JPH0343706A - Image display device - Google Patents

Abstract

PURPOSE:To securely correct the linearity of a display by obtaining a timing signal for scanning by using reference light, correcting the linearity of the display with this timing signal, and making a specific signal precede this timing signal. CONSTITUTION:The timing signal for scanning is obtained by using the reference light to correct the linearity of the display with the timing signal, and the specific signal is made to precede the timing signal. Namely, a dichroic mirror 21 and an infrared-ray laser light source 22 are provided on the optical path of laser beam Lw between a dielectric mirror and a polygon mirror 11 and a reference infrared laser beam Li is emitted by the light source 22. Further, a dichroic mirror 24 is provided on the optical path of the laser beam Lw be tween relay lenses 13 and 14 and separates the original display beam Lw and the reference beam Li ; and the beam Lw is supplied to a lens 14 and the beam Li is supplied to a grating plate 25. Consequently, the display with good linearity is made.

Description

[Detailed description of the invention] The explanation will be given in the following order.

A. Industrial application field B. Summary of the invention C Conventional technology D Problems to be solved by the invention E. Means to solve the problem F Effect G Example (Figures 1 to 4) Effect of H invention A. Industrial application field The present invention relates to an image display device.

B. Summary of the Invention The present invention, for example, uses a reference light to obtain a scanning timing signal in a laser display device of the rusk scan type, and corrects the linearity of the display using this timing signal. By preceding the timing signal with a predetermined signal, the linearity of the display can be corrected reliably.

C. Prior Art As a projection-type, rask-scan type image display device using a laser beam, the one shown in FIG. 5 has been considered.

That is, in the same figure, (IR), (IG),
(1B) shows laser light sources that output red, green, and blue laser beams, respectively, and these light sources (I
The laser beams output from R) to (IB) are supplied to optical modulators (2R) to (2B), and the three primary color signals R, G, and B of red, green, and blue are supplied to the modulator (2R). ~(2
B) as its modulation input, and each laser beam is modulated in intensity (intensity) by the signal R-B.

Each laser beam whose intensity has been modulated passes through lenses (3R) to (3B) for beam diameter adjustment, and is further passed through a dielectric material ξ (4R) that reflects the corresponding colored light but transmits other colored light. ) to (4B) into one display laser beam L-, and this beam L- is supplied to a rotating polygon mirror (11) for horizontal deflection.

This polygon mirror (11) is formed, for example, into a regular 25-sided prism, and its surface is mirror-finished. Furthermore, this polygon mirror (11) is rotated by a driving means (12) at a rotation frequency of 1/25 of the horizontal frequency of the signal RB in synchronization with a horizontal synchronizing pulse. Therefore, by one rotation of the polygon mirror (11), the laser beam Lw
, horizontal deflection will be performed 25 times.

And this beam L1. I is the first relay lens (
13) into a parallel beam, and this parallel beam is passed through the second relay lens (13), which has the same focal length as the lens (13).
14), the reflection point of the polygon mirror (11) is reproduced at the focal position of the lens (14), and a galvanometer mirror (15) for vertical deflection is provided at this focal position.

This galvanomirror (15) is rotated by a driving means (16) at the vertical frequency of the signal RB in synchronization with the vertical pulse thereof.

In this way, the laser beam L- is transmitted through the galvano mirror (1
5), the beam is vertically deflected in a direction perpendicular to the horizontal deflection by the polygon mirror (11).

The horizontally deflected and vertically deflected beam L
- passes through the projection lens (17) to a flat screen (
18) from the back side. In addition, the lens (17
) is for narrowing down the beam Lw on the screen (18) to improve resolution.

Further, the screen (18) is of a type in which the image projected on the back surface is viewed from the front surface.

Therefore, when the screen (18) is viewed from its surface, a color image based on the signal R-B is displayed here.

Documents: Japanese Patent Application Laid-Open No. 48-38997, Specification and Drawings of Japanese Patent Application No. 63-324875
Description and Drawing D of No. 3-324876 Problems to be Solved by the Invention By the way, while the above-mentioned rotating polygon mirror (11) rotates at a constant angular velocity, the screen (18) is, for example, a flat surface. Therefore, the horizontal scanning of the laser beam Lw on the screen (18) is not constant, and the rotation angle θ of the polygon mirror (11) and the horizontal scanning position of the beam Lw have a relationship of tan θ. Close, screen (18
) The horizontal linearity of the image displayed becomes worse toward the left and right edges.

