JPH0843940A - Camera - Google Patents

Abstract

PURPOSE:To provide a camera of a simplified structure while taking countermeasure for light shield with regard to the camera in which a spatial light modulation element is used for a shutter mechanism. CONSTITUTION:A camera is constituted by being provided with a photography lens 31 for focusing the optical image of an object, a spatial light modulation element arranged on the optical axis of a photography lens 31 and capable of reflecting the incident light flux and changing the direction of the reflection light flux to a first direction and the other directions, a photosensitive member 33 arranged in the first direction, a stop 35 arranged on an optical passage between the photography lens 31 and the photosensitive member 33 and capable of opening and closing an opening part through which the light flux passes, a drive member 34 by which the reflection light flux of the spatial light modulation element is oriented to the first direction only during exposure period and oriented to the other directions during periods other than the exposure period, and a stop drive means 35a by which the opening part of a stop 35 is opened to a pre-determined stop value during specified periods including exposure period and the opening part of the stop 35 is closed and the passing light flux is shielded during periods other than the specified period.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, when photographing a fast-moving subject,
A high shutter speed is required to prevent subject shake.

Further, there is a photographing method in which the background is blurred by opening the aperture of the lens, but in such photographing, a high shutter speed is required in order to maintain proper exposure in a state where the subject brightness is high such as in fine weather. You will need it.

As such a high-speed shutter, conventionally,
Focal plane shutters are known. Figure 5
It is a figure which shows the camera which used the focal plane shutter.

In the figure, a photosensitive member 2 is arranged on the image forming surface of a taking lens 1, and a focal plane shutter 4 composed of a front curtain 4a and a rear curtain 4b is arranged immediately before the photosensitive member 2.

A shutter drive mechanism 5 is connected to the focal plane shutter 4, and a shutter button 5a is connected to the shutter drive mechanism 5. On the other hand, a diaphragm 6 is arranged at a position close to the taking lens 1, and a diaphragm driving mechanism 6a for opening and closing the diaphragm 6 is arranged. Further, a finder 9 is provided independently of the optical system of the taking lens 1.

With a camera having such a configuration, the photographer
Look through the finder 9 to determine the subject. The light from the subject passes through the taking lens 1 and the diaphragm 6 and reaches the focal plane shutter 4.

When the shutter button 5a is pressed here, the front curtain 4a and the rear curtain 4b move laterally with a time lag. The incident light flux is between the front curtain 4a and the rear curtain 4b (hereinafter,
Say "slit". ) To expose the photosensitive member 2.

The exposure period T at this time is T = S / V depending on the slit spacing S and the curtain speed V.

However, in such a camera, when the slit spacing S is narrowed, uneven exposure of the photosensitive member 2 occurs due to uneven speed of the curtain speed V. Therefore, the slit spacing S
Could not be narrowed indefinitely.

Further, since the mass of the movable parts such as the front curtain 4a, the rear curtain 4b, and the like is large, it is difficult to increase the curtain speed V.
It was difficult. Due to such restrictions, the current upper limit of the shutter speed is 1/4000 second to 1/12000.
It is about a second, and there has been a demand for a shutter mechanism that realizes a faster shutter speed.

Further, in such a camera, the front curtain 4a,
Since the trailing blades 4b and other movable parts have a large mass, the vibrations generated at the time of starting and braking are large, which is a major cause of camera shake. Since such camera shake significantly impairs the sharpness of photographs, improvement thereof has been demanded.

The slit traverses just before the photosensitive member 2 in about 1/300 second. As a result, there is a gap in the shooting time at both ends of the picture. Therefore, when the subject moves at high speed, a distorted image is captured. For example, a car running in the moving direction of the slit has its body stretched and is photographed.

Therefore, the present inventor has previously used a digital micromirror element as a camera for solving all the above problems (hereinafter referred to as "DMD camera").
Was filed and filed as Japanese Patent Application No. 6-126165.

