KR100734677B1 - Display Device Of Laser Scannig Type - Google Patents

Abstract

The present invention relates to a laser scanning display device, comprising: a laser for irradiating light, an optical modulator for controlling the light irradiated from the light source to be synchronized with an input image signal, and the direction of the irradiated light with the light irradiated from the laser A polarization beam splitter for reflecting in a direction to deviate, a quarter wave plate for transmitting the light reflected by the polarization beam splitter, a scanner for reflecting the light transmitted through the quarter wave plate to transmit the quarter wave plate again; And a screen that provides an image from the light reflected by the scanner.

Due to this feature, the present invention can not only significantly reduce the asymmetrical distortion of the image caused by the deflection, but can also achieve miniaturization and cost reduction of the display device.

Scanner, laser display

Description

Display device of laser scan type

1 is a view showing a schematic configuration of a laser scanning type display apparatus according to the prior art;

2a and 2b is an image implemented by a laser scanning display device according to the prior art,

3 is a view showing a schematic configuration of an embodiment of a laser scanning type display device according to the present invention;

4 is a view showing a schematic configuration of another embodiment of a laser scanning type display device according to the present invention;

5 is a view showing a schematic configuration of another embodiment of a laser scanning display device according to the present invention;

6 is a view showing a schematic configuration of another embodiment of a laser scanning display device according to the present invention;

7 is an image implemented by the laser scanning display device according to the present invention.

*** Explanation of the main signs in the drawings ***

10, 10a, 10b, 10c: laser 11, 11a, 11b, 11c: optical modulator

12, 12d: polarizing beam splitter 12a, 12b, 12c: wavelength selective beam splitter

13: 1/4 wavelength plate 14: scanner

15: screen 16, 16a, 16b, 16c: laser diode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser scanning display device. More particularly, the present invention relates to an optical system in which a difference between an incident angle of light incident on a scanner and a reflection angle of light reflected and formed on a screen is small. It is a laser scanning type display device that can be significantly reduced.

Laser scanning type display technology is a method of displaying images by oscillating three lasers of red, green, and blue. The laser scanning display technology is known to display video images up to 600 inches by displaying high-definition and high-definition screens due to the long-range projection capability and the high density of the laser beam, which are inherent in lasers. It has a wide range of features. In addition, since the power consumption is small and the screen is limited, the device can be miniaturized, which is advantageous as a portable small display device.

1 is a view schematically showing a laser scanning display device according to the prior art, a plurality of laser (101a, 101b, 101c) for emitting light, modulating the light emitted from the laser to be synchronized with the input image signal Optical modulators 102a, 102b, 102c, beam splitters 103a, 103b, 103c for reflecting light modulated by the optical modulator, scanner 104 for deflecting and reflecting light reflected from the reflector and the scanner It consists of a screen 105 for providing an image with deflected reflected light.

The scanner is a device that performs linear motion or nonlinear motion so that an image can be realized by reflecting light (a light signal) at an appropriate position on a screen. When the light is incident, the scanner rotates about the rotation axis to change the reflection direction of the incident light so that the light is transmitted to the screen. In the case of a single-axis scanner having one axis, a vertical scan scanner and a horizontal scan scanner are required to realize a two-dimensional image. For this reason, recently, two-axis scanner devices have been developed. The two-axis scanner can scan both the vertical and horizontal directions by reflecting the incident light while rotating one scanner about two vertical axes. That is, when the vertical and horizontal scanning of the scanner is performed with a ratio of a certain period, the screen is filled with a plurality of horizontal scanning lines in one vertical scanning to realize an image.

As shown in the related art, the conventional laser scanning type display apparatus has a structure in which light incident on a scanner is deflected and travels. 2A and 2B show image distortion by a laser scanning display device according to the prior art, and when light incident on a screen is incident with a deflection angle, as shown, the image is distorted and is particularly asymmetrical. Distortion is a problem. In particular, there is a problem in the case of the laser display device in which the optical path of the laser display device employing the 1-axis scanner is applied to the 2-axis scanner as it is.

Therefore, there is a need for a scanner laser display device configured to solve this problem.