As a way to solve this problem, the rotational phase of the polygon mirror (11) for horizontal deflection can be changed during horizontal scanning, just as in a television receiver, the horizontal deflection waveform is corrected to correct horizontal linearity. This controls the screen (18
) can be considered to correct the linearity above.

However, the polygon mirror (11) requires considerable precision, and for this reason, for example, the polygon mirror (11) is obtained by cutting an aluminum material and giving it a mirror finish.

Therefore, the polygon mirror (11) has a large mass, and
Since the rotation frequency is as fast as 1/25 of the horizontal frequency, that is, approximately 630 rps, even if the polygon mirror (11) can be rotated in synchronization with the horizontal synchronization pulses of signals R to B, l horizontal scanning Polygon mirror during the period (11
) It is actually impossible to control the rotational phase of the polygon mirror (11) during the horizontal scanning period to correct the linearity on the screen (18). It's impossible.

Of course, when the scanning surface is small like a laser printer, horizontal linearity can be corrected using a correction lens, but when the scanning surface is large like a laser display device,
Correction using a correction lens is extremely difficult.

The present invention solves these problems, and in particular, ensures that the timing signals required to solve the problem are
Moreover, it is designed to be easily formed.

E. Means for Solving the Problems Therefore, in the present invention, a reference light is used to obtain a scanning timing signal, and the linearity of display is corrected using this timing signal. The signal is placed in advance.

F The linearity of the image is corrected regardless of the linearity of the scanning of the laser beam with respect to the working screen.

Embodiment First, an example of the essential parts of the optical system will be explained with reference to FIG.

This figure is a view of the rotating polygon mirror (11) viewed from the direction in which the laser beam Lw enters and exits.

Then, on the optical path of the laser beam Lw between the dielectric mirror (4R) and the polygon mirror (11), there is provided a quick clock mirror (21) that reflects the infrared light but transmits the laser beam Lw as is. At the same time, an infrared laser light source (22) is provided, and a reference infrared laser beam Li is taken out from this light source (22), and this beam Li passes through a collimator lens (23) to a mirror (22).
1) and is combined into a display beam Lw from a mirror (4R).

However, the beam Lw obtained from the polygon mirror (11) includes the beam Li, and this beam L
i is equally horizontally deflected at the same time as beam Lw.

Also, on the optical path of the laser beam Lw (including beam Li) between the relay lenses (13) and (14), like the dichroic mirror (21), the infrared light is reflected but the laser beam Lw remains unchanged. A transparent mirror (24) is provided, and this mirror (24) separates the original display beam Lw from the reference beam Li, and the beam Lw is directly passed through the lens (1) as described above.
4), the beam Li is supplied to the grating plate (25).

This grid plate (25) is made of a rectangular transparent glass substrate (25A) with a light-shielding film (25B
) is formed, and light-transmitting patterns Pp, Ps, Pc, and Pe are formed in a predetermined shape on this light-shielding film (25B). That is, for example, a light shielding film (25
In B), a metal film of Cr, Ti, Ni, etc. is formed by a vacuum film forming method to a thickness that is opaque to the laser beam Li, and this light-shielding film (25B) is photo-etched to form a pattern Pp=Pe. is formed.

In this case, the pattern Pp=Pe has a plurality of linear transparent parts (25C) arranged in the length direction of the substrate (25A), and the width of the pattern pp to Pe (length in the arrangement direction). is made equal to or slightly smaller than the horizontal scanning width of the laser beam Li separated by the ξ beam (24).

The pattern Pc is for obtaining a clock signal during horizontal scanning, and the transparent portion (25C) extends over an area corresponding to at least the effective horizontal scanning range of the screen (18), and They are formed at equal intervals corresponding to the horizontal curvature of.

Further, the number of transparent parts (25C) in this pattern Pc is set so that an integral multiple thereof is equal to the number of pixels in one horizontal line, for example, 910 pixels.

