KR101167747B1 - An optical engine for micro projector - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical engine for a micro-projector, which improves process productivity by easily aligning a distortion of an R / G / B optical axis emitted from each R / G / B light source using a dichroic mirror. It is an object of the present invention to provide an optical engine structure for a micro projector that can achieve miniaturization of the projector more effectively by reducing the number of optical components provided in the micro projector.

The present invention provides a light source unit including a laser diode, a condenser lens for focusing R / G / B light emitted from the light source unit, a dichroic mirror for selectively reflecting or transmitting incident light, and an optical axis twisting. An adjustment device installed in the mirror to align the light, an optical modulator for converting light emitted from the light source unit into an image image, and an R / G located between the dichroic mirror and the optical modulator and incident from the light source unit. / B is composed of a beam shaper for converting light into the shape of the active region of the optical modulator, and a projection lens for magnifying and projecting an image image emitted through the optical modulator to form an image on a screen.

Laser light source, micro projector

Description

An optical engine for micro projector

1 is a schematic diagram illustrating an optical engine for a micro projector of an embodiment according to the present invention.

2 is a cross-sectional view showing an active plane of the optical modulator.

3 is a view showing a reflection angle and a tilt angle of light incident on a mirror seated in the adjusting device.

4 is a perspective view showing the configuration of an adjusting device in which a mirror is mounted and fixed;

5 is a view showing the movement of the adjustment device inserted into the barrel.

6 is a schematic diagram showing the movement of the mirror adjusting device for adjusting the optical axis in the X axis direction.

Fig. 7 is a schematic diagram showing the movement of the mirror adjusting device for adjusting the optical axis in the Y axis direction.

8 is a schematic diagram showing a motion of advancing or retracting the mirror adjusting device to align light reaching the beam shaper.

9 is a configuration diagram schematically showing an optical engine for a micro projector according to an embodiment of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

5: light source packaged in one set

10, 20, 30: light source 40: condensing lens

50, 120: mirror 60, 70: dichroic mirror

80: beam shaper 90: optical modulator

100 projection lens 110 moving diffusion element

130: field lens 140: active plane of the optical modulator

150: optical axis alignment device 151: frame

152: protrusion 153: optical axis operation unit

154: barrel 155: groove

156: auxiliary groove

The present invention is an optical engine for a micro projector, and more particularly, by easily aligning the optical axis of the R / G / B light emitted from each R / G / B light source using a dichroic mirror, The present invention relates to an optical engine for a micro projector, which can improve productivity and reduce the number of optical components included in the micro projector, thereby achieving the miniaturization of the projector more effectively.

In order to commercialize a portable small projector smaller than the size of a palm, or a projector enough to be embedded in a small multimedia terminal such as a laptop or a mobile phone, a projector having a small size and low power consumption must be developed. In order to reduce the size of the projector, a single-panel projector method should be applied, and the structure of the optical system used for this should be simplified. In addition, to achieve a low power projector, the light utilization efficiency of the light source must be increased.

A projector is a device that converts R / G / B light into an image and projects it. An optical modulator that converts incident light into an image is used, and a liquid crystal display device, a liquid crystal on silicon (LCoS), and a digital micromirror device (DMD) are used as the optical modulator.

In order to increase the light efficiency, it is preferable that the light emitted from the R / G / B light source is incident so as to exactly match the active area of the optical modulator. When each color light incident on the R / G / B light source enters an area smaller than the active plane size of the optical modulator, the outer portion of the image enlarged through the projection lens becomes dark. On the contrary, when each color light incident to the R / G / B light source enters an area larger than the active plane size of the optical modulator, the energy consumed as heat is increased without being converted into an image, thereby degrading light efficiency. In consideration of these two points, it is desirable that each color light emitted from the R / G / B light source is slightly larger than the active plane size of the optical modulator when implementing the projector.

The active plane of the optical modulator means an area that contributes to the actual image formation among the entrance plane or the exit plane of the optical modulator, and the area where each color light emitted from the R / G / B light source is incident is entered by the optical modulator. The margin beyond the active plane, including the active plane of the face, will be defined as the lighting margin.

