JPS6190122A - Laser display device - Google Patents

Abstract

PURPOSE:To prevent scanning performance from being spoiled even when a set is compacted by spreading a scanned laser light beam horizontally and then projecting it on a screen. CONSTITUTION:The luminance modulation signal of an image signal is sent to an optical modulator 4 from an image signal source 2 through a video amplifier 3, and the luminance of a laser light beam emitted by a light source 1 is modulated individually with the video signal. Three modulated laser light beams of red, green, and blue are put into one laser light beam by a dichroic mirror 5 to illuminate a deflecting device 6. A vertical and a horizontal synchronizing signal are sent to the deflecting device 6 from the video signal source 2 through a horizontal and vertical driving device 7. The deflecting device 6 consists of a horizontal scanner 6b and a vertical scanner 6a which each consist of a rotary polygon mirror to scan the laser light. The scanned laser light beam is expanded horizontally by a semicylindrical convex mirror 8 and projected on the screen 9.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention modulates three color laser beams of red, green, and blue with an image signal using an optical modulator, combines them into one beam, and then A deflector performs horizontal and vertical deflection,
The present invention relates to an improvement of a laser display device that projects images onto a screen.

[Background of the invention]

As a light deflection device used in a laser display device that displays an image by projecting a laser beam onto a screen, a horizontal scanner consisting of a disk-shaped rotating mirror and a drum-shaped rotating mirror are used, as described in Japanese Patent Laid-Open No. 57-41076. Vertical scanners consisting of mirrors are known. The operating principles of these scanners will be explained below.

FIG. 3(a) is a plan view of a horizontal scanner as an optical deflection device, and FIG. 3(b) is a side view of the same.

In these figures, 6b is a rotating polygon mirror (in this example, a five-sided mirror consisting of pentagons), K is its center of rotation, and B is one polygon mirror.
It's a laser beam.

One laser beam I! When BI is projected near one end E1 of one mirror surface S1 of the five-sided mirror, the light beam is reflected and reaches 81 points. The mirror surface sl rotates around the rotation center in the direction of the arrow, and the other end E2
When reaching a position near , the light MBt is reflected and reaches 82 points. Distance between El and B2! is the horizontal scanning width, and θ1
In other words, if the rotating polygon mirror 6b is a five-sided mirror, horizontal scanning can be performed up to 0, where is the horizontal deflection angle. One rotation allows horizontal scanning from 81 points to 82 points to be repeated five times.

The above is the operating principle of the horizontal scanner. Next, the vertical scanner will be explained.

FIG. 4(A) is a plan view of a vertical scanner as an optical deflection device, and FIG. 4(A) is a side view of the same.

In these figures, 6a is a cylindrical rotating polygon mirror (in this example, a five-sided mirror). B2 is a laser beam scanned in the horizontal direction by the horizontal scanner shown in FIG. 3, that is, a beam having a scanning width l. The rotating polygon mirror 6a is
Since the beam B2 having a scanning width l is projected, it is required to be a cylindrical (drum-shaped) polygon mirror having at least a thickness j.

When the laser beam B2 is projected near one edge E3 of one mirror surface S2 of the five-sided mirror, the mirror surface S2 rotates in the direction of the arrow around the center of rotation KO, and the other edge E4
When reaching a position near B3 shown in the figure, the light beam B2 is reflected and reaches E4yE4. The distance m between B4 and B3 corresponds to the vertical scanning width, and the angle θ2 is the vertical deflection angle.

In other words, when the cylindrical rotating polygon mirror 6a is a five-sided mirror, one rotation of the mirror allows the incident beam to be vertically scanned once, and one rotation of the mirror allows the vertical scanning to be repeated five times.

Now, as described above, when the conventionally known horizontal and vertical scanners are used in a laser display device, the deflection angle width (angle θ1 in FIG. 3, angle θ2 in FIG. 4) of each scanner is generally used. is small, so when trying to obtain a screen of a given size,
There is a problem in that the distance to the screen becomes longer and the set size of the display device becomes larger (that is, it becomes larger).

Furthermore, in a rotating polygon mirror, the precision of the polygon mirror is the most important, and in particular, the parallelism of the mirror surface to the axis (rotation center K) causes unevenness in the pitch of the scanning line, which deteriorates the scanning performance. However, this becomes a particular problem when the shape of the rotating polygon mirror becomes large, as it becomes difficult to obtain parallelism from the viewpoint of machining accuracy.

As for making the set more compact, one possible method is to reduce the number of mirror surfaces of the polygon mirror, increase the deflection angle width, and shorten the projection distance to the screen. However, in order to keep the scanning period constant, the product of the number of surfaces of the polygon mirror and the number of rotations must be constant, so if the number of surfaces is decreased, the number of rotations must be increased. However, horizontal scanners have always rotated at high speeds, and further increasing the rotation speed may cause problems with the bearings, such as uneven rotation, and deformation of the scanner due to increased centrifugal force. Problems arise with the strength required to prevent this.

[Purpose of the invention]

The present invention has been made in view of the conventional technical circumstances as described above, and therefore, an object of the present invention is to maintain the screen size of a predetermined size and to make the set compact, without the need for a rotating polygon mirror. It is an object of the present invention to provide a laser display device that does not require enlarging its shape or forcibly increasing its rotational speed, and does not impair scanning performance.

