JPH086108A - camera - Google Patents

Abstract

PURPOSE:To provide a camera capable of increasing the number of photographing per unit time in consecutive photographing. CONSTITUTION:The camera is constituted of a photographic lens 21 forming the image of the optical image of an object, a spatial light modulating element 10 which is arranged in the optical axis of the lens 21, reflects a luminous flux entering from the lens 21 and can change the direction of the reflected luminous flux to the first direction and other directions, a film 23 arranged in the first direction, a driving means 24 driving the spatial light modulating element 10 in the first direction only during a previously set exposure period and other directions except a exposure period, a motor driving means 26 winding the film after the exposure period is completed and a consecutive photographing means 25 starting the exposure in the exposure period, when a shutter button is depressed and the exposure in accordance with the completion of the winding while the shutter button is depressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera which uses a spatial light modulator for changing the direction of a reflected light beam in a shutter mechanism and performs continuous photographing.

[0002]

2. Description of the Related Art Generally, continuous shooting means that the camera continuously releases the shutter while the shutter button is pressed.
This refers to shooting in which multiple frames of film are sequentially exposed.

With such continuous photographing, a series of movements such as sports photographs can be photographed. In addition, by performing continuous shooting, it is possible to reliably capture a momentary photo opportunity for a subject that changes every moment, such as a facial expression of a person.

In recent years, functions such as an auto winder and a motor drive have been built into the camera so that continuous shooting can be easily performed. FIG. 6 is a diagram showing a camera that performs continuous shooting of this type.

In the figure, a film 2 is arranged on the image forming surface of a taking lens 1, and a quick return mirror 3 is arranged between the taking lens 1 and the film 2 in an inclined manner. A focal plane shutter 4 including a front curtain 4a and a rear curtain 4b is arranged immediately before the film 2, and a motor drive 5 is arranged as a film winding mechanism.

A shutter / mirror driving circuit 6 is connected to the focal plane shutter 4, and a quick return mirror 3 and a continuous shooting circuit 7 are connected to the shutter / mirror driving circuit 6. The continuous shooting circuit 7 has a shutter button 7a.
And the motor drive 5 is connected.

A pentaprism 8 is arranged at a position where the light flux from the taking lens 1 is reflected by the quick return mirror 3 and forms an image. In the camera having such a structure, the incident light from the subject is condensed by the photographing lens 1, is reflected by the quick return mirror 3, and forms an optical image on the lower surface of the pentaprism 8. This optical image is reflected inside the pentaprism 8 and viewed by the photographer as an erect image.

Here, when the shutter button 7a is pressed,
The shutter / mirror drive circuit 6 is activated by the continuous shooting circuit 7, the quick return mirror 3 is flipped up, and the incident light flux from the taking lens 1 reaches the focal plane shutter 4.

In this focal plane shutter 4,
The front curtain 4a and the rear curtain 4b move laterally with a time lag. The incident light flux passes between the front curtain 4a and the rear curtain 4b (hereinafter referred to as “slit”) to expose the film 2.

When such crossing of the slit is completed,
The front curtain 4a and the rear curtain 4b are returned to the initial positions in the closed state, and the continuous drive circuit 7 activates the motor drive 5 to wind the film 2.

As described above, the photographing of one frame of the film is completed. While the shutter button 7a is pressed,
Continuous shooting is performed by the continuous shooting circuit 7 repeating the above-described shooting of one frame.

[0012]

However, the conventional camera has a problem that the quick return mirror 3 needs to be moved up and down every time one frame is photographed, which requires a lot of time for its operation.

In order to expose one frame, the front curtain 4a
Further, there is a problem in that it is necessary to move the trailing curtain 4b to traverse the exposed surface of the film 2, which requires time for its operation.

Further, there is a problem that it is necessary to brake the front curtain 4a and the rear curtain 4b that have traversed the exposure surface and return them to their initial positions each time the photographing of one frame is completed. In this way, because it takes a long time to shoot one frame,
In the conventional camera, the number of frames to be photographed per second is limited to about 2 to 5 frames / sec.

Therefore, the continuous shooting using the conventional camera has a problem that the shooting speed is slow. By performing continuous shooting with the quick return mirror 3 removed from the optical path, the speed can be increased to about 10 frames / sec. However, since the viewfinder's field of view is blocked during continuous shooting, normal continuous shooting is possible. Not suitable for.

Therefore, it is an object of the present invention to provide a camera in which the shooting speed in continuous shooting is increased.