The projector generates color illumination light by synthesizing each color light emitted from the R / G / B light source. In order to synthesize the color light, alignment is required to align the light source in a straight line on the optical axis.

One of the methods of aligning the light emitted from each color light source composed of the R / G / B light sources with the active plane of the optical modulator is to align the optical axis by adjusting the physical position of each light source.

However, the method of aligning the optical axis by adjusting the position of the light source can be easily applied. However, since the physical position of each light source must be adjusted at every production time, the productivity is reduced. In addition, in order to dissipate the heat generated from the light source to the outside, the surface of the light source should be as close as possible to the structure of the outer set.However, when using this alignment method, the surface of the light source is separated from the outer set structure so that the light source is fast. There is a problem that the wavelength of the output light emitted from the light source due to deterioration in time changes.

Another method of aligning the optical axis is to use two fly-eye lenses as beam shapers, and to adjust one of them. However, in an optical engine such as a micro-projector, in order to reduce the volume, two fly-eye lenses are usually formed by forming two optical eyes and forming one optical element to reduce volume. The adjustment using the fly's eye lens caused a problem that precise optical axis alignment could not be achieved.

The present invention has been made to solve the problems of the prior art as described above, the object of the present invention is that the three-color light emitted from the R / G / B light source to reach the optical modulator implements the optimal illumination margin and easily the optical axis It is to provide an optical engine for a micro projector that can be aligned on the image.

Another object of the present invention is to enable the packaging of R / G / B light sources into a set by applying an efficient alignment method, thereby improving the heat dissipation and the productivity of the light generated by the light source. To provide.

Still another object of the present invention is to provide an optical engine for a micro projector that can further maximize the miniaturization of the projector by reducing the number of optical components provided in the micro projector.

In order to achieve the above object, an optical engine for a micro-projector according to the present invention includes a light source unit including a laser diode, and red (R), green (G), and blue (B) first colors constituting the light source unit. A light source, a second light source, a third light source, a condensing lens provided at the front of each light source to focus emitted light, a first mirror which totally reflects the light incident from the first light source, and the second light source A first dichroic mirror that reflects light incident from the first light source and transmits light incident from the first light source; and light incident from the third light source reflects light incident from the first and second light sources; A second dichroic mirror for transmitting, an adjusting device provided in the mirror to align the distortion of the optical axis, an optical modulator for converting light emitted from the light source into an image image, A beam shaper and an optical modulator positioned between the second dichroic mirror and the optical modulator to convert first to third light emitted from the mirrors into a shape of an active region of the optical modulator; And a projection lens configured to enlarge and project the image image emitted through the image.

Hereinafter, the advantages, features and preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram illustrating an optical engine for a micro projector of an embodiment according to the present invention.

Referring to FIG. 1, an optical engine for a micro projector according to the present invention includes a projector light source 10, 20, 30, a condenser lens 40, a first mirror 50, a first dichroic mirror 60, Second dichroic mirror 70, adjusting device 150, beam shaper 80, optical modulator 90 and projection lens installed in the mirrors 50, 60, 70 to align the optical axis distortion; It consists of 100.

Representative examples of the light sources 10, 20, and 30 having low luminous energy characteristics include a laser light source called a laser diode and an LED (electroluminescent element) light source. More specifically, as the R laser diode, six laser diodes having one luminous energy of 60 mW were used in combination. In field sequential color display, the duty is divided by 33%, which requires about 200mW. However, in the process of making multiple laser diodes as one optical beam as one optical element, the efficiency is reduced, and six are used in combination. Therefore, if the optical design is designed efficiently, a combination of three or four R laser diodes may be possible.

G laser diodes combine nonlinear elements with infrared laser diodes to produce green light. Generally, DPM is used to convert 800nm IR light into 500nm light. In more detail, DPM consists of a combination of Nd: YV04 and KTP. Nd: YV04 crystal pumps 800nm IR light into 1000nm and KTP frequency doubling to convert 1/2 wavelength of light to produce 500nm green light. This uses the principle of generating harmonics when a nonlinear element is loaded.

As the B laser diode, one laser diode having a light emission energy of about 150 mW was used in consideration of the white balance. It should be provided with a light source having such a size and luminous energy or less, so that it can be easily applied to a small projector that is about the size of a mobile phone.