The present invention provides a laser scanning display device that can significantly reduce the asymmetrical distortion of an image caused by deflection by providing an optical system in which the difference between the incident angle of the light incident on the scanner and the reflected angle of the light reflected on the screen is small. It is to.

The present invention provides a laser for irradiating light, an optical modulator for controlling the light irradiated from the laser to be synchronized with an input image signal, a polarizing beam splitter for reflecting the light irradiated from the laser in a direction orthogonal to the direction of irradiated light, A quarter wave plate for transmitting the light reflected by the polarization beam splitter, a scanner for reflecting the light transmitted through the quarter wave plate to pass through the quarter wave plate, and an image from the light reflected by the scanner It is a laser scanning display device including a screen for providing.

A laser diode for irradiating light synchronized with an input image signal, a polarizing beam splitter for reflecting light emitted from the laser diode in a direction orthogonal to the direction of irradiated light, and for transmitting the light reflected by the polarizing beam splitter A laser scanning display comprising a quarter wave plate, a scanner for reflecting light transmitted through the quarter wave plate back through the quarter wave plate and a screen providing an image from the light reflected by the scanner Device.

A plurality of lasers for irradiating light, a plurality of light modulators for respectively controlling the light irradiated from the plurality of lasers to be synchronized with the input image signal, and the light irradiated from the plurality of lasers orthogonal to the direction of the irradiated light A plurality of wavelength selective beam splitters each reflecting in a direction, a polarizing beam splitter reflecting the light reflected by the plurality of wavelength selective beam splitters in a direction orthogonal to the direction of the reflected light, and transmitting the light reflected by the polarizing beam splitter A laser scanning display comprising a quarter wave plate, a scanner for reflecting light transmitted through the quarter wave plate back through the quarter wave plate and a screen providing an image from the light reflected by the scanner Device.

Also, a plurality of laser diodes for irradiating light synchronized with an input image signal, a plurality of wavelength selective beam splitters for reflecting light irradiated from the plurality of laser diodes in a direction orthogonal to the direction of irradiated light, the plurality of A polarization beam splitter for reflecting the light reflected by the wavelength selective beam splitter in a direction orthogonal to the direction of the reflected light, a quarter wave plate for transmitting the light reflected by the polarization beam splitter, and a quarter wave plate A laser scanning display device comprising a scanner that reflects light back through a quarter wavelength plate and a screen that provides an image from the light reflected by the scanner.

The optical system of the laser scanning display device of the present invention is as follows. The light irradiated from the laser is synchronized with the input image signal while passing through the optical modulator, and the light is reflected in a direction orthogonal to the direction of the light irradiated by the polarizing beam splitter and then transmitted through the quarter wave plate. The light transmitted through the quarter wave plate is converted into circular polarization, reflected by the scanner, and then passed through the quarter wave plate, and the polarization mode is changed to be transmitted without being reflected by the polarizing beam splitter. do.

In addition, the optical system for implementing a color image of the laser scanning display device of the present invention is as follows. Light (e.g., green, red, and blue) irradiated from a plurality of lasers is synchronized with the input image signal while passing through each optical modulator, and the light is irradiated by a plurality of beam splitters that transmit and reflect differently depending on the wavelength. The light is reflected in a direction orthogonal to the direction of the light so as to be incident on a single polarizing beam splitter. Light incident on the polarizing beam splitter is reflected in a direction orthogonal to the incident direction, and passes through a quarter wavelength plate. The light transmitted through the quarter wave plate is converted into circular polarization, reflected by the scanner, and then passed through the quarter wave plate, and the polarization mode is changed to be transmitted without being reflected by the polarizing beam splitter. do.

In addition, the present invention can be implemented without a separate optical modulator by using a laser diode. That is, when adjusting the magnitude of the input voltage of the laser diode in synchronization with the image signal, it is possible to generate modulated light such as by an optical modulator.

The scanner of the present invention, as a movable mirror, scans the light onto the screen by rotating the light having the quarter wavelength plate reflected at different angles. The present invention is remarkable in the case of a scanner having two axes, but a scanner having one axis may be used.

As can be seen from the optical system of the present invention described above, the laser scanning display device of the present invention has no or small deflection angle, that is, an image due to deflection by reducing the difference between the incident angle of the light incident on the scanner and the reflected angle of the reflected light. Can solve the distortion.