[0017]

According to a first aspect of the present invention, there is provided a photographing lens for forming an optical image of an object, a photographing lens arranged on the optical axis of the photographing lens, and reflecting an incident light beam from the photographing lens. In addition, the spatial light modulation element in which the direction of the reflected light beam can be changed between the first direction and the other direction, the film arranged in the first direction, and the direction of the reflected light beam are changed only during a predetermined exposure period. In the direction of 1 and driving means for driving the spatial light modulating means in other directions other than the exposure period, when the exposure period ends, motor drive means for winding the film, and when the shutter button is pressed, The present invention is characterized by comprising continuous shooting means for starting exposure during the exposure period and during the period when the shutter button is pressed, in response to the end of winding.

The invention described in claim 2 is characterized in that the above spatial light modulation element is a digital micromirror element in which a plurality of reflection mirrors are arranged on the surface of a substrate in a variable tilt manner.

[0019]

In the camera of the first aspect, when the shutter button is pressed, the predetermined exposure period is started by the continuous photographing means.

With the start of this exposure period, the driving means changes the reflection direction of the spatial light modulator to the first direction and irradiates the film with the light flux incident from the taking lens. The film is exposed by holding this reflection direction during the exposure period.

When this exposure period ends, the driving means
The reflected light flux is diverted from the film, the exposure of the film is completed, and the film is wound by the motor drive means. In this way, one frame is photographed.

While the shutter button is being pressed, the continuous shooting means restarts the exposure period following the film winding. Therefore, the above operation is repeated and continuous shooting is performed.

As described above, the camera according to claim 1 realizes the shutter function by changing the direction of the light flux, unlike the conventional open / close shutter. Therefore, in the conventional camera, the moving parts such as the quick return mirror, the front curtain and the rear curtain, which require driving time, are not necessary, and the time required for photographing one film frame is shortened. Therefore, high-speed continuous shooting becomes possible.

According to the second aspect of the present invention, as the spatial light modulator, a digital micromirror device having a plurality of reflecting mirrors arranged on the substrate in a variable tilt is used. By dividing the reflective surface of this element into multiple reflective mirrors,
The reflection mirror alone has a small mass and a small displacement. Therefore, the time required to change the direction of the light flux is shortened, and higher-speed continuous shooting becomes possible.

[0025]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention.

First, an example of the digital micromirror device 10 used in this embodiment will be described first. The digital micromirror device is based on “Nikkei Electronics 19
93.6-21 "(p. 65, published by Nikkei BP).

FIG. 2 is a diagram showing an example of a digital micromirror element. FIG. 2A is a top view of the device. On the surface of the substrate 10a, a minute aluminum mirror 11 having a side of about 17 μm is laid on, for example, about 640 × 480 pixels.

2B to 2D are cross-sectional views of the aluminum mirror 11 in the diagonal direction (AA '). Posts 12a and 12b are projected on the substrate 10a, and diagonals of the aluminum mirror 11 are individually supported by the posts 12a and 12b. Electrodes 13 and 14 are arranged on the substrate 10a so as to face the other diagonal of the aluminum mirror 11.

In the digital micromirror device having such a structure, the aluminum mirror 11 is mounted on the substrate 10a when the columns 12a and 12b and the electrodes 13 and 14 are at the same potential.
Parallel to (Fig. 2 (b)).

When a potential difference (for example, 5 volts) is applied between the columns 12a and 12b and the electrode 13, the Coulomb attractive force causes the aluminum mirror 11 to tilt toward the electrode 13 side (FIG. 2 (c)).

On the other hand, when a potential difference is applied between the columns 12a and 12b and the electrode 14, the aluminum mirror 11 tilts toward the electrode 14 side (FIG. 2 (d)). In this way, the voltage applied to the electrodes 13 and 14 tilts the individual aluminum mirrors 11,
The reflection direction of incident light can be changed.

Since the aluminum mirror 11 has a small mass and a small displacement, the time required for tilting is as short as about 10 μsec. Further, since the reflection efficiency of such an aluminum mirror 11 is high, the light utilization efficiency is higher than that of liquid crystal.

The first embodiment of the present invention will be described below with reference to FIG. In the figure, on the optical axis of the taking lens 21,
Digital micromirror device 1 which is a spatial light modulator
0 is arranged in a tilted manner.

A film 23 is arranged on the optical axis of the taking lens 21 which is geometrically specularly reflected from the surface of the substrate 10a of the digital micromirror element 10. A drive circuit 24 for changing the inclination of the aluminum mirror 11 (FIG. 2) is connected to the digital micromirror element 10, a continuous shooting circuit 25 is connected to the drive circuit 24, and a shutter button 25a is connected to the continuous shooting circuit 25. To be done.

The continuous shooting circuit 25 is composed of, for example, a microcomputer and controls the operation of continuous shooting. Also,
A motor drive 26 for winding the film 23 is connected to the continuous shooting circuit 25.

