JPH09200616A - Imaging device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head separated type image pickup device with which signals can be sampled for a flat period without any error even when an inexpensive cable having adverse waveform characteristics or a cable for a long distance is used. SOLUTION: This image pickup device has a cable 5 for connecting a camera head 10 and a main control part 10 and has a CCD 1, 1st sample/hold (S/H) circuit 2, 2nd S/H circuit 3 and timing controller 4 or the like. The image pickup device mutually samples/holds the output of the CCD 1 for every two picture elements while shifting one picture element through the 1st and 2nd S/H circuits, transmits sampled/held 1st and 2nd CCD signals and selectively switches only the flat periods of two 1st and 2nd CCD signals just before an A/D converter 7. Even when a transient period is long, only the signals for the flat periods can be effectively extracted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device.

[0002]

2. Description of the Related Art Recently, in an image pickup apparatus using a solid-state image pickup device (CCD), a CCD image pickup section and a signal processing section for processing a signal from the CCD and outputting it as a video signal are separated.
Many image pickup devices called so-called head-separated type cameras have been proposed in which the distance between them is extended by a cable or the like.

Further, in such an image pickup device using a CCD, the size and weight of the image pickup device have been reduced with the progress of electronic technology in recent years. In particular, a method of processing a signal from a CCD as a digital signal using a high-speed analog-digital (AD) converter and a digital-analog (DA) converter has been proposed due to the progress of semiconductor technology.

Most of the head-separated type cameras sample and hold analog signals spatially sampled by the CCD and then transmit them with a cable. Therefore, the sampling clock frequency increases due to the increase in the pixels of the CCD, and the waveform characteristics are further increased. Good drive systems, termination circuits and transmission systems are required.

FIG. 3 is a block diagram showing the structure of a conventional image pickup apparatus. The conventional image pickup device includes a camera head 10a and a main control unit 11a.

Reference numeral 1a is a CCD, and 2a is a sample and hold circuit that samples and holds the output of the CCD 1a for each pixel. Reference numeral 4a is a timing controller that generates timing signals necessary for the CCD 1a, the sample hold circuit 2a, and the like.

Reference numeral 5a is a cable connecting the camera head 10a and the main controller 11a. C by cable 5a
A clock CLK synchronized with the CD signal and the CCD signal is output from the camera head 10a to the main controller 11a. Further, the HD signal and the VD signal for synchronizing the CCD 1a and the signal processing circuit 8a are output from the main control unit 11a to the camera head 10a by the cable 5a.

The CCD signal is clocked by the AD converter 7a at the clock C.
The signal is converted into a digital signal in synchronization with LK, and a signal processing circuit (DSP) 8a requires a filter for a color image pickup device.
Digital signals such as color separation, gamma, matrix, and clip are processed, digital-analog converted by the DA converter 9a, and output as NTSC signals.

FIG. 4 is a timing chart showing signal waveforms of a conventional image pickup apparatus. The figure (a) shows the output waveform of CCD, the figure (b) shows the input waveform of the AD converter 7a, and the figure (c) shows the waveform of the clock CLK of the AD converter 7a.

By sampling and holding the CCD signal, the output of the CCD 1a is divided into a sampling period and a holding period. Further, the waveform of the CCD signal is distorted by passing through the transmission system such as the cable 5a, and the AD converter 7a
In the input of, the transient period and the flat period in which the waveform is distorted occur as shown in FIG. If the sampling timing of the AD converter 7a occurs in the transient period, an error occurs in the signal, so the clock CLK of the AD converter 7a must be adjusted so as to sample in the flat period.

[0011]

However, when an inexpensive cable having bad waveform characteristics is used or the cable is made to have a long distance, the transient period becomes long and the flat period cannot be sampled. There was a problem that an error occurred.

Further, when a CCD image pickup device having a high pixel frequency with a higher sampling clock frequency is used, it becomes more difficult to secure a flat period. Therefore, an expensive device that operates at high speed or an expensive device having a wide band and good waveform characteristics is used. Transmission cable was needed.