FIG. 6 is a diagram showing an example of this DMD camera. In the figure, a digital micromirror element 12 is arranged on the optical axis of the taking lens 11 in an inclined manner.

The photosensitive member 13 is arranged on the upper surface of the substrate 12a of the digital micromirror element 12 in a direction in which the optical axis of the taking lens 11 is geometrically regularly reflected. A drive circuit 14 is connected to the digital micromirror element 12, and a shutter button 14a is connected to the drive circuit 14.

Further, a diaphragm 15 is provided close to the photographing lens 11.
And a diaphragm drive mechanism 15 for opening and closing the diaphragm 15.
a is connected to the shutter button 14a. Further, the photosensitive member 13 is covered with an openable / closable light shielding member 16, and a light shielding member drive mechanism 17 is connected to the light shielding member 16. A shutter button 14a is connected to the light shielding member drive mechanism 17.

A light absorbing plate 18 is arranged at a position where the light flux diverted from the photosensitive member 13 is irradiated, and the photographing lens 1
The finder 19 is arranged independently of the first optical system. FIG. 7 is a diagram showing an example of the digital micromirror element 12 described above.

This digital micromirror element 12
Is "Nikkei Electronics No. 193.6-21"
(Page 65, published by Nikkei BP Co., Ltd.).

FIG. 7A is a top view of the device. A minute aluminum mirror 2 with a side of about 17 μm on the surface of the substrate 12a.
1 is laid in, for example, about 640 × 480 pixels.

FIGS. 7B to 7D are cross-sectional views of the aluminum mirror 21 in the diagonal direction (A-A '). Supports 22a and 22b are provided on the substrate 12a so that the diagonals of the aluminum mirror 21 are individually supported by the supports 22a and 22b. Aluminum mirror 2
The electrode 2 on the substrate 12a facing the other diagonal of 1
3, 24 are provided.

First, the digital micromirror element 12
The operation of will be described first. In the digital micromirror device having such a configuration, the columns 22a and 22b and the electrode 2 are
When the electric potentials of 3 and 24 are set to the same potential, the aluminum mirror 21 moves to the substrate 12
It is parallel to a (Fig. 2 (b)).

When a potential difference (for example, 5 V) is applied between the columns 22a and 22b and the electrode 23, the aluminum mirror 21 tilts toward the electrode 23 side due to Coulomb attractive force (FIG. 2 (c)).

On the other hand, when a potential difference is applied between the columns 22a and 22b and the electrode 24, the aluminum mirror 21 tilts toward the electrode 24 side (FIG. 2 (d)). In this way, the voltage applied to the electrodes 23 and 24 tilts each aluminum mirror 21,
The reflection direction of incident light can be changed.

Since the aluminum mirror 21 has a small mass and a small displacement, the tilting time is as short as about 10 μsec, which can be sufficiently ignored. Also, such an aluminum mirror 2
Since the reflection efficiency of 1 is high, the light utilization efficiency is higher than that of the liquid crystal.

The operation of the DMD camera will be described below with reference to FIGS. 6 and 7. First, when the shutter button 14a is not pressed, the drive circuit 14 applies a voltage to one electrode 23 of the digital micromirror element 12 to individually tilt the minute aluminum mirrors 21 on the substrate 12a. .

Therefore, the light beam incident from the taking lens 11 is deviated from the photosensitive member 13 and absorbed by the light absorbing plate 18. Further, the light shielding member driving means 17 keeps the light shielding member 16 in a closed state, and prevents the photosensitive member 13 from being exposed to stray light for a long time.

Next, when the shutter button 14a is pressed halfway, the light-shielding member driving means 17 opens the light-shielding member 16 to prepare for exposing the photosensitive member 13.

Then, when the shutter button 14a is fully pressed, the driving means 14 sets the electrodes 23 and 24 of the digital micromirror element 12 to the same potential and sets the minute aluminum mirror 21 to the substrate 12a. Make them parallel.

