JPH06189307A - Picture recording system for video interphone - Google Patents

Abstract

PURPOSE:To use an inexpensive memory whose operating speed is slow by writing picture digital data converted from a picked-up video signal to the memory while sampling timing is deviated over plural fields without interleaving the data. CONSTITUTION:A camera section 1 picks up an image of a visitor and outputs a video signal. The video signal is converted into picture digital data at an A/D converter section 2. Furthermore, a synchronizing signal separator section 3 extracts a synchronizing signal. Since a memory 4 is an inexpensive memory whose speed is low, a picture write control section 5 generates a write address and a write clock control signal to write the picture digital data over plural fields of the memory 4. Thus, picture data equivalent to one picture of the visitor are written in the memory 4 even when the memory 4 whose write speed is low.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording system for a television intercom, and is used, for example, for storing an image of a visiting person.

[0002]

2. Description of the Related Art Conventionally, a television intercom has been widely used in which an image of a visitor is photographed by a television camera and can be monitored from inside a house. In such a television intercom, if an image of a person who has visited while he / she is away is recorded and an attempt is made to add a function that can be monitored after returning home, it is necessary to record the person image by some means. Conventionally, to record this person image, a video signal input from a television camera is recorded on a VTR (video tape recorder), or a video signal input from the camera is digitized to record information of the entire image as an image. It was stored in memory.

[0003]

However, the method of recording a video signal in a VTR has a problem that the mechanical structure is complicated and the size is large, and that it is sensitive to the usage environment such as temperature and humidity. Further, the method of digitizing a video signal and storing it in a memory requires a high-speed A / D conversion means and a high-speed memory, which causes a problem of high cost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the operating speed in an image recording system of a television interphone in which an image of the television interphone is digitalized and stored in a memory. The purpose is to enable the use of slow and inexpensive memory and to control the cost.

[0005]

In order to solve the above-mentioned problems, in the image recording system for a television interphone according to the present invention, as shown in FIG. 1, a television interphone having a function of recording a photographed video signal. In the above, a camera unit 1 for photographing an image and outputting a video signal, and an A / D conversion unit 2 for converting the video signal into image digital data
A sync signal separating unit 3 for separating a sync signal from the video signal; a memory 4 for recording image digital data; and a memory 4 for writing the image digital data in the memory 4 over a plurality of fields. And an image writing control section 5 for generating a writing clock control signal and a writing clock control signal based on the synchronizing signal.

[0006]

In the image recording system of the present invention shown in FIG. 1, the camera section 1 shoots an image, the A / D conversion section 2 converts the video signal into image digital data, and the sync signal separation section 3 converts the video signal. A synchronizing signal is extracted from the memory 4, and an address for writing to the memory 4 is generated based on the synchronizing signal so that writing to the memory 4 is performed over a plurality of fields, and a write clock control signal is sent to the image writing control unit. 5 outputs.

[0007]

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, 1 is a camera unit, 2 is an A / D conversion unit,
Reference numeral 3 is a sync signal separation unit, 4 is a memory, 5 is an image writing control unit, 6 is an A / D clock generation unit, and 7 is a field determination unit. The camera unit 1 captures an image of a visitor and outputs a video signal. This video signal is converted into image digital data by the A / D converter 2. Further, the sync signal separating unit 3 extracts the sync signal from the video signal. The memory 4 is a low-speed and inexpensive memory, and has a slow response speed for recording image digital data in real time.
The image writing controller 5 generates a write address and a write clock control signal for the memory 4 based on the synchronization signal so that the image digital data is written in the memory 4 over a plurality of fields. In addition, in order to determine the timing of A / D conversion, the A / D clock generation unit 6
Generates an A / D clock based on the synchronization signal, and inputs this to the A / D converter 2. The field determination unit 7 performs field determination with the vertical synchronization signal, and sends the result as a field signal to the image writing control unit 5.

FIG. 3 is a time chart for explaining the operation of the present invention. The write speed of the memory 4 is specified by the write clock, and the A / D is set at the A / D clock timing.
The converted image digital data n, n + 1, n + 2,
... cannot be written continuously. Therefore, although the image digital data is written in the memory 4 while being thinned out, the resolution is insufficient only with the images of the first and second fields in FIG. 3, and the screen is blurred. Also, 3, 4
The resolution is insufficient for the image of the field alone or the image of the field 5 or 6 and the screen is blurred. Therefore, by writing the images of the first field to the sixth field in the memory 4 while shifting the timing,
The image digital data of one screen is written in the memory 4 over a time period of six fields. In the present embodiment, in the odd field, as shown in FIG.
Image digital data whose horizontal address is a multiple of 3, a multiple of 3 + 1, and a multiple of 3 + 2 in three fields of 5 are written in the memory 4. Similarly for even fields, 2,
Horizontal address is 3 in each of 3 fields 4 and 6.
Data of multiples of 3 + multiples of 3 + 2 is written in the memory 4. These writing clocks are generated by the image writing controller 5 based on the field signal and the synchronizing signal. Further, the write address to the memory 4 is also generated based on the synchronization signal. In the present invention, since data is written in the memory 4 over a plurality of fields, the A / D conversion is performed on the basis of the falling edge of the sync signal so that the sampling timing of the A / D conversion unit 2 does not shift between the fields. By adjusting the clock heads, it is possible to reduce sampling deviation between fields. As described above, even when the memory 4 having a slow writing speed is used, the image data for one screen of the visitor can be written. This image data has 6 fields,
In other words, it is a composite of images of 3 frames, but it can be used enough for applications such as TV intercom that you want to know who came even if you do not know the details of the face of the visitor. .

[0009]

According to the present invention, the image digital data obtained by A / D converting the captured video signal can be written in the memory while shifting the sampling timing over a plurality of fields without thinning. Therefore, even when an inexpensive memory with a slow writing speed is used, the image digital data can be recorded without a lack of resolution, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a block diagram of an embodiment of the present invention.

FIG. 3 is an operation waveform diagram of one embodiment of the present invention.

[Explanation of symbols]

 1 camera section 2 A / D conversion section 3 sync signal separation section 4 memory 5 image writing control section

Claims (1)

[Claims] 1. A television interphone having a function of recording a captured video signal, a camera section for capturing an image and outputting the video signal, and an A / D conversion section for converting the video signal into image digital data. A sync signal separating unit for separating a sync signal from the video signal, a memory for recording image digital data, a write address and a write clock to the memory so as to write the image digital data to the memory over a plurality of fields. An image recording system for a television interphone, comprising: an image writing control unit that generates a control signal based on the synchronization signal.