JPH0534763A - Camera - Google Patents

Abstract

PURPOSE:To adjust incident light quantity without changing the depth of a field and to enable a shutter speed and shutter timing to be optionally set,. CONSTITUTION:A liquid crystal filter 41 is arranged on the front surface of an image pickup lens 1. The output signal of a level detection circuit 9 is supplied to a controller 6 and a voltage impressed on the filter 41, therefore the transmissivity is controlled according to the incident light quantity on an image pickup element 3. Thus, the incident light quantity on the element 3 can be controlled to be fixed and the filter 41 functions as an automatic iris. The light quantity is adjusted without mechanically stopping an aperture and changing the depth of the field. Besides, the transmissivity is enhanced by impressing the voltage on the filter 41 only when a shutter is opened by the control of the controller 6. Then, a term Ttm until the voltage is impressed from a vertical synchronizing signal VD (shutter timing) and a term Tsp that the voltage is impressed on it (shutter speed) are optionally set by the operation of a keyboard 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, and more particularly to iris and shutter technology.

[0002]

2. Description of the Related Art FIG. 7 shows an example of the structure of a video camera.

In FIG. 1, image light from a subject passes through an image pickup lens 1 and an iris 2 and a CCD solid state image pickup device 3
Is supplied to. The image sensor 3 is of an IT (interline transfer) type as shown in FIG. Here, 3a is a sensor formed of a photodiode, 3b is a vertical shift register, 3c is a horizontal shift register, and 3d is a signal detection unit. In addition, the image pickup device 3
Has a VOD (vertical overflow drain) structure, for example, and has a charge sweeping function.

A sensor gate pulse SGP, a vertical transfer pulse VTP, a horizontal transfer pulse HTP, a shutter pulse SHP and the like are supplied to the image pickup device 3 from a timing generator 4 via a driver 5. Timing generator 4
Are supplied with vertical and horizontal synchronizing signals VD and HD.

The signal charge accumulated in the sensor 3a by the sensor gate pulse SGP is applied to the vertical shift register 3
b. Signal charges are transferred through the shift registers 3b and 3c by the transfer pulses VTP and HTP. The signal charge accumulated in the sensor 3a is swept to the substrate by the shutter pulse SHP.

The synchronizing signals VD and HD are supplied to the controller 6, and the controller 6 is supplied with the system clock CLK from the timing generator 4. The timing generator 4 is controlled by the controller 6, and the above-mentioned pulses SGP, VTP, HTP, SHP
Supply to the image sensor 3 is controlled as follows.

FIG. 9A shows the vertical synchronizing signal VD.
The shutter pulse SHP is supplied for a predetermined period t1 from the start time of each field (shown in FIG. 9B), and the sensor gate pulse SGP is supplied at the end time of each field (shown in FIG. 9C).

The period until the sensor gate pulse SGP is supplied after the supply of the shutter pulse SHP is stopped is the exposure period t2, and the signal charge is accumulated in the sensor 3a.

Further, the transfer pulse VT is provided in each field period.
P and HTP are supplied (shown in FIG. 9D), the signal charges accumulated in the sensor 3a in the previous field period are transferred, and the image signal for one field is output from the signal detection unit 3d.

By operating the keyboard 7, the shutter pulse SHP supply time t1, and hence the exposure period (shutter time) t2, is set. In this case, the shutter pulse SHP and the sensor gate pulse SGP
Are formed in synchronization with the horizontal synchronizing signal HD, and the shutter time t2 is set to an integral multiple of the horizontal period.

Returning to FIG. 7, the image pickup signal output from the image pickup device 3 is supplied to the sample hold circuit 8 to remove an unnecessary signal in the reset state. The image pickup signal output from the sample hold circuit 8 is supplied to the level detection circuit 9. The output signal of the detection circuit 9 is supplied to the iris 2 as a control signal via the iris driver 10.
The aperture stop of the iris 2 is automatically controlled.

The image pickup signal output from the sample hold circuit 8 is passed through the AGC circuit 11 to the signal processing circuit 1.
The video signal is output to the output terminal 13 by being supplied to the output terminal 2 and subjected to processing such as gamma correction and addition of a sync signal.

[0013]

The iris 2 of the above-mentioned video camera is adjusted so that the amount of light incident on the image pickup element 3 becomes constant by mechanically narrowing the aperture. Since the depth of field changes, it is impossible to freely select the depth of field to create a free image.

Further, in the above-mentioned video camera, the setting of the shutter speed is limited to an integral multiple of the horizontal period.

Further, since the shutter speed is adjusted by adjusting the supply time t1 of the shutter pulse SHP from the start of the field, the shutter timing is uniquely determined corresponding to the shutter speed, and the shutter timing is arbitrarily set. Could not be set.

