture value F
max. reaches and begins to move in the closing direction. thus,
The delay timer is set so that the total exposure while the shutter is open is the appropriate exposure.

On the other hand, when the subject is dark and proper exposure cannot be achieved even when the shutter is fully opened, shutter control using an electronic flash device (hereinafter referred to as FA control) is performed as follows. The CPU determines a control aperture value calculated from the guide number of the electronic flash device, film sensitivity, and subject distance information output from the distance measuring device. The CPU has appropriate light emission timing information corresponding to this aperture value, for example, as a data table, and uses this timing information to control the electronic flash device. In the aforementioned AE control, there is a gap of several milliseconds between the shutter energization stop control timing and the actual movement of the shutter blade in the closing direction due to mechanical constraints such as inertia. Almost no control deviation occurs between actual light emission timings. Therefore, it is only necessary to trigger the electronic flash device at a predetermined light emission timing while the shutter starts to open and the aperture value gradually changes from a pinhole to a fully open value. At this time, the shutter closing command may be output at any timing after the shutter blades are fully opened, and there is no problem as long as it is a time that does not cause camera shake. That is, since the electronic flash device was used so that the subject would be properly exposed, there would be no problem with the photograph even if the total exposure, that is, the background, was not proper.

Now, even when the subject is bright, when using an electronic flash device as an auxiliary light source in a backlit situation, the above-mentioned AE control and FA control must be skillfully combined. With SW3 in Figure 6 turned ON, press the shooting button S.
When W1 is pressed, the CPU determines that the mode is a so-called forced flash mode, in which the electronic flash device is used regardless of the brightness of the subject. In this case, the trigger timing of the electronic flash device is a problem. A qualitative explanation of this is as follows. As shown in FIG. 7, if the FA control is performed in exactly the same way as the FA control described above, the shutter close timing will be earlier than the trigger point when the photometric value is very bright. Therefore, when the electronic flash device is triggered, the shutter is not at the predetermined aperture value but at a much smaller aperture value, which reduces the effect of emitting light as auxiliary light. Furthermore, in an extreme case, the trigger point will be the point at which the shutter has closed, resulting in unnecessary light emission that is completely meaningless as auxiliary light.

On the other hand, as shown in FIG. 9, if the electronic flash device is triggered in synchronization with the shutter closing command timing, the completely meaningless light emitted as described above will not occur, and the shutter will always open. It will start emitting light when the light is on. However, in this case, even when the shooting distance of the subject is small and the appropriate FA light emission timing is * in the figure, the light is emitted at a larger aperture value (●), resulting in overexposure.

[0011] Therefore, during daytime synchronized shooting,
A control device is known that is configured to trigger an electronic flash device at the earlier of shutter closing timing and FA appropriate light emission timing, that is, giving priority to a small aperture.

Furthermore, considering that there is a delay of several milliseconds between the time when the shutter closing command is output and the time when the shutter reaches its maximum aperture diameter as described above, it is also possible to A control device that is equipped with a means for measuring the delay time or a mechanical mechanism linked to the shutter closing command, and configured to trigger the electronic flash device at the earlier of the time when the delay time has elapsed or the appropriate FA time. is also known.

[0013]

[Problem to be Solved by the Invention] However, as described above, during daytime synchronized photography, it is necessary to control the electronic flash device as an auxiliary light source to maximize its effect while ensuring proper exposure for both the subject and the background. That is very complicated.

[0014]Furthermore, the light emission timing that provides the appropriate subject exposure level must be determined from a large number of combinations of photometry values and distance measurement values. Having it as a table is impractical and very inefficient.

Furthermore, as already mentioned, in order to realize the control that prioritizes small apertures by taking into account the difference between the shutter closing timing and the timing when the shutter actually reaches its maximum aperture diameter, a new timing means is required. It becomes necessary to provide one. However, for example, in a shutter control system configured to correct the trigger timing of an electronic flash device according to the shutter opening speed, the CP
If you include the shutter speed detection timer built into the U, the closing timing timer, the light emission timing timer, and even the energization cutoff timer in the unlikely event that the shutter does not open, the number of timers to be managed will increase. As a result, the control program for managing these timers becomes extremely complex.

[0016] Furthermore, since the shutter described here is often used in compact cameras and has very large manufacturing cost constraints, if it is constructed from the mechanical structural members mentioned above, This is undesirable because it causes increased manufacturing costs, space-saving problems, and decreased reliability.

[0017] As described above, when controlling the subject and background to have proper exposure during daytime synchronized photography, the control method becomes complicated, the number of timers increases, the number of mechanical components increases, and the space taken up is increased. This was not very desirable as it led to an increase in The purpose of the present invention is to solve the problems inherent in the conventional cameras described above, and to make it possible to properly expose the subject and background even during daytime synchronization shooting.
Moreover, it is an object of the present invention to provide a camera (particularly a lens shutter camera) that does not cause a complicated control method, an increase in the number of clock timers, or an increase in the number of mechanical components.

[0018]

[Means for Solving the Problems] The present invention simplifies the control method by providing a first aperture value information output means that changes depending on the brightness of the subject, and also controls the exposure during daytime synchronized shooting. To provide a camera that can be controlled to an appropriate level.

[0019]

[Embodiment] FIG. 1 shows a first embodiment of the present invention.
FIG. 3 shows the control timing of the program shutter provided in the camera according to the present invention. In Figure 1,
1 is a CPU, 2 is a photometer, 3 is a shutter maximum aperture information output means, 4 is a distance measuring device, 5 is an electronic flash device, and 6 is a shutter drive device. Further, SW1 is a switch that closes with the first stroke of pressing down a shooting button (not shown);
2 is a switch that similarly closes on the second stroke of pressing down the shooting button.

