KR20060031453A - Color display apparatus having multiple filter - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color display device. In particular, the present invention relates to a color display apparatus, in which the incident angle of incident light incident on the diffractive optical modulator is made close to the vertical to improve diffraction efficiency, and to obtain diffraction light having a desired order using a plurality of Fourier filters. It relates to the color display apparatus used.

According to the present invention, there is also provided an illumination lens system which changes each of a plurality of light emitted from a plurality of light sources into linear parallel light and emits the light; A plurality of diffraction type optical modulation systems for modulating the corresponding parallel light among a plurality of parallel light incident near the vertical from the illumination lens system to form diffracted light having a plurality of diffraction orders; A plurality of Fourier filter systems which receive diffracted light from a corresponding diffractive light modulator among the plurality of diffractive light modulators and filter out diffracted light having a desired diffraction order; A coupling system that receives a plurality of diffracted light incident from the plurality of Fourier filter systems, and collects the diffracted light; And a projection system for scanning the diffracted light collected by the coupling system onto a target object.

Light Modulators, Pixels, Actuating Cells, Steps, Diffraction, Multibeam, Color

Description

Color display apparatus having multiple filters             

1 illustrates a conventional laser scanning method using a single light source and an f-θ lens.

2 is a diagram illustrating a conventional laser scanning method for performing laser scanning by a multi-beam formed by an LED array configured in an image head.

3 is a block diagram of a color display apparatus using a plurality of filters according to an embodiment of the present invention.

4 is a perspective view, side cross-sectional view, and cross-sectional view including the optical path of the illumination lens of FIG.

5 is a perspective view of the diffraction type optical modulator of FIG.

6 is a view for explaining a reflection angle of the diffraction type optical modulator of FIG.

7 is a schematic diagram of diffracted light generated by the diffractive light modulator of FIG.

8 is a plan view including the optical path of the Fourier lens of FIG.

9A is a plan view including an optical path according to an embodiment of the coupling system of FIG. 3, and FIG. 9B is a plan view including an optical path according to another embodiment of the coupling system of FIG. 3.

<Description of the symbols for the main parts of the drawings>

310: illumination lens system 311: cylinder lens

312: collimator lens 315: diffraction optical modulator

316: diffractive optical modulator 317: reflection mirror

320: Fourier filter system 321: Fourier lens

322: mechanical filter 330: coupling system

331: reflection mirror 332: color screening filter

340: projection system 350: screen

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color display device. In particular, the present invention relates to a color display apparatus, in which the incident angle of incident light incident on the diffractive optical modulator is made close to the vertical to improve diffraction efficiency, and to obtain diffraction light having a desired order using a plurality of Fourier filters. It relates to the color display apparatus used.

The light beam scanning device is an image forming apparatus such as a laser printer, a display device, an LED printer, an electrophotographic copying machine, a word processor, or the like, which scans a light beam and spots the light beam onto a photosensitive medium to form an image image.                         

The light beam scanning device has been steadily researched and developed to have the characteristics of miniaturization, high speed, and high resolution as the image forming apparatus is developed in the direction of miniaturization, high speed, and high resolution.

The light beam scanning device of the image forming apparatus can be roughly classified into a laser scanning method using an f · θ lens and an image head printer method according to the light beam scanning method and the configuration of the light beam scanning device.

Fig. 1 shows a conventional laser scanning device using a f? Lens.

As shown, a conventional laser scanning apparatus includes a laser diode (LD) 10 for emitting a light beam according to a video signal, a collimator lens 11 for converting the light beam output from the LD 10 into parallel light, Cylindrical lens 12 which makes the parallel light which passed through the collimator lens 11 into a horizontal linear light with respect to a scanning direction, and the horizontal linear light which passed through the cylinder lens 12 at the isoline speed are scanned. A polygon mirror 13, a polygon mirror driving motor 14 for rotating the polygon mirror 13 at a constant speed, and a light at an equiangular velocity reflected from the polygon mirror 13 with a constant refractive index with respect to the optical axis. The f · θ lens 15 for deflecting in the direction and correcting the aberration to focus on the irradiated surface, and the surface of the photosensitive drum 17 as an image plane by reflecting a light beam through the f · θ lens 15 in a predetermined direction. Phased into Receives and synchronizes a laser beam reflected by the horizontal synchronous mirror 18 and a horizontal synchronous mirror 18 for reflecting the laser beam through the image forming reflection mirror 16, the f? Lens 15 in a horizontal direction. It is configured to include an optical sensor 19 to fit.                         

