JPH0646424A - Monitoring device - Google Patents

Abstract

PURPOSE:To provide a monitoring device which can obtain the clear images even with the subjects of low luminous intensity when the synthetic video signals acquired through each camera are projected for monitoring plural subjects. CONSTITUTION:The coding circuit 12 and 13 are provided at the side of a camera control unit 6 to manually set and code the electric charge storing time. The code signals obtained by the circuits 12 and 13 are superposed on each other by a superposing means 14 in a vertical blanking period of a video signal. A camera A decodes the code signals transmitted by a circuit 3 and control the electric charge storing time of an image pickup element 1. Furthermore the circuits 5 and 15 perform the write control in response to the end pulse sent from the element 1 for a memory 11 which changes the time base of the video signal. The memory 11 is read for each field and the video signals received from plural memories are synthesized by an adder means 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring device for monitoring a plurality of subjects by a camera and displaying a composite video signal on a display screen, and more particularly to a monitoring device for obtaining a good video in low illuminance.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional monitoring device. The illustrated monitoring device is four cameras A, B, C, D.
Each camera has a CCD 1 and a video process unit 2 as represented by a camera A, and a camera control unit (hereinafter, referred to as a camera control unit) via a coaxial cable 16.
CCU) 6). The CCU 6 has one memory 11 for each camera, stores each video signal from the cameras A to D in each memory 11 once, converts the time axis, and, for example, as shown in FIG. One composite video signal for displaying the video signals from the cameras A to D on the divided display screens is sent from the superimposing unit 7 as a video output.

FIG. 5 illustrates the charge accumulation and transfer timing of the CCD 1, and FIG. 6 illustrates the read operation of the memory 11. As shown in FIG. 5, a half period t1 after one field of the video signal
In, the charges are accumulated in each CCD 1 and the accumulated charges are transferred in a relatively short period t2 thereafter, and the video process unit 2 in FIG. 3 processes the output signal of the CCD 1 and outputs it as a video signal. The CCU 6 stores the video signals from the video processing unit 2 in the memory 11 at the clock frequency f.
In order to change the time axis, the writing is sequentially performed and the reading from the memory 11 is performed by a clock having twice the writing clock frequency f, that is, 2f.

At this time, as shown in the timings (a) and (b) of FIG. 6, the reading of the video signal from each memory 11 is performed in different combinations in the first half and the second half of one field, so that one line is read. By alternately performing the first half and the second half, the video signals of the cameras A to D are obtained on the divided display screen as shown in FIG. That is, in the first half of one field, the signal of camera A is read in the first half of one line, and the signal of camera B is read in the second half.
In the latter half of the field, the signals of cameras C and D are similarly read out.

[0005]

However, in the above-described conventional monitoring device for monitoring a plurality of subjects, the charge accumulation time by the CCD 1 of each camera, that is, FIG.
Since the charge accumulation time t1 by the CCD 1 shown in Fig. 2 is shorter than one field period, sufficient charges are not accumulated when monitoring a subject with low illuminance, and therefore a clear reproduced image cannot be obtained, which hinders monitoring. Bring Further, if the accumulation time is set to 1 field or more so that sufficient charges can be obtained, there is a problem that the transfer of charges (t2 in FIG. 5) is not performed for each field and the image is lost in each field. .

The present invention has been made in order to solve the above problems, and provides a monitoring device capable of obtaining clear images of a plurality of subjects even when monitoring a subject with low illuminance. is there.

[0007]

In order to achieve the above object, in the monitoring apparatus according to the present invention, the light receiving time in each image sensor, that is, the charge storage time can be set to a desired number of fields according to the intention of the user. The desired number of fields is coded, superimposed and transmitted in the vertical blanking period, and the code is decoded to control the charge storage time of each image sensor. Further, in response to an end pulse indicating the end of charge accumulation output from each image sensor, writing of a video signal to the memory is controlled and the video signal is read from each field memory. That is, according to the present invention, a plurality of cameras each having an image pickup device for picking up an image of a subject and a video process unit for producing a video signal according to the accumulated charges transferred from the image pickup device are provided, and Camera control having a plurality of memories for respectively storing and reading the video signals to convert the time axis of the video signals, and an adding means for synthesizing the plurality of video signals from the plurality of memories to obtain a composite video signal In a monitoring device including a unit, means for encoding a desired charge accumulation time that is manually set, and means for superimposing the code signal obtained by the encoding on a vertical blanking period of the video signal. An accumulation time control unit that controls the charge accumulation time of the image sensor based on the superimposed code signal, and the charge accumulation of the image sensor Upon completion pulse generated Ryoji controls the writing of the video signal by the memory, the monitoring apparatus is provided, characterized in that it comprises a memory control means for reading a video signal from each field the memory.

