JPH01177195A - Supervising device - Google Patents

Abstract

PURPOSE:To minimize the use quantity of a tape by efficiently recording the picture signal of a recording object according to the change status of a supervising object. CONSTITUTION:When a recording control circuit 17 receives a recording start signal outputted according to the discrete value of the number of changing elements from a recording interval determining circuit 16, the circuit 17 sends a recording signal to a recorder 18, and the recorder 18 records the picture signal from a video camera 11 while the recording signal is sent from the recording control circuit 17. The recording signal outputted from the recording control circuit 17 is also connected to a picture memory 14, and for the picture memory 14, its picture is updated to a new input picture all the time when the picture is recorded in the recorder 18. Thus, since the recorder 18 can efficiently record the picture signal of the recording object according to the change status of the supervising object based on the recording signal, the use quantity of the tape can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a monitoring device that records and monitors an image signal of a monitored object based on changes in the image signal obtained by a video camera or the like.

(Prior Art) Conventionally, as this type of monitoring device, for example, Japanese Patent Application Laid-Open No. 1986-
There is one disclosed in Japanese Patent No. 206:100, and an example of its configuration is shown in FIG. The monitoring device in the figure includes a video camera 19 image memory 2. Difference comparison detection circuit 3, identification circuit 4.
Video tape recorder control circuit (hereinafter referred to as VTR control circuit)5. Video tape recorder (hereinafter referred to as VTR)
6 and a monitor television receiver (hereinafter referred to as monitor TV) 7.

Next, the operation will be explained.

An image signal of the monitored area photographed by the video camera 1 is displayed on the monitor TV 7 and is input to the image memory 2. Image memory 2 stores one screen of image signals. The difference comparison detection circuit 3 compares the output of the image memory 2 with the image signal after a certain period of time, and outputs a difference signal. The identification circuit 4 outputs an output when the difference signal output from the difference comparison detection circuit 3 exceeds a certain value. VTR control circuit 5
operates the VTR 6 for a certain period of time based on the output of the identification circuit 4. Therefore, this monitoring device can operate the VTR 6 and record an image signal only when there is some change on the screen.

(Problem to be Solved by the Invention) However, in the monitoring device having the above configuration, if there is no change on the screen after a certain period of time, it will not be recorded on the VTR 6, so a situation that changes slowly will be judged as no change on the screen, and
There were cases where data was not recorded on TR6, which was a problem. On the other hand, if there are constant changes, even if the changes are small and unimportant (for example, the fluctuation of curtains), they will be recorded continuously on the VTR 6, resulting in the problem of increased tape usage. there were.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a monitoring device capable of recording image signals to be recorded in accordance with changes in the monitored object.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a monitoring device that records and monitors image signals of a monitored object based on changes in the image signals. A conversion means for converting into a signal, a storage means for storing the output signal of the conversion means, and a differential stitch count for counting the number of pixels changing in the image signal for each predetermined amount based on the difference between the outputs of the conversion means and the storage means. means for determining a recording time interval based on the count value of the difference counting means and outputting a recording signal indicating recording timing; and recording the image signal based on the output signal of the determining means. and a recording means.

(Function) According to the present invention, since the monitoring device is configured as described above,
The technical means work as follows. The difference counting means counts the number of pixels that change in the image signal by a predetermined amount, for example, per frame, based on the difference between the output signal of the conversion means and the output signal of the storage means, and outputs the counted value to the determination means. work.

The determining means operates to determine the recording time interval based on the counted value of the number of changed pixels, and output a recording signal indicating recording timing according to the determination result. For example, a recording signal is output to the recording means after an appropriate predetermined time period according to the count value, from a certain time when the count value is zero to a continuous recording time (1730 seconds) when the count value is greater than or equal to a predetermined value. As a result of this, the recording means (for example, a VTR) can efficiently record the image signal to be recorded according to the changing situation of the monitored object based on the recording signal, so that the problems of the prior art described above can be solved. It is.

