JP2002124724A - Laser apparatus and projection-type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an optical element from being melted and damaged due to the generation of a pulsed laser beam having an abnormally high peak value when a plurality of Q-switched laser oscillators are used as the light source of a liquid crystal projector. SOLUTION: The laser apparatus is provided with the Q-switched laser oscillators 21 and 22, 23 and 24, 25 and 26 which correspond respectively to RGB liquid crystal panels 51, 52, 53, one drive means 1 which drives Q-switches for the oscillators 21 to 26, delay means 2 to 6 which shift drive timings of the Q-switches for the oscillators 21 to 26 by delaying a drive signal to be output from the drive means 1 and optical elements 41, 44, 47 which composite laser beams radiated from the oscillators 21 and 22, 23 and 24, 25 and 26. The laser beams which are composited by the optical elements 41, 44, 47 are made incident on the panels 51, 52, 53, and the laser beams which are modulated by the panels 51, 52, 53 are composited by an optical element 54 so as to be incident on a projection lens 55.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a laser device for synthesizing pulsed laser beams emitted from a plurality of Q-switched laser oscillators, and a projection display device using such a laser device as a light source.

[0002]

2. Description of the Related Art A liquid crystal projector that modulates light from a light source with a liquid crystal panel and projects the light on a screen has been widely used as a large-screen image display device. As a light source of the liquid crystal projector, a white light lamp such as a metal halide lamp or an ultra-high pressure mercury lamp is often used.

However, it is desirable to use a light source that is as close to a point light source as possible in order to further increase the brightness and contrast of a liquid crystal projector. For this reason, attempts have been made to use a laser oscillator as a light source.

[0004]

For example, when a laser oscillator is used as a light source in a three-panel color liquid crystal projector, each of the R, G, and B liquid crystal panels has a Y
A method is considered in which laser light in the infrared wavelength range emitted from the AG laser oscillator is converted into laser light in the R, G, and B wavelength ranges by a wavelength conversion element and incident.

At this time, since the conversion efficiency of the wavelength conversion element is generally proportional to the square or the cube of the electric field intensity of the incident light, in order to increase the conversion efficiency, a YAG laser oscillator having a high peak value of the output laser light is required. It is desirable to use Therefore, if the YAG laser oscillator has the same output,
It is preferable to use a YAG laser oscillator that performs Q-switch oscillation rather than a YAG laser oscillator that performs steady oscillation.

When the output of each Q-switched YAG laser oscillator is not so large, laser light emitted from two or more Q-switched YAG laser oscillators is synthesized for each of the R, G, and B liquid crystal panels. It is desirable that the wavelength be converted by a post-wavelength conversion element to be incident on a liquid crystal panel.

FIG. 5 shows a configuration example of such a three-panel color liquid crystal projector. Two Q-switched YAG laser oscillators 21 and 22, 23 and 24, corresponding to the R, G and B liquid crystal panels 51, 52 and 53, respectively.
25 and 26 are provided. Q of each Q-switched YAG laser oscillator 21, 22, 23, 24, 25, 26
Each switch is a separate Q switch driver 3
It is driven by drive signals supplied from 1, 32, 33, 34, 35, 36.

The pulsed laser light emitted from the Q-switched YAG laser oscillators 21 and 22 is
Are converted into pulse laser light in the R wavelength range by the wavelength conversion element 42, and enter the liquid crystal panel 51 via the condenser lens 43. Similarly, the pulsed laser beams emitted from the Q-switched YAG laser oscillators 23, 24, 25, and 26 are synthesized by prisms 44 and 47, respectively, and are converted by the wavelength conversion elements 45 and 48 into the G and B wavelength bands. And then enter the liquid crystal panels 52 and 53 via the condenser lenses 46 and 49.

The pulse laser light modulated by the liquid crystal panels 51, 52, and 53 in accordance with the R, G, and B video signals, respectively, is synthesized by a color synthesis prism 54, and the projection lens 5
5 and is projected on a screen (not shown).

