JP2005121705A - Optical engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical engine increasing illuminating light quantity to yield color rendering properties bright and nearer to natural light, and further enhancing the transmission efficiency of illuminating light to obtain high light emission luminance. <P>SOLUTION: The optical engine 1 is provided with a red light source part 11R, a green light source part 11G, a blue light source part 11B, a video display means 20 which composes and emits the light beams of three primary colors emitted by the three light sources, and a projection lens 30 which projects the light emitted by the display means 20. A yellowish green LED module 12Y and a cyan LED module 12C are used as the green light source. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light source of a display device, and more particularly to an optical engine of a projection display device using a light emitting diode as a light source.

  Conventionally, as an optical engine used for a liquid crystal projector or the like, a full-color optical engine using an ultrahigh pressure mercury lamp as a light source is known. Recently, development of optical engines using light emitting diodes (LEDs) of three colors as light sources has been advanced.

As shown in FIG. 7, in the optical engine 1 using LEDs, three types of LEDs corresponding to the three primary colors of light, R (red), G (green), and B (blue) are provided for full color display. Used. Usually, in order to secure the amount of light, the light source is integrated as a light source module in which a plurality of LEDs of the same color are mounted on the substrate surface for each primary color. That is, a plurality of red LEDs are provided on the surface of the substrate to form a red LED module 2R, a green LED is integrated as a green LED module 2G, and a blue LED is integrated as a blue LED module 2B. Further, as shown in FIG. 8, a lens array 3, a polarization conversion panel 4, and a field lens 5 are arranged in this order on the emission surface side of the LED light source module 2R, and a light source unit is configured by these (see FIG. 8). FIG. 8 shows the case of a red light source, but the configuration is the same for the other two primary colors).
In detail, the LED elements 22 constituting the LED light source module 2R are usually arranged in a straight line in the vertical and horizontal directions at a predetermined interval on the surface of the substrate 21, as shown in FIG. The polarization conversion elements 41 constituting the polarization conversion panel 4 are arranged so that the combination units (unit element blocks 9) with the LED elements 22 are in a stripe shape (see, for example, Patent Document 1).
The light of each color from such a light source unit is incident on the liquid crystal panels 6R, 6G, and 6B, which are video display elements provided exclusively for RGB colors. Here, predetermined image information is given to each of the light of the three primary colors, and is emitted to the color image synthesis prism (three-color synthesis dichroic prism) 7. The color image synthesizing prism 7 synthesizes RGB light, and the synthesized light is projected onto a screen via a projection lens 8.
JP 2002-374004 A

However, in the optical engine 1 described above, if the LED light source modules 2R, 2G, and 2B for each color are independently emitted at the maximum ratings in an attempt to ensure the maximum illumination light amount, the white balance of the image is lost and the color rendering is deteriorated. The problem occurs. On the other hand, when the white balance of the image is properly maintained, there is a problem that the light emission amount from the LED light source module 2G that emits green light is insufficient as compared with the other two primary colors, particularly red. Therefore, an increase in the amount of radiation from the green LED module 2G has been strongly desired, but it has been difficult to realize.
Further, as can be seen from FIG. 8 and Patent Document 1, the LED light source module 2R is effectively a surface light source. Therefore, the combination unit (unit element block 9) of the LED light source module 2R and the polarization conversion element 41 is determined. When arranged in a stripe shape as in the prior art, it is difficult to increase the mounting density of the LED elements 22 in the LED light source module 2R. As a result, from the LED light source module 2R to the video display element (liquid crystal panel 6). There is a problem that the transmission efficiency of the illumination light is low. For this reason, improvement of the light emission luminance of the LED light source module 2R has been desired.

  The present invention has been made in view of the above circumstances, can increase the amount of illumination light, can be bright and have a color rendering property that is closer to natural light, and further enhances the transmission efficiency of illumination light and high light emission. It is an object to provide an optical engine capable of obtaining luminance.