Therefore, the light beam incident from the taking lens 11 is reflected by the aluminum mirror 21 parallel to the substrate 12a and is applied to the photosensitive member 13. When the driving unit 14 detects the elapse of a preset exposure period, the driving unit 14 reapplies a voltage to the electrode 23 of the digital micromirror element 12 to tilt the aluminum mirror 21. Therefore, the luminous flux is
It deviates from the photosensitive member 13.

Here, the light blocking member driving means 17 closes the light blocking member 16 again to block stray light. In this way, a shutter that exposes the photosensitive member 13 for a preset exposure period is realized. Therefore, by setting the exposure period as described above, the shutter speed can be arbitrarily set, and a high shutter speed can be realized. For example,
If you set the exposure period to 1/20000 seconds, 1/200
The shutter speed is 00 seconds.

Further, since the movable part made up of the aluminum mirror 21 has a small mass and a small displacement, the vibration generated at the time of starting and braking the shutter is extremely small, and camera shake hardly occurs.

Further, since the entire surface of the photosensitive member 13 is exposed at the same time, it is possible to photograph an object moving at high speed without distortion. As described above, the DMD invented by the present inventor
With the camera, a high shutter speed can be realized, camera shake can be greatly reduced, and a subject moving at high speed can be photographed without distortion.

[0034]

However, in such a DMD camera, there is a problem in that the light-shielding member 16 and the light-shielding member driving mechanism 17 are provided so that the light-shielding measure of the photosensitive member 13 must be strictly performed. there were.

That is, in the DMD camera, the photosensitive member 1
Since the shutter function is realized by diverting the light flux from 3, it is difficult to completely shield the photosensitive member, unlike the conventional shutter that completely shields the light flux, and it is weakly reflected irregularly inside the camera. The stray light may expose the photosensitive member 13 for a long time.

If the light blocking member 16 and the light blocking member driving mechanism 17 are provided to block such stray light, the structure of the DMD camera becomes complicated, the cost becomes high, and the camera becomes large. There was a problem.

The present invention has been made in view of the above problems, and shields stray light applied to the photosensitive member while
An object of the present invention is to provide a camera whose structure can be simplified.

[0038]

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. The spatial light modulator capable of changing the direction of the reflected light flux between the first direction and the other direction, the photosensitive member arranged in the first direction, and the optical path between the taking lens and the photosensitive member. A diaphragm that is arranged and has an opening that can be opened and closed through which the light flux passes, and a space that directs the light flux reflected by the reflecting surface in the first direction only during the exposure period of the photosensitive member and in other directions during the non-exposure period. Driving means for the light modulator and aperture driving for opening the aperture of the aperture to a predetermined aperture value for a predetermined period including the exposure period and for closing the aperture of the aperture and blocking the passing light beam except for the predetermined period. And means.

According to a second aspect of the present invention, in the camera of the first aspect, the spatial light modulation element is a digital micromirror element in which a plurality of reflection mirrors are arranged on the surface of the substrate in a variable tilt. Characterize.

According to a third aspect of the present invention, in the camera of the first or second aspect, the aperture driving means sets the aperture of the aperture to a predetermined aperture value when the shutter button is pressed halfway. It is characterized by opening and closing the opening after the exposure period described above to shield the passing light flux.

[0041]

In the camera according to the first aspect, the diaphragm driving means closes the diaphragm to block stray light except during a predetermined period including the exposure period. In this way, by using the diaphragm as a means for shielding the photosensitive member, it is possible to prevent the photosensitive member from being exposed to stray light for a long time.

On the other hand, during a predetermined period including the exposure period, the aperture driving means opens the aperture to a predetermined aperture value.
Therefore, the amount of light of the light flux incident from the taking lens is appropriately limited by the diaphragm and reaches the reflecting surface of the spatial light modulator.