Therefore, according to the present invention, the incident light amount can be adjusted to be constant without changing the depth of field, and the shutter speed and timing can be arbitrarily set.

[0017]

A camera according to a first aspect of the invention comprises an iris using a liquid crystal filter.

The camera according to the second aspect of the invention constitutes a shutter using a liquid crystal filter.

The camera according to the third aspect of the present invention uses the same liquid crystal filter to form an iris and a shutter.

[0020]

Operation: For example, the liquid crystal filter 2 is provided on the front surface of the imaging lens 1.
By disposing Nos. 1 and 41 and controlling the transmittance of the liquid crystal filter, the amount of incident light on the image sensor 3 is adjusted to be constant. Since the aperture is not mechanically narrowed, the amount of incident light can be adjusted without changing the depth of field.

Further, for example, by disposing the liquid crystal filters 31 and 41 on the front surface of the image pickup lens 1 and adjusting the transmission period and the timing of the liquid crystal filter, the shutter speed and the timing can be controlled without being restricted by the timing of the synchronizing signal. It can be set arbitrarily.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. This example is an example applied to a video camera. In FIG. 1, parts corresponding to those in FIG. 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this example, a liquid crystal filter (liquid crystal panel) 21 is arranged in front of the image pickup lens 1. 2A
The relationship between the applied voltage (AC) of the liquid crystal filter 21 and the transmittance is shown. The transmittance becomes 0 as the voltage value increases.
Change to ~ 100%. The maximum transmittance of the liquid crystal filter 21 does not have to be 100%.

The output signal of the level detection circuit 9 is supplied to the controller 6, and the operation of the above-mentioned liquid crystal filter 21 is controlled by the controller 6. That is, when the amount of light incident on the image sensor 3 increases, the output signal of the level detection circuit 9 increases, and the value of the voltage VL (illustrated in FIG. 2B) applied to the liquid crystal filter 21 decreases, so that the transmittance is reduced. Controlled to be low. On the contrary, the image sensor 3
When the amount of light incident on is small, the output signal of the level detection circuit 9 is small, the value of the voltage VL applied to the liquid crystal filter 21 is large, and therefore the transmittance is controlled to be high.

As a result, the amount of light incident on the image pickup device 3 is controlled to be constant, and the liquid crystal filter 21 functions as an auto iris.

The present example is constructed as described above, and the others are constructed similarly to the example of FIG.

According to this embodiment, the incident light amount of the image pickup device 3 is controlled by controlling the transmittance of the liquid crystal filter 21, and the aperture is not mechanically narrowed, but the depth of field is changed. There is no such thing. Therefore, by using an ordinary mechanical iris (equivalent to the iris 2 in the example of FIG. 7 (not shown)), the aperture and therefore the depth of field can be arbitrarily selected to create a free image. can do.

Further, in the case of a normal mechanical iris, it is necessary to put it in the afocal portion constituting the lens block, but in this example, the incident light amount of the image pickup device 3 is controlled by controlling the transmittance of the liquid crystal filter 21. Since it is controlled, it can be placed in any part of the lens, and can be arranged on the front surface of the imaging lens 1 to eliminate the iris from the lens block as in this example.

Further, since the liquid crystal filter 21 is arranged on the front surface of the image pickup lens 1, there is an advantage that it can also be used as a protective cap of the image pickup lens 1.

Further, since the usual mechanical iris can be eliminated, the reliability of the equipment can be improved.

Next, another embodiment of the present invention will be described with reference to FIG. This example is also an example applied to a video camera. 3, parts corresponding to those in FIG. 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this example, a liquid crystal filter (liquid crystal panel) 31 is arranged on the front surface of the image pickup lens 1. FIG. 4A shows
The relationship between the applied voltage (AC) of the liquid crystal filter 31 and the transmittance is shown. The transmittance becomes 0 as the voltage value increases.
Change to ~ 100%. The maximum transmittance of the liquid crystal filter 31 may not be 100%.

In this example, the shutter pulse SHP is not supplied to the image pickup device 3, and the image pickup device 3 does not function as an electronic shutter. Instead of this, the liquid crystal filter 31 is made to function as a shutter.

The operation of the liquid crystal filter 31 is performed by the controller 6
Controlled by. That is, when the shutter is opened, the voltage VLM (having a voltage value at which the transmittance is 100%) is applied to the liquid crystal filter 31.

Here, the period Ttm (shutter timing) from the vertical synchronizing signal VD to the application of the voltage VLM and the period Tsp (shutter speed) of the application of the voltage VLM.
Is arbitrarily set by operating the keyboard 7 (see FIG. 4B).

The present example is constructed as described above, and the other parts are constructed similarly to the example of FIG.