Therefore, the present invention provides a head-separated type image pickup device capable of sampling a signal in a flat period without error even when an inexpensive cable having bad waveform characteristics or a long-distance cable is used. To aim.

[0014]

According to a first aspect of the present invention, there is provided an image pickup device comprising an image pickup means for converting an optical signal into an electric signal and outputting the converted electric signal in pixel units. A plurality of sample and hold circuits that sequentially sample and hold the electric signal output from the image pickup unit for each pixel, a transmission unit that transmits the sample and hold electric signal through a cable, and a plurality of the transmitted electric signals It is characterized by further comprising a selecting means for selecting any one of the above in synchronization with the sample hold for each pixel and a signal processing means for processing the selected electric signal.

An image pickup method according to a second aspect of the present invention is an image pickup method of converting an optical signal into an electric signal by using an image pickup means and outputting the converted electric signal in pixel units, using a plurality of sample hold circuits. The electric signal output from the image pickup unit is sequentially sampled and held for each pixel, the sampled and held electric signal is transmitted through a cable, and any one of the plurality of transmitted electric signals is sampled and held for each pixel. Is selected in synchronism with, and the selected electric signal is processed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an image pickup apparatus of the present invention will be described. FIG. 1 is a block diagram showing the configuration of the image pickup apparatus according to the embodiment. In the figure, 1 is CC
D and 2 are first sample and hold circuits that sample and hold the output of the CCD 1 for every two pixels, 3 is a second sample and hold circuit that samples and holds the output of the CCD1 for every two pixels, and 4 is the CCD 1 and the first sample and hold circuit 2. And a timing controller that outputs a timing signal necessary for the second sample hold circuit 3.

Reference numeral 5 denotes a camera head 10 and a main controller 11
It is a cable that connects to. A clock CLK synchronized with the first CCD signal from the first sample and hold circuit 2 and the second CCD signal from the second sample and hold circuit 3, and the first CCD signal and the second CC through the cable 5.
The SEL signal for selecting the D signal is output from the camera head 10 to the main controller 11.

The HD signal and the VD signal for synchronizing the CCD 1 and the signal processing circuit 8 are output from the main controller 11 to the camera head 10 through the cable 5. The first and second sample and hold circuits 2 and 3 sample and hold the CCD signals for every two pixels and shift them by one pixel, and output signals from the first and second sample and hold circuits 2 and 3 from the CCD 1. 1 / of output signal
It is sent to the main control unit 11 through the cable 5 at the frequency of 2.

In the main controller 11, the first CCD signal and the second CCD signal are connected to the switch 6. 1st C
The CD signal and the second CCD signal are set to 1 by the SEL signal.
It is switched for each pixel and sent to the AD converter 7.

The first signal input to the AD converter 7 for each pixel
The CCD signal and the second CCD signal are converted into digital signals in synchronization with the clock CLK, and the signal processing circuit 8 processes digital signals such as filters, color separation, gamma, matrix, and clip necessary for the color image pickup device,
Digital-to-analog conversion by the DA converter 9 and NTSC
Output as a signal.

FIG. 2 is a timing chart showing the signal waveform of each part of the image pickup device. The same figure (a) is clock CLK
Waveform of the first sample and hold circuit (SH
1) the waveform of the output signal, FIG. 7C shows the waveform of the output signal of the second sample hold circuit SH2, and FIG. 7D shows the SEL signal for selecting the first CCD signal and the second CCD signal. (e) is the first CCD signal, (f) is the second CCD signal
CD signal, the same (g) is the first CCD signal and the second CC
The D signal is a waveform of a signal which is selected by the SEL signal for a flat period and is input to the AD converter 7.

That is, the output of the CCD 1 is shifted by one pixel, and the first and second sample and hold circuits alternately sample and hold every two pixels, and the sample-held first C is sampled and held.
The CD signal and the second CCD signal are transmitted, and the AD converter 7
Immediately before, by selectively switching only the flat periods of the two first CCD signals and the second CCD signals, it is possible to effectively extract only the signals of the flat period even when the transient period is long.

