JPH0273794A - Surveillance camera - Google Patents

Abstract

PURPOSE:To always attain proper exposure and to eliminate need for the manual operation by an operator by providing a control means varying the illuminance of an infrared ray lighting device and applying lighting/extinguishing in response to a detected luminance level. CONSTITUTION:A control means (CPU6, latch circuit 9) is provided which varies the illuminance of the infrared ray lighting device 10 in response to the detected luminance level and applies lighting/extinguishment. The number of times of lighting of a light radiated from the infrared ray lighting device 10 is switched in response to the level of the luminance signal obtained from R.G.B signals outputted from a solid-state image pickup element 1 and the illuminance is varied. Moreover, when the brightness reaches a certain level or over, radiation lights 1R1-1Rn are extinguished. Thus, the control of the illuminance and lighting/extinguishment of the infrared lighting device 10 are attained automatically, the exposure is always optimized and a sharp picture is obtained and no manual operation by the operator is required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This issue 1 relates to a surveillance camera that is applied to a crime prevention system or a surveillance system and monitors a surveillance range using a solid-state image pickup device such as a COD.

[Prior Art] For example, in a surveillance system, a surveillance camera is used as a surveillance means, or an infrared illumination device is used for illumination. This infrared illumination device is not turned on all the time, but is turned on and off as needed.In the past, the infrared illumination device was turned on and off by some external method depending on the movement, while checking the status of the output image of the monitor shade through operation t1. In addition, the IIr variation of illuminance during lighting is similarly controlled from the outside.

[Problem to be solved by the invention] In conventional surveillance cameras as described in 1-, the irradiation light of the infrared illumination device is constant, so it is necessary to properly expose the object to changes in illuminance and obtain clear images. I couldn't even get a picture.

Additionally, the infrared lighting device had to be turned on and off from the outside.

This invention was made in order to solve this problem, and it is possible to automatically control the amount of light irradiated by the infrared illumination device and to turn it on and off, so that the optimum exposure can always be achieved and a clear image can be captured. Providing a camera is [1.

[Means for Solving the Problems] In order to achieve the object described in item L, the present invention includes a control means for varying the illuminance of the infrared illumination Eg1 device and turning on/off the infrared illumination device according to the detected brightness level. It was established.

[Function] By configuring as described in item 1-, the number of lighting lights of the infrared illumination device can be adjusted depending on the level of the luminance signal obtained from the R, G, and B signals output from the solid-state image sensor. This changes the illuminance by i+r. Also, when the brightness reaches a level higher than that, the irradiation light will turn off. Therefore, the illuminance of the infrared illumination device and the point
This allows you to turn off the lights, always keep the exposure at the optimum level, and obtain clear images.

[Example] 1 [A is a block diagram showing the main configuration of the embodiment of the present invention] [A] Fig. 2 is a flowchart showing the operation of Fig. 1, and Fig. 3 is a diagram showing the brightness level and illumination of the lighting device. FIG. 3 is an explanatory diagram showing the relationship between the timing of turning on and turning off a light.

In Fig. 1, l is CCD (Charge Cou
2 is a clock circuit for driving the solid-state image sensor l at a predetermined timing, and 3 is a RoG output from the solid-state image sensor l.
, a sample hold circuit that complements B, 4 is 1% from the R, G, and B obtained from the sample hold circuit 3.
A process circuit that generates an Iff signal 1+ and outputs it to an encoder section (not shown), 5 an analog-to-coupled digital conversion circuit that digitizes an analog luminance signal, and 6 an aperture that corresponds to the luminance signal information from the analog-digital circuit 5. 7 is a digital-to-analog conversion circuit that converts the aperture amount from the CPU 6 from digital to analog; 8 is a digital-to-analog conversion circuit that includes an automatic diaphragm mechanism and an optical lens; Automatic exposure aperture mechanism that performs automatic aperture according to the aperture command value, 9 is the CPU
It is a latch circuit that controls the number of infrared irradiation lights of the infrared illumination device turned on according to the control signal obtained from 6, and IO includes a plurality of infrared irradiation lights IRI to IRo, ) is an infrared illumination device that irradiates the area.

The control signal given to the latch circuit 9 divides the iris control range into reference level 1 and reference level 2, as shown in FIG. It is divided into mote n. Then, the number of infrared irradiation lights IR, to IR, to be lit is assigned to each of the light lighting modes, and lighting control is sequentially performed. Next, the operation of the embodiment L will be explained with reference to FIG.

First, the color imaging information I411 (R, G, B signals) that has been optically converted by the solid-state image sensor l is sent to the process circuit 4.
The luminance signal is detected by (Sl).

This luminance signal is analog-to-digital (A/D) converted by the analog-to-digital conversion circuit 5 (S2), and this is read into the CPU 6 (S3).

The state of the luminance signal level is determined (S4).

When the luminance signal level is in a state of (reference level l) < (luminance signal level) < (reference level 2) with respect to the reference level in FIG. 3, the aperture amount for that luminance signal level is calculated and the light lighting mode l is Infrared irradiation light IR
, is turned on (S5), an aperture signal is calculated and sent to the digital-analog conversion circuit 7 (S6), and the digital-analog conversion circuit 7 converts the aperture signal into a digital-analog (D
/A) Then, the aperture mechanism of the automatic exposure aperture mechanism 8 is controlled by this analog aperture signal (S8).

On the other hand, when (reference level l)> (luminance signal level), it is determined which of light lighting mode l to light lighting mode n to be executed according to the luminance signal level (
S9. Sll, 5I3).

Light lighting mode 1 when brightness signal level is highest
(S9), and only the infrared light (-IR) is turned on by the latch circuit 9 (SIO). If the light lighting mode 1 is not selected, the process moves to the next step (Sll), and it is determined whether the light lighting mode 2 is selected. When it is determined that the light lighting mode is 2, the infrared irradiation light IR and IR
2 lights up (S12). From then on, as the brightness signal level decreases, the number of modes used increases, and at the minimum brightness level, light lighting mode n is adopted, and n infrared irradiation lights IR, ~IR, All the lights are lit (S14)
.

Further, in step S4, (reference level 2)
(2) If it is determined that the illuminance to the subject is sufficient, the infrared irradiation light is turned off, that is, the infrared irradiation light IR is turned off (S15).

[Effects of the Invention] 1. As explained above, the present invention has a system for changing the illuminance of the infrared illumination device according to the detected luminance level and turning it on and off. Therefore, you can always use the appropriate IE exposure to obtain clear images. In addition, since the light turns on and off automatically, there is no need to perform a "movement operation" using the operation t'k.

[Brief explanation of the drawing]

Figure 1 shows a surveillance camera 71 as an embodiment of the present invention.
Figure 2 is a flowchart showing the operation of the embodiment shown in Figure 1, and Figure 3Z is an explanatory diagram showing the relationship between the brightness level and the timing of turning on and off the illumination light of the lighting device. l: Solid-state image sensor process circuit PU Automatic exposure aperture mechanism latch circuit Infrared illumination device ~IRn: Infrared irradiation light

Claims (1)

[Claims] In a surveillance camera that photo-electrically converts a subject with a solid-state image sensor and illuminates the subject with an infrared illumination device, control for varying the illuminance of the infrared illumination device and turning it on and off according to a detected brightness level A surveillance camera characterized in that a means is provided.