Hereinafter, with reference to the accompanying drawings will be described in detail the technical features of the present invention. The invention can be better understood by the examples, the following examples are for illustrative purposes of the invention and are not intended to limit the scope of protection defined by the appended claims.

3 is a view schematically showing an optical system of an embodiment of a laser scanning display device according to the present invention. As shown, a laser 10 for irradiating light and an image signal to which light irradiated from the laser is input An optical modulator 11 for controlling to be synchronized, a polarization beam splitter 12 for reflecting the light emitted from the laser in a direction orthogonal to the direction of the irradiated light, and a quarter wavelength for transmitting the light reflected by the polarization beam splitter A plate 13, a scanner 14 that reflects light transmitted through the quarter wave plate back through the quarter wave plate, and a screen 15 that provides an image from the light reflected by the scanner. do.

The laser 10 employs a laser having excellent coherence and excellent linearity. Preferably helium-neon lasers using an optically homogeneous gas medium are preferred. The helium-neon laser includes a helium gas, a neon gas, a discharge tube in which helium gas and neon gas are mixed and sealed, and a resonator installed at both ends of the discharge tube to resonate the discharged light. Briefly describing the light emission mechanism, a plasma discharge is generated in a discharge tube by a power source applied to the discharge tube and predetermined light is emitted, and the emitted light is resonated between the resonators, and has a predetermined wavelength suitable for a resonance condition. Only light passes through the resonator and is emitted.

In the present embodiment, the helium-neon laser has been described as an example. However, this is only an example, and a solid state laser such as a gas laser such as an excimer laser, a ruby laser Nd: YAG laser, or a semiconductor laser may be used.

The light irradiated by the laser may be polarized and irradiated, may not be polarized, and may be polarized by a polarizer (not shown) after being irradiated.

The optical modulator 11 controls the light irradiated from the laser to be synchronized with the input image signal. In this embodiment, an optical modulator using an acoustic optical effect is used. An optical modulator using an acoustic optical effect is a transducer that converts the piezoelectric substrate and applied electrical energy into acoustic energy to generate sound waves on opposite sides of the piezoelectric substrate, thereby generating Bragg grating on the piezoelectric substrate. It is composed.

The mechanism of the optical modulator is described in more detail as follows. When a voltage is applied to the transducer, the transducer converts the applied electrical energy into acoustic energy. The generated acoustic energy appears in the form of sound waves traveling in the direction of the other surface facing from one surface of the piezoelectric substrate to which the transducer is attached. The Bragg grating is formed inside the piezoelectric substrate by the progress of the sound wave, and the lattice period of the Bragg grating is changed according to the electric energy applied to the transducer. When laser light is irradiated onto the piezoelectric substrate in a direction perpendicular to the direction in which sound waves travel in the above state, light diffraction occurs at an angle inversely proportional to the period of the Bragg grating. This phenomenon of diffraction through the Bragg grating is referred to as Bragg diffraction. When the optical modulator using the acousto-optic effect changes the frequency of the voltage applied, the frequency of the sound wave generated from the transducer is changed, and thus the period of Bragg grating generated in the piezoelectric substrate is changed to enter the piezoelectric substrate. The diffraction angle of the light is changed. In addition, the intensity of the sound wave is changed according to the intensity of the voltage applied to the transducer, and the diffraction efficiency of the diffracted light is changed at this time.

As the optical modulator, an optical modulator using a magnetic field may be used in addition to the optical modulator using the above-described acoustic optical effect.

The polarizing beam splitter 12 transmits some light and reflects some light depending on the polarization state. That is, when unpolarized light is incident, S-polarized light is reflected and P-polarized light is transmitted. Therefore, when the light polarized in advance is reflected or transmitted according to the polarization mode. In the present invention, light that is not polarized may be incident to obtain S-polarized light, or light that is previously polarized may be incident. In either case, the S-polarized light is changed in the traveling direction in a direction orthogonal to the direction reflected by the polarized beam splitter and irradiated.