The laser scanning method is difficult to obtain high speed printing due to the low switching speed of the laser diode 10 and the scanning speed of the polygon mirror 13.

That is, in order to increase the scanning speed of the light beam, the polygon mirror 13 should be rotated by using a higher speed motor. In this case, the high speed motor is expensive and the high speed motor causes heat, vibration and noise. Therefore, there is a problem such as lowering the operation reliability, it is not expected to greatly increase the scanning speed.

Another method of improving the speed of the optical scanning device is an image head printing method using a multi-beam type beam forming apparatus.

Such a multi-beam optical scanning device has a plurality of light emitters (laser apex) as a light source means, and a plurality of light beams emitted by the plurality of light emitters by means of an imaging lens via an optical reflector. By imaging, the recording medium surface is simultaneously optically scanned with a plurality of light spots formed on the recording medium surface.

In order to achieve high speed printing using only one light spot, the number of optical scanning of the recording medium surface per unit time should be very large, so that the rotational speed of the light reflector, image clock, etc. Optical scanning cannot be followed. Therefore, if the number of beam spots simultaneously scanning the recording medium surface increases, the rotational speed, image clock, etc. of the light reflector decreases in inverse proportion to the number of beam spots.

As the most effective method of forming a plurality of beam spots, a laser element serving as a light source has a plurality of light emitting points (light emitting portions) that can be driven independently.

Such laser devices having a plurality of light emission points are generally referred to as "monolithic multi-beam laser elements". When monolithic multi-beam laser elements are used, the various optical elements placed behind the light source can usually be used by multiple beams of rays, providing great advantages in cost, operation, control, and the like.

2 is a diagram illustrating a conventional laser scanning method for performing laser scanning by a multi-beam formed by an LED array configured in an image head.

Referring to FIG. 2, a multi-beam is formed by forming a large amount of LED array 21 to fill printing paper in the image head 20, so that unlike a laser scanning method, a polygon mirror and a f-θ lens are not used. By printing one line at a time at the same time, print speed can be significantly improved.

Such monolithic multi-beam laser elements include, for example, so-called surface emitting lasers (surface emitting semiconductor lasers).

Surface emitting lasers emit emission beams parallel to the thickness direction of the silicon layer, whereas conventional semiconductor lasers emit light beams in a direction perpendicular to the thickness direction of the silicon layer.

The surface emitting laser has the following characteristics. That is, conventional semiconductor lasers emit elliptical cross-sections and emit divergent rays of varying divergence angles, while surface emitting lasers can emit circular beams with stable divergence angles.

However, surface emitting lasers have a problem of unstable polarization direction of the output light beam. Although the polarization direction can be adjusted to some extent by the manufacturing method, the polarization direction varies with the light emission point, the ambient temperature, and the output.

Usually the reflectance, transmittance of optical elements that make up an optical scanning device such as a polygonal mirror such as a light reflector, a scanning lens as an imaging optical system (f-theta), an echo mirror to change the optical path, and the like, And the angle characteristic changes according to the polarization direction of the input light beam.

For this reason, when a monolithic multi-beam laser element including a surface emitting laser is used as a light source of an optical scanning device, a plurality of beam spots that optically scan the recording medium surface are located at different polarization directions of individual light emission points. According to different strengths. And, this difference in intensity appears as pitch unevenness in the image, which significantly reduces the image quality.

In order to solve this problem, Korean Patent Application No. 2003-77391 uses a plurality of diffraction beams formed by a piezoelectric / electric distortion diffraction type optical modulator composed of an actuating cell driven on / off by a driving voltage applied from the outside. Disclosed is a scanning apparatus using a piezoelectric / electric distortion diffraction type optical modulator that performs high speed scanning.