Further, a light absorbing plate 28 is arranged at a position where the light flux deviated from the film 23 is irradiated. FIG.
6 is a flowchart showing continuous shooting in the first embodiment.

The operation of this embodiment will be described below with reference to this drawing. In the state where no image is taken, the drive circuit 24
A voltage is applied to one electrode 13 of the digital micromirror element 10 to form a minute aluminum mirror 11 on the substrate 10a.
Is tilted toward the electrode 13 side.

Therefore, the light beam incident from the taking lens 21 is deviated from the film 23 and absorbed by the light absorbing plate 28. When the shutter button 25a is pressed (step S1), the continuous shooting circuit 25 gives a signal to the drive circuit 24 to start the exposure period (step S2).

The drive circuit 24, to which this signal is applied, sets the electrodes 13 and 14 of the digital micromirror element 10 to the same potential and sets the minute aluminum mirrors 11 to the substrate 10a.
Parallel to.

The light flux incident from the taking lens 11 is reflected by the aluminum mirror 11 parallel to the substrate 10a to expose the film 23 (step S3). When the exposure period ends (step S4), the drive circuit 24 applies the voltage again to the electrode 13 of the digital micromirror element 10,
The aluminum mirror 11 is tilted. Therefore, the light flux deviates from the film 23 (step S5).

The continuous shooting circuit 25 outputs a signal for driving the motor drive 26 to wind up one frame of film (step S6). By the above-mentioned operation, the photographing for one frame is completed.

The continuous shooting circuit 25 determines whether or not the shutter button 25a is pressed (step S7). If the button is pressed, the shooting for one frame is repeated again (return to step S2), and continuous shooting is performed.

If the shutter button 25a is not pressed, the photographing is finished. In the camera of the first embodiment described above, the conventional moving parts, such as the front curtain and the rear curtain, which require driving time are unnecessary, and the mass and displacement of the moving part formed of the minute aluminum mirror 11 are small. The time required for starting and braking is about 10 μsec, which is sufficiently negligible.

Therefore, the time required to shoot one frame is
Only the exposure period of the film and the winding time of the film are required, and high-speed continuous shooting of 10 frames / sec or more becomes possible.

Further, in this embodiment, the drive circuit 24 is
For example, the shutter driving mechanism can be simplified as compared with the related art by including a switch circuit that switches the voltage applied to the digital micromirror element 10 and a delay circuit that detects the elapse of the exposure period.

Further, in the conventional shutter, since the exposure period is determined by driving mechanical parts, the accuracy of the shutter speed is low and the exposure period varies widely. However, in this embodiment, by using a highly accurate delay circuit using a crystal oscillator or the like, the exposure period becomes accurate, and a highly accurate shutter speed can be realized.

FIG. 4 is a diagram showing a second embodiment of the present invention. In the figure, the substrate 10 a of the digital micromirror element 10 is arranged on the image plane of the taking lens 21.

In the first reflection direction of the digital micromirror element 10, the film side lens 31 is provided on the substrate 10.
The film 23 is arranged in parallel with a, and the film 23 is further arranged at an image forming position on the extension.

Further, the digital micromirror element 10
For other reflection directions by, the finder side lens 32
Are arranged in parallel with the substrate 10a, and a finder screen 33 is arranged at an image forming position on an extension thereof.

Further, the digital micromirror device 1
A drive circuit 24 for changing the inclination of the aluminum mirror 11 (FIG. 2) is connected to 0, and a motor drive 26 for winding the film 23 is arranged on the film 23. A continuous shooting circuit 25 is connected to the drive circuit 24 and the motor drive 26,
A shutter button 25a is connected to the continuous shooting circuit 25.

FIG. 5 is a flow chart showing continuous shooting in the second embodiment. The operation of this embodiment will be described below with reference to this figure. The drive circuit 2 is used in a state where no image is taken.
Reference numeral 4 applies a voltage to one electrode 13 of the digital micromirror element 10 to reflect the light flux incident from the taking lens 21 in the other reflection directions.

Such a reflected light beam is projected on the finder screen 33 via the finder side lens 32. The photographer views this projected image. When the shutter button 25a is pressed here (step S1), the continuous shooting circuit 2
5 gives a signal to the drive circuit 24 to start the exposure period (step S2).

The drive circuit 24, to which this signal is given, operates on the electrodes 13 and the columns 12 of the digital micromirror element 10.
The potentials a and 12b are set to the same potential, and a voltage is applied to the other electrode 14 to reflect the light flux incident from the taking lens 21 in the first reflection direction.

