JP3158220B2 - Electronic camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for appropriately determining a photographing condition of a color image in an electronic camera (video camera).

[0002]

2. Description of the Related Art In an electronic camera, a color image signal is obtained by photoelectrically converting an optical image signal obtained by an optical system by a solid-state image sensor. Here, an electronic camera generally needs an optical low-pass filter (hereinafter abbreviated as OLPF) to discretely input images. This OLPF has a function of cutting unnecessary high-frequency components of an image in order to suppress aliasing distortion known as moiré or beat. In order to cut high-frequency components, it is necessary to use an optical element that converts a single point image into a point image having an appropriate spread.

Conventionally, as such an OLPF, one that splits a light beam into two beams using birefringence of a uniaxial crystal such as quartz is generally used. In addition, there has been proposed an optical element in which a diffraction grating is provided in a lens system to separate an image at one point by using diffraction.

[0004]

However, the OLPF in the conventional electronic camera is used to eliminate a false signal of a color.
When using the photoelectric conversion signal of the solid-state imaging device to determine the focus position and the exposure amount in E (automatic exposure control), it is not particularly necessary. I was Further, even when a photoelectric conversion signal of a solid-state image sensor is used for displaying a monochrome image on a monochrome EVF (electric viewfinder), the resolution is reduced, so that it is difficult to adjust the focal length by the monochrome image.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and an electronic camera in which high-frequency components are not restricted when a photoelectric conversion signal of a solid-state imaging device is used except when a color image is taken. The purpose is to provide.

[0006]

For this reason, the electronic camera according to the present invention has a structure in which the high-frequency component removing means can be switched between the operation state and the non-operation state, and the high-frequency component removing means performs the photographing operation after the photographing condition of the color image is determined. Operation switching means for operating only at the time of operation and stopping the operation at other times.

[0007]

[Function] To determine the focusing condition and the exposure conditions of the exposure amount
When the photoelectric conversion signal of the imaging unit is used (including the manual adjustment based on the display image of the black and white EVF), the operation of the high frequency component removing unit is stopped, so that the high frequency component cut off by the high frequency component removing unit is included. The shooting conditions of the color image are determined with high accuracy based on the signal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration of a still video camera according to one embodiment of the present invention. In the figure, an image pickup optical system 1 provided with an image pickup lens, a focus lens, and the like on the optical axis of incident light in a camera, an aperture 2, and an OL as high frequency component removing means
A PF 3, an IR cut filter 4 for cutting infrared rays, and a solid-state imaging device (CCD) 5 as imaging means are provided.

The image pickup optical system 1 is driven to a focus position by a lens drive motor 7 driven based on a lens drive signal from a CPU 6. Similarly, the diaphragm 2 is driven via a diaphragm drive motor 8 based on a signal from the CPU 6. Is driven, OL
The operation of the PF 3 is controlled via the control circuit 9 to determine
The reading of the CD 5 is controlled via the CCD driving circuit 10. With this configuration, at the time of shooting, an optical image of the subject obtained through the imaging optical system 1 is appropriately controlled in focus position and exposure amount, and is formed on the CCD 5 with high-frequency components removed by the OLPF 3. .

The analog image signal read from the CCD 5 is input to an analog processing circuit 11 where the signal is processed, and then input to a monochrome EVF 12 to be displayed in black and white, and to an A / D converter 13. And converted into a digital image signal. The digital image signal is input to an AE processing circuit 14 and an AF processing circuit 15 to calculate an exposure amount and a focus position, respectively,
The signal for one image is once recorded in the frame memory 16 through the interface 6. The image information recorded in the frame memory 17 is transferred to the IC memory card 18 as needed, and a plurality of image contents are recorded on the IC memory card 18.

A mechanism according to the present invention is added to the basic configuration of such a still video camera. That is, the OLPF
As shown in FIG. 2, a holder 32 on which a filter body 31 is mounted is rotatably supported around a support shaft 33, and an end of the holder 32 is
Connect to 4. A torsion coil spring 35 is attached to the support shaft 33.
And both ends thereof are fixed to the holder 32 and the fixing portion (camera body). Here, when the electromagnetic actuator 34 is not energized, the plunger 34a is expanded by the urging force of the torsion coil spring 35, and in this state, the filter main body 31 moves the optical path of the incident light (the image area received by the CCD 5). When the electromagnetic actuator 34 is energized, the plunger 34a is retracted, the holder 32 is rotated clockwise in the figure, and the filter body 31 is set on the optical axis of the incident light. (Shown by the solid line). This allows O
The LPF 3 has a configuration in which the presence or absence of a high-frequency component removal operation of incident light can be switched by energization or non-energization of the electromagnetic actuator 34.

On the other hand, the CPU 6 completes the calculation of the in-focus position and the exposure amount, and energizes the electromagnetic actuator 34 only during the color image shooting operation to operate the OLPF 3;
At other times, the control program is set so that the electromagnetic actuator 34 is de-energized and the operation of the OLPF 3 is stopped. The control program by the CPU 6 corresponds to an operation switching unit.

The photographing control by the CPU 6 will be described with reference to the time chart of FIG. The power is turned on by the trigger of the power switch, and a monochrome image is displayed on the monochrome EVF 12 (T ₁ ). In this state, the electromagnetic actuator 34 is not energized and the filter body 31 of the OLPF 3 is not energized.
Is set at a position deviating from the optical path of the incident light, the high-frequency component of the incident light is not removed, and a high-resolution black-and-white image is displayed based on the photoelectric conversion signal from the CCD 5.

