JP3346802B2 - Video camera light receiving device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving device for a video camera, and more particularly to a light receiving device for a video camera using a solid-state image sensor.

[0002]

2. Description of the Related Art There is a video camera as a device for recording a video by converting light containing a video into an electric signal and recording the electric signal. In this video camera, as a light receiving device that converts light including an input image into an electric signal,
A charge transfer device (CCD) which is a solid-state imaging device is used. FIG. 4 is a configuration diagram showing a configuration of a conventional light receiving device using a CCD. In FIG.
Reference numeral 306 denotes a CCD driver / clock generation unit for controlling the CCD 301, and reference numeral 308 denotes light including an image. The light 308 including the image is transmitted to the CCD by a lens (not shown) or the like.
An image is formed on an image 301, photoelectrically converted by the CCD 301, and output as an electric signal as shown in FIG. The maximum amplitude and the minimum amplitude of this signal indicate a range between the white level and the black level, and a predetermined output signal value between the white level and the black level is determined by the subsequent circuit as the luminance of each pixel.

[0003]

Since the conventional light receiving device is configured as described above, when the size of each light receiving cell of the CCD is reduced, the effective light receiving area is reduced.
The level of the output signal from D decreases, and with this, S /
There is a problem that the N ratio also decreases. Further, increasing the speed of the charge transfer of each cell reduces the accumulation time of electrons, so that the level of the output signal from the CCD decreases as described above, and the S / N ratio also decreases accordingly. There was a problem of doing. Therefore, these reductions in output and the accompanying reduction in the S / N ratio have been limiting conditions in miniaturizing the light receiving cells in the CCD and increasing the speed of the CCD. The output increases when it is amplified, but the CCD output signal contains noise, which is the physical characteristic of the CCD that is generated when the optical signal is converted to an electrical signal. Even if the output signal itself from the CCD, which has been reduced due to the above factors, is amplified, even the noise is amplified, and S / S
The N ratio could not be improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to reduce noise due to the physical characteristics of a CCD and to obtain a signal with a good S / N ratio. And

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a spectroscope that divides the same light into a first light and a second light; A first solid-state imaging device that receives light and converts it into an electric signal; a second solid-state imaging device that receives second light and converts it into an electric signal; and an electric signal output by the first solid-state imaging device. Phase inverting means for inverting, and synchronizing the electric signal whose phase has been inverted by the phase inverting means with the electric signal output by the second solid-state imaging device.
And signal processing means for performing differential addition and synthesis.

[0006]

The signals from the first and second solid-state imaging devices have a large amplitude because they are added and synthesized in a synchronized state.
Those having no synchronism such as noise among the signal components are not added.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a configuration diagram showing a configuration of a light receiving device of a video camera according to an embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a first CCD for performing photoelectric conversion to extract a one-dimensional electric signal from a two-dimensional optical image; 102, a second CCD having the same characteristics as the first CCD;
Reference numeral 3 denotes a spectroscope that splits light (two-dimensional optical image) including an image to be captured into two and distributes the light to the first and second CCDs 101 and 102, and 104 denotes a photoelectric conversion signal from the first CCD 101. An inverter 105 for inverting the phase of the signal; a signal processing unit 105 for synthesizing the inverted signal from the inverter 104 with the photoelectric conversion signal from the second CCD 102; 106, a clock generation circuit, a timing circuit, a CCD driver, and the like; A CCD drive unit for driving the first CCD 101 and the second CCD 102, and an encoder 107 converts a signal synthesized by the signal processing unit 105 into a video signal. Reference numeral 108 denotes light including an image, and reference numeral 108a denotes a first light which the light 108 is split by the spectroscope 103 and enters the CCD 101.
And 108b is a second spectral light in which the light 108 is split by the spectroscope 103 and is incident on the second CCD 102.

Next, the operation of the light receiving device of the video camera will be described. First, light 108 that has passed through an optical lens (not shown) of the video camera is
The light beams are divided into directions and reach the surfaces of the first and second CCDs 101 and 102. The first spectral light 108a that has reached the first CCD 101 is photoelectrically converted and output as an electric signal A, and then becomes an inverted signal A 'whose phase is inverted by the inverter 104, and is input to the signal processing unit 105. On the other hand, the second spectral light 108 that has reached the second CCD 102
As described above, b is photoelectrically converted and output as an electric signal B. In this case, the signal b is directly input to the signal processing unit 105.