Further, the pattern Ps is a pattern for detecting the start point of effective horizontal scanning of the beam Li and specifying the start point of modulation of the beam Lw by the signal R-B.
5C) has a transparent part (
25C), and are formed at the same pitch while maintaining the regularity of the arrangement with the pattern PcO transparent parts (25C).

Furthermore, pattern pp is a preamble pattern for phase locking of PLL, which will be described later, and is located on the horizontal scanning start side of pattern Ps by one length of the transparent part (25C), and is apart from pattern Pc. They are formed at the same pitch while maintaining the regularity of the arrangement with the transparent parts (25C).

Further, the pattern Pe is a pattern for detecting the end point of effective horizontal scanning of the beam Lt and specifying the end point of modulation of the beam L- by the signal R-B.
5C) is a transparent part (
25C), and are formed at the same pitch while maintaining the regularity of the arrangement with the transparent portions (25C) of the pattern Pc.

The grating plate (25) is provided at the focal point of the lens (13) for the beam Li, and at this time, the horizontal scanning direction of the beam Li is aligned with the pattern Pp=Pe.
are arranged in the direction of arrangement.

Therefore, since the pattern Pp=Pe is horizontally scanned by the beam Li, a laser beam Li whose intensity changes in accordance with the horizontal scanning is obtained from the grating +N(2s).

This beam Li is then supplied to the photosensor (27) through the condensing lens (26), and the sensor (27) outputs a pulse signal Sp that rises or falls according to the change in the intensity of the laser beam Li. An alternating signal Sp of frequency and phase corresponding to changes in the intensity of the beam Li is extracted.

In this case, the frequency and phase (rising and falling points) of the signal Sp are such that the laser beam Li
5) corresponds to the horizontal scanning position when horizontally scanning. Also, the horizontal scanning position when the laser beam Li horizontally scans the grating plate (25), and the laser beam L-
corresponds to the horizontal scanning position during full horizontal scanning of the screen (18). Therefore, the frequency and phase (rising point and falling point) of the signal Sp correspond to the horizontal scanning position when the laser beam L- is horizontally scanning the screen (18).

Therefore, this signal Sp modulators (2R) to (
If the time axis of the signal R-B supplied to 2G) is controlled for each horizontal period, the horizontal linearity of the image displayed on the screen (one day) can be corrected.

Figure 2 shows how the screen (18) is formed by this method.
An example of a correction circuit that corrects the horizontal linearity of an image displayed on the screen is shown.

That is, the color composite video signal Sc is supplied to the forming circuit (39) through the terminal (31), and signals with various timings necessary for subsequent signal processing are formed based on the vertical synchronizing pulse, horizontal synchronizing pulse, and burst signal. be done. Then, the video signal Sc is sent to the color demodulation circuit (32)
At the same time, the color subcarrier signal is supplied from the formation circuit (39) to the color demodulation circuit (32) to demodulate the color signal R-B from the signal Sc, and these signals R-B are sent to the A/D converter ( 33R) to (33B), and a clock pulse Pg having a frequency that is, for example, four times as high as the color subcarrier frequency "C" is supplied from the forming circuit (39) to the converters (33R) to (33B) to generate the signal R.
-B is converted into a digital signal.

This digital signal R-B is then transferred to the line memory (34
R) to (34B), and the formation circuit (3
9) to the memories (34R) to (34B) as a write clock, and the signal R-B
The 910 pixels are sequentially written into the memories (34R) to (34B) every horizontal period.

By the way, if the horizontal frequency is fh, then 4 fc =
It is 910fh.

Further, the signal Sp from the sensor (27) is supplied as a first comparison input to the phase comparison circuit (42) through the waveform shaping circuit (41). This comparison circuit (42), together with circuits (43> to (45)), includes a frequency multiplication PLL (
46), in which the comparison output of the comparison circuit (42) is passed through the low-pass filter (43) to V CO (4
4) as its control signal, and this V CO(4
The oscillation signal Po of 4) is supplied to a frequency dividing circuit (45) and divided into a frequency equal to that of the signal Sp, and the frequency-divided output is supplied to a comparator circuit (42) as a second comparison input.