In the liquid crystal projector shown in FIG. 5, when pulsed laser beams are emitted from the Q-switch YAG laser oscillators 21 to 26 at timings at which the pulse positions overlap each other, the prisms 41, 44,
When the pulse laser beams are combined by the color combining 47 or the color combining prism 54, a pulse laser beam having an abnormally high peak value is instantaneously generated.

FIGS. 6A and 6B show the Q switch YA at time t.
FIG. 6C shows an example in which the emission timings of the pulse laser light overlap with each other in the G laser oscillator 21 and the Q-switch YAG laser oscillator 22. In this case, as shown in FIG. Will occur. Also, as shown in FIG. 6D, when the emission timing of the pulse laser light overlaps at this time t even in the Q-switch YAG laser oscillator 23,
As shown in FIG. 6E, the pulse laser light having a higher peak value is generated by the color combining prism 54.

For example, each of the Q switch drivers 31 to 3
6 output drive signals having the same frequency as each other (therefore, each Q-switched YAG laser oscillator 21
26, pulse laser beams are emitted at the same period from each other), even if the output timings of the drive signals from the respective Q switch drivers 31 to 36 are shifted from each other in the initial setting, the subsequent conditions such as temperature and the like are not satisfied. Since it is inevitable that the output timing of the drive signal from one of the Q switch drivers 31 to 36 coincides with the output timing of the drive signal from the other Q switch drivers 31 to 36 due to the influence of change or electric noise. When the emission timing of the pulse laser light overlaps between the Q-switched YAG laser oscillators 21 to 26, such an abnormally high pulse laser light may be generated.

The generation of such an abnormally high pulse laser beam causes melting and breakage of the coating on the surfaces of the prisms 41, 44, 47 and the color synthesizing prism 54, and also causes the condenser lenses 43, 46, It also causes melting and breakage of the coating on the surface of the projection lens 49 and the projection lens 55. Further, for example, when a pulse laser beam is guided between the wavelength conversion elements 42, 45, 48 and the liquid crystal panels 51, 52, 53 using an optical fiber, this may cause melting and breakage of the optical fiber.

In view of the above, the present invention provides a laser apparatus for synthesizing pulsed laser light emitted from a plurality of Q-switched laser oscillators, such as the light source of the liquid crystal projector in FIG. An object of the present invention is to prevent melting and breakage of an optical element due to generation of high pulse laser light.

[0015]

In order to solve this problem, the present applicant has developed a plurality of Q-switched laser oscillators,
One drive means for driving the Q switches of these Q-switched laser oscillators, and a delay means for shifting the drive timing of the Q switches of these Q-switched laser oscillators by delaying the drive signal output from the drive means. And an optical element for synthesizing the pulsed laser light emitted from these Q-switched laser oscillators.

In this laser device, the Q switches of the plurality of Q switch laser oscillators are driven by one driving means. Then, the drive signals output from the drive means are delayed by the delay means, so that the drive timings of the Q switches of these Q switch laser oscillators are shifted from each other.

The Q of each Q-switched laser oscillator
Since a common drive signal is supplied to the switch from one drive means, even if the output timing of the drive signal from this drive means changes due to changes in conditions such as temperature and the influence of electrical noise, each Q Q of switch laser oscillator
The drive timings of the switches also maintain a state shifted from each other.

As described above, since the drive timings of the Q switches of the respective Q switch laser oscillators are always shifted from each other, the emission timings of the pulse laser light from the respective Q switch laser oscillators do not overlap.

Thus, when the pulsed laser beams emitted from the respective Q-switch laser oscillators are combined, the pulsed laser beam having an abnormally high peak value is not instantaneously generated, so that the pulsed laser beams are combined. The melting and breakage of the optical element are prevented.

In this laser device, of the drive signals output from the drive means, the drive signal supplied to the Q switches of some of the Q switch laser oscillators is changed to an integral multiple of the frequency. Frequency converting means for converting the driving signal output from the driving means and / or the driving signal converted by the frequency converting means. Are preferably shifted from each other.