[0020] When the CPU detects that SW1 is closed in response to the first press of the shooting button, the CPU
Controls the photometric device and receives information such as brightness and distance information about the subject. First, R
The data is read from the OM and stored in the data RAM inside the CPU. This aperture value information can also be written on the ROM where the control program is normally written, but here
This shows a case where data is read from a ROM external to the U. Subsequently, second aperture value information corresponding to the light emission timing of the electronic flash device according to the subject distance information is read from the ROM and similarly stored in the data RAM inside the CPU.

The CPU compares and calculates the two aperture value information stored in the RAM, and stores data corresponding to the smaller aperture value in the RAM as control aperture value data.

Next, trigger signal output timing information corresponding to the aperture value data stored in this RAM is read out from the ROM, and this is used as trigger timing data for the RA.
Store in M.

On the other hand, the shutter closing timing control information corresponding to the luminance information of the subject is also read out from the ROM and then stored in the RAM.

Now, in response to further pressing of the shooting button, S
When W2 is further closed, the CPU detects this, performs a predetermined lens driving operation, and then enters a shutter control sequence. First, the CPU sets the SHiRED terminal to H.
By setting the level, the photointerrupter is energized,
By setting the SHOPN terminal to H level, the shutter driving means, which is an electromagnetic driving means, is commanded to open the shutter. As a result, as the shutter begins to open, a waveform-shaped digital signal (hereinafter referred to as PI signal) is generated at the output terminal of the comparator depending on whether or not light passes through the slit provided in the shutter blade. do. The CPU counts the state changes of this PI signal, and when the CPU counts the number corresponding to the pinhole position, for example, it starts the operation of a timer for measuring control time. Thereafter, the CPU compares the value counted by this timer with the shutter closing timing value and trigger timing value stored in the RAM described above. Then, when the timer count value and the trigger timing value match, the CPU
The terminal is set to H level and a trigger signal is output to trigger the electronic flash device. Also, when the timer count value and the shutter closing timing value match, the CPU
The OPN terminal is set to L level and a closing command is output to the shutter driving means to close the shutter.

[0025] In this way, the flash trigger timing of the electronic flash device is calculated in advance by the CPU so as to always give priority to the small aperture in accordance with the subject brightness and subject distance. Both the image and the background can be properly exposed, and the electronic flash device can be used most efficiently as an auxiliary light source.

In the above-mentioned embodiment, the CPU has been treated as a sequence control device to simplify the explanation, but the present invention is not limited to this embodiment, and for example, as shown in FIG. It is also possible to implement the embodiment as shown. In this embodiment, a voltage converter 8 is used which outputs a voltage corresponding to the maximum aperture diameter of the shutter in accordance with the voltage value BVOUT which changes in accordance with the brightness of the subject.

Furthermore, as shown in FIG. 5, the distance measuring device may obtain a plurality of pieces of distance information within the screen and output one piece of distance information. The distance measuring device of the first embodiment may be replaced as is.

[0028]

[Effects of the Invention] As explained above, in the camera of the present invention, the flash trigger timing of the electronic flash device is calculated in advance by the CPU so that priority is always given to the small aperture according to the subject brightness and subject distance. Therefore, both the subject and the background can be properly exposed during daytime synchronized photography. In both cases, the electronic flash device can be used most efficiently as an auxiliary light source.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a camera according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a camera according to a second embodiment of the present invention.

3 is a diagram for explaining the timing of shutter control and light emission control of a flash device in the camera shown in FIGS. 1 and 2. FIG.

FIG. 4 is a diagram showing the configuration of a camera according to another embodiment of the present invention.

FIG. 5 is a diagram showing the configuration of a camera according to still another embodiment of the present invention.

FIG. 6 is a diagram showing a schematic configuration of a conventional camera.

7 is a diagram for explaining shutter control and light emission control of a flash device in the camera shown in FIG. 6. FIG.

FIG. 8 is a diagram for explaining shutter control in the camera shown in FIG. 6.

9 is a diagram for explaining shutter control and flash device control in the camera shown in FIG. 6. FIG.

[Explanation of symbols]

1: Sequence control device (CPU) 2: Photometer 3: Shutter maximum aperture information output means 4
: Distance measuring device 5: Electronic flash device
6: Shutter drive device 7: External data ROM
8: Voltage converter 9: A/D converter

Claims (3)

[Claims] 1. A photometer that outputs brightness information of a photographic subject; a distance measuring device that outputs distance information of a photographic subject;
It is equipped with a film sensitivity reading device that detects the sensitivity information of the film loaded in the camera, a programmable shutter that also serves as an aperture blade that gradually opens its aperture over time, and an electronic flash device that illuminates the subject. In the camera, means for outputting first aperture value information corresponding to a maximum aperture value of the shutter corresponding to output information of the photometry means, distance information output from the distance measurement device and a guide for the electronic flash device. means for calculating second aperture value information from the number and the film sensitivity information; and means for calculating the electronic flash device at a timing corresponding to the smaller aperture value information of the first aperture value information and the second aperture value information. A camera comprising: means for triggering; and a means for triggering. 2. The electronic flash device according to claim 1, further comprising means for outputting correction information corresponding to the opening speed of the shutter, and means for correcting timing for triggering the electronic flash device in accordance with the correction information. camera. 3. The camera according to claim 1, wherein the distance measuring device is configured to calculate and output one piece of distance information from distance information of a plurality of points within the photographic screen.