According to this embodiment, the shutter timing is not uniquely determined by the shutter speed unlike the conventional electronic shutter, and the shutter timing Ttm can be arbitrarily set by operating the keyboard 7. Further, unlike the conventional electronic shutter, the shutter speed is not restricted to an integral multiple of the horizontal period, and the shutter speed Tsp can be set arbitrarily by operating the keyboard 7. Further, when performing iris priority AE (automatic exposure) or the like, the shutter speed can be continuously selected.

Furthermore, since the shutter timing Ttm can be arbitrarily selected, the shutter timing Ttm can be controlled by an external trigger. For example, the sound sensor 32 and the optical sensor 33 are connected to the controller 6 (see FIG.
It is also possible to release the shutter by detecting sound, or to release the shutter when an object is crossed. As a result, the degree of freedom in image pickup is increased and it is possible to freely create an image.

Further, since the liquid crystal filter 31 is arranged on the front surface of the image pickup lens 1, there is an advantage that it can also be used as a protective cap of the image pickup lens 1.

Next, another embodiment of the present invention will be described with reference to FIG. This example is also an example applied to a video camera. 5, parts corresponding to those in FIG. 7 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this example, a liquid crystal filter (liquid crystal panel) 41 is arranged on the front surface of the image pickup lens 1. Figure 6A
The relationship between the applied voltage (AC) of the liquid crystal filter 41 and the transmittance is shown. The transmittance becomes 0 as the voltage value increases.
Change to ~ 100%. The maximum transmittance of the liquid crystal filter 41 may not be 100%.

The output signal of the level detection circuit 9 is supplied to the controller 6, and the operation of the liquid crystal filter 41 is controlled by the controller 6. That is, when the amount of light incident on the image sensor 3 increases, the output signal of the level detection circuit 9 increases, and the value of the voltage VL (shown in FIG. 6B) applied to the liquid crystal filter 41 decreases, so that the transmittance is reduced. Controlled to be low.

On the contrary, when the amount of light incident on the image pickup device 3 becomes small, the output signal of the level detection circuit 9 becomes small,
The value of the voltage VL applied to the liquid crystal filter 41 is large,
Therefore, the transmittance is controlled to be high. As a result, the amount of light incident on the image sensor 3 is controlled to be constant,
The liquid crystal filter 41 functions as an auto iris.

Further, in this example, the shutter pulse SHP is not supplied to the image pickup device 3, and the image pickup device 3 does not function as an electronic shutter. Instead of this, the liquid crystal filter 41 functions as a shutter. That is, the liquid crystal filter 41 is controlled by the controller 6, and the voltage VL is applied when the shutter is opened.

Here, a period Ttm (shutter timing) from application of the vertical synchronizing signal VD to the voltage VL and a period Tsp (shutter speed) in which the voltage VL is applied.
Is arbitrarily set by operating the keyboard 7 (see FIG. 6B).

The present example is constructed as described above, and the others are constructed in the same manner as the example of FIG.

According to this example, since the iris and the shutter are constituted by the liquid crystal filter 41, the same effects as those of FIGS. 1 and 3 can be obtained, and the iris and the shutter can be formed by the same component (liquid crystal filter 41). There are benefits that can be configured.

Although the above embodiment is an example applied to a video camera, it goes without saying that the present invention can also be applied to a still camera (film camera).

[0049]

According to the present invention, by controlling the transmittance of the liquid crystal filter, the incident light quantity of the image pickup device can be adjusted to be constant, and the aperture is not mechanically narrowed like the conventional iris. The amount of incident light can be adjusted without changing the depth of field. Further, the shutter speed and timing can be set by adjusting the transmission period and timing of the liquid crystal filter, and the shutter speed and timing can be set arbitrarily without being restricted by the timing of the synchronization signal and the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is a diagram showing an operation of the liquid crystal filter in the example of FIG.

FIG. 3 is a block diagram showing the configuration of another embodiment.

FIG. 4 is a diagram showing an operation of the liquid crystal filter in the example of FIG.

FIG. 5 is a block diagram showing the configuration of another embodiment.

6 is a diagram showing an operation of the liquid crystal filter in the example of FIG.

FIG. 7 is a block diagram showing a configuration of a conventional example.

FIG. 8 is a diagram showing a configuration of an interline transfer type CCD solid-state imaging device.

FIG. 9 is a timing chart showing the operation of the image sensor.

[Explanation of symbols]

1 Imaging lens 2 iris 3 CCD solid-state image sensor 4 Timing generator 6 controller 7 keyboard 9 Level detection circuit 12 Signal processing circuit 21, 31, 41 Liquid crystal filter

Claims (4)

[Claims] 1. A camera comprising an iris using a liquid crystal filter. 2. A camera comprising a shutter using a liquid crystal filter. 3. A camera comprising an iris and a shutter using the same liquid crystal filter. 4. The camera according to claim 1, wherein the liquid crystal filter is arranged in front of an imaging lens.