In order to solve the above-mentioned problem, the invention of claim 1 of the present invention is, for example, as shown in FIG. 1, a red light source (red light source unit 11R), a green light source (green light source unit 11G), and a blue light source (blue). A light source unit 11B), an optical display unit 20 that synthesizes and emits light of the three primary colors emitted by these three light sources, and an optical unit that projects the light emitted by the video display unit (projection lens 30). An engine 10,
As the green light source, a yellow-green light emitting diode (yellow-green LED module 12Y) and a cyan light-emitting diode (cyan LED module 12C) are used.

According to the invention of claim 1, since the yellow-green light emitting diode and the cyan light-emitting diode are used as the green light source, a part of the light amount of the cyan light-emitting diode can be matched with the light amount of the yellow-green light-emitting diode. The total amount of green light can be increased as compared with the green light source of only the green light emitting diode, and a brighter optical engine can be realized.
Further, since it is possible to obtain a green light source having a wider band than a green light source using only a green light emitting diode as in the prior art, it is possible to obtain a full-color optical engine having color rendering properties closer to natural light.

The invention of claim 2 is an optical engine according to claim 1, for example, as shown in FIG.
As the green light source, the light from the yellow-green light emitting diode and the light from the cyan light emitting diode are combined by a dichroic mirror 16.

  According to invention of Claim 2, it can be easily used as a green light source by synthesize | combining the light from a yellow-green light emitting diode and the light from a cyan light emitting diode using a dichroic mirror.

The invention of claim 3 is the optical engine according to claim 2,
The dichroic mirror is characterized in that the reflection and transmission characteristics are switched around a wavelength of 530 nm at an incident angle of 45 °.

  According to the invention of claim 3, a light component having a wavelength of 530 nm or less is reflected by the dichroic mirror, and a light component having a wavelength of 530 nm or more that is perpendicular to the light beam is transmitted through the dichroic mirror, both for green. The light enters the video display means. Alternatively, a light component having a wavelength of 530 nm or more is reflected, and only a light component having a wavelength of 530 nm or less is transmitted and incident on the green image display means.

The invention of claim 4 is an optical engine according to any one of claims 1 to 3, as shown in FIGS. 5 (a) to (c), for example.
The light source of each color has a light emitting diode (LED element 122) and a polarization conversion element 141,
A unit (unit element block 18) in which each of these light emitting diodes and one polarization conversion element is combined is arranged in a check pattern.

  According to the invention of claim 4, since the unit in which each one of the light emitting diode and the polarization conversion element is combined is arranged in a check pattern, the polarization conversion function is maintained and compared with the conventional stripe shape. The mounting density of the light emitting diodes can be increased. As a result, the luminance of the light source can be increased, and therefore the transmission efficiency of the illumination optical system is improved, and a bright optical engine can be realized also in this respect.

The invention of claim 5 is an optical engine according to claim 4, for example, as shown in FIG.
A corner cube prism sheet 19 is provided on a non-incident surface on the light emitting diode side of the polarization conversion element.

  According to the fifth aspect of the present invention, since the corner cube prism sheet is provided on the non-incident surface on the light emitting diode side of the polarization conversion panel, the illumination light that has been thrown away conventionally can be reused to transmit the illumination optical system. In this respect, a bright optical engine can be realized.

Invention of Claim 6 is an optical engine as described in any one of Claims 1-5,
The video display means includes video display elements (red image liquid crystal panel 22R, green image liquid crystal panel 22G, blue liquid crystal panel 22B),
A corner cube prism sheet is provided around the video display element so as to surround the video display element and to be substantially parallel to the video display element surface.

  According to the invention of claim 6, since the corner cube prism sheet is provided around the video display element so as to surround the video display element and to be substantially parallel to the video display element surface, it has been conventionally discarded. By reusing the illumination light, the transmission efficiency of the illumination optical system can be improved, and a bright optical engine can be realized in this respect as well.