When the exposure period is started by operating the shutter button or the like, the driving means changes the reflection direction of the spatial light modulator to the first direction, and the reflected light flux is applied to the photosensitive member in the first direction.

When this exposure period ends, the driving means changes the reflection direction of the spatial light modulation element to another direction so that the light beam is diverted from the photosensitive member. In this way, the diaphragm functions as a unit that adjusts the amount of passing light within a predetermined period, and functions as a light-shielding unit that blocks the incident light beam from the photographing lens outside the predetermined period.

According to the second aspect of the present invention, as the spatial light modulation element, a digital micromirror element in which a plurality of reflection mirrors are arranged on the substrate in a variable tilt is used. Therefore, the direction of the reflected light flux can be changed by changing the inclination angle of the reflection mirror.

In the camera of claim 3, the diaphragm driving means closes the diaphragm to block stray light until the shutter button is pressed halfway. When the shutter button is pressed halfway, the diaphragm driving means opens the diaphragm to a predetermined diaphragm value, closes the diaphragm after the exposure period, and shields light again.

As described above, by half-pressing the shutter button, the light blocking is released immediately before the start of photographing, so that the period in which the photosensitive member is exposed to stray light can be shortened.

[0048]

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.

In the figure, on the optical axis of the taking lens 31,
The digital micromirror element 12 is arranged so as to be inclined, and the photosensitive member 33 is arranged in a direction in which the optical axis of the taking lens 31 is geometrically regularly reflected with respect to the upper surface of the substrate 12a of the digital micromirror element 12. .

The digital micromirror element 12 includes
A driving means 34 for driving the aluminum mirror 21 (FIG. 7) is connected, and a shutter button 34a is connected to the driving means 34. Further, a fully closed diaphragm 35 is arranged close to the taking lens 31, and a fully closed diaphragm drive mechanism 35a for opening and closing the fully closed diaphragm 35 is connected to a shutter button 34a.

Further, a light absorbing plate 38 is arranged at a position where the light flux diverging from the photosensitive member 33 is irradiated, and a finder 39 is arranged at a position independent of the optical system including the taking lens 31.

FIG. 2 is a flow chart showing the operation of the first embodiment. The operation of this embodiment will be described below with reference to FIGS. 1, 2 and 7. When the shutter button 14a is not pressed, the fully closed diaphragm drive mechanism 35a is
Is closed to block the incident light flux from the taking lens 31 (step S1).

By blocking the incident light beam in this manner, the phenomenon that the photosensitive member 33 is exposed to stray light for a long time is prevented. Further, the driving means 14 applies a voltage to one electrode 23 of the digital micromirror element 12 to cause the substrate 12
The minute aluminum mirror 21 on a is tilted to the electrode 23 side.

When the shutter button 14a is pressed halfway (step S2), the fully closed diaphragm drive mechanism 35a.
When the fully closed diaphragm 35 is opened to a predetermined diaphragm value, the photosensitive member 33 is prepared for exposure (step S3).

In this state, the light beam incident from the taking lens 31 is reflected by the tilted aluminum mirror 21 of the digital micromirror element 12, escapes from the photosensitive member 33, and is absorbed by the light absorbing plate 38.

Further, when the shutter button 34a is fully pressed (step S4), the driving means 34 sets the electrodes 23 and 24 of the digital micromirror element 12 to the same potential, and the minute aluminum mirror 21 is placed on the substrate. It is parallel to 12a.

Therefore, the light flux incident from the taking lens 31 is reflected by the aluminum mirror 21 parallel to the substrate 12a to expose the photosensitive member 33 (step S5). When the driving means 34 detects the elapse of the preset exposure period (step S6), the digital micromirror element 12 is detected.
The voltage is applied again to the electrode 23, and the aluminum mirror 21 is tilted toward the electrode 23 side. Therefore, the luminous flux is generated by the photosensitive member 3
3 is deviated (step S7).