The quarter wave plate 13 changes the polarization of the transmitted light into circularly polarized light, and changes the polarization mode again when the light reflected by the scanner 14 passes through the quarter wave plate again. Therefore, since the light has a polarization mode perpendicular to the light reflected by the polarization beam splitter 12, the light may be transmitted without being reflected by the polarization beam splitter to reach the screen 15.

The scanner 14 scans the light onto the screen by rotating the incident light so as to be reflected at different reflection angles. The scanner may have one axis or two axes. In this embodiment, one having two axes is used. In the scanner having two axes, a movable frame is installed around the scanner, and a first hinge axis is coupled between the scanner and the movable frame so that the scanner can rotate about the first hinge axis. In addition, a fixed frame is provided around the movable frame, and a second hinge shaft is coupled between the movable frame and the fixed frame so that the movable frame can rotate about the second hinge shaft. The first hinge axis and the second hinge axis are arranged to be orthogonal to each other. Therefore, the scanner rotates about the first hinge axis, and the movable frame rotates about the second hinge axis to perform biaxial drive.

Such a two-axis scanner is capable of scanning in both the vertical and horizontal directions by reflecting the incident light while one scanner rotates about two axes perpendicular to each other. That is, when the vertical and horizontal scanning of the scanner is performed with a ratio of a certain period, the screen is filled with a plurality of horizontal scanning lines in one vertical scanning to realize an image.

The screen 15 provides an image from the light reflected by the scanner.

4 is a cross-sectional view schematically showing an optical system of another embodiment of a laser scanning display device according to the present invention, in which a plurality of lasers 10a, 10b, 10c for irradiating light and light irradiated from the plurality of lasers are input. A plurality of light modulators 11a, 11b, 11c for respectively controlling the light source to be synchronized with an image signal, and a plurality of wavelength selective beam splitters for reflecting light emitted from the plurality of lasers in a direction orthogonal to the direction of irradiated light 12a, 12b, and 12c, a polarization beam splitter 12d for reflecting light reflected by the plurality of wavelength selective beam splitters in a direction orthogonal to the direction of reflected light, 1 for transmitting light reflected by the polarization beam splitter Half by the four-wavelength plate 13, the scanner 14 which reflects the light transmitted through the quarter-wave plate again through the quarter-wave plate and It includes a screen 15 to provide an image from the light.

The embodiment obtains light of different colors (wavelengths) from the plurality of lasers 10a, 10b, 10c to implement a color image. In this embodiment, a combination of R (red), G (green), and B (blue) that is generally used is used to implement a color image. The light irradiated by the lasers is modulated by the plurality of optical modulators 11a, 11b, and 11c, respectively, and then reflected in a direction orthogonal to the direction irradiated by the plurality of wavelength selective beam splitters 12a, 12b, and 12c, respectively. .

The wavelength selective beam splitter serves to reflect light of a specific wavelength and transmit light of another wavelength. Thus, as shown, the propagation path of each light is the same. Thereafter, the optical path passing through the polarization beam splitter-quarter wave plate-scanner-quarter wave plate-polarization beam splitter is the same as in the above-described embodiment.

7 is a photograph of an image implemented by the above embodiment. It can be seen that the asymmetric distortion is significantly reduced compared to 2a and 2b according to the prior art.

FIG. 5 is a cross-sectional view schematically showing an optical system according to another embodiment of a laser scanning display device according to the present invention, wherein a laser diode 16 for irradiating light synchronized with an input image signal and light irradiated from the laser diode are shown in FIG. The polarization beam splitter 12 reflects in the direction orthogonal to the direction of the irradiated light, the quarter wave plate 13 transmitting the light reflected by the polarization beam splitter, and the light passing through the quarter wave plate is again It includes a scanner 14 that reflects through a quarter wave plate and a screen 15 that provides an image from the light reflected by the scanner.

This embodiment is characterized in that the laser diode 16 is used to obtain laser light synchronized with the image signal without using an optical modulator. The laser diode is excellent in response speed, thereby making it possible to generate light synchronized with the image signal by adjusting the input voltage. Synchronization of the image signal with the light emitted from the laser diode is possible by the laser modulation circuit. When irradiating light synchronized with the image signal in advance, an optical modulator is not required, and thus there are various advantageous effects such as miniaturization and reduction of production cost.