According to the optical engine of the present invention, since the yellow-green light emitting diode and the cyan light-emitting diode are used as the green light source, a part of the light amount of the cyan light-emitting diode can be matched to the light amount of the yellow-green light-emitting diode, The total amount of green light can be increased, and a brighter optical engine can be realized. In addition, a full-color optical engine having a color rendering property closer to natural light can be obtained.
Furthermore, by arranging units each combining one light emitting diode and one polarization conversion element in a check pattern, it is possible to increase the mounting density of the light emitting diodes while maintaining the polarization conversion function. As a result, the luminance of the light source can be increased, and thus the transmission efficiency of the illumination optical system is improved.
Further, since the corner cube prism sheet is provided on the non-incident surface on the light emitting diode side of the polarization conversion panel, it is possible to improve the transmission efficiency of the illumination optical system by reusing the conventionally discarded illumination light.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the optical engine 10 of the present embodiment includes three light source units 11R, 11G, and 11B, a video display unit 20, and a projection lens (projection unit) 30.

  The red light source unit 11R, the green light source unit 11G, and the blue light source unit 11B illuminate the image display means 20 by converting light of the three primary colors R (red), G (green), and B (blue) into linearly polarized light, respectively. To do.

The red light source unit 11R includes a red LED module 12R, a lens array 13, a polarization conversion panel 14, and a field lens 15. The red LED module 12R is a module in which a plurality of red LEDs having an emission spectrum shown in FIG. 2 are mounted, and has a peak wavelength of about 630 nm.
The lens array 13 is disposed on the light emission side of the red LED module 12R, and efficiently condenses the diverging light incident from the red LED module 12R as a substantially collimated light on a predetermined incident surface of the polarization conversion panel 141.
The polarization conversion panel 14 is a well-known element that is disposed on the optical axis of the lens array 13 and converts light incident from the lens array 13 into linearly polarized light in a predetermined direction.
The field lens 15 narrows incident light having a large cross section to a narrower incident surface of the image display means 20, and emits light incident from the polarization conversion panel 14 to the image display means 20.

The blue light source unit 11B includes a blue LED module 12B, a lens array 13, a polarization conversion panel 14, and a field lens 15.
The blue LED module 12B is a module in which a plurality of blue LEDs having the emission spectrum shown in FIG. 2 are mounted, and has a peak wavelength of about 470 nm.
The lens array 13, the polarization conversion panel 14 and the field lens 15 are the same as described above, and the field lens 15 emits the light emitted from the blue LED module 12B and passed through the polarization conversion panel 14 to the image display means 20.

The green light source unit 11G is different from the other two primary color light source units 11R and 11B in that the yellow green LED module 12Y, the cyan LED module 12C, the lens arrays 13 and 13, the polarization conversion panels 14 and 14, the field lenses 15 and 15, A dichroic mirror 16 and a light absorption damper 17 are provided.
The yellow-green LED module 12Y is a module on which a plurality of yellow-green LEDs showing the emission spectrum shown in FIG. 2 are mounted, and the peak wavelength is about 560 nm.
The cyan LED module 12C is a module on which a plurality of cyan LEDs having the emission spectrum shown in FIG. 2 are mounted, and has a peak wavelength of about 510 nm.
The lens arrays 13 and 13 and the polarization conversion panels 14 and 14 provided on the light emission sides of the yellow-green LED module 12Y and the cyan LED module 12C are the same as described above. The field lenses 15 and 15 emit light emitted from the polarization conversion panels 14 and 14 to the dichroic mirror 16. At this time, the two optical axes emitted from the field lenses 15 and 15 are combined by the dichroic mirror 16.
The combination unit of the LED light source modules 12R, 12B, 12Y, and 12C for each color and the polarization conversion panel 14 will be described later.