When the exposure of the photosensitive member 33 is completed in this way, the fully-closed diaphragm drive mechanism 35a closes the fully-closed diaphragm 35 again (step S8) to block the light flux incident from the taking lens 31.

As described above, the fully closed diaphragm 35 functions as a light-shielding member when the photographer does not touch the shutter button 34a, and when the photographer touches the shutter button 34a, it opens and functions as a diaphragm.

Therefore, it is not necessary to separately provide the light shielding member and the driving means thereof, and the structure can be simplified. Further, by omitting these mechanisms, the cost and size of the camera can be reduced.

FIG. 3 is a diagram showing a second embodiment of the present invention. In the figure, the substrate 12a of the digital micromirror element 12 is arranged on the imaging plane of the taking lens 31.

The driving means 34 is connected to the digital micromirror element 12, and the shutter button 34a is connected to the driving means 34. Digital micromirror device 1
The photosensitive member side lens 33a is arranged in parallel with the substrate 12a in the first reflection direction by 2, and the photosensitive member 33 is further arranged at the extended image forming position.

Further, a fully closed diaphragm 35 is arranged close to the taking lens 31, and a fully closed diaphragm drive mechanism 35a for opening and closing the fully closed diaphragm 35 is connected to the shutter button 34a. Further, a light absorption plate 38 is arranged in the other reflection direction by the digital micromirror element 12, and the photographing lens 31
The finder 39 is arranged independently of the optical system consisting of.

FIG. 4 is a flow chart showing the operation of the second embodiment. The operation of this embodiment will be described below with reference to FIGS. 3, 4 and 7. When the shutter button 34a is not pressed, the fully closed diaphragm drive mechanism 35a is
Is closed to block the light flux incident from the taking lens 31 (step S1).

The driving means 14 applies a voltage to one electrode 23 of the digital micromirror element 12,
The aluminum mirror 21 is tilted toward the electrode 23 side. In this state,
When the shutter button 34a is pressed halfway (step S
2) The fully closed diaphragm drive mechanism 35a opens the fully closed diaphragm 35 to a predetermined diaphragm value (step S3), and prepares for exposing the photosensitive member 13.

Therefore, the light flux incident from the photographing lens 31 is appropriately limited in its light quantity by the fully closed diaphragm 35, reaches the digital micromirror element 12, and is reflected by the aluminum mirror 21 inclined to the electrode 23 side. The absorption plate 38 is irradiated.

Here, when the shutter button 34a is fully pressed (step S4), the driving means 34 causes the electrode 23 of the digital micromirror element 12 and the columns 22a, 22.
b and the other electrode 24 have the same potential, and a voltage is applied to the other electrode 24 to reflect the light flux incident from the taking lens 31 in the first reflection direction (step S5).

The reflected light flux forms an optical image on the photosensitive member 33 via the lens 33a on the photosensitive member side. When the preset exposure period has elapsed (step S6), the driving means 34 applies a voltage to one electrode 23 of the digital micromirror element 12, and the other electrode 24 and the support column 2 are applied.
2a and 22b are set to the same potential, and the aluminum mirror 21 is used as the electrode 2
Incline to the 4 side. Therefore, the light flux incident from the photographing lens 31 is reflected in other reflection directions, and the photosensitive member 3
It deviates from 3 (step S7).

In this state, the fully-closed diaphragm drive mechanism 35a closes the fully-closed diaphragm 35 to block the light beam incident from the taking lens 31 again (step S8). As described above, in the present embodiment, the fully closed diaphragm 35 functions as a light blocking member when the photographer does not touch the shutter button 34a, and the fully closed diaphragm 35 functions as a diaphragm when the photographer touches the shutter button 34a.

Therefore, it is not necessary to separately provide the light shielding member and the driving means thereof, and the structure can be simplified. Further, by omitting these mechanisms, the cost and size of the camera can be reduced.