Therefore, even if an inexpensive cable having a bad waveform characteristic is used or the cable is made a long distance, a sufficient flat period can be secured, so that an error does not occur in the analog-digital converted signal. .
Further, even when a high pixel CCD image pickup device having a higher sampling clock frequency is used, a sufficient flat period can be secured. This eliminates the need for an expensive device that operates at high speed and an expensive transmission cable that has a wide band and good waveform characteristics.

In the present embodiment, the case where two sample hold circuits are provided has been described, but three or more sample hold circuits may be provided, and the output signals from each sample hold circuit are sequentially switched in pixel units. By inputting to the AD converter, it is possible to sufficiently cope with the case where a high pixel CCD image pickup device having a higher sampling clock frequency is used.

[0025]

According to the image pickup device of the first aspect of the present invention, a plurality of sample and hold circuits are used when an optical signal is converted into an electric signal by the image pickup means and the converted electric signal is output in pixel units. Sample-holds the electric signal output from the image pickup means in sequence for each pixel, transmits the sampled-hold electric signal by the transmitting means through a cable, and selects one of the plurality of electric signals transmitted by the selecting means. Is selected in synchronism with the sample hold for each pixel, and the selected electric signal is processed by the signal processing means. Therefore, a plurality of sample hold circuits are used to sample and hold each pixel in order and transmit it by a cable. By this, the signal can be slowed down and a sufficient flat period can be secured. Therefore, it is possible to use an inexpensive cable having a long waveform characteristic or a long-distance cable. Further, even when a high-pixel CCD image pickup device having a higher sampling clock frequency is used, a flat period can be sufficiently secured, and an expensive device that operates at high speed or an expensive cable that has a wide band and has good waveform characteristics is not required. It's done.

According to a second aspect of the image pickup method, in the image pickup method of converting an optical signal into an electric signal using the image pickup means and outputting the converted electric signal in pixel units, a plurality of sample hold circuits are provided. Sample-hold the electrical signal output from the image pickup means for each pixel in order,
The sampled and held electric signal is transmitted through a cable, and any one of the plurality of transmitted electric signals is selected in synchronization with the sample and hold for each pixel, and the selected electric signal is processed. The signal can be slowed down and the flat period can be sufficiently secured by sample-holding each pixel in order using the sample-hold circuit and transmitting the data through the cable.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an imaging device according to an embodiment.

FIG. 2 is a timing chart showing a signal waveform of each part of the image pickup apparatus.

FIG. 3 is a block diagram showing a configuration of a conventional imaging device.

FIG. 4 is a timing chart showing a signal waveform of a conventional image pickup device.

[Explanation of symbols]

 1 CCD 2 1st sample hold circuit 3 2nd sample hold circuit 4 Timing controller 5 Cable 6 Switch 7 AD converter 8 Signal processing circuit 10 Camera head 11 Main controller

Claims (2)

[Claims] 1. An image pickup apparatus comprising an image pickup means for converting an optical signal into an electric signal and outputting the converted electric signal for each pixel, wherein the electric signal output from the image pickup means is sequentially provided for each pixel. A plurality of sample and hold circuits for sample and hold, a transmission means for transmitting the sampled and held electric signal through a cable, and one of the plurality of transmitted electric signals is selected in synchronization with the sample and hold for each pixel. An imaging apparatus comprising: a selection unit and a signal processing unit that processes the selected electric signal. 2. An image pickup method for converting an optical signal into an electric signal by using an image pickup means and outputting the converted electric signal for each pixel, wherein a plurality of sample hold circuits are used to output from the image pickup means. Sample and hold an electrical signal for each pixel in sequence, transmit the sampled and held electrical signal through a cable, and select any of the plurality of transmitted electrical signals in synchronization with the sample and hold for each pixel, An imaging method comprising processing the selected electrical signal.