A scanning apparatus using a piezoelectric / electric distortion diffraction type optical modulator according to the disclosed improved technique includes: first lens means for horizontally scanning a single beam output from a predetermined light source in a direction of an optical path; Comprising a plurality of actuating cells to drive on / off by the drive power applied from the outside, and the plurality of diffraction beams from the single beam by the reflection and diffraction phenomenon by the on / off driving between the actuating cells Piezoelectric / electric distortion diffraction type optical modulators; A slit for performing filtering on a diffraction beam having a predetermined diffraction coefficient among a plurality of diffraction beams incident from the piezoelectric / electric distortion diffraction type optical modulator; And second lens means for irradiating a photosensitive surface of the photosensitive member with a diffraction beam having a predetermined diffraction coefficient selectively filtered by the slit.

On the other hand, when the scanning device using the piezoelectric / electric distortion diffraction type optical modulator according to the conventional improved technique as described above is used for color display or printing, λ ₁ , λ ₂ , λ ₃ .. Since there is a different slit spacing for each color wavelength, it is required to develop a simple and suitable slit accordingly.

The present invention improves the diffraction efficiency by making the angle of incidence of the incident light incident on the diffractive optical modulator close to vertical in order to meet the above-described request, and obtains a plurality of diffracted light of the desired order by using a plurality of Fourier filters It is an object to provide a color display device using a filter.

The present invention for achieving the above object is an illumination lens system for changing each of the plurality of light emitted from the plurality of light sources to a linear parallel light to emit; A plurality of diffraction type optical modulation systems for modulating the corresponding parallel light among a plurality of parallel light incident near the vertical from the illumination lens system to form diffracted light having a plurality of diffraction orders; A plurality of Fourier filter systems which receive diffracted light from a corresponding diffractive light modulator among the plurality of diffractive light modulators and filter out diffracted light having a desired diffraction order; A coupling system that receives a plurality of diffracted light incident from the plurality of Fourier filter systems, and collects the diffracted light; And a projection system for scanning the diffracted light collected by the coupling system onto a target object.

Hereinafter, with reference to the accompanying drawings, the configuration of a color display device using a plurality of filters according to the present invention will be described in detail.

3 is a block diagram of a color display apparatus using a plurality of filters according to an embodiment of the present invention.

Referring to the drawings, a color display apparatus using a plurality of filters according to an embodiment of the present invention, a plurality of light sources 300, illumination lens system 310, diffraction type optical modulation system 315, Fourier filter system 320, a coupling system 330, a projection system 340, and a screen 350.

The plurality of light sources 300 may include, for example, a red light source 301a, a blue light source 301b, and a green light source 301c. The light sources 300 used herein may be light sources manufactured using semiconductors such as light emitting diodes (LEDs) and laser diodes (LDs). Such semiconductor light sources have many properties suitable for use in color display devices compared to other light sources.

An example of a cross-sectional view of such a light source 300 is shown in FIG. 4A. Referring to FIG. 4A, the cross-section of the light source 300 is circular, and the intensity profile of the light is FIG. 4B. As shown in the figure, Gaussian distribution is obtained.

The illumination lens system 310 changes incident light into linear parallel light having an elliptical cross section, and includes a plurality of cylinder lenses 311a to 311c and a plurality of collimator lenses 312a to 312c.

That is, the illumination lens system 310 converts each beam output from each of the light sources 301a to 301c of the plurality of light sources 300 into linear light in a horizontal direction with respect to the optical path direction to be described later. It focuses on 316c, and consists of several cylinder lenses 311a-311c and collimator lenses 312a-312c.

Here, the cylinder lenses 311a to 311c are horizontally incident on the corresponding diffraction type optical modulators 316a to 316c which horizontally position each parallel light incident from the light sources 310a to 310c in the optical path direction. In order to achieve this, as shown in FIG. 4C, the balanced light is converted into linear light in the horizontal direction, and the incident light is incident on the diffractive light modulators 316a to 316c through the corresponding collimator lenses 312a to 312c.

Here, the plurality of collimator lenses 312a to 312c respectively convert spherical light incident from the plurality of light sources 300 through the cylinder lenses 311a to 311c into parallel light, and then the corresponding diffraction type light modulators 316a to Incident at 316c).                     