[Summary of the invention]

In order to achieve the above object, the laser display device according to the present invention is provided with a semi-cylindrical convex mirror for horizontally expanding a scanned laser beam and projecting it onto a screen, thereby making the set more compact. In addition, the number of polygonal mirror surfaces of the horizontal scanner is increased to shorten the horizontal scanning width, which in turn makes it possible to shorten the cylindrical dimension of the vertical scanner to improve scanning performance.

[Embodiments of the invention]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory diagram showing one embodiment of the present invention. In the same figure, 1 is a light source, and a krypton ion laser (6
471A red) 1a, argon ion laser (4880
It consists of an argon ion laser (5145A green) lc, and an argon ion laser (5145A green) lc.

Among the image signals, the brightness modulation signal is sent from the image signal source 2 to the optical modulator 4 via the video amplifier 3. The optical modulator 4 is composed of a KDP type crystal and an analyzer, and the light source 1
The brightness of the toza rays emitted from the rays is individually modulated by the image signal.

The three modulated laser beams of red, green, and blue are combined into one laser beam by a dichroic mirror 5 and irradiated onto a deflection device 6 .

A horizontal and vertical drive device 7 is connected to the deflection device 6 from the image signal source 2.
The vertical synchronization signal and horizontal synchronization signal are each sent separately via the . The deflection device 6 is composed of a horizontal scanner 6b made of a disc-shaped rotating polygon mirror and a vertical scanner 6a made of a cylindrical rotating polygon mirror, and converts one laser beam synthesized by the dichroic mirror 5 into a video signal. Scan vertically and horizontally in synchronization.

The laser beam scanned in the vertical and horizontal directions reaches a semi-cylindrical (Kamabot-shaped) convex mirror 8 placed in front of the deflection device 6, where it is magnified in the horizontal direction of the screen and reflected onto the screen 9. projected on. At this time, since the light is not enlarged or reduced in the vertical direction but only reflected, the magnifications in the vertical and horizontal directions become unequal.

Therefore, in the horizontal direction, the image signal source 2 provides a compressed image signal corresponding to the magnification of the convex mirror 8.

The convex mirror 8 and deflection device 6, which are features of the present invention, will be explained in further detail.

In the conventional deflection device 6, the horizontal scanner 6b has a diameter of 41w5 [16 polygon mirrors] corresponding to 515 scanning lines. The vertical scanner 6a has a polygon mirror with a diameter of 100 + m, a length of 100 mm, and a number of sides of 24, which is rotated at a distance of 120 m from the horizontal scanner.
It is rotating at rpm. As a result, due to constraints on projection distance, a set depth dimension of 1,500 mm was required for a screen size of 60 inches.

On the other hand, in the display device according to the present invention,
As shown in FIG. 2 (however, FIG. 2(a) is a plan view of the screen 9 and convex mirror 8 in FIG. 1, and FIG. 2(b) is a side view of the same), in front of the deflection device 6, there is a radius of curvature 1
It has a structure in which 94 convex mirrors 8 are arranged to project the scanned laser beam in the horizontal direction.

Therefore, the horizontal deflection angle θl has changed from the conventional 456 to 22.
As a result, the horizontal scanner 6
By setting the number of surfaces of b to 32, it became possible to reduce the rotational speed by half to 30.00 rpm. Furthermore, the length of the vertical scanner 6a could be halved to 50 tm.

As a result, the set depth dimension of a 60-inch screen size could be compared to more than 700 inches and 50 inches. On the other hand, since the projection distance has become shorter, it is necessary to expand the deflection angle θ2 of the vertical scanner.
This was solved by setting the number of surfaces to 18 and the number of rotations to 200rl)m. There were no practical problems with bearings or the like when the rotational speed increased in this range.

[Effect of venting]

With the present invention, the number of rotations of the high-speed horizontal scanner can be reduced to 7, and by increasing the length of the vertical scanner, the parallelism between the rotation axis and the mirror surface can be improved from the viewpoint of machining accuracy. Although difficult, the length of such a vertical scanner could be reduced to 1.

As a result, it is possible to reduce the load on scanner bearings, etc., and improve the machining accuracy of individual parts, and improve image quality such as raster distortion and scan line pitch unevenness by 30% due to improved scanning performance.
I was able to change my tongue.

Furthermore, the set depth was halved, making it more compact and reducing costs.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing one embodiment of the present invention, Figure 2 (a)
is a plan view of the main part in FIG. 1, FIG. 2(b) is a side view of the same, FIG. 3 is a diagram explaining the principle of a horizontal scanner as an optical deflection device, and FIG. 4 is a diagram explaining the principle of a vertical scanner. It is. Code explanation 1... light source, 2... image signal source, 3.
...Video amplifier, 4...Light modulator, 5.
...Dilock mirror, 6... Deflection device, 7... Horizontal and vertical drive device, 8...
Convex mirror, 9... Screen agent Patent attorney
Akio Namiki Figure 1 KTA-kaku! Figure 2 @3 Figure m4 Figure

Claims (1)

[Claims] 1) A modulation means for applying brightness modulation to each of the red, green, and blue laser beams using an image signal;
A means for combining the laser beams of a book into one laser beam;
A horizontal scanner consisting of a rotating polygon mirror for horizontally scanning the combined single laser beam, and a vertical scanner also consisting of a rotating polygon mirror for vertically scanning the horizontally scanned laser beam. In a laser display device that projects the laser beam scanned in the horizontal and vertical directions onto a screen, a semi-cylindrical convex mirror is arranged in front of the screen, and the laser beam is scanned in the horizontal and vertical directions. A laser display device characterized in that the scanned laser beam is horizontally expanded by the convex mirror and then projected onto a screen.