[0014] When the release switch is pressed to the position of S _1, metering based on the photoelectric conversion signal from the CCD 5, distance measurement is started (T _2), calculates the amount of exposure by the photometry, the drive motor aperture diaphragm 3 8 by determining the opening time of the shutter to drive to a predetermined aperture value (AE; ends at T _3), the imaging optical system is computed focus position via the lens drive motor 7 is calculated by the distance measurement driven to an in-focus position (AF; ends at T _4). During this time, the electromagnetic actuator 34 is kept in a non-energized state, and the operation of removing the high-frequency component of the OLPF 3 is not performed. Thus, accurate AE and AF can be performed using all the luminance components.

Furthermore, when the release switch is pushed to the position of the large S ₂ of stroke than S _1, the electromagnetic actuator 34 is energized, since the filter body 31 of OLPF3 is set on the optical axis of the incident light,
The high frequency component removing operation is started (T ₅ ). Subsequently, a shutter (not shown) is opened for an exposure time set in accordance with the exposure amount, and a photographing operation for obtaining a desired color image is started (T ₆ ).

When the shutter is closed after the exposure time and the photographing is completed (T ₇ ), the power supply to the electromagnetic actuator 34 is cut off and the OLPF 3 is returned to the non-operation position after a certain period of time (T ₈ ). After confirming the end of such shooting,
The release switch is returned (T ₉ , T ₁₀ ), and after a predetermined time, the power is turned off (T ₁₁ ).

These operations are executed in synchronization with the generation of the synchronization pulse. In addition, a stepping motor may be used as the electromagnetic actuator in addition to the linear solenoid. In the above embodiment, the OLPF 3 is operated mechanically _,
Although the non-operation is configured to be switched, an OLPF configured to be electrically switched may be used.

FIG. 4 shows an embodiment using an OLPF whose electric operation _and non-operation are switched and controlled. In the figure, a diffraction grating type OLPF 21 is formed by polymerizing and fixing a transparent polymer layer 22 disposed on the light incident side and a transparent electrode layer 23 disposed on the output side. The transparent polymer layer 22 is formed with a thin film portion 22a which is easily deformed by an electrostatic force intermittently in one direction, while a portion of the transparent electrode layer 23 facing the thin film portion 22a is a concave portion, and the transparent electrode layer 23 has a transparent portion inside the concave portion. An electrode 23a having optical properties is attached.

The transparent polymer layer 22 and the electrode 2
3A, no voltage is applied to the electrode 23a and no electrostatic force is generated at the electrode 23a, as shown in FIG.
Since a does not bend, the incident light passes straight through the thin film portion 22a. Also, the transparent polymer layer 22 and the electrode 2
When a voltage is applied to the electrode 3a, an electrostatic force is generated at the electrode 23a as shown in FIG. 3B, and the thin film 22a of the transparent polymer layer 22 is attracted to the electrode 23a and bent by the electrostatic force. When light is incident from the transparent polymer layer 22 side in this state, the curved thin film portion 22a has a function of a concave lens, and the incident light is diffused after passing through the thin film portion 22a as shown by the arrow in the drawing, and the diffracted light causes a high frequency. The components are removed.

A diffraction grating type OLPF 21 having such a configuration is interposed in place of the OLPF 3 in FIG. 1, and the same control circuit 9 controls the energization of the diffraction grating type OLPF 21 in place of the electromagnetic actuator 34 before the photographing conditions of the color image are determined. Is turned on only during the photographing operation, and the high-frequency component removal is activated by turning it on. At other times, the energization of the OLPF 21 is turned off and the operation of high-frequency component removal is stopped.

Therefore, in this embodiment, the same effect as in the above embodiment can be obtained.

[0022]

As described above, according to the present invention, the high-frequency component is removed only during the photographing operation after the photographing condition of the color image from the incident light is determined, and the high-frequency component is not removed otherwise. Therefore, in the focus position control, the exposure control, the monochrome display, and the like, high-precision control using high-frequency components is performed, or an effect of obtaining an image with high resolution can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing hardware of a still video camera according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an OLPF used in the embodiment;

FIG. 3 is a time chart showing a signal state of each unit at the time of photographing in the embodiment.

FIG. 4 is a cross-sectional view and an exploded perspective view showing a configuration of a diffraction grating OLPF used in a second embodiment of the present invention and a state during operation and a state during non-operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Imaging optical system 3 OLPF 5 CCD 6 CPU 9 Control circuit 14 AE processing circuit 15 AF processing circuit 21 Diffraction grating type OLPF 22 Transparent polymer layer 22a Thin film part 23 Transparent electrode layer 23a Electrode 31 Filter body 32 Holder 34 Electromagnetic actuator 35 Twist Coil spring

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-48951 (JP, A) JP-A-63-307424 (JP, A) JP-A-60-259074 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G02B 27/46 H04N 5/222-5/257

Claims (1)

(57) [Claims] 1. An optical image signal obtained by an optical system, wherein high-frequency components are removed by a high-frequency component removing means, and then the image signal is made incident on an imaging means, and the image signal is photoelectrically converted by the imaging means to obtain a color image signal. In the electronic camera, the high-frequency component removing means is configured to be able to switch the presence or absence of operation,
An electronic camera, comprising: an operation switching unit that operates the high-frequency component removing unit only during a photographing operation after determining a photographing condition of a color image, and stops the operation at other times.