The collimator lens (here described with reference to 312a, but the rest of the same) has a concave lens 312aa and a convex lens 312ab as an example, as shown in FIG.

The concave lens 312aa extends up and down the linear light incident from the cylinder lens 311a and enters the convex lens 312b as shown in FIG. 4D. The convex lens 312ab emits incident light incident from the concave lens 312aa by changing parallel light as shown in Fig. 4E. In Figure 4 (a) is a perspective view of an optical system consisting of a light source, a cylinder lens, a collimator lens, (b) is a plan view, Figure 4 (c) is a side cross-sectional view, Figure 4 (d) is a cut surface. It is also.

Next, the diffraction light modulator 315 is composed of a plurality of diffraction light modulators 316a to 316c and a plurality of reflection mirrors 317a to 317c. Here, the reflection mirrors 317a to 317c reflect the parallel light incident from the illumination lens system 310 and make the reflection mirrors 317a to 316c perpendicular to the corresponding diffraction type optical modulators 316a to 316c. As such, when the incident light incident on the diffractive light modulators 316a to 316c is close to the vertical, the light efficiency is increased by that much.

The diffractive light modulators 316a to 316c preferably reflect or diffract incident incident light as an open hole diffraction light modulator to form diffracted light. In this case, the reflection mirrors 317a to 317c reflect the diffracted light formed by the diffractive light modulators 316a to 316c so that the diffracted light proceeds in the same way as the optical path emitted from the illumination lens system 310.

An example of the open hole diffraction type optical modulators 316a to 316c used herein is illustrated in FIG. 5. Referring to the drawings, the open hole based diffraction light modulator includes a silicon substrate 501 and an insulating layer. 502, a lower micromirror 503, and a plurality of elements 510a to 510n. Here, although the insulating layer and the lower micromirror are configured as separate layers, if the insulating layer has a property of reflecting light, the insulating layer itself can function as the lower micromirror.

The silicon substrate 501 includes depressions to provide air space to the elements 510a to 510n, an insulating layer 502 is stacked, and a lower micromirror 503 is deposited thereon, and the depressions The lower surfaces of the elements 510a to 510n are attached to both sides that deviate. As the material constituting the silicon substrate 501a, a single material such as Si, Al2O3, ZrO2, Quartz, SiO2, etc. may be used, and the bottom surface and the upper layer (indicated by dotted lines in the drawing) may be formed by using different heterogeneous materials. have.

The lower micromirror 503 is deposited on the silicon substrate 501 and reflects and diffracts incident light. Metal (Al, Pt, Cr, Ag, etc.) may be used as the material used for the lower micromirror 503.

The elements (typically, only the reference numeral 510a is described but the rest are the same) have a ribbon shape, and the bottom surfaces of both ends are recessed of the silicon substrate 501 so that the center portion is spaced apart from the recessed portion of the silicon substrate 501. The lower support part 511a attached to the both side area | regions which deviated from a part is provided.

Piezoelectric layers 520a and 520a 'are provided on both side surfaces of the lower support 511a, and the driving force of the element 510a is provided by contraction and expansion of the provided piezoelectric layers 520a and 520a'.                     

The material constituting the lower support 511a may be Si oxide (for example, SiO2), Si nitride series (for example, Si3N4, etc.), ceramic substrate (Si, ZrO2, Al2O3, etc.), Si carbide, or the like. The lower support 511a may be omitted as necessary.

The left and right piezoelectric layers 520a and 520a 'are stacked on the lower electrode layers 521a and 521a' for providing the piezoelectric voltage and the lower electrode layers 521a and 521a 'and contract and expand when voltage is applied to both surfaces. And the upper electrode layers 523a, which are stacked on the piezoelectric material layers 522a and 522a 'that generate the vertical driving force, and provide the piezoelectric voltage to the piezoelectric material layers 522a and 522a'. 523a '). When voltage is applied to the upper electrode layers 523a and 523a 'and the lower electrode layers 521a and 521a', the piezoelectric material layers 522a and 522a 'contract and expand to generate vertical movement of the lower support 511a.