When a laser diode for irradiating laser light synchronized with the image signal is applied to an optical system for implementing a color image, as illustrated in FIG. 6, a plurality of laser diodes for irradiating light synchronized with an input image signal ( 16a, 16b, and 16c, a plurality of wavelength selective beam splitters 12a, 12b, and 12c for reflecting light irradiated from the plurality of laser diodes in a direction orthogonal to the direction of irradiated light, and the plurality of wavelength selective beam splitters A polarization beam splitter 12d for reflecting the light reflected by the light in a direction orthogonal to the direction of the reflected light, a quarter wave plate 13 for transmitting the light reflected by the polarization beam splitter, and a quarter wave plate A scanner 14 reflects the transmitted light back through the quarter wave plate and a screen 15 providing an image from the light reflected by the scanner.

The above-described laser scanning display device of the present invention may include a magnification lens on the optical path between the screen and the polarizing beam splitter to obtain a larger image.

In addition, the laser scanning display device of the present invention may include a correction lens (not shown) on the optical path between the screen and the polarizing beam splitter. The correction lens is used to correct light aberrations and gaps between scanning lines constituting each pixel. In addition, the size of the light spot of the image implemented on the screen is adjusted.

The present invention significantly reduces asymmetrical distortion of an image caused by deflection by presenting an optical system in which the difference between the incident angle of the light incident on the scanner and the reflected angle of the light reflected on the screen is small.

In addition, by using a scanner having two axes to scan both the vertical and horizontal directions with one scanner, it is possible to achieve miniaturization and cost reduction of the display device.

In addition, by generating light synchronized with an image signal without an optical modulator using a laser diode, it is possible to achieve miniaturization and cost reduction of the display device.

In addition, a more accurate image can be realized by including a correcting lens on an optical path between the screen and the polarizing beam splitter to correct aberrations of light and a gap error between scan lines constituting each pixel.

Claims (8)

Laser for irradiating light; An optical modulator for controlling the light irradiated from the laser to be synchronized with an input image signal; A polarizing beam splitter for reflecting the light irradiated from the laser in a direction orthogonal to the direction of the irradiated light; A quarter-wave plate for transmitting the light reflected by the polarizing beam splitter; And a scanner for reflecting the light transmitted through the quarter-wave plate back through the quarter-wave plate to scan the screen. A laser diode for irradiating light synchronized with an input image signal; A polarizing beam splitter for reflecting the light emitted from the laser diode in a direction orthogonal to the direction of the irradiated light; A quarter-wave plate for transmitting the light reflected by the polarizing beam splitter; And a scanner for reflecting the light transmitted through the quarter-wave plate back through the quarter-wave plate to scan the screen. A plurality of lasers for irradiating light; A plurality of light modulators for controlling the light irradiated from the plurality of lasers to be synchronized with the input image signal, respectively; A plurality of wavelength selective beam splitters each reflecting the light emitted from the plurality of lasers in a direction orthogonal to the direction of the irradiated light; A polarization beam splitter for reflecting the light reflected by the plurality of wavelength selective beam splitters in a direction orthogonal to the direction of the reflected light; A quarter-wave plate for transmitting the light reflected by the polarizing beam splitter; And a scanner for reflecting the light transmitted through the quarter-wave plate back through the quarter-wave plate to scan the screen. A plurality of laser diodes for irradiating light synchronized with an input image signal; A plurality of wavelength selective beam splitters each reflecting light emitted from the plurality of laser diodes in a direction orthogonal to the direction of the irradiated light; A polarization beam splitter for reflecting the light reflected by the plurality of wavelength selective beam splitters in a direction orthogonal to the direction of the reflected light; A quarter-wave plate for transmitting the light reflected by the polarizing beam splitter; And a scanner for reflecting the light transmitted through the quarter-wave plate back through the quarter-wave plate to scan the screen. The method according to any one of claims 1 to 4, And the scanner has two axes. The method according to any one of claims 1 to 4, And a magnifying lens on an optical path between the polarizing beam splitter and the screen. The method according to any one of claims 1 to 4, And a correction lens on an optical path between the polarizing beam splitter and the screen. The method according to claim 3 or 4, And the plurality of lasers or the plurality of laser diodes generate light of red, green, and blue, respectively.

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