JPH05199454A - Photodetecting device of video camera - Google Patents

Abstract

PURPOSE:To decrease a noise caused by physical information of a CCD, and to fetch a signal whose S/N is satisfactory. CONSTITUTION:A photoelectric converting signal outputted from a first CCD 101 is inverted as to its phase by an inverter 104, and this inverted signal and a photoelectric converting signal outputted from a second CCD 102 are synthesized differentially by a signal processing part 105. In such a way, a synchronized signal becomes two folds, and an unsynchronized noise is not added.

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 pickup device.

[0002]

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

[0003]

Since the conventional light receiving device is configured as described above, when the miniaturization of each light receiving cell of the CCD is attempted, the effective light receiving area is reduced and CC
The level of the output signal from D decreases, and S /
There is a problem that the N ratio also decreases. Further, since the speeding up of the charge transfer of each cell shortens the electron accumulation time, the level of the output signal from the CCD is lowered as described above, and the S / N ratio is also lowered accordingly. There was a problem to do. Therefore, the decrease in the output and the accompanying decrease in the S / N ratio have been the limiting conditions for promoting miniaturization of the light receiving cells in the CCD and speeding up of the CCD. The output increases with amplification, but the CCD output signal contains noise due to the physical characteristics of the CCD that are generated at the time of converting an optical signal into an electrical signal. Even if the output signal itself from the CCD, which is lowered due to such factors, is amplified, the noise is also amplified and S /
The N ratio could not be improved.

The present invention has been made in order to solve the above problems, and an object thereof is to reduce noise due to the physical characteristics of CCD so that a signal having a good S / N ratio can be taken out. And

[0005]

In order to solve the above problems, in the present invention, a spectroscope for splitting the same light into a first light and a second light, and a first light A first solid-state image sensor that receives light and converts it into an electric signal, a second solid-state image sensor that receives second light and converts it into an electric signal, and an electric signal output by the first solid-state image sensor Signal processing means for inputting and synthesizing the electrical signal output from the solid-state image pickup device of No. 2; Further, it is characterized in that it has a phase inverting means for inverting the phase of the electric signal output from the first solid-state imaging device.

[0006]

Since the signals from the first and second solid-state image pickup devices are added and combined in a synchronized state, they have a large amplitude.
Among the signal components, noise-free components such as noise are not added.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a configuration diagram showing the configuration of a light receiving device of a video camera according to an embodiment of the present invention. In FIG. 1, 101 is a first CCD that performs photoelectric conversion to extract a one-dimensional electric signal from a two-dimensional optical image, 102 is a second CCD having the same characteristics as the first CCD, and 10
Reference numeral 3 denotes a spectroscope for splitting light (two-dimensional optical image) including an image to be captured into two and distributing it to the first and second CCDs 101 and 102, and 104 denotes a photoelectric conversion signal from the first CCD 101. An inverter for inverting the phase of the signal, a signal processing unit 105 for synthesizing an inversion signal from the inverter 104 and a photoelectric conversion signal from the second CCD 102, a reference numeral 106 having a clock generation circuit, a timing circuit, a CCD driver, A CCD drive unit for driving the first CCD 101 and the second CCD 102, and 107 is an encoder for converting the signal synthesized by the signal processing unit 105 into a video signal. It is to be noted that reference numeral 108 denotes light containing an image, and reference numeral 108 a denotes a first light which is dispersed by the spectroscope 103 and is incident on the CCD 101.
And 108b is the second spectroscopic light that is incident on the second CCD 102 after the light 108 is dispersed by the spectroscope 103.

Next, the operation of the light receiving device of this video camera will be described. First, the light 108 that has passed through the optical system lens (not shown) of the video camera is reflected by the spectrometer 103.
It is divided into directions and reaches the surfaces of the first and second CCDs 101 and 102. The first spectroscopic 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
Similarly to the above, b is photoelectrically converted and output as the electric signal B, and in this case, is input to the signal processing unit 105 as it is.