A first CCD 101 and a second CCD 102
Are driven by the same CCD driving unit 106, and thus are output from the first CCD 101 and output from the inverter 104.
As shown in FIG. 2A, the inverted signal A 'whose phase has been inverted in step (a) and the photoelectric conversion signal B output from the second CCD 102 have opposite phases but have synchronized timings, as shown in FIG. . These signals are differentially added and synthesized by the signal processing unit 105, and the added and synthesized signal is shown in FIG.
The total output signal is doubled between the white level and the black level, and the range between the white level and the black level is correspondingly doubled. Here, the physical factors of the CCD surface and noise components due to thermionic electrons included in the two signals input to the signal processing unit 105 are generated irregularly and are not synchronized with the clock signal. Even if the amplitude is added by the processing unit 105, the amplitude does not double, and these noise components in the output signal do not increase twice. Therefore, the output signal synthesized by the signal processing unit 105 is a signal having an improved S / N ratio.

(Embodiment 2) By the way, the CCD takes in light containing an image and photoelectrically converts it. The time for taking in this light is reduced from 1/60 second to 1/500 second, 1/1.
By setting the time to 000 seconds, the resolution at the time of capturing a fast-moving image can be improved. This is a shutter operation in a video camera. A voltage for sweeping out unnecessary charges is applied to the CCD to remove unnecessary charges constantly stored in the CCD and capture light containing an image for 1/500 second, for example. This enables the shutter operation.

FIG. 3 is a configuration diagram showing the configuration of the light receiving device of the video camera when performing the shutter operation.
Is controlled by the CCD driving unit 106a and the first CC
A shutter operation unit for performing a shutter operation of the D101 and the second CCD 102, and the other components are the same as those in FIG. The shutter operation unit 109 applies a voltage several times higher than normal to the first CCD 101 and the second CCD 102 for a predetermined time, thereby sweeping the accumulated charge and shortening the time for photoelectric conversion to reduce the image. Take in light containing. As a result, motion blur is reduced and resolution is improved, but sensitivity is reduced because the amount of light to be captured is reduced.
However, as described in the first embodiment, also in the second embodiment, the phase of the photoelectric conversion signal A from the first CCD 101 is inverted by the inverter 104, and this phase inverted signal A 'is output from the second CCD 102. Since the photoelectric conversion signal B and the photoelectric conversion signal B are differentially added and synthesized by the signal processing unit 105, a decrease in the output signal level caused by the shutter operation can be improved, and in addition, the S / N ratio can be improved.

(Embodiment 3) In the first embodiment, the phase of the photoelectric conversion signal output from the first CCD 101 is inverted by the inverter 104, and the inverted signal is converted into the second CCD signal.
2 is combined with the photoelectric conversion signal B output from the second CCD 102, but the invention is not limited thereto. The photoelectric conversion signal A output from the second CCD 102 is output without inverting the phase of the photoelectric conversion signal A from the first CCD 101. B may be combined.
In this case, the signal processing unit 105 except for the inverter 104 in FIG.
The signal processing unit 105a may be configured to add and synthesize the signal B from the second CCD 102 in synchronization.

In the embodiment 2 shown in FIG.
The same operation as that of FIG.
With the exception of 04, the signal processing unit 105 may be a signal processing unit 105a that adds and synthesizes the signal A from the first CCD 101 and the signal B from the second CCD 102.

[0014]

As described above, according to the present invention, only the photoelectrically converted signal can be amplified without increasing the noise of the electric signal at the time of photoelectric conversion due to the physical characteristics of the surface of the solid-state imaging device. It is possible to improve the / N ratio, and theoretically the S / N ratio can be increased to about 1.4 times. Therefore, even when the amount of light to be taken in is small, such as when shooting a dark place with a video camera or when performing a shutter operation, the S / N ratio is improved, so that the photoelectrically converted signal can be amplified without increasing noise. , The sensitivity can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a light receiving device of a video camera according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a change in a signal in signal processing of a signal processing unit.

FIG. 3 is a configuration diagram showing a configuration of a light receiving device of a video camera according to another embodiment of the present invention.

FIG. 4 is a configuration diagram showing a configuration of a light receiving device of a conventional video camera.

5 is a waveform chart showing an output signal level of the solid-state imaging device shown in FIG.

[Explanation of symbols]

 Reference Signs List 101 First CCD 102 Second CCD 103 Spectroscope 104 Inverter 105 Signal processing unit 106 CCD driving unit 107 Encoder 108 Light 108a First spectral light 108b Second spectral light

Claims (1)

(57) [Claims] 1. A spectroscope that divides the same light into a first light and a second light, a first solid-state imaging device that receives the first light and converts the same into an electric signal, A second solid-state imaging device that receives the light of the first solid-state imaging device and converts the light into an electric signal; a phase inversion device that inverts the phase of the electric signal output from the first solid-state imaging device; A light receiving device for a video camera, comprising: signal processing means for synchronously and differentially adding and synthesizing a signal and an electric signal output from the second solid-state imaging device.