(Embodiment) FIG. 1 is a configuration diagram of a monitoring device showing an embodiment of the present invention. The monitoring device of this embodiment includes a video camera 11 that photographs a monitoring target, a monitor TV 12, and an A/D converter 13 that converts the output signal (image signal) of the video camera 11 into a digital signal. Image memory 14 for storing signals; Difference counting circuit 15 for counting the number of pixels that change in the image signal for each frame; Recording interval that determines the recording time interval based on the counted value of the pixels that change and outputs a recording start signal The decision circuit 16 selects the image memory 1 based on the recording start signal.
a recording control circuit 17 for controlling writing and recording of No. 4;
and an image signal recording device 1 such as a VTR or video disc;
Consists of 8.

Next, the operation of this embodiment will be explained.

The image signal output from the video camera 11 is sent to the monitor T.
The signal is displayed on the display screen of the V12, and the analog signal is converted into a digital signal by the A/D converter 13. The image memory 14 stores -frames of digital image signals output from the A/D converter 13. The differential stitch count circuit 15 compares and subtracts the already stored image data (output of the image memory 14) and the current image data (output of the A/D converter 13) for each pixel, and calculates the absolute value of the difference result. The number N of changed pixels larger than a preset threshold P is counted. The difference counting circuit 15 outputs this counting result to the recording interval determining circuit 16. The recording interval determining circuit 16 determines the time interval at which image data is recorded based on the number of changed pixels N, which is the output of the difference counting circuit 15. When the number of changed pixels N is zero, the recording time interval is fixed at T seconds. When the number of change point pixels N is small, the recording time interval is T/a seconds (a is 1
positive number). When the number N of changed pixels is large, the recording time interval is 1730 seconds (same as the image frame period), that is, recording is performed continuously. The recording interval determining circuit 16 outputs a recording start signal indicating the recording start timing to the recording control circuit 17 according to the determined recording time interval. Based on the output signal of the recording interval determining circuit 16, the recording control circuit 17
A recording signal synchronized with the frame of the image signal is output to the recording device 18 and the image memory 14. The recording device 18 records the output image signal of the video camera 11 based on the recording signal output from the recording control circuit 17. Recording control circuit 1
The output signal of 7 is connected to an image memory 14, which is updated with a new input image whenever an image signal is recorded on a recording device 18.

Next, the differential stitch count circuit 15 will be explained in detail. FIG. 2 is a circuit diagram showing an example of the internal configuration of the differential counting circuit 15. The differential stitch count circuit 15 in the figure includes a subtracter 21, an absolute value circuit 22. It is composed of a comparator 23 and a counter 24. Subtractor 21
subtracts the output of the image memory 14 from the output of the A/D converter I3 and outputs the result to the absolute value circuit 22. The absolute value circuit 22 determines the absolute value of the calculation result of the subtracter 21 and outputs it to the comparator 23. The comparator 23 compares the output of the absolute value circuit 22 with a preset threshold P (positive number),
If the output of the absolute value circuit 22 is greater than the threshold P, an enable signal is output to the counter 24. When the counter 24 receives the enable signal from the comparator 23, it adds "1" to the counter value. Note that the counter 24 is cleared by the image frame start signal.

Therefore, the differential stitch count circuit 15 outputs the current image data (
The output of the D/D converter 13) and image data already stored in the image memory 14 are compared and differentiated pixel by pixel, and the number N of changed pixels for which the absolute value of the difference result is larger than the threshold value P is counted. In other words, the number of pixels that change in the image data (number of changed pixels) is counted for each frame.

Next, the recording interval determining circuit 16 will be explained in detail. FIG. 3 is a circuit diagram showing an example of the internal configuration of the recording interval determining circuit 16. The recording interval determining circuit 16 in the figure includes a zero detector 31, a comparator 32, inverters 33, 34, an AND gate 35,
36, T seconds timer 37, T/a seconds timer 38.17
It consists of a 30 second timer 39 and an OR gate 40.

Output of the counter 24 of the difference counting circuit 15 (number of changed pixels N
) is connected to a zero detector 31 and a comparator 32.

The zero detector 31 determines whether the value of the number of changed pixels N is zero,
Outputs “1” when the value of N is zero, and “0” when it is other than zero.
Output. The comparator 32 compares the number of changed pixels N with a preset threshold D (positive number), and if N≦D, “
1", and outputs "0" when N>D. The output of the zero detector 31 is connected to the set terminal of a timer 37 for 'r seconds (T is a positive number) and the human power of the inverter 33. .