This makes it possible to drive the Q switches of some of the Q-switched laser oscillators at a period that is a fraction of the integer of the Q-switches of the remaining Q-switched laser oscillators, and also to use a pulse laser having an abnormally high peak value. The melting and breakage of the optical element due to the generation of light is prevented.

Next, the applicant of the present invention discloses a plurality of Q-switched laser oscillators corresponding to the same spatial light modulator, and a driver for driving the Q-switches of these Q-switched laser oscillators.
Drive means, delay means for delaying the drive signal output from the drive means to shift the drive timing of the Q switches of these Q-switch laser oscillators, and pulses emitted from these Q-switch laser oscillators An optical element for synthesizing laser light,
We propose a projection display device in which the pulse laser light synthesized by the optical element is made incident on a spatial light modulator, and the pulse laser light modulated by the spatial light modulator is made incident on a projection lens.

This projection type display apparatus uses the laser apparatus according to the present invention when combining pulse laser beams emitted from a plurality of Q-switched laser oscillators, modulating them with one spatial light modulator, and making the modulated laser beam enter a projection lens. Applied to prevent optical elements that combine pulsed laser light emitted from each Q-switched laser oscillator, other optical elements in the illumination optical system (such as condenser lenses), and melting and breakage of the projection lens Is done.

Next, the present applicant has developed a plurality of Q-switched laser oscillators corresponding to different spatial light modulators,
One drive means for driving the Q switches of these Q-switched laser oscillators, and a delay means for shifting the drive timing of the Q switches of these Q-switched laser oscillators by delaying the drive signal output from the drive means. The pulsed laser light emitted from these Q-switched laser oscillators is made incident on the corresponding spatial light modulating elements, and the pulsed laser light modulated by these spatial light modulating elements is synthesized and incident on the projection lens. A projection display device is proposed.

This projection display apparatus uses a plurality of spatial light modulators to modulate pulse laser beams emitted from different Q-switch laser oscillators, synthesize the pulse laser beams, and make the pulse laser beams incident on a projection lens. The laser device according to the present invention is applied to prevent an optical element for synthesizing a pulse laser beam modulated by each spatial light modulator and a projection lens from being melted or damaged.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a three-panel color liquid crystal projector will be described below.

FIG. 1 shows an example of the configuration of a three-panel color liquid crystal projector to which the present invention is applied, and portions common to FIG. 5 are denoted by the same reference numerals. This liquid crystal projector has all Q-switched YAG laser oscillators 21 to
One Q switch driver 1 for driving 26 Q switches and delay circuits 2 to 6 are provided. The delay time of the delay circuits 2, 3, 4, 5, and 6 is determined by the period of the drive signal output from the Q switch driver 1 (that is, the pulse repetition period of the pulse laser beam emitted from the Q switch YAG laser oscillator by the drive signal). ) As T, T / 6, T / 3, T / 2, 2T / 3, 5
It is T / 6.

The Q of the Q-switched YAG laser oscillator 21
The switch is supplied with the drive signal output from the Q switch driver 1 as it is (without delay). Q-switched YAG laser oscillators 22, 23, 2
The drive signals output from the Q switch driver 1 are applied to the Q switches 4, 25, and 26 respectively.
It is supplied after being delayed at 3, 4, 5, and 6.

As a result, the drive timings of the Q switches of the Q switch laser oscillators 21 to 26 are set to T
/ 6 at a time.

Then, each Q-switched laser oscillator 21
Since the drive signal from one common Q switch driver 1 is supplied to the ~ 26 Q switches, the output timing of the drive signal from the Q switch driver 1 changes due to changes in conditions such as temperature and the influence of electrical noise. Also in this case, the drive timings of the Q switches of the Q switch laser oscillators 21 to 26 also maintain a state shifted from each other by T / 6.