It is preferable that the light source 10, 20, 30 irradiates R / G / B light sequentially. Irradiating the R / G / B light sources 10, 20, and 30 sequentially means that the total time to irradiate one frame is T, irradiating the R light source for T / 3 hours, and subsequently for T / 3 hours. Irradiating the G light source, and irradiating the B light source for T / 3 hours subsequent to the G light source irradiation time.

In addition, although any of the R / G / B light may use an LED light source as the light source 10, 20, 30, a blue (B) LED light source is used instead of a relatively expensive blue (B) laser light source. It is preferable.

In addition, R / G / B light sources 10, 20, and 30 can be packaged into a set 5 to increase process productivity, with the light sources packaged in sets of units separately for the physical position of each light source. Since it cannot be adjusted, a method of aligning the optical axis through another optical element, that is, the adjusting device 150 according to the present invention is required.

The condenser lens 40 functions to focus each light emitted from the light sources 10, 20, 30 to each mirror 50, 60, 70 at the front end.

The first mirror 50 may use dichroic mirrors 60 and 70 that selectively transmit or reflect light, but in view of production cost, it is preferable to use a general mirror that reflects all visible light regions. desirable.

The first light 10a focused by the condensing lens 40 is totally reflected after reaching the first mirror 40 provided at the front end, so that the first dichroic mirror 60 and the second dichroic mirror 70 are separated. It passes through and reaches the beam shaper 80.

The second light 20a focused by the condenser lens 40 is reflected by the first dichroic mirror 60 provided at the front end, passes through the second dichroic mirror 70, and transmits the light to the beam shaper 80. To reach.

The third light 30a focused by the condenser lens 40 is reflected by the second dichroic mirror 70 provided at the front end to reach the beam shaper 80.

The R / G / B light reaching the beam shaper 80 is deformed by the beam shaper 80. The reason for modifying the beam shape is to improve the light efficiency by shaping the beam shape incident to the active plane 140 of the optical modulator.

Representative examples of the beam shaper 80 include a fly's eye lens and a light pipe. In the fly's eye lens, a plurality of small lens bodies are formed on a transparent substrate, and the diameter of the small lens bodies is appropriately in the range of 50 μm to 2 mm. When the diameter of such a small lens body is smaller than 50 μm, a lattice pattern due to coherence of the laser appears in the beam, and when larger than 2 mm, uniform light cannot be obtained and a clean image image can be formed from the optical modulator 90. It is not possible to use it as the beam shaper 80.

In particular, when the small lens body is not composed only of the same diameter, but mixed with the small lens body having various diameters, it is possible to more effectively reduce the appearance of the grid pattern due to coherence. In the case of using a mixture of small lens bodies of various sizes, the coherent lens body having a diameter (D) of the small lens body outside the range of 50 μm to 2 mm is included even if less than about 20% of the total lens lens volume is included. It is effective in removing the run.

In addition, in the optical engine according to the present invention, since an adjustment device for optical axis alignment is separately provided, two fly-eye lenses used as the beam shaper 80 may be formed in one body on both sides to form one optic. This can reduce the volume of the optical element.

The optical modulator 90 refers to an element that selectively transmits, blocks, or changes an optical path of incident light to form an image image. Representative examples of the optical modulator 90 include a digital micromirror device (DMD), a liquid crystal display device, and an LCOS. DMD is a driving method using field sequential and is a device used in a DLP (Digital Light Processing) projector using a digital mirror arranged in a matrix form by the number of pixels. DLP is a projector that realizes gray scales and images by reflecting light emitted from a light source to a screen by adjusting a light path by a digital mirror. Liquid crystal display devices (Liquid Crystal Display Device) is a device for forming an image by selectively turning on and off the liquid crystal. Projectors using liquid crystal display elements include direct view type, projection type and reflective type. The direct view projector is a method in which light from the backlight behind the liquid crystal display device directly observes an image generated while passing through the liquid crystal panel, and the projection projector enlarges an image generated while passing through the liquid crystal display device using a projection lens. Projected onto the back screen to observe the image reflected from the screen. The reflective type has the same structure as the projection type, but forms a reflective film on the lower substrate to enlarge and reflect the reflected light onto the screen. Liquid crystal on silicon (LCoS) is a type of reflective liquid crystal display, and is an optical device that operates a reflective substrate using a silicon substrate instead of transparent glass among double-sided substrates of a conventional liquid crystal display device.

