JP2796684B2 - Laser display - Google Patents

Description

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

<Prior Art> There is a projection scanning type as a laser display device using laser light. This laser display device is a device that scans the screen while the laser light is blinking and projects and displays characters or patterns on the screen in a stapling manner. A polygon mirror is used for the scanning of the laser light. . FIG. 2 shows the principle of operation of the polygon mirror in the projection-type scanning laser display device.

The polygon mirror 30 is usually a four-sided mirror, and rotates at high speed around an axis. The laser light is output from the light source 10 in a blinking state, is reflected by the polygon mirror 30, and is guided onto the screen 20. The rotation of the polygon mirror 30 causes the laser beam to scan on the screen 20, the scanning cycle is determined by the rotation speed of the polygon mirror 30, and the scanning line length x is determined by the deflection angle θ of the polygon mirror 30 and the deflection angle. It is determined by the distance L from the center P of the angle θ to the screen 20.

In a projection-type scanning laser display device using the polygon mirror 30, the scanning speed cannot be inevitably higher than when scanning the edge of the screen 20, because the polygon mirror 30 rotates at a constant speed. for that reason,
Even if the dot image of the laser beam projected on the screen 20 is circular at the center of the screen 20, it is distorted at the end into an ellipse long in the scanning direction.

As a solution to this, generally, the correction of the scanning speed by the f · θ optical system is adopted.
It is expensive because it is composed of special lenses,
When used on a large screen, a large screen is required, which may make the production itself difficult. Therefore, a technique has been developed for correcting the distortion of the dot image of the laser beam at the edge of the screen by controlling the blinking timing of the laser beam without using the f · θ optical system (Japanese Patent Laid-Open No. 1-221818). .

<Problems to be Solved by the Invention> However, in the above-described conventional laser light dot image correction technology by blink timing control, although the laser light dot image is corrected to the same degree as that of the f · θ optical system, the screen edge portion is not corrected. The shorter the lighting time, the darker the projected image is at the screen edge.

The present invention has been made in view of such circumstances,
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 degree as that of the f · θ optical system without using the θ optical system, and that sufficient image brightness is secured 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 the 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 the blinking and intensity of the laser light, a speed correction memory unit that stores the blinking timing of the laser light calculated in advance for each scanning position, and A light intensity correction memory unit for storing the output of the laser light, wherein the operation of the light control unit is corrected based on the respective storage contents of the speed correction memory unit and the light intensity correction memory unit. It is characterized by:

<Operation> By correcting the operation of the light control unit based on the stored contents of the speed correction memory unit, the same dot image shape of the laser light as that at the center portion can be obtained at the end in the scanning direction. In addition, since the operation of the light control unit is corrected based on the contents stored in the light intensity correction memory unit, a dot image having the same brightness as that at the center at the scanning direction end is obtained. Therefore, the dot image of the laser beam scanned on the screen is
It has good shape and brightness throughout the scanning direction.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a laser display device showing one 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 polygon mirror 30 that reflects a group of laser beams from the optical pickup array 10 and guides the group to the screen 20.

The optical pickup array 10 has a structure in which a plurality of pickup modules 11 are sequentially stacked in the Y direction. On / off control and intensity control of the laser light output from each pickup module 11 are performed by the light control unit 40.

The polygon mirror 30 is, for example, a four-sided mirror, has an axis in the Y direction, and scans the laser beam group from the optical pickup array 10 in the X direction on the screen 20 by rotating around the axis. . Reference numeral 31 denotes a rotation drive unit of the polygon mirror 30.

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

The dot memory unit 50 stores a dot pattern necessary for displaying a predetermined character or pattern on the screen 20, and outputs a lighting signal based on the dot pattern from the rotation driving unit 31 of the polygon mirror 30. The data is output to the speed correction memory unit 60 and the light intensity correction memory unit 70 in synchronization with the input rotational position signal.

The speed correction memory unit 60 stores a flashing pattern of the laser light whose lighting time is shortened toward the end of the screen 20 for each scanning position so that a dot image of the same shape is obtained in the entire scanning direction on the screen 20. I have. Then, the signal (blinking timing control signal) is transmitted to the control unit 40 in accordance with the lighting signal from the dot memory unit 50. Light control unit
The rotation position signal from the rotation driving unit 31 is also input to the speed correction memory unit 60 so that the signal transmission timing to the scanning unit 40 is synchronized with the scanning position.

The light intensity correction memory unit 70 is provided at the end of the screen 20 in order to correct the light amount change in the scanning direction due to the blinking pattern stored in the speed correction memory unit 60, that is, the tendency that the light amount decreases toward the end of the screen 20. The output pattern is stored for each scanning position in which the laser light output is increased as the output increases. The signal (laser light intensity control signal) is sent to the control unit 40 in response to the lighting signal from the dot memory unit 50. The rotation position signal from the rotation drive unit 31 is also input to the light intensity correction memory unit 70.

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

According to such a laser display device, while the same number of laser beams as the number of the pickup modules 11 in the optical pickup array 10 blink, the rotation of the polygon mirror 30 causes Y
Scanning is performed simultaneously in the direction, and predetermined characters or patterns are displayed on the screen 20. The laser beam scanned on the screen 20 in the Y direction is corrected by the contents of the speed correction memory unit 60, and the lighting time is shortened toward the end of the screen 20, so that the entire scanning direction on the screen 20 is The result is a dot image of the same shape. Further, under the correction by the light intensity correction memory unit 70, the output increases toward the end of the screen 20, and the decrease in the amount of light accompanying the reduction of the lighting time at the end of the screen 20 is corrected. Accordingly, the dot image shape of the laser beam is corrected to the same degree as that of the f · θ optical system even though the f · θ optical system is not used, and sufficient and uniform image brightness is secured in the entire scanning direction. Is done.

Although the above embodiment has a simple scanning system in which a plurality of laser light sources are arranged in a one-dimensional direction and a group of laser light from the light sources is guided on a screen by a polygon mirror, the present invention is not limited to this. For example, a scanning system such as a raster scanning system may be used, and any system may be used.

Further, if the cross-sectional shape of the laser beam output from the light source is a non-circular shape such as an ellipse flattened in the scanning direction, it is easy to correct the distortion of the dot image at the edge of the screen.

<Effects of the Invention> As described above, in the case of the laser display device according to the present invention, the f · θ optical system is not required, so that the device cost is reduced and application to a large screen is possible. Further, despite the fact that the f · θ optical system is unnecessary, the dot image shape of the laser beam is corrected to the same degree as the device having the f · θ optical system, and the image brightness is sufficient and uniform throughout the scanning direction. Is secured. Therefore, a clear laser projection image can be obtained over the entire screen.

[Brief description of the drawings]

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 operation principle of a polygon mirror in a projection scanning type laser display device. 10 Optical pickup array 20 Screen 30 Polygon mirror 40 Light control unit 60 Speed correction memory unit 70 Light intensity correction memory unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G09G 3/02 G02B 26/10

Claims (1)

(57) [Claims] A light source for outputting laser light; a polygon mirror for rotating and reflecting the laser light toward the screen so that the laser light from the light source scans on the screen; A light control unit for performing intensity control, a speed correction memory unit for storing a flashing timing of laser light calculated in advance for each scanning position, and a light intensity correction memory unit for storing the output of laser light for each scanning position. Wherein the operation of the light control unit is corrected based on the stored contents of the speed correction memory unit and the light intensity correction memory unit.