FIG. 2 shows the emission timing of the pulse laser light from each of the Q-switch YAG laser oscillators 21 to 26 in this liquid crystal projector. Each Q switch Y
Since the drive timings of the Q switches of the AG laser oscillators 21 to 26 are always shifted from each other by T / 6, the pulse laser light is emitted from each of the Q switch YAG laser oscillators 21 to 26 at a timing such that the pulse positions do not overlap with each other. Is emitted.

As described above, since the emission timings of the pulsed laser beams from the Q-switched YAG laser oscillators 21 to 26 do not overlap, the pulsed laser beams emitted from the Q-switched laser oscillators 21 and 22 are combined by the prism 41. When, Q switch laser oscillator 2
When the pulsed laser beams emitted from the lasers 3 and 24 are combined by the prism 44 or when the Q-switched laser oscillator 25
Pulsed laser light emitted from the
7, when the pulse laser light modulated by the liquid crystal panels 51, 52, 53 is synthesized by the color synthesizing prism 54, a pulse laser light having an abnormally high peak value is instantaneously generated. There is no.

Thus, melting and breakage of the prisms 41, 44, 47, the color synthesizing prism 54, the condenser lenses 43, 46, 49, and the projection lens 55 due to the generation of a pulse laser beam having an abnormally high peak value are prevented. It has become.

FIG. 3 shows another example of the configuration of a three-panel color liquid crystal projector to which the present invention is applied.
5 and FIG. 5 are denoted by the same reference numerals. This liquid crystal projector is provided with a frequency multiplier 7 for doubling the frequency of an input signal, and delay circuits 8 to 12. The delay times of the delay circuits 8, 9, 10, 11, and 12 are T / 4, T / 3, 5T / 12, and 7T / 1, respectively.
2, 2T / 3 (T is the period of the drive signal output from the Q switch driver 1).

The Q of the Q-switched YAG laser oscillator 21
A drive signal from the Q switch driver 1 is supplied to the switch as it is. The drive signal from the Q switch driver 1 is doubled in frequency by the frequency multiplier 7 and supplied to the Q switch of the Q switch YAG laser oscillator 22 after being delayed by the delay circuit 8. Q switch Y
The drive signal from the Q switch driver 1 is supplied to the Q switch of the AG laser oscillator 23 after being delayed by the delay circuit 9. The Q switch of the Q switch YAG laser oscillator 24 is supplied with a drive signal from the Q switch driver 1 whose frequency is doubled by the frequency multiplier 7 and delayed by the delay circuit 10. The drive signal from the Q switch driver 1 is supplied to the Q switch of the Q switch YAG laser oscillator 25 after being delayed by the delay circuit 11. The drive signal from the Q switch driver 1 is doubled in frequency by the frequency multiplier 7 and supplied to the Q switch of the Q switch YAG laser oscillator 26 after being delayed by the delay circuit 12.

Thus, the drive timings of the Q switches of the Q switch laser oscillators 21 to 26 are always shifted from each other.

FIG. 4 shows the emission timing of pulse laser light from each of the Q-switch YAG laser oscillators 21 to 26 in this liquid crystal projector. Each Q switch Y
Since the drive timings of the Q switches of the AG laser oscillators 21 to 26 are always shifted from each other, each of the Q switches YA
Pulse laser beams are emitted from the G laser oscillators 21 to 26 at timings such that the pulse positions do not overlap each other.

Thus, in this liquid crystal projector,
Since the emission timings of the pulse laser beams from the respective Q-switch YAG laser oscillators 21 to 26 do not overlap, when the pulse laser beams are combined by the prisms 41, 44, 47 and the color combining prism 54, they are instantaneously abnormal. Pulse laser light having a high peak value is not generated.

Thus, the Q switches of some of the Q-switched laser oscillators 22, 24, and 26 can be driven with a half cycle of the remaining Q-switched laser oscillators 21, 23, and 25. Also, melting and breakage of the prisms 41, 44, 47, the color synthesizing prism 54, the condenser lenses 43, 46, 49, and the projection lens 55 due to the generation of pulse laser light having an abnormally high peak value are prevented. I have.