In addition, the field sequential color display method applied to the optical modulator 90 according to the present invention sequentially turns on the light source of R / G / B, thereby displaying color using the afterimage effect of the human eye. The field sequential method includes a light source of three colors of R / G / B and a monochromatic display element, and switches the flashing of the three color light sources at high speed while simultaneously displaying the data of each color in a single color display element. Can be either reflective or transmissive.

By using the field sequential color display method, it is possible to achieve a resolution equivalent to the three-plate type while using one optical modulator 90, and to simplify the optical system.

The projection lens 100 is formed by using a plurality of lenses, and enlarges and projects an image image output through the optical modulator 90 to form an image on a screen.

The rectangle shown in FIG. 2 represents the active plane of the optical modulator.

3 to 8 are views showing the movement and configuration of the adjusting device for aligning the optical axis of the incident R / G / B light installed in the mirror provided in the optical engine for the micro projector according to the present invention.

Each R / G / B color light emitted from the light source unit 5 and incident on the optical modulator 90 should have a shape that matches the active plane 140 of the optical modulator. If each of the color lights 10a, 20a, 30a arriving at the optical modulator 90 is smaller than the active plane 140 of the optical modulator, the outer portion of the image enlarged through the projection lens 100 becomes dark, If it is larger than the active plane 140 of the optical modulation, the optical loss is generated by that amount.

The optimum illumination margin is most preferably adjusted so that the shape of each color light reaching the optical modulator 90 is slightly larger than the active plane 140 of the optical modulator. However, in order to realize such lighting margin, the optical axis alignment must be precise.

4 and 5, the adjustment device 150 according to the present invention is coupled to the frame 151 on which the mirror is seated and fixed and the projection 152 of the frame 151 to reflect the reflection angle of the adjustment device 150. and an optical axis operating portion 153 in the form of a hexahedron for adjusting θ1 and tilt angle θ2. In addition, both edges of the vertical axis of the frame 151 are formed in a semicircle shape and are inserted in close contact with the barrel 154. Grooves 155 are formed at both sides of the barrel 154 into which the adjusting device 150 is inserted. The groove 155 is formed in a semi-elliptic shape to enable the rotation of the adjustment device 150 and the movement of the front and the back within a limited range.

3, 5, and 6, the adjustment device 150 installed on the mirrors 50, 60, 70 is formed by rotating the optical axis operation unit 153 attached to the adjustment device 150. It is comprised so that the reflection angle (theta) 1 of the optical axis 10a, 20a, 30a which may reach the mirror 50, 60, 70 may be adjusted. Semi-elliptical grooves 155 are formed on both sides of the barrel 154 so that the adjustment device 150 can rotate left and right about the reference axis 160 within a range of about 5 °. On the X axis of the optical axes 10a, 20a, 30a reaching the active plane 140 of the optical modulator shown in FIG. 2 through adjustment of the reflection angle θ1 by left and right rotation of the adjusting device 150. Optical axis alignment is performed.

3, 5, and 7, the adjustment device 150 installed on the mirrors 50, 60, 70 is formed by tilting the optical axis operation unit 153 attached to the adjustment device 150. It is comprised so that the tilt angle (theta) 2 with respect to the optical axis 10a, 20a, 30a of the mirror 50, 60, 70 may be adjusted. The optical axis alignment on the Y axis of the light 10a, 20a, 30a that reaches the active plane 140 of the optical modulator shown in FIG. 2 through the up / down tilt of the adjusting device 150 is performed.

Further, in aligning the light to reach the beam shaper 80, the barrel 154 is provided with the adjusting device 150 provided in the mirrors 50, 60, 70 as shown in Figs. Through the operation of advancing forward or retracting back within the range of the groove 155 and the auxiliary groove 156 formed in the above), the emitted light reaches the desired point of the beam shaper 80, and the angle incident on the beam shaper Can be adjusted.

The order and method of aligning the R / G / B tricolor light are as follows.