As shown in FIG. 3, the dichroic mirror 16 reflects light components having a wavelength of 530 nm or less and transmits light components having a wavelength of 530 nm or more at an incident angle (θ) of 45 °. The dichroic mirror 16 is at an angle of 45 ° with respect to the light emitted from the yellow-green LED module 12Y and the light emitted from the cyan LED module 12C, and is emitted from the yellow-green LED module 12Y and transmitted through the dichroic mirror 16. The light emitted from the cyan LED module 12C and the light reflected by the dichroic mirror 16 are arranged so as to overlap each other.
The light absorbing damper 17 is disposed on the opposite side of the dichroic mirror 16 with respect to the cyan LED module 12C on the optical axis of the light emitted from the cyan LED module 12C. The light absorbing damper 17 absorbs light reflected from the dichroic mirror 17 out of the emitted light from the yellow-green LED module 12Y and light transmitted through the dichroic mirror 17 out of the emitted light from the cyan LED module 12C.

Of the light emitted from the yellow-green LED module 12Y, a component having a wavelength of 530 nm or less is reflected by the dichroic mirror 16 and absorbed by the light absorption damper 17. On the other hand, a component having a wavelength of 530 nm or more passes through the dichroic mirror 16 and enters the image display means 20.
Further, a component having a wavelength of 530 nm or less out of the light emitted from the cyan LED module 12C is reflected by the dichroic mirror 16 and enters the video display means 20. On the other hand, components having a wavelength of 530 nm or longer are transmitted through the dichroic mirror 16 and absorbed by the light absorption damper 17.
Therefore, the spectral distribution of the emitted light from the green light source unit 11G is as shown in FIG. Compared with the conventional example (green light spectrum in FIG. 2), a broadband green spectrum distribution is obtained. Further, as can be seen from FIG. 2 and FIG. 3, since the ratio of the light emitted from the dichroic mirror 16 out of the light emitted from the yellow-green LED module 12Y and the cyan LED module 12C is small, as a result of synthesis, the normal vicinity of 540 nm is obtained. The image display means (green image liquid crystal panel 22G, which will be described later) 20 can be irradiated with a light amount larger than the light amount from the monochromatic green LED light source having a peak, and the bright optical engine 10 can be realized as compared with the conventional case. it can.

The video display means 20 is provided to emit light of three colors incident from the light source units 12R, 12G, and 12B to the projection lens 30, and includes a liquid crystal panel 22R, 22G, and 22B, and a dichroic prism 23 for combining three primary colors. I have.
The polarizing plate 21 provided on the incident side of each of the liquid crystal panels 22R, 22G, and 22B transmits only linearly polarized light in a predetermined direction of incident light, and the contrast is improved.
The liquid crystal panel for red image 22R, the liquid crystal panel for green image 22G, and the liquid crystal panel for blue image 22B are video display elements, and the direction of linearly polarized light incident from the polarizing plate 21 is rotated and transmitted by a voltage applied to each pixel. By controlling the rate, predetermined video information is given and emitted to the dichroic prism 23 for three-color synthesis.

  The projection lens 30 enlarges and projects the light incident from the video display means 20 onto a screen (not shown).

Next, a combination unit of the LED light source modules 12R, 12B, 12Y, and 12C for each color and the polarization conversion panel 14 will be described. Here, the case of the red light source unit 11R will be described as an example.
As shown in FIGS. 5A and 5B, the red LED module 12 </ b> R includes a substantially rectangular support substrate 121 and a plurality of LED elements 122 provided on the surface of the support substrate 121.
The plurality of LED elements 122 are provided along the entire surface of the support substrate 121 at predetermined intervals in the vertical and horizontal directions. Further, the LED elements 122 and 122 adjacent to each other in the horizontal direction are slightly shifted in the vertical direction, and the LED elements 122 and 122 adjacent to each other in the vertical direction are slightly shifted in the horizontal direction. That is, in the vertical direction and the horizontal direction, locations where the LED elements 122 are arranged and locations where the LED elements 122 are not arranged are alternated.

As shown in FIG. 5A, the polarization conversion panel 14 includes a plurality of polarization conversion elements 141, and the plurality of polarization conversion elements 141 are laid in a panel shape. The polarization conversion element 141 is a known element that aligns the light beam formed by the lens array 13 with a predetermined polarization component, and the polarization conversion element 141 in the present embodiment has a half-wavelength position on the surface on the emission side. A phase difference film 142 is provided, and an element that aligns randomly polarized radiated light emitted from the LED element 122 with S-polarized light is used (see FIG. 6).
In particular, the units (hereinafter referred to as unit element blocks 18; see FIG. 6) in which one LED element 122 and one polarization conversion element 141 are combined are arranged in a check pattern (FIG. 5 ( c)). That is, only the unit element blocks 18 adjacent to each other in the vertical direction are alternately rotated by 180 ° with respect to the optical axis.

