JPH0437892A - Laser display device - Google Patents

Abstract

PURPOSE:To obtain effective shape and brightness in the whole scanning direction by correcting the operation of a light control part for controlling the flashing and intensity of laser beams by a speed correcting memory part for storing the flashing timing of laser beams and a light intensity correcting memory part for storing the output of a laser beam in each scanning position. CONSTITUTION:The laser display device is provided with a polygon mirror for reflecting laser beam groups from an optical pickup array 10 to be a light source for outputting plural laser beams and guiding the reflected laser beam groups to a screen 20. The light control part 40 executes the ON/OFF control and intensity control of laser beams outputted from individual pickup modules 11. The control part 40 executes operation based upon respective stored contents of a dot memory part 50, the speed correcting memory part 60 and the light intensity correcting memory part 70. Consequently, the dot image shape of laser beams is corrected and sufficie tly uniform image brightness can be secured in the whole scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a projection scanning type laser display device using laser light.

<Prior Art> There is a projection scanning type laser display device using laser light. This laser display device is a device that projects and displays letters, designs, etc. on the screen in a point-to-point manner by flashing a laser beam and scanning the screen, and a polygon mirror is used to scan the laser beam. . FIG. 2 shows the operating principle of a polygon mirror in a projection scanning type laser display device.

The polygon mirror 30 is normally a four-sided mirror and rotates around its axis at high speed. The laser light is output from the light source 10 in a blinking state,
The light is reflected by the polygon mirror 30 and guided onto the screen 20. As the polygon mirror 30 rotates, the laser beam is scanned on the screen 20, and the scanning period is determined by the rotation speed of the polygon mirror 301, and the scan line length X is determined by the deflection angle θ of the polygon mirror 30 and the deflection. It is determined by the distance ML from the center P of the angle θ to the screen 20.

In a projection scanning type laser display device using a polygon mirror 30, since the polygon mirror 30 rotates at a constant speed, it is inevitable that the scanning speed becomes faster when scanning the edge of the screen 20. . Therefore, even if the dot image of the laser beam projected onto the screen 20 is circular at the center of the screen 20, it is distorted into an elliptical shape elongated in the scanning direction at the ends.

As a solution to this problem, scanning speed correction using an f/theta optical system is generally adopted, but the f/theta optical system is expensive and large because it consists of a special lens. When used as a screen, a large one is required, which may be difficult to produce. Therefore, a technique has been developed that corrects the distortion of the dot image of the laser beam at the edge of the screen by controlling the flashing timing of the laser beam without using the f/θ optical system (Japanese Patent Application Laid-Open No. 1-20C) No. 218. Public bulletin).

<Problems to be Solved by the Invention> However, in the conventional laser beam dot image correction technology using blinking timing control, although the laser beam dot image is corrected to the same extent as the f/θ optical system, Since the lighting time becomes shorter, there is a problem that the projected image becomes dark at the edges of the screen.

The present invention was devised in view of such circumstances, and f・θ
An object of the present invention is to provide a laser display device in which the image shape of laser light is corrected to the same extent as an f/θ optical system without using an optical system, and sufficient image brightness is ensured in the entire scanning direction.

<Means for Solving the Problems> A laser display device according to the present invention includes a light source that outputs a laser beam, and a laser beam that is rotated and directed toward the screen so that the laser beam from the light source scans the screen. A polygon mirror that reflects light, a light control unit that controls blinking and intensity of the laser beam, a memory unit for speed correction that stores the blinking timing of the laser beam calculated in advance for each scanning position, and a memory unit that stores the blinking timing of the laser beam calculated in advance for each scanning position. and a light intensity correction memory section that stores the output of the laser beam, and the operation of the light control section is corrected based on the respective storage contents of the speed correction memory section and the light intensity correction memory section. It is characterized by

<Operation> By correcting the operation of the light control section based on the stored contents of the speed correction memory section, the same dot image shape of the laser beam can be obtained at the end portions in the scanning direction as at the center portion. Also,
By correcting the operation of the light control unit based on the stored contents of the light intensity correction memory unit, a to-node image having the same brightness at the end portions in the scanning direction as at the center portion can be obtained. Therefore,
The dot image of the laser beam scanned on the screen has good shape and brightness throughout the scanning direction.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a laser display device showing an embodiment of the present invention.

This laser display device includes an optical pickup array 10 as a light source that outputs a plurality of laser beams, and a screen 2 that reflects a group of laser beams from the optical pickup array 10.
It is equipped with a polygon mirror 30 that leads to zero.

The optical pickup array 10 has a structure in which a plurality of pickup modules 11 are sequentially stacked in the y direction. The laser light output from each pickup module 11 is subjected to ON/OFF control and intensity control by the light control section 40.