Such a reflected light flux forms an optical image on the film 23 via the film side lens 31 (step S3). When the exposure period ends (step S4), the drive circuit 24 applies a voltage to one electrode 13 of the digital micromirror element 10 and the other electrode 14 and the support 1.
2a and 12b are made to have the same potential, and the light flux incident from the taking lens 21 is reflected in the other reflection directions so that the light flux is diverted from the film 23 (step S5).

When the exposure of the film 23 is completed in this manner, the continuous shooting circuit 25 outputs a signal for driving the motor drive 26 to wind up one frame of film.
By the above-mentioned operation, the photographing for one frame is completed.

Next, the continuous shooting circuit 25 uses the shutter button 25a.
It is determined whether or not is pressed (step S7). If the button is pressed, continuous shooting is performed by repeating shooting for one frame again (return to step S2).

If the shutter button 25a is not pressed, the photographing is finished. Also in the camera of the first embodiment, substantially the same effect as in the first embodiment can be obtained, and continuous shooting of 10 frames / second or more can be realized.

Further, in the camera of this embodiment,
The operability during continuous shooting can be improved. That is,
In a conventional camera, there is a period in which the viewfinder cannot be seen because the quick return mirror is flipped up, and there is a problem that the field of view of the photographer is intermittently interrupted during continuous shooting. However, in this embodiment, the field of view of the photographer is blocked only during the exposure period of the film 23. Normally, this exposure period is as short as a few hundredths of a second, so that the photographer has a sufficiently small sensation that the field of view is blocked. Therefore, the photographer never loses sight of the subject, and the operability in continuous shooting by the camera is improved.

In the above-described embodiment, the taking lens 21, the film side lens 31, and the finder side lens 32 may be compound lenses, or a reflecting mirror, a prism or other optical elements may be arranged in the middle of the optical system. ,
The optical path may be bent, and the vertical and horizontal sizes of the image may be changed.

Further, there is provided light-shielding member driving means which covers the film 23 with an openable / closable light-shielding member to open the path of the incident light beam in the light-shielding member before starting the exposure period and closes the path of the incident light beam after the exposure period. It may be provided. With this configuration, it is possible to prevent the film 23 from being exposed to stray light for a long time. Further, the light shielding member driving means may be a low speed and low precision driving mechanism, and can be realized by a simple and inexpensive mechanism.

[0061]

As described above, in the camera according to the first aspect, the shutter function is realized by changing the reflection direction of the luminous flux, so that the quick return mirror, the front curtain and the rear curtain are driven as in the conventional case. It is possible to increase the shooting speed of continuous shooting by eliminating the need for a moving part that requires time.

In the camera of the second aspect, since the digital micromirror element is used as the spatial light modulator,
Since the mass of the movable part is small and the displacement is small, the time required for starting and braking the shutter is short, and the shooting speed for continuous shooting can be increased.

Therefore, in continuous shooting using the camera of the present invention, the number of shots per unit time can be increased, a series of movements such as sports pictures can be taken more finely, and a photo opportunity is surely obtained. I can catch it.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a digital micromirror element.

FIG. 3 is a flowchart showing continuous shooting in the first embodiment.

FIG. 4 is a diagram showing a second embodiment of the present invention.

FIG. 5 is a flowchart showing continuous shooting in the second embodiment.

FIG. 6 is a diagram showing a conventional camera for continuous shooting.

[Explanation of symbols]

 10 Digital Micromirror Element 10a Substrate 11 Aluminum Mirror 12a, 12b Support 13, 14 Electrode 21 Photographing Lens 23 Film 24 Drive Circuit 25 Continuous Shooting Circuit 25a Shutter Button 26 Motor Drive 28 Light Absorbing Plate 31 Film Side Lens 32 Finder Side Lens 33 Finder Side screen

Claims (2)

[Claims] 1. A taking lens (21) for forming an optical image of a subject, and an optical flux which is arranged on the optical axis of the taking lens (21), reflects the incident light flux from the taking lens (21), and reflects the reflected light flux. Of the spatial light modulation element whose direction can be changed between the first direction and the other direction, the film (23) arranged in the first direction, and the direction of the reflected light flux only in a predetermined exposure period. Driving means (24) for driving the spatial light modulator in the first direction and in the other directions other than the exposure period.
When the exposure period ends, the motor drive means (26) for winding up the film (23), and when the shutter button is pressed, the exposure in the exposure period is started and the shutter button is pressed. During the period, continuous shooting means (2
5) A camera characterized by comprising: 2. The spatial light modulator is a substrate (10a).
2. The camera according to claim 1, wherein the camera is a digital micromirror element (10) in which a plurality of reflecting mirrors are arranged on the surface of the lens in a variable tilt manner.