JPH04178530A - Sunlight detector - Google Patents

Abstract

PURPOSE:To enable automatic operation for changing the facing direction of an ITV camera by movably disposing a sunlight detecting element along the axis of a shielding cylinder to detect the direct projection of sunlight on an image pick-up element of the ITV camera. CONSTITUTION:A shielding cylinder 11 is installed on an objective lens portion, and a base plate 21 is moved along a slot 26 in the axial direction of the cylinder 11 to detect the output of a photo diode 12 of a sunlight detecting element provided on the base plate 21. The diode 12 is installed in a point of a distance (f) from an opening where the angle of incidence theta is equal to the angle of visibility of the ITV camera according to the detected output. Thus, automatic change operation for controlling the facing direction of the ITV camera to correspond to the direct projection of sunlight on an image pickup element can be conducted so as to prevent burning of an image pickup element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sunlight detection device applied to an ITV monitoring device using an ITV camera.

[Prior art] IT that monitors a specific area separated by an ITV camera
In the V monitoring device, by placing the ITV camera on a preset tremor base whose opposing angle can be changed within a prespecified range by remote control, it is possible to change the direction and take images.

By the way, when using an ITV camera outdoors, if the sun enters the imaging range, the sunlight will directly enter the image sensor, such as a CCD, inside the ITV camera, and if this condition continues for a long time, the image sensor There is a possibility that this could lead to burn-in, deterioration, and damage.

Conventionally, a supervisor constantly checks the image capture screen of the ITV camera on a monitor TV or the like, and operates to change the facing direction of the ITV camera so that sunlight does not directly enter the screen.

[Problems to be Solved by the Invention] However, the above-mentioned monitoring of the imaging screen and I
There is a problem in that the operation to change the facing direction of the TV camera must be carried out all the time, and the supervisor must concentrate on this task. The image sensor may deteriorate or be damaged.

This invention was made in view of the above-mentioned actual situation,
The purpose is to provide a sunlight detection device that can detect direct sunlight hitting an image sensor of an ITV camera and contribute to an automatic change operation of the facing direction of the ITV camera.

[Means and effects for solving the problem] That is, the present invention includes an external cylindrical body for shielding light, and a photodiode, etc., disposed within the external cylindrical body so as to be movable along the axis of the cylindrical body. The device is equipped with a sunlight detecting element according to the invention, and a signal output circuit that outputs a detection signal from the sunlight detecting element. By adjusting the movement within the external cylindrical body along the axis of the cylindrical body in accordance with the positional relationship of the image pickup element, sunlight can be directed directly onto the image pickup element of the ITV camera using the signal output from the signal output circuit. It is possible to perform corresponding control.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

First, the principle will be explained with reference to FIG.

FIG. 2 (2) shows a lens 1 and an image sensor 2 of an ITV camera, and schematically shows a state in which sunlight is taken into the image sensor 2 through the lens 1. In the same figure, ITV
The light capture angle of the camera, that is, the viewing angle ω, is the second
Image size H1V in the horizontal and vertical directions of the image sensor 2 shown in Figure (1), from the principal point O of the lens 1 to the image sensor 2
Determined by the focal length F to the imaging plane, in the horizontal direction,
Vertical viewing angles ω□ and ω9 are (IJH-2tan-' (H/2F)
-(1) ωv = 2 tan-' (V/2F
) =12>.

Further, the ratio of the viewing angle ωH1ω is determined by the image size of the image sensor 2, and is the same for different types of ITV cameras, and is ωH: ωv −H: V
= 4 : 3'' (3), so it is always almost constant.

When the above relationship holds true, the image sensor 2 is affected by sunlight when sunlight is incident within the viewing angle ωH1ω shown by equations (1) and (2) above. It's time.

The basic structure according to an embodiment of the present invention will be explained with reference to FIG. 3 which follows. As shown in FIG. 3 (1), this device includes a light-shielding tube 11 made of, for example, a prismatic cylindrical body, and a sunlight detection element disposed within the light-shielding tube 11 so as to be movable along an axis. The main component is a photodiode 12. A photodiode 12, which is a sunlight detection element that converts an optical signal into an electrical signal, is disposed inside the light-shielding tube 11 at a position A at a distance f from the opening surface.