Further, a corner cube prism sheet 19 is attached to a surface that is not exposed to light on the incident surface side design of the polarization conversion panel 141 (non-incident surface on the LED element 122 side) (see FIG. 5A). . The corner cube prism sheet 19 is formed by laying minute corner cube prisms in a sheet shape.
Although not shown, a corner cube prism sheet is also attached to the frame of the lens holder of the optical system. Further, although not shown, a corner cube is formed so as to surround the video display element around the frame of the liquid crystal panels 22R, 22G, and 22B of the video display means 20, that is, around the video display element and to be substantially parallel to the liquid crystal panel surface. A prism sheet is attached.

The corner cube prism used in this embodiment has a characteristic of returning to the incident direction when reflecting incident light. Therefore, if the corner cube prism is installed in the illumination optical system at the location where the leaked light beam hits, the leaked light beam can be returned to the LED element. However, as a characteristic of the corner cube prism, the optical axis of the reflected light does not exactly coincide with the optical axis of the incident light, and is shifted laterally by a length depending on the size of the corner cube prism, so that the returned light is strictly Does not return to the original light emitting point in the LED, and when it is re-radiated from the LED element, it does not become a ray of the same locus. For this reason, there is a possibility that the re-radiated light is effectively incorporated in the illumination optical system.
Thus, by providing the corner cube prism sheet at the above-mentioned predetermined location, an increase of about 5 to 10% in the effective illumination light amount can be seen.

Next, how light travels in the optical engine 10 configured as described above will be described with reference to FIG.
In the red light source unit 11 </ b> R, red light emitted from the red LED module 12 </ b> R is converted into linearly polarized light in a predetermined direction by the polarization conversion panel 14 via the lens array 13. Here, if the illumination light is aligned in advance with linearly polarized light in a predetermined direction, the light utilization efficiency is dramatically improved. The red light emitted from the polarization conversion panel 14 enters the image display means 20 through the field lens 15.
The red light incident on the video display means 20 passes through the polarizing plate 21 and enters the red image liquid crystal panel 22R. The liquid crystal panel 22R gives red video information to red light. The red light given the video information is incident on the dichroic prism 23 for three-color synthesis.

  Also in the blue light source unit 11B, similarly to the red light source unit 11R, the light emitted from the blue LED module 12B passes through the polarization conversion panel 14 and enters the video display means 20 through the field lens 15. The blue light incident on the video display means 20 passes through the polarizing plate 21, is given blue video information by the blue image liquid crystal panel 22 </ b> B, and enters the three-color composition dichroic prism 23.

  In the green light source unit 11G, the light emitted from the yellow-green LED module 12Y passes through the polarization conversion panel 14 and enters the dichroic mirror 16 via the field lens 15. Of the yellow-green light incident on the dichroic mirror 16, a component having a wavelength of 530 nm or less is reflected and absorbed by the light absorption damper 17, and only a component having a wavelength of 530 nm or more is transmitted and incident on the image display means 20.

On the other hand, the light emitted from the cyan LED module 12 </ b> C passes through the polarization conversion panel 14 and enters the dichroic mirror 16 through the field lens 15. Of the cyan light incident on the dichroic mirror 16, a component having a wavelength of 530 nm or less is reflected and incident on the image display means 20, and a component having a wavelength of 530 nm or more is transmitted and absorbed by the light absorption damper 17.
Therefore, light obtained by superimposing a component having a wavelength of 530 nm or more in the emitted light of the yellow-green LED and a component having a wavelength of 530 nm or less in the emitted light of the cyan LED is obtained as the emitted light of the green light source unit 11G.