In the liquid crystal projector shown in FIGS. 1 and 4, pulsed laser light is guided between the wavelength conversion elements 42, 45, 48 and the liquid crystal panels 51, 52, 53 using optical fibers. In this case as well, the melting and breakage of the optical fiber due to the generation of the pulse laser light having an abnormally high peak value is prevented.

The delay time in the delay circuits 2 to 6 in FIG. 1 and the delay circuits 8 to 12 in FIG. 4 is not limited to the time shown in the above example, and each of the Q-switch YAG laser oscillators 21 to 26
An appropriate time may be such that the emission timings of the pulsed laser beams from the Q switches do not overlap (that is, the drive timings of the Q switches of the Q switch YAG laser oscillators 21 to 26 are shifted from each other).

In the example shown in FIG. 4, a frequency multiplier is provided to drive the Q switches of some of the Q-switched laser oscillators at a half cycle of the Q-switches of the remaining Q-switched laser oscillators. However, it goes without saying that a frequency divider may be provided instead of the frequency multiplier.

Further, in the example of FIG. 4, the frequency of the drive signal supplied to the Q switches of some Q-switched laser oscillators is doubled, but supplied to some Q-switched laser oscillators. The frequency of the drive signal may be increased to an appropriate integer multiple. (In this case as well, the delay time in the delay circuits 8 to 12 is changed according to the frequency of the drive signal supplied to the Q switch of each of the switch laser oscillators 21 to 26.
The time may be set so that the emission timings of the pulse laser light from the laser beam do not overlap. )

In each of the above examples, the laser light emitted from the two Q-switched YAG laser oscillators is combined for each of the R, G, and B liquid crystal panels, and then wavelength-converted to be incident on the liquid crystal panel. . However, not limited to this, R,
For each of the G and B liquid crystal panels, the wavelength of laser light emitted from one Q-switched YAG laser oscillator may be converted and incident on the liquid crystal panel. Alternatively, for each of the R, G, and B liquid crystal panels, laser light emitted from three or more Q-switched YAG laser oscillators may be combined, wavelength-converted, and incident on the liquid crystal panel. In these cases, the supply timings of the drive signals to the Q switches of the respective YAG laser oscillators may be shifted from each other by a delay circuit so that the emission timings of the pulse laser beams from the respective Q switch YAG laser oscillators do not overlap.

In each of the above examples, a Q-switched YAG laser oscillator is used as a light source, but other Q-switched laser oscillators are used as light sources (for example, R, G,
For each B liquid crystal panel, using a Q-switched laser oscillator that emits pulsed laser light in the R, G, and B wavelength ranges,
The laser light emitted from the Q-switched laser oscillator may be incident on the liquid crystal panel without wavelength conversion.

In each of the above embodiments, the present invention is applied to a three-panel color liquid crystal projector. However, the present invention may be applied to a single-panel liquid crystal projector using a plurality of Q-switch laser oscillators as light sources. Further, a projection type display device other than a liquid crystal projector using a plurality of Q-switched laser oscillators as a light source (for example, a device using a Texas Instruments DMD as a spatial light modulator),
The present invention may be applied to appropriate applications other than the projection display device (for example, an exposure apparatus for manufacturing a semiconductor using a plurality of Q-switched laser oscillators as a light source).

Further, the present invention is not limited to the above-described example, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0048]

As described above, according to the laser device of the present invention, when the pulse laser beams emitted from the plurality of Q-switch laser oscillators are combined, the pulse laser beam having an abnormally high peak value instantaneously is obtained. Does not occur, so that the effect of preventing melting and breakage of the optical element for synthesizing the pulsed laser light can be obtained.

The Q-switched laser oscillator of the section
The effect that the switch can be driven at a cycle of an integral number of the Q switch of the remaining Q-switched laser oscillator, and that the optical element can be prevented from being melted or damaged due to the generation of a pulse laser beam having an abnormally high peak value. Is obtained.