Therefore, the oscillation frequency and phase of the VCO (44) change following the frequency and phase of the signal Sp. Note that the average oscillation frequency of VC○ (44) is set to frequency 4fc, which is equal to the frequency of pulse pg.

Then, this oscillation signal Po is transmitted to the memories (34R) to (34R).
4B) as its read clock.

Also, at this time, the signal Sρ from the shaping circuit (41) is
It is supplied to the pattern detection circuit (49), and when the beam Li is horizontally scanning the start pattern Ps, a signal indicating this is extracted, and this signal is stored in the memories (34R) to (
34B) as a read start signal.

Therefore, when the laser beam Li starts horizontal scanning of the pattern Pc, from this point on, the memories (34R) to (
34B) is started, and thereafter, the signals R-B are sequentially read out in synchronization with the signal Po. That is, the signal R-B is read out in synchronization with the horizontal scanning of the laser beam Li with respect to the pattern Pc. Therefore, the signal R-B is read out in synchronization with the horizontal scanning of the laser beam Lw with respect to the screen (18).
will be read out.

Furthermore, from the detection circuit (49), a laser beam Li
When horizontally scanning the end pattern Pe, a signal indicating this is taken out, and this signal is stored in the memory (34R) ~
(34B) as a read end signal, and when the signal Se is supplied, the read in the horizontal period is
be terminated.

The signals R-B read from the memories (34R) to (34B) are then transmitted to the D/A converters (35R) to (34B).
35B), and the signal Po is also supplied as a clock pulse to the converters (35R) to (35B) to convert the signal R-B into an analog signal, and this analog signal R-B is supplied to the drive circuit (36R). ~(36B
) are respectively supplied to modulators (2R) to (2B) as modulation inputs.

Therefore, a color image based on the signal Sc is displayed on the screen (18).

In this way, a color image is displayed by the laser beam L-, but in this case, according to the present invention, the display laser beam Lw is combined with the reference laser beam Li, and the reference beam Li and the grid plate ( 25), the horizontal scanning position of the display beam Lw is detected, and the time axis of the signal R-B is controlled in accordance with the detected horizontal scanning position. Images can be displayed with excellent linearity without distortion.

Moreover, in particular, according to the present invention, since the grating plate (25) is provided with the preamble pattern pp, the frequency multiplication P L L (46) is pre-excited by the preamble pattern pp. Continued start pattern p
The signal Sp can be stably formed with respect to p and the clock pattern Pc.

Also, a start pattern P is placed before the clock pattern Pc.
s is provided to output the signal R from the memories (34R) to (3411).
-B is used as the reference when reading out, so the starting position of horizontal scanning of the image displayed on the screen (18) is not affected by processing accuracy or uneven rotation of the rotating polygon mirror (11).

Furthermore, even if the color signal Sc contains jitter, it is absorbed by the memories (34R) to (34B) and does not appear on the screen (18).

Furthermore, simply by forming the patterns Pp and Ps on the grating plate (25), it is possible to improve the formation and stability of the signal Sp or pulse Po.

Furthermore, when configuring a projection type television receiver by integrating the laser light sources (IR) to (IB) to the screen (18), the galvano mirror (15) and the screen are combined to reduce the depth of the television receiver. It is necessary to install a wide-angle lens between the clock pattern Pc of the grating plate (25) and the transparent part (
25C) to a pitch corresponding to the wide-angle lens, the linearity of the image on the screen (18) can be corrected.

Alternatively, even when the screen (18) is not flat but has a certain curvature, the transparent portion (25C) of the clock pattern Pc of the lattice plate (25) may be arranged at a pitch corresponding to the curvature of the screen (18). The linearity of the image on the screen (18) can be corrected simply by
Furthermore, even if the screen is wide-angle, such as a high-definition television receiver, the linearity of the image can be easily corrected.

FIG. 4 shows a case where the linearity of vertical deflection is corrected.

