JPH0218896A - Illumination device and image pickup device - Google Patents

Abstract

PURPOSE:To decrease time variation in the intensity of an illuminative light by feeding a plurality of light sources with current in different phases. CONSTITUTION:Current supplied to No.1 light source 1 from No.1 power supply circuit 3 shall have different phase from that of the current supplied to No.2 light source 2 from No.2 power supply circuit 4. This decreases time variation in the light irradiated onto an object 5, and a person does not perceive flickering on the reflected light from this object 5. Even in case photographing is made with a scanning type TV camera 6, therefore, generation of stripes on an image is prevented, likely in any conventional arrangement, and thus distinct display pictures are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an illumination device and an imaging device used, for example, in a security system or forward monitoring of a vehicle.

BACKGROUND ART FIG. 2 shows a configuration diagram of a conventional illumination device and an imaging device. In FIG. 2, 1 is a first light source, 2 is a second light source, 3 is a first power supply circuit, 4 is a second power supply circuit, 5 is an object to be illuminated, 6 is a scanning television camera, 7 is a display, 8 is a lighting device, and 9 is an imaging device. The current necessary to light up the light sources 1 and 2 is supplied from power supply circuits 3 and 4, respectively. The lighting device 8 is connected between a first light source 1, a second light source 2, and a first power source l! 83 and the second power supply circuit 4. The light emitted from the illumination device 8 configured in this manner needs to have a sufficient amount of light and a high illuminance uniformity so that the object 5 illuminated by it can be easily seen by humans. There is. For this reason, the light sources 1 and 2 are generally comprised of discharge lamps such as metal halide lamps with good luminous efficiency, and an optical system for effectively utilizing the light emitted from them.

The imaging device 9 includes an illumination device 8, a scanning television camera 6, and a display 7. The object 5 illuminated by the illumination device 8 is shaded by the scanning television camera 6, and the image is displayed on the display 7. By arranging such an imaging device 9, it becomes possible to monitor outdoor conditions from various positions, such as in a security system, by viewing a display from one indoor location. Furthermore, in recent years, in order to reliably obtain various information such as signs and traffic lights without relying solely on the movement of the driver's line of sight, it has been considered to install such an imaging device in a vehicle.

Problem to be Solved by the Invention Fig. 3 shows the optical waveform of the illumination light from the conventional illumination device 8 on the object 6 to be illuminated. Corresponds to the power frequency at 4. For example, when light sources 1 and 2 are HID lamps, power is supplied from power supply circuits 3 and 4 at a frequency of 60 Hz, and the discharge per cycle is symmetrical, the frequency of illumination light emitted from the light sources is 120 Hz.

Flickering is not a problem because the human eye only senses fluctuations in light up to about 100 Hz, but light source 1
And the discharge in 2 is asymmetric! , the frequency of the illumination light is 50 Fl z. Reflected light from an object illuminated with such illumination light, or power supply frequency 50H
When the illumination light is turned on at a temperature below z, flickering may be felt, which hinders the visual recognition of objects.

Furthermore, in recent years, there has been an increase in the use of high-frequency power supplies composed of electronic circuits as the power supply circuits 1 and 2. When a HID lamp is lit using this high-frequency power source, the frequency of the illumination light is much higher than the frequency at which the human eye senses fluctuations, so the illumination light and the reflected light from the object 5 are Flickering does not pose a problem, but when the object 5 is photographed by the scanning television camera 6, there is a problem in that the image has a striped pattern corresponding to the brightness/darkness cycle of the illumination light.

Means for Solving the Problems The light source is composed of a plurality of light sources and a power supply circuit that supplies current to them, and the phase of the current supplied to each light source in the power supply circuit is made different.

Effect: Temporal fluctuations in the amount of illumination light from a plurality of light sources are canceled out, and temporal fluctuations in the intensity of illumination light are reduced.

Embodiment 61 The configuration of the illumination device and imaging device of the conventional example shown in FIG.
As shown in FIG. 1, they are different from each other. In FIG. 1, A indicates the temporal change in the current supplied from the first power supply circuit 3 to the first light source 1, and x indicates the time variation in the current supplied from the second power supply circuit 4 to the second light source 2. This is a major change. Light waveforms from light sources 1 and 2 turned on by a power source having such a current waveform are shown in C and 2.

A temporal change in the amount of illumination light on the illuminated object 5 is shown in E. As shown in waveform E, on the illuminated surface,
Since the temporal change in the amount of light is canceled out and the temporal change in the amount of irradiated light is reduced, it is possible for humans to avoid flickering in the reflected light from the object 5 on the illuminated surface.

Furthermore, even when photographing with the scanning television camera 6, it is possible to reduce temporal fluctuations in the reflected light from the object 5 on the illuminated surface, thereby preventing the occurrence of striped patterns in the image as seen in the conventional example. , you can get a clear display screen. Therefore, when the illumination device and the imaging device of the present invention are used as a headlight of a vehicle such as an automobile, it is possible to improve forward visibility in addition to the above-mentioned effects. In addition, when driving on a road such as a tree-lined road where striped patterns, display objects, and obstacles exist at equal intervals in the direction perpendicular to the direction of travel, conventional lighting devices and imaging devices cannot handle the relative speed of the vehicle. The repeating cycle of stripes, display objects, and obstacles that change as a result of synchronization with the cycle of the illumination light may cause bright and dark patterns to appear at the same location on the road, which may indicate the presence of obstacles and pedestrians. Although there has been a problem in that it becomes difficult to detect protrusions, the present invention can prevent the occurrence of the bright and dark patterns, thereby increasing safety.

Effects of the Invention With respect to the reflected light from the object on the illuminated surface, the human [Δ1
It is possible to realize an illumination device and an imaging device that can eliminate the flicker experienced by people and can take clear images with a scanning television camera.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the optical waveform of a light source constituting an illumination device and an imaging device according to the present invention, and the optical waveform of reflected light from an object illuminated by the device, and FIG. 2 is a diagram showing a conventional example and an illumination according to the present invention. FIG. 3 is a block diagram of a device and an imaging device, and is a diagram showing the optical waveform of illumination light from a conventional illumination device and an imaging device. 1.2...Light source, 3.4...Power supply circuit, 8...Lighting device, 9...Imaging device. Name of agent: Patent attorney Shigetaka Awano

Claims (3)

[Claims] (1) A lighting device comprising a plurality of light sources and a power supply circuit that supplies current to them, and in which the phase of the current supplied to each light source in the power supply circuit is different. (2) An imaging device comprising the illumination device according to claim 1 and a scanning television camera. (3) The lighting device according to claim 1 or the imaging device according to claim 2, wherein the light source is a vehicle headlamp.