Further, in the second embodiment, the aluminum mirror 21
By switching the inclination angle of 2 between the electrode 23 side and the electrode 24 side, the distance between the photosensitive member 33 and the light absorbing plate 38 is increased, so that stray light generated near the light absorbing plate 38 reaches the photosensitive member 33. Therefore, the phenomenon that the photosensitive member 33 is exposed to stray light can be further prevented.

In the above embodiment, the taking lens 11, the photosensitive member side lens 24 and the finder side lens 25a 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 directions of the image or the size may be changed.

Further, unlike the conventional lens shutter and the like, the fully-closed diaphragm 35 of the above-mentioned embodiment can be opened and closed at a low speed, so that it can be realized by an inexpensive and simple mechanism.

[0074]

As described above, in the camera according to the first aspect, the incident light flux from the photographing lens is blocked by the diaphragm except during the predetermined period including the exposure period, so that the photosensitive member is exposed to stray light for a long time. The phenomenon of exposure can be prevented.

Further, since the diaphragm also serves as a means for blocking stray light, the structure of the camera can be simplified and the cost and size of the camera can be reduced. In the camera according to claim 2, since the reflecting surface is divided into a plurality of reflecting mirrors by using the digital micromirror element as the spatial light modulator, the mass of the reflecting mirror alone is small, and the displacement is small. The speed can be increased.

Further, since vibrations at the time of starting and braking of the reflecting mirror are small, camera shake can be prevented and a photograph with a high sharpness can be taken. In the camera of the third aspect, the diaphragm is closed until the photographer presses the shutter button halfway. Therefore, stray light is blocked until just before shooting, and the period in which the photosensitive member is exposed to stray light can be shortened.

As described above, in the camera to which the present invention is applied, the structure of the camera can be simplified while blocking the stray light applied to the photosensitive member, so that the cost and size of the camera can be reduced. be able to.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing the operation of the first embodiment.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the second embodiment.

FIG. 5 is a diagram showing a camera using a focal plane shutter.

FIG. 6 is a diagram showing an example of a camera using a digital micromirror element.

FIG. 7 is a diagram showing an example of a digital micromirror element.

[Explanation of symbols]

 12 Digital Micro Mirror Element 12a Substrate 21 Aluminum Mirror 22a, 22b Support 23, 24 Electrode 31 Photographing Lens 33 Photosensitive Member 33a Photosensitive Member Side Lens 34 Drive Means 34a Shutter Button 35 Fully Closed Aperture 35a Fully Closed Aperture Drive Mechanism 38 Light Absorbing Plate 39 finder

Claims (3)

[Claims] 1. A photographing lens (31) for forming an optical image of a subject, and a luminous flux which is arranged on the optical axis of the photographing lens (31) and which reflects an incident light flux from the photographing lens (31) and is a reflected light flux. Of the spatial light modulation element whose direction can be changed between the first direction and the other direction, the photosensitive member (33) arranged in the first direction, the taking lens (31) and the photosensitive member (33). ) And an aperture (35) that is arranged on the optical path between the first and second apertures and is capable of opening and closing the opening through which the light flux passes, and directs the reflected light flux in the first direction only during the exposure period of the photosensitive member (33). And a driving means (34) for the spatial light modulator which is directed in other directions except during the exposure period.
During a predetermined period including the exposure period, the aperture of the aperture stop (35) is opened to a predetermined aperture value, and the aperture of the aperture stop (35) is closed to block the passing light flux except the predetermined period. A diaphragm drive means (35a) for controlling the camera. 2. The spatial light modulator is a substrate (12a).
The camera according to claim 1, wherein the camera is a digital micromirror element (12) in which a plurality of reflecting mirrors (21) are arranged on the surface of the lens in a variable tilt manner. 3. The aperture driving means (35a) opens the aperture of the aperture (35) to a predetermined aperture value when the shutter button is pressed halfway, and the aperture is opened after the exposure period ends. The camera according to claim 1, wherein the portion is closed to block the passing light flux.