First, the first light 10a is adjusted and fixed to coincide with the active plane 140 of the optical modulator, and then in turn, the remaining second light 20a and the third light 30a are fixed to the fixed first light 10a. Adjust and fix to match. For example, after adjusting and fixing the blue light corresponding to the first light 10a while viewing the shape of the optical modulator active plane 140 exiting through the projection lens 100, the second light 20a corresponding to the green light is provided. Is adjusted and fixed again to match the blue active plane and then the red light is aligned in the same way. When the alignment of the R / G / B optical axis is completed, the adjusting device 150 is attached to the barrel 154.

Therefore, when the optical engine apparatus is designed and manufactured with high precision, the first light 10a, which first reaches the active plane 140 and serves as a reference for the remaining light sources 20a, 30a, is already lighted without alignment. Since the first mirror 50 to which the first fixed light 10a is reflected in this case may be installed to coincide with the modulator active plane 140, the adjustment device 150 for aligning the optical axis is required. It will not be.

In order to maintain the illumination margin slightly larger than the active plane 140 of the optical modulator, the precise optical axis alignment process described above is required. However, in the optical axis alignment process, in some cases, a means for easily changing the size of the illumination margin, that is, the entire area of the illumination screen reaching the active plane 140 of the optical modulator may be needed.

In this case, two field lenses 130 can be provided between the beam shaper 80 and the optical modulator 90 by the above means. One of the field lenses is provided with a position adjusting device which enables forward / backward movement in the optical axis direction, and the distance between the field lenses 130 changes as the front and back movements are parallel to the optical axis direction. The area of the lighting margin is changed.

9 is a block diagram showing an optical engine for a micro projector as an embodiment according to the present invention.

9, an optical engine for a micro projector according to the present invention includes a projector light source unit 5, a condenser lens 40, a first mirror 50, a first dichroic mirror 60, a second dichro Wing mirror 70, adjusting device 150 installed in the mirrors 50, 60, 70, beam shaper 80, moving diffusion element 110, second mirror 120, field lens 130, It consists of an optical modulator 90 and a projection lens 100.

The optical engine structure shown in FIG. 9 differs in that the optical engine structure of FIG. 1 further includes a moving diffusion element 110, a second mirror 120, and a field lens 130.

As the laser passes through or diffuses through the optical system, the phase pattern creates a specific interference pattern called a speckle. Interference patterns often cancel each other, resulting in noisy and smeared screens, so speckles cannot be seen clearly, which is more severe when three lasers of R / G / B color are used. The screen you want to damage will be damaged. In order to eliminate this speckle phenomenon, it is preferable to allow the light emitted from the light source unit 5 to pass through the moving diffusion element 110, that is, the diffuser, before the light modulator 90 reaches the optical modulator 90. The same effect may be obtained by vibrating the beam shaper 80 with a vibrator instead of a diffuser.

The diffuser is an optical element composed of a diffuser element and a drive element that rotates or vibrates such a diffuser element. The diffuser allows speckle to be diffused by the diffuser, thereby preventing interference between patterns by the laser light source. If the diffuser's diffusion element is rotated or vibrated quickly, the speckle will appear to disappear. This is due to the integration time of the human eye on a moving object. If the eye moves faster than the time it can detect the speckle, the speckle becomes invisible to the human eye.

In order to maximize the miniaturization of micro-projectors, first of all, the reduction of the number of optical parts, the simplification of the optical engine structure, and the compact layout must be achieved.

By installing the second mirror 120 in front of the beam shaper 80, each R / G / B light emitted from the light source unit 5 is reflected in the direction in which the light source unit 5 is located, and then reaches the optical modulator 90. By doing this, the density of the optical component arrangement installed in the optical engine can be further increased.

In addition, two field lenses 130 can be provided between the beam shaper 80 and the optical modulator 90. One of the field lenses includes a position adjusting device that enables forward / backward movement in the optical axis direction so that the distance between the field lenses 130 changes as the front and rear motions move in parallel with the optical axis direction. The area itself of the illumination screen reaching the active plane 140 of the optical modulator can be easily changed.