[0008]

In the present invention, the charge accumulation time of the image pickup device of the camera is set on a field unit basis by the setting unit on the camera control unit side, and is sent to the camera side as a coded code signal during the blanking period of the video signal. Then, the control unit on the camera side controls the charge accumulation time of the image sensor based on the input of the code signal. The camera control unit side controls the writing of the video signal to the memory by detecting the end pulse generated at the end of the charge accumulation of the image pickup device by the end pulse detector. After that, each video signal is read out from each memory for each field and combined by the addition means to obtain a combined video signal whose time axis is changed.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a monitoring device according to this embodiment. In the illustrated monitoring device, each of the cameras A to D is provided with a configuration similar to that represented by the camera A, and the CCU 4 is represented by a signal processing circuit corresponding to the camera A corresponding to each camera. A signal processing circuit 10 having the same configuration is provided. Hereinafter, the camera A will be described as a representative.

First, the camera A has a CC as an image sensor.
D1, a video process unit 2 that encodes the charges transferred from this CCD1 into a video signal, and CC so that sufficient accumulated charges can be obtained in the CCD1 to obtain a clear image.
A storage time control unit 3 for controlling the storage time in field units based on the serial code signal sent from the U6 side, a video signal from the video process unit 2 and the charge of the CCD 1 within the blanking period of this video signal. A second end pulse generator 5 that generates a second end pulse from a first end pulse that is generated when the storage is completed, and a second end pulse that is superposed on the video signal to the CCU 6 side via the coaxial cable 16. The superimposing unit 4 for sending out is provided.

On the other hand, the camera control unit CCU
The signal processing circuit 10 corresponding to the camera A in 6 includes a memory 11 for writing and reading a video signal transmitted from the camera A via the coaxial cable 16, and the C
A field number setting unit 12 that sets the number of fields given as the charge storage time of the CD 1, and a serial code generation unit 1 that converts the set number of fields into a serial code.
3 and 3. Although not shown, a video signal as an analog signal is digitized by an A / D converter and given to the memory 11. Also each memory 1
A D / A converter is provided on the output side of 1 as necessary.

Further, the serial code is sent to the camera A via the coaxial cable 16 within the blanking period of the video signal.
A superimposing unit 14 for sending to the side, and an end pulse detecting unit 15 for detecting the second end pulse and switching the second end pulse to write the video signal in the memory 11 for one field period are provided. In addition, as in the conventional example, the memory 1
The writing of the video signal to 1 is performed at the clock frequency f, and the reading is performed at the clock frequency 2f.

Next, the operation of each section according to the above configuration will be described with reference to the signal timing chart shown in FIG. First, the field number setting unit 12 on the CCU 6 side sets the CCD
The accumulation time is manually set for each field so that a sufficient charge can be obtained with 1 (2 fields in this embodiment), and serial code is generated by the serial code unit 13. As a manual setting method, for example, a ten key or the like is used to set a desired number of fields out of 2 to 12 fields. Further, the superimposing unit 14 detects the vertical blanking period of the video signal and superimposes the serial code signal on the video signal on the coaxial cable 16 within the period (t1 in FIG. 2). The number of bits of the serial code is determined by the maximum settable number of fields, but in the case of this embodiment, 4 bits is sufficient.

Further, on the camera A side, the storage time number control unit 3 detects the serial code signal on the coaxial cable 16 and controls the storage time of the CCD 1 based on this. That is, in the period t2 of FIG. 2, the charge is stored in the CCD 1, and when the charge is completed, the charge is transferred, and at the same time, the first end pulse indicating the end of the storage is generated (t in FIG. 2).
3). The transferred charge is converted into a video signal (composite video signal) by the video process unit 2 and is given to the coaxial cable 16 via the superimposing unit 4 together with the second end pulse gated for one line. Here, the superimposition of the second end pulse is performed within the vertical blanking period so as not to affect the video signal (t4 in FIG. 2).