The output of comparator 32 is connected to the input of inverter 34 and one input of AND gate 35. The output of inverter 33 is connected to the other input of AND gate 35 and one input of AND gate 36, and the output of inverter 34 is connected to the other input of AND gate 36. Due to the configuration of these inverters 33, 34 and AND gates 35, 36, when the number of changed pixels N is zero in the three outputs of the comparator 32, AND gate 35, and AND gate 36, the output of the comparator 32 only is "1", and the outputs of the other two AND gates 35 and 36 are "0". Similarly, when the number of changed pixels N≦threshold, only the output of the AND gate 35 is “1” and the other two outputs are “0”, and when N>D, the AND gate 35 is “1” and the other two outputs are “0”.
Only the output of 6 is “1”, the other two outputs are “0”
It is.

The output of the AND gate 35 is connected to the set terminal of a T/a second timer 38 (a is a positive number of 1 or more), and the output of the AND gate 36 is connected to the set terminal of a 1730 second timer 39. .

Therefore, depending on the value of the number of changed pixels N, a timer 37 of T seconds when N=0 and a timer 38 of T/a seconds when N≦D.
, N>D, the 1/30 second timer 39 is set to a ready state. The signal line of the frame start signal is connected to the start terminals of timers 37, 38, and 39, and each timer is started in synchronization with the frame start signal, and after the time specific to each timer has elapsed ( For example, one second after the T second timer 37 is activated, the output signal is output in synchronization with the frame start signal. The outputs of the timers 37, 38, and 39 are logically summed in an OR gate 40, and the OR gate 40 sends a recording start signal to the recording control circuit 17.

As described above, when the recording control circuit 17 receives the recording start signal output from the recording interval determining circuit 16 in accordance with the counted value of the number of changed pixels N, it sends a recording signal to the recording device 18. The recording device 18 records the image signal from the video camera 11 while the recording signal is being sent from the recording control circuit 17.

The recording signal outputted by the recording control circuit 17 is sent to the image memory 14.
The image memory 14 is updated with a new human image whenever an image is being recorded on the recording device 18.

In the embodiment described above, three types of recording time intervals are determined according to the number N of changed pixels, but the recording time intervals can be changed in three or more types or continuously according to the number N of changed pixels. You can.

(Effects of the Invention) As described in detail above, according to the present invention, there is provided a difference counting means for counting the number of changed pixels of image data, and a recording means for recording image data according to the magnitude of the counted value of the number of changed pixels. Since a determining means is provided for determining the time interval to be recorded in the recording means, slowly changing image signals will not be recorded on the recording means at all, and even if unimportant small changes continue, the recording means will not be recorded continuously. is not recorded, but is recorded at fixed time intervals, so it is possible to reduce the amount of recording media (tape, etc.) used in the recording device. Moreover, since the occurrence of a large change is continuously recorded on the recording means, it is possible to efficiently record according to changes in the situation.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a monitoring device showing an embodiment of the present invention, FIG. 2 is an internal configuration diagram of the difference counting circuit in FIG. 1, and FIG. 3 is an internal configuration diagram of the recording interval determining circuit in FIG. 1. , FIG. 4 is a block diagram of a conventional monitoring device. 11--Video camera, 12--Monitor television receiver (monitor TV), 13-A/D converter, 14--Image memory, 15
--Difference counting circuit, 16--Recording interval determining circuit, 17--Recording control circuit, 18--Recording device, 21--
Subtractor, 22-... Absolute value circuit, 23.32-...
-Comparator, 24--Counter, 31--Zero detector, 33.34--Inverter, 35.36--AND gate, 37-39--Timer, 40--OR gate.

Claims (1)

[Scope of Claims] A monitoring device that records and monitors an image signal of a monitored object based on a change in the image signal, comprising a converting means for converting the image signal into a digital signal, and storing an output signal of the converting means. storage means for counting the number of pixels that change in the image signal for each predetermined amount based on the difference between the outputs of the conversion means and the storage means; and a time interval for recording based on the counted value of the difference counting means. What is claimed is: 1. A monitoring device comprising: determining means for determining the timing of recording and outputting a recording signal indicating recording timing; and recording means for recording the image signal based on the output signal of the determining means.