According to the optical engine for a micro-projector according to the present invention, it is possible to reduce the number of optical components, such as lenses, mirrors, panels, etc. of the projection system to reduce the size of the projector, it is possible to reduce the cost, such as mobile phones, PDAs, game machines, digital cameras, etc. There is a remarkable effect that can be utilized in small multimedia terminals.

In addition, by using the adjustment means attached to the mirror, the optical axis of the three-color light that reaches the optical modulator from the R / G / B light source is easily and precisely aligned, so that a remarkable effect of achieving optimal lighting margin and light efficiency is achieved. have.

In addition, since the alignment of each optical axis can be achieved by different optical elements, each R / G / B light source can be packaged as a set to improve process productivity, and the light source is fixed in close contact with the outer set surface. There is a remarkable effect that can be installed so as to efficiently dissipate heat generated from the light source.

Although specific embodiments of the present invention have been described and illustrated above, it will be apparent that various modifications may be made by those skilled in the art without departing from the technical spirit of the present invention. Such modified embodiments should not be understood individually from the spirit and scope of the present invention, but should fall within the claims appended to the present invention.

Claims (16)

A light source unit 5 including a first light source 10, a second light source 20, and a third light source 30 of red (R), green (G), and blue (B) colors, and the light source unit (5) An optical engine for a micro-projector having an optical modulator 90 for modulating output light from an image signal in response to an image signal, and a projection device for projecting light modulated by the optical modulator 90, The light source unit 5 includes at least one laser light source, and on the optical path between the light source unit 5 and the optical modulator 90, the first light source 10, the second light source 20, and a third light source ( A plurality of mirrors corresponding to 30) are disposed, In order to align the distortion of the optical axis, at least one adjustment device 150 is installed in each of the mirrors, The adjustment device 150 is coupled to the frame 151 on which the mirror is seated and fixed and the protrusion 152 of the frame 151 to adjust the reflection angle θ1 and the tilt angle θ2 of the adjustment device 150. It is comprised by the optical-axis operation part 153 to adjust, Both edges of the vertical axis of the frame 151 are formed in a semicircular shape and are inserted in close contact with the barrel 154. An optical engine for a micro projector, characterized in that a semi-circular groove (groove: 155) is formed to rotate and move back and forth within a limited range. The method of claim 1, The plurality of mirrors include a first mirror (50) for total reflection of the light incident from the first light source; A first dichroic mirror 60 which reflects light incident from the second light source 20 and transmits light incident from the first light source 10; And a second dichroic mirror 70 for reflecting light incident from the third light source 30 and transmitting light incident from the first light source 10 and the second light source 20. Optical engine for micro projector. The method of claim 1, And the laser light source comprises a red laser diode. The method of claim 1, Wherein said laser light source comprises a green laser light source that emits a green laser through a nonlinear optical element at an IR laser diode. delete delete delete The method of claim 1, The light source unit 5 An optical engine for a micro projector, comprising: an R laser light source for irradiating R light, a G laser light source for irradiating G light, and a B laser light source for irradiating B light. The method of claim 1, The light source unit (5) is an optical engine for a micro-projector, characterized in that at least one of the light sources irradiating the R / G / B light is made of an LED light source. The method of claim 1, The optical modulator (90) is an optical engine for a micro projector, characterized in that any one selected from a liquid crystal display element, LCoS, DMD. The method of claim 1, An optical engine for a micro projector, comprising: a moving diffusion element (110), further comprising a diffuser or a vibrator. The method of claim 1, A beam shaper (80) positioned between the light source unit (5) and the optical modulator (90) and converting light emitted from the light source (5) into the shape of the active plane (140) of the optical modulator. Optical engine for micro projector, characterized in that. 13. The method of claim 12, The beam shaper (80) is an optical engine for a micro-projector, characterized in that two fly-eye lenses composed of two optical elements. 13. The method of claim 12, And further comprising two field lenses 130 between the beam shaper 80 and the optical modulator 90, wherein at least one of the two field lenses 130 is capable of forward / backward movement in the optical axis direction. Optical engine for micro projectors. The method of claim 1, The optical modulator (90) is a field sequential color display method. 16. The method of claim 15, The field sequential color display method is an optical engine for a micro-projector, characterized in that the reflection is implemented.

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