First CCD 101 and second CCD 102
Are driven by the same CCD driving unit 106, and therefore are output from the first CCD 101 and the inverter 104
As shown in FIG. 2A, the inverted signal A ′ whose phase has been inverted in step 1 and the photoelectric conversion signal B output from the second CCD 102 have opposite phases in amplitude but synchronized timing. .. Each of these signals is 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, a physical factor of the CCD surface and a noise component due to thermoelectrons included in the two signals input to the signal processing unit 105 are irregularly generated and are not synchronized with the clock signal. Even if they are added by the processing unit 105, their amplitudes do not double, and these noise components in the output signal are not doubled. Therefore, the output signal combined by the signal processing unit 105 is a signal with 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 the light is 1/60 second to 1/500 second, 1/1
By setting it to 000 seconds, it is possible to improve the resolution when capturing a fast-moving image. This is the shutter operation in the video camera, but a voltage for sweeping unnecessary charges is applied to the CCD to remove unnecessary charges accumulated in the CCD at all times, and for example, capture light containing an image for 1/500 seconds. This allows the shutter operation.

FIG. 3 is a block diagram showing the structure of the light receiving device of the video camera when the shutter operation is performed.
Is controlled by the CCD driving unit 106a and the first CC
A shutter operation unit for causing the D101 and the second CCD 102 to perform a shutter operation, and is otherwise similar to FIG. The shutter operation unit 109 applies a voltage that is several times higher than usual to the first CCD 101 and the second CCD 102 for a predetermined time, thereby sweeping the accumulated charge and shortening the photoelectric conversion time, thereby reducing the image. Captures light including. This reduces the blur of the moving image and improves the resolution, but the amount of light taken in decreases, and thus the sensitivity decreases.
However, as described in the first embodiment, also in the second embodiment, the photoelectric conversion signal A from the first CCD 101 is phase-inverted by the inverter 104, and this phase-inverted signal A ′ is output from the second CCD 102. Since the signal processing unit 105 differentially adds and synthesizes the photoelectrically converted signal B, the reduction in the output signal level caused by the shutter operation can be improved, and in addition, the S / N ratio can be improved.

(Third Embodiment) In the first embodiment, the photoelectric conversion signal output from the first CCD 101 is phase-inverted by the inverter 104, and the phase-inverted signal is applied to the second CCD 10.
The photoelectric conversion signal B output from the second CCD 102 is not combined with the photoelectric conversion signal B output from the second CCD 102, but the photoelectric conversion signal A output from the first CCD 101 is not phase-inverted. It may be combined with B.
In this case, in FIG. 1, the signal processing unit 105 is provided with the signal A from the first CCD 101, except for the inverter 104.
The signal processing unit 105a may be configured to add and synthesize the signal B from the second CCD 102 in synchronization.

In the second embodiment shown in FIG. 3, the third embodiment is also used.
The same can be done with the inverter 1 in FIG.
Except for 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, it is possible to amplify only the photoelectrically converted signal 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 image pickup device. The / N ratio can be improved, and theoretically the S / N ratio can be increased to about 1.4 times. Therefore, the S / N ratio is improved even when the amount of light to be captured is small, such as when shooting a dark place with a video camera or when performing a shutter operation, so that the photoelectrically converted signal can be amplified without increasing noise. It is possible to improve the sensitivity.

[Brief description of 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 showing changes in signals 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 which is 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 diagram showing an output signal level of the solid-state imaging device shown in FIG.

[Explanation of symbols]

 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 (2)

[Claims] 1. A spectroscope for splitting the same light into a first light and a second light; a first solid-state image sensor for receiving the first light and converting it into an electric signal; Second solid-state image sensor for receiving the light of the above and converting it into an electric signal, and a signal for inputting and combining the electric signal output by the first solid-state image sensor and the electric signal output by the second solid-state image sensor A light receiving device for a video camera, comprising: a processing means. 2. The light receiving device for a video camera according to claim 1, further comprising phase inverting means for inverting a phase of an electric signal output from the first solid-state imaging device. ..