However, the video signal at this time is an intermittent signal in which the video is missing except in the field of the transfer period. Therefore, the end pulse detection unit 15 in the signal processing circuit 10 on the CCU 6 side detects the second end pulse on the coaxial cable 16 and uses it as a trigger to set the video signal to the memory 11 for one field period (t5 in FIG. 2). A write gate pulse (t6 in the figure) is written to write to the memory 11, a write clock frequency f is given to the memory 11 for writing during this period t6, and then reading is performed for each field (t6 in FIG. 2). The video is interpolated in the missing parts other than the transfer period to obtain a normal video. That is, the memory 11 over a plurality of fields
Read from and output. In this embodiment, two fields are continuously stored, the memory 11 is written in the next field, and then each field is read.
Accumulation of charges is continuously performed every two fields. Therefore, the CCD 1 continuously accumulates the electric charge without taking a rest in each field, so that the sensitivity can be improved. The reading period t6 in FIG. 2 shows the reading period from the memory 11 corresponding to the camera A or B, and is the first half of one field. Therefore, the reading period from the memory 11 corresponding to the camera C or D is the latter half of one field, unlike the one shown in the figure. Since the control of the reading period is similar to that of the conventional example, the frequency 2
The gate pulse generating means for the read pulse of f is not shown.

In this manner, the video signal from each memory 11 corresponding to each camera is alternately read out and controlled to be supplied to the adder 7 as an adding means, as in the conventional example shown in FIG. A synthesized video signal as shown in FIG. 4 is displayed as a clear video on a display screen (not shown).

[0017]

As described above, according to the present invention,
The charge accumulation time of the image sensor is controlled by the code signal set in field units, the end of accumulation is detected by the pulse generated at the end of accumulation, and the video signal is written in the memory.
The video signal of each memory is read field by field, and the time axis is changed to obtain a composite video signal, so sufficient charges can be accumulated and a clear image can be obtained even when monitoring a subject with low illumination. In addition, it is possible to obtain a clear image for monitoring a plurality of subjects without causing the video signal to be lost in field units.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a monitoring device of the present invention.

FIG. 2 is a timing chart of operation waveforms of respective parts of FIG.

FIG. 3 is a block configuration diagram of a conventional monitoring device.

FIG. 4 is an explanatory diagram showing an example of a display screen of a composite video signal.

5 is an explanatory diagram of a charge accumulation period and a transfer period of the CCD of FIG.

FIG. 6 is an explanatory diagram of read control of a video signal from each memory of FIG.

[Explanation of symbols]

 1 CCD 2 Video Process Section 3 Storage Time Control Section 4, 14 Superposition Section 5 Second End Pulse Generation Section 6 Camera Control Unit (CCU) 7 Adder (Adding Means) 11 Memory 12 Field Number Setting Section 13 Serial Code Generation Section 15 Second end pulse detector 16 Coaxial cable A to D camera

Claims (2)

[Claims] 1. A plurality of cameras each having an image pickup device for picking up an image of a subject and a video process unit for producing a video signal according to accumulated charges transferred from the image pickup device, and the image from each of the cameras. A camera control unit having a plurality of memories for respectively accumulating and reading the video signals to convert the time axis of the signals, and an adding means for synthesizing the plurality of video signals from the plurality of memories to obtain a composite video signal. And a means for encoding a manually set desired charge storage time, a means for superimposing a code signal obtained by the encoding on a vertical blanking period of the video signal,
An accumulation time control unit that controls the charge accumulation time of the image sensor based on the superimposed code signal, and a writing of a video signal by the memory according to an end pulse generated when the charge accumulation of the image sensor is completed. And a memory control means for reading a video signal from the memory for each field. 2. A surveillance device in which the camera and its corresponding camera control unit are connected by a coaxial cable, wherein the encoding means and the superimposing means are in the camera control unit, and A storage time control unit is provided in the camera, and as the memory control unit, a unit for generating another end pulse generated only in the vertical blanking period in response to the end pulse generated from the image sensor. Means for superimposing the other end pulse on the output video signal of the video process section is provided in the camera, and the other end pulse is detected, and the video signal to the memory over one field after detection. 2. An end pulse detection section for writing the data is provided in the camera control unit. The monitoring device described.