Pt, Ta / Pt, Ni, Au, Al, RuO2, etc. may be used as the electrode material of the electrodes 521a, 521a ', 523a, 523a', and deposited by a sputter or evaporation method in a range of 0.01-3 μm. do.

On the other hand, the upper micro mirror 530a is deposited on the central portion of the lower support 511a and has a plurality of open holes 531a1 to 531a3. Here, the shape of the open holes 531a1 to 531a3 is preferably rectangular, but any closed curve such as circular or elliptical may be used. If the lower supporter is formed of a light reflective material, it is not necessary to deposit the upper micromirror separately, and the lower supporter may function as the upper micromirror.

The open holes 531a1 to 531a3 allow incident light incident on the element 510a to penetrate the incident light to the lower micromirror 503 corresponding to the portion where the open holes 531a1 to 531a3 are formed. The micro mirror 503 and the upper micro mirror 530a can form pixels.

That is, for example, the (i) portion of the upper micro mirror 530a and the (i) portion of the lower micro mirror 503 having the open holes 531a1 to 531a3 may form one pixel.

At this time, incident light incident through the portions where the open holes 531a1 to 531a3 of the upper micromirror 530a are formed may be incident on a corresponding portion of the lower micromirror 503, and the upper micromirror 530a and the lower micromirror may be incident. The maximum diffracted light is generated when the interval 503 becomes an odd multiple of lambda / 4. In addition, the open-hole diffraction light modulator usable in the present invention is disclosed in Korean Application No. P2004-030159.

On the other hand, each of the open hole diffraction type optical modulators 316a to 316c diffracts each linear light incident from the illumination lens system 310 to form diffracted light as described above, and then diffracts the diffracted light to the Fourier filter system 320. Incident).

In this case, the reflection angle of the formed diffracted light is shown in FIG. 6. Referring to the drawings, it can be seen that the incident angle and the reflection angle are the same. That is, when the incident angle enters θ ° to the diffraction optical modulators 316a to 316c, the reflection angle becomes θ °.

Next, the diffracted light formed by the diffractive light modulators 316a to 316c is shown in FIG. 7, where zero-order and ± first-order diffraction light are formed in the periodic direction of the grating.

On the other hand, the Fourier filter system 320 includes a plurality of Fourier lenses 321a to 321c corresponding to the diffracted light and a plurality of mechanical filters 322a to 322c corresponding to the diffracted light.

The Fourier lenses 321a to 321c of the Fourier filter system 320 separate the incident diffracted light for each order, and the mechanical filters 322a to 322c transmit only the diffracted light of the desired order.

Here, the Fourier lenses 321a to 321c condenses the light emitted from the diffractive light modulator 315 as shown in FIG. 8, where FIG. 8A is a plan view, and FIG. (B) is a side cross-sectional view.

Referring to Fig. 8A, when the diffracted light is incident on the Fourier lens 331, the Fourier lens 331 condenses the diffracted light of each order of the diffracted light.

In addition, FIG. 8B shows a side cross-sectional view where zero-order diffracted light is focused at any point when passing through Fourier lenses 321a to 321c, where + -first-order diffracted light is zero-order diffraction. The -1st order diffracted light away from the position where light is collected and the -1st diffraction light are focused downward away from the position where the 0th order diffracted light is collected. If the mechanical filters 322a to 322c are positioned near the condensing point, only diffracted light of a desired order can pass.

On the other hand, the coupling system 330 includes a plurality of reflection mirrors 331a and 331b, and a plurality of color discriminating filters 332a and 332b. The plurality of reflection mirrors 331a and 331b reflect the diffracted light incident from the respective filters 322a to 322c and enter the corresponding color filter 332a and 332b. That is, as an example, the reflective mirror 331a injects diffracted light into the color-coded filter of 332a, and the reflective mirror 331b injects diffracted light to the color-coded filter of 332b.                     

At this time, the inclination angles of the reflection mirrors 331a and 331b are important. If the inclination angles are properly adjusted, the diffraction light reflected by the color filter 332a and 332b has the same path (strictly speaking, zero-order diffraction light). This same path), which is well illustrated in Figures 9a and 9b.