Next, according to the projection type display device of the present invention, an optical element for synthesizing pulsed laser light emitted from each Q-switched laser oscillator and another optical element (condensing lens) in the illumination optical system And the like, and an effect of preventing melting and breakage of an optical element for synthesizing pulsed laser light modulated by each spatial light modulation element and a projection lens.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a three-panel color liquid crystal projector to which the present invention is applied.

FIG. 2 is a diagram showing emission timing of pulsed laser light from each Q-switched YAG laser oscillator in FIG. 1;

FIG. 3 is a diagram showing another configuration example of a three-panel color liquid crystal projector to which the present invention is applied.

FIG. 4 is a diagram showing emission timing of pulsed laser light from each Q-switched YAG laser oscillator in FIG. 3;

FIG. 5 is a diagram illustrating a configuration example of a three-panel color liquid crystal projector using a plurality of Q-switched laser oscillators as light sources.

6 is a diagram illustrating a pulse laser beam emitted from each Q-switched YAG laser oscillator in FIG. 5 and a pulse laser beam obtained by combining them;

[Explanation of symbols]

1 Q switch driver, 2-6, 8-12 delay circuit, 7 frequency multiplier, 21-26 Q switch YAG laser oscillator, 41,44,47 prism,
42, 45, 48 wavelength conversion elements, 43, 46, 4
9 condenser lens, 51, 52, 53 liquid crystal panel,
54 color synthesis prism, 55 projection lens

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 9/31 H04N 9/31 C // G02F 1/13 505 G02F 1/13 505 F-term (reference) 2H088 EA13 EA14 HA06 HA24 HA28 MA20 5C058 AA06 AB03 BA29 EA02 EA11 EA26 EA51 5C060 AA01 BA04 BA08 BC05 BD02 BD05 DB13 EA02 GA02 GB02 GB06 HB09 HC01 HC10 HC22 HD00 JA26 5F072 AB01 HH03 JJ05 MM03 QQ02 SS06

Claims (4)

[Claims] A plurality of Q-switched laser oscillators; one driving unit for driving a Q-switch of the plurality of Q-switched laser oscillators; and a delaying drive signal output from the driving unit, thereby providing the plurality of Q-switched laser oscillators. A laser device comprising: delay means for shifting the drive timing of a Q switch of a Q-switch laser oscillator with respect to each other; and an optical element for synthesizing pulsed laser light emitted from the plurality of Q-switch laser oscillators. 2. The laser device according to claim 1, wherein the drive signal output from the drive unit is supplied to a Q switch of a part of the plurality of Q switch laser oscillators. A frequency conversion unit that converts the drive signal into a drive signal having an integral multiple of a frequency, wherein the delay unit delays the drive signal output from the drive unit and / or the drive signal converted by the frequency conversion unit. A laser device wherein the drive timings of the Q switches of the plurality of Q switch laser oscillators are shifted from each other. 3. A plurality of Q-switched laser oscillators corresponding to the same spatial light modulator, one drive unit for driving a Q-switch of the plurality of Q-switched laser oscillators, and a drive signal output from the drive unit Delay means for delaying the drive timings of the Q switches of the plurality of Q-switched laser oscillators by delaying, and an optical element for synthesizing pulsed laser light emitted from the plurality of Q-switched laser oscillators, A projection type display device, wherein a pulsed laser beam synthesized by an optical element is made incident on the spatial light modulation element, and the pulsed laser light modulated by the spatial light modulation element is made incident on a projection lens. 4. A plurality of Q-switched laser oscillators corresponding to mutually different spatial light modulators; one drive unit for driving a Q-switch of the plurality of Q-switched laser oscillators; and a drive signal output from the drive unit. Delay means for delaying the drive timings of the Q switches of the plurality of Q-switched laser oscillators by delaying the pulsed laser beams emitted from the plurality of Q-switched laser oscillators. A projection type display device, wherein the light is incident on an element, and the pulse laser light modulated by the spatial light modulation element is synthesized and incident on a projection lens.