The polygon mirror 30 is, for example, a four-sided mirror, and has an axis in the Y direction, and by rotating around the axis, directs a group of laser beams from the optical pick-up array 10 onto the screen 2.
0 in the x direction. Reference numeral 31 denotes a rotation drive unit for the polygon mirror 30.

The light control section 40 operates based on the contents stored in the dot memory section 50, the speed correction memory section 60, and the light intensity correction memory section 70.

The dot memory section 50 stores dot patterns necessary for displaying predetermined characters or designs on the screen 20, and inputs a lighting signal based on the dot pattern from the rotation drive section 31 of the polygon mirror 30. The rotational position signal is output to the speed correction memory section 60 and the light intensity correction memory section 70 in synchronization with the rotational position signal.

The speed correction memory section 60 stores a blinking pattern of the laser beam for each scanning position, in which the lighting time is shortened at the edge of the screen 20 so that a dot image of the same shape can be obtained in the entire scanning direction on the screen 20. ing. Then, the signal (blinking timing control signal) is transmitted to the dot memory section 50.
The lighting signal is sent to the control unit 40 in response to the lighting signal from. The rotation drive unit 31 is also connected to the speed correction memory unit 60 so that the signal sending timing to the light control unit 40 is synchronized with the scanning position.
A rotational position signal is input from.

The light intensity correction memory section 70 is the speed correction memory section 60.
In order to correct the change in light intensity in the scanning direction that accompanies the blinking pattern stored in the memory, that is, the tendency for the light intensity to decrease at the edges of the screen 20, the laser light output is increased at the edges of the screen 20 for each scanning position. I remember the cover turn. The signal (laser light intensity control signal) is sent to the dot memory section 5.
It is sent to the control unit 40 in response to the lighting signal from 0.

The rotational position signal from the rotational drive unit 31 is also input to the light intensity correction memory unit 70 .

The light control unit 40 controls the light based on the signal input from the speed correction memory unit 60 (blinking timing control signal) and the signal input from the light intensity correction memory unit 70 (laser light intensity control signal). The laser light output in each big knob module 11 of the pickup array 10 is controlled.

According to such a laser display device, the same number of laser beams as the pickup modules 11 in the optical pickup array 10 are scanned all at once in the Y direction by the rotation of the polygon mirror 30 while blinking, and predetermined characters are displayed on the screen 20. Or a pattern etc. is displayed. The laser beam scanned in the Y direction on the screen 20 is transmitted to the speed correction memory section 6.
Since the end portions of the screen 20 are illuminated for a shorter period of time due to the correction based on the contents of 0, dot images of the same shape are formed on the entire screen 20 in the scanning direction. Furthermore, the light intensity correction memory unit 70 also receives correction, and the output at the end of the screen 20 increases, thereby correcting the reduction in light amount at the end of the screen 20 due to the shortening of the lighting time.

Therefore, even though the f/θ optical system is not used, the dot image shape of the laser beam is corrected to the same extent as the f/θ optical system, and the image brightness is sufficient and uniform throughout the scanning direction. Secured.

The above embodiment has a scanning system with a simple structure in which a plurality of laser light sources are arranged in a one-dimensional direction and a group of laser beams from the light sources is guided onto the screen by a polygon mirror, but the system is not limited to this. For example, a scanning system such as a raster scanning method may be used, and the method is not limited.

Furthermore, if the cross-sectional shape of the laser beam output from the light source is non-circular, such as an ellipse flattened in the scanning direction, distortion of the dot image at the edge of the screen can be easily corrected.

<Effects of the Invention> As described above, in the case of the laser display device according to the present invention,
Since f/θ optical system is not required, equipment cost is reduced.
Application to large screens is also possible. Furthermore, even though an f/θ optical system is not required, the dot image shape of the laser beam is corrected to the same degree as a device having an f/θ optical system, and furthermore,
Sufficient and uniform image brightness is ensured throughout the scanning direction. Therefore, a clear laser projection image can be obtained over the entire screen.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a laser display device showing an embodiment of the present invention, and FIG. 2 is a schematic diagram for explaining the operating principle of a polygon mirror in a projection scanning type laser display device. 10. 20. 30. 40. 60. Optical pickup array screen polygon mirror light control section memory section for speed correction memory section for light intensity correction

Claims (1)

[Claims] (1) A light source that outputs a laser beam, a polygon mirror that rotates and reflects the laser beam toward the screen so that the laser beam from the light source scans the screen, and blinking and intensity control of the laser beam. a light control unit that performs this, a speed correction memory unit that stores the flashing timing of the laser beam calculated in advance for each scanning position, and a light intensity correction memory unit that also stores the output of the laser beam for each scanning position. What is claimed is: 1. A laser display device comprising: a laser display device, wherein the operation of a light control section is corrected based on the contents stored in the speed correction memory section and the light intensity correction memory section.