9A is a cross-sectional view including an optical path according to an embodiment of the coupling system used in the present invention, wherein the reflection mirrors 331a and 331b are inclined at a 45 ° angle, and the reflected light is also inclined by 45 °. As a result, the reflected light reflected by the section-specific filters 332a and 332b becomes 0 ° with respect to the X-plane.

9A shows a cross-sectional view of diffracted light passing through the dichroic filters 332a and 332b. The diffracted light of the first wavelength has a zeroth order diffracted light and ± 1 as can be seen from (a) of FIG. 9A. It can be seen that the diffracted light overlaps each other.

9B is a cross-sectional view including an optical path according to another embodiment of a coupling system used in the present invention, and includes a plurality of reflective mirrors 331a to 331c and a beam splitter 332.

As shown in FIG. 9B, when the reflection mirrors 331a to 331c are inclined by 45 °, the emission angle is 45 °.

Next, the diffracted light reflected by the reflecting mirrors 331a to 331c is incident on the beam splitter 332, where the incident angle is 45 °, and as a result, the diffracted light reflected on the beam splitter 332 is X It has a reflection angle of 0 ° with respect to the prism plane.

9B shows a cross-sectional view of the diffracted light passing through the beam splitter 332. The diffracted light of the first wavelength has zero-order diffraction light and ± first-order diffraction light as can be seen from (a) of FIG. 9B. It can be seen that the light overlaps each other.

Projection system 340 projects the incident diffracted light onto screen 350. That is, the projection system 340 focuses a diffraction beam having a predetermined diffraction coefficient incident through the color filter 332 on the screen 350 to form a spot, and more specifically, a projection lens. to be.

Using a plurality of mechanical filters according to the present invention has the effect of implementing a color image by configuring a simple optical system.

Herein, the present invention described above has been described with reference to preferred embodiments, but those skilled in the art will variously modify the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. And can be changed.

Claims (5)

An illumination lens system which changes each of the plurality of light emitted from the plurality of light sources into linear parallel light and emits the light; A plurality of diffraction type optical modulation systems for modulating the corresponding parallel light among a plurality of parallel light incident near the vertical from the illumination lens system to form diffracted light having a plurality of diffraction orders; A plurality of Fourier filter systems which receive diffracted light from a corresponding diffractive light modulator among the plurality of diffractive light modulators and filter out diffracted light having a desired diffraction order; A coupling system that receives a plurality of diffracted light incident from the plurality of Fourier filter systems, and collects the diffracted light; And And a projection system for scanning the diffracted light collected by the coupling system onto a target object. The method of claim 1, The diffraction type optical modulation system, A diffraction type optical modulator for modulating a corresponding parallel light among a plurality of parallel lights incident from the illumination lens system to form diffracted light having a plurality of diffraction orders; And And a first reflection mirror configured to reflect incident light incident from the illumination lens system to be incident perpendicularly to the diffractive optical modulator. The method of claim 1, The Fourier filter, A Fourier lens which receives diffracted light having a plurality of diffraction orders from the corresponding diffraction light modulator among the plurality of diffraction light modulators and condenses and emits the light for each order; And And a mechanical filter for filtering the diffracted light having a desired diffraction order from the diffracted light collected for each order from the Fourier lens. The method of claim 1, The binding system, A plurality of prisms which condense and exit the diffracted light when a plurality of diffracted light having a selected diffraction order is incident; And And a plurality of second reflection mirrors for injecting diffracted light emitted from a corresponding Fourier filter system among the plurality of Fourier filter systems at a predetermined angle so that the plurality of diffracted light emitted from the plurality of prisms are collected. A color display device using a plurality of filters made. The method of claim 1, The binding system, A beam splitter for condensing and emitting a plurality of diffracted lights having a plurality of diffraction orders when they are incident; And A plurality of second reflections for injecting diffracted light incident from the diffractive light modulator among the plurality of diffractive light modulators into the beam splitter at a predetermined angle so that the plurality of diffracted light emitted from the beam splitter is focused A color display device comprising a mirror.

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