Sunlight enters the photodiode 12 within the range shown by the loci B-A and C-A shown in the figure, and within the range shown by the loci B-A-
Let angle θ of C be the incident angle of the sunlight detection device. “+ g+
The light shown by e is blocked by the light-shielding cylinder 11 and does not reach the photodiode 12.

The horizontal and vertical incident angles θH1θ7 are 0 m −2
jan-' (h/2 f) -(4)θ
v = 2 jan-' (v/2 f)
−(5).

Therefore, by making the incident angle θ the same as the viewing angle ω of the ITV camera in FIG.
2 can detect sunlight. That is, h: v-H: V-(
6) θh■ω□ -17
)θv−ωV...(
8) The above-mentioned ((
The photodiode 12 may be placed at a distance f from the aperture that satisfies equations 7) and (8).

Next, a specific example of the configuration of this device will be explained using FIG. 1.

FIG. 1 (1) is a cross-sectional view seen from above, and FIG. 1 (2) is a longitudinal cross-sectional view, with the left side of the figure being the front end of the opening. The photodiode 12 is arranged on the substrate 21 together with a signal output circuit (not shown).

Here, the signal output circuit waveforms the detection signal from the photodiode 12, amplifies it to a predetermined level, generates an alarm signal, and outputs it. The substrate 21 is provided integrally with a fixing plate 22, and this fixing plate 22 is attached to the bottom plate of the light-shielding tube 11 together with the sliding plate 23 by fixing screws 24, 24 and spacers 25.25 through which the fixing screws 24.24 pass. It is fixed along the formed slit 26. This slit 26 is formed in the bottom plate of the light-shielding tube 11 along the axial direction of the light-shielding tube 11, and by loosening the fixing screws 24 and 24, the fixed plate 22 and the sliding plate 23
The clamping fixation of the bottom plate of the light-shielding tube 11 is released, and the substrate 21 on which the photodiode 12 is disposed, the fixed plate 22, and the sliding plate 23 are slid integrally along the slit 26.

Therefore, the light-shielding tube 11 is attached to the lens part of an ITV camera (not shown), and the above (
7) Adjust and fix the slide position so that the photodiode 12 is located at a distance f from the opening that satisfies equations (8).

The inner wall surface of the light-shielding tube 11 is entirely coated with a black matte coating that minimizes the reflection of light, so as to prevent sunlight from reaching the photodiode 12 due to reflection from the wall surface as shown in FIG. 3 (1) above. to prevent accidental incidence of

[Effects of the Invention] As described above, according to the present invention, there is provided an external cylindrical body for shielding light, and a photodiode, for example, disposed in the external cylindrical body so as to be movable along the axis of the cylindrical body. Since the external cylindrical body is equipped with a sunlight detection element such as a solar light detection element and a signal output circuit that outputs a detection signal from this sunlight detection element, the external cylindrical body can be
By attaching it to a V camera and adjusting the movement of the sunlight detecting element along the axis of the external cylinder in accordance with the positional relationship between the lens and image sensor of the ITV camera, it is possible to detect sunlight even in different ITV cameras. A detection signal is generated at an appropriate timing by appropriately adjusting the position of the photodetection element, and a signal output from the signal output circuit according to the detection signal is used to direct sunlight onto the image sensor of the ITV camera. It is possible to provide a sunlight detection device that can perform control corresponding to the above, and can contribute to automatic changing operation of the facing direction of the ITV camera.

[Brief explanation of drawings]

FIG. 1 (1) is a cross-sectional view showing a specific configuration according to an embodiment of the present invention, FIG. 1 (2) is a longitudinal cross-sectional view of FIG. 1 (1), and FIG.
The figure shows the relationship between the lens and image sensor of an ITV camera,
FIG. 3 is a diagram showing a basic configuration according to an embodiment of the present invention corresponding to FIG. 2. DESCRIPTION OF SYMBOLS 1... Lens, 2... Image pickup element, 11... Light-shielding tube, 12... Photodiode, 21... Substrate, 22...
・Fixing plate, 23...Sliding plate, 24...Fixing screw, 2
5...Spacer, 26...Slit. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (1)

[Scope of Claims] An external cylindrical body for shielding light, a sunlight detecting element disposed within the external cylindrical body so as to be movable along the axis of the cylindrical body, and a detection signal from the sunlight detecting element. A sunlight detection device characterized by comprising a signal output circuit that outputs.