That is, in the same figure, the infrared laser light source (52)
A reference infrared laser beam Lj is taken out from this light source (52), and this laser beam Lj
However, the laser beam L from the lens (14) is transmitted to the galvanometer mirror (15) through the collimator lens (53).
The reflected laser beam L- is supplied at an incident angle different from w and is supplied to the photosensor (57) through the grating plate (55) and the condensing lens (56).

In this case, the grating plate (55) is constructed in the same manner as the grating plate (25), and the laser beam Lj is vertically deflected by the mirror (15) and passes through the grating plate (25).
55).

Therefore, if, for example, the drive means (16) of the galvano mirror (I5) is controlled by the output of the sensor (57),
This means that the vertical linearity of the image displayed on the screen (18) can be corrected.

H Effects of the Invention According to this invention, a reference laser beam Li is combined with a display laser beam L-, and this reference beam L
i and the grid plate (25) to form a display beam L L-1
Since the horizontal scanning position of the horizontal scanning position is detected and the time axis of the signal R-B is controlled in accordance with the detected horizontal scanning position, the image displayed on the screen (18) may be distorted. Therefore, it is possible to perform display with excellent linearity.

Moreover, in particular, according to the present invention, since the grating plate (25) is provided with the preamble pattern pp, the frequency multiplication P L L (46) is pre-excited by the preamble pattern pp. Continued start pattern p
The signal Sp can be stably formed with respect to p and the clock pattern Pc.

In addition, a start pattern Ps is provided before the clock pattern PcO to output the signal R from the memories (34R) to (34B).
-B is used as the reference when reading out, so the starting position of horizontal scanning of the image displayed on the screen (18) is not affected by processing accuracy or uneven rotation of the rotating polygon mirror (11).

Furthermore, even if the color signal Sc contains jitter, this is absorbed by the memories (34R) to (34B) and does not appear on the screen (18).

Furthermore, simply by forming the patterns Pp and Ps on the grating plate (25), it is possible to improve the formation and stability of the signal Sp or pulse Po.

Furthermore, when configuring a projection type television receiver by integrating the laser light sources (IR) to (IB) to the screen (18), the galvano mirror (15) and the screen are combined to reduce the depth of the television receiver. (18), it is necessary to install a wide-angle lens between the clock pattern PcO transparent part (18) of the grating plate (25).
25C) to a pitch corresponding to the wide-angle lens, the linearity of the image on the screen (18) can be corrected.

Alternatively, even when the screen (18) is not flat but has a certain curvature, the transparent portion (25C) of the clock pattern Pc of the lattice plate (25) has a pitch corresponding to the curvature of the screen (18). The linearity of the image on the screen (18) can be corrected simply by
Furthermore, even if the screen is wide-angle, such as a high-definition television receiver, the linearity of the image can be easily corrected.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a main part of an example of the present invention, FIG. 2 is a system diagram of the entire system, and FIG. 3 is a front view and a perspective view of the main part.
FIG. 4 is a perspective view of essential parts of another example of the invention, and FIG. 5 is a diagram for explaining the same. (IR) to (Fil) are laser light sources, (2R) to (2
B) is a light modulator, (11) is a rotating polygon mirror, (15) is a galvanometer mirror, (18) is a screen, (25) is a grating plate, L- is a display laser beam, Li and Lj are reference laser beams , (34R) to (34B) are line memories, and (46) is a PLL.

Claims (1)

[Claims] A light beam whose intensity is modulated by a video signal is supplied to horizontal deflection means and vertical deflection means to perform horizontal deflection and vertical deflection, and the deflected light beam is projected onto a screen. and a light source for supplying reference light to at least one of the horizontal deflection means and the vertical deflection means, and a reference light from the deflection means. It has a grating plate that is scanned by light, and a photosensor that receives reference light from the grating plate, and corrects the scanning position of the light beam on the screen based on the output of the photosensor, and the grating plate a first pattern scanned by the reference light to define the scanning position of the light beam on the screen; and a first pattern scanned by the reference light prior to the first pattern to define the scanning position of the light beam on the screen; a second pattern indicating the start of scanning of the reference light; and a second pattern that is scanned by the reference light prior to the second pattern, and when the reference light scans the second and first patterns. and a third pattern for outputting a signal serving as a pre-excitation signal in response to the output of the photosensor.