The combined green light incident on the video display means 20 passes through the polarizing plate 21 and enters the green image liquid crystal panel 22G. The green image liquid crystal panel 22G gives video information to the synthesized green light. The combined green light given the image information is incident on the three-color combining dichroic prism 23.
The RGB three-color lights incident on the three-color composition dichroic prism 23 are combined to form a full-color image, enter the projection lens 30, and are projected from the projection lens 30 onto the screen.

As described above, according to the optical engine 10 of the embodiment of the present invention, a component having a wavelength of 530 nm or more of the emitted light of the yellow-green LED module 12Y and a component of the emitted light of the cyan LED module 12C having a wavelength of 530 nm or less are combined. Since the light emitted from the green light source unit 11G is superposed at 16, the total amount of green light can be increased as compared with the conventional green light source using only the green light emitting diode, and a brighter optical engine 10 can be realized. Further, since it is possible to obtain a green light source having a wider band than a green light source using only a green light emitting diode as in the prior art, it is possible to obtain a full-color optical engine 10 having a color rendering property closer to natural light.
In addition, since the unit element blocks 18 each combining one LED element 122 and one polarization conversion element 141 in each color light source unit 11R, 11G, and 11B are arranged in a check pattern, the polarization conversion function is maintained. However, the mounting density of the LED elements 122 can be increased. As a result, the transmission efficiency of the illumination optical system is improved with high brightness.
In addition, the corner cube prism sheet 19 is provided on the incident light side of the polarization conversion panel 141 where no light is incident on the design and on the frame of the liquid crystal panels 22R, 22G, 22B. Thus, the transmission efficiency of the illumination optical system is improved.

In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can change suitably.
For example, in this embodiment, in order to illuminate the green image liquid crystal panel 22G, the emitted light from the cyan LED module 12C is bent by 90 ° by the dichroic mirror 16 and reflected, and the emitted light from the yellow-green LED module 12Y is transmitted. However, conversely, the emitted light from the cyan LED module 12C may be transmitted through the dichroic mirror 16, and the emitted light from the yellow-green LED module 12Y may be bent by 90 ° and reflected. In that case, the two LED modules 12Y and 12C are replaced, and a light component having a wavelength of 530 nm or less is transmitted as the dichroic mirror 16, but a light component having a wavelength of 530 nm or more is reflected.

It is a schematic block diagram which shows an example of the optical engine of embodiment of this invention. It is a figure which shows the wavelength characteristic of the light source shown in FIG. It is a figure which shows the reflection / transmission characteristic of the dichroic mirror shown in FIG. FIG. 2 is an emission spectrum distribution diagram of the green light source unit of FIG. 1. (a) is a plan sectional view for explaining the relative positional relationship between the LED light source module and the polarization conversion element, (b) is a front view of the LED light source module, and (c) is a front view of the polarization conversion panel. It is. It is a figure for demonstrating the combination unit of an LED light source module and a polarization conversion element. It is a schematic block diagram which shows the optical engine of a prior art example. It is a perspective view for demonstrating the relative positional relationship of the LED light source module of a prior art example, and a polarization conversion element.

Explanation of symbols

10 Optical Engine 11R Red Light Source (Red Light Source)
11G Green light source (green light source)
11B Blue light source (blue light source)
12Y yellow-green LED module (yellow-green light-emitting diode)
12C cyan LED module (cyan light emitting diode)
16 Dichroic mirror 18 Unit element block (combination unit)
19 Corner cube prism sheet 20 Image display means 22R Liquid crystal panel for red image (image display element)
22G Green image liquid crystal panel (video display device)
22B Blue image liquid crystal panel (video display device)
30 Projection lens (projection means)
122 LED element 141 Polarization conversion element

Claims (6)

An optical device having a red light source, a green light source, a blue light source, an image display unit that synthesizes and emits light of the three primary colors emitted by these three light sources, and a projection unit that projects the light emitted by the image display unit. An engine,
An optical engine using a yellow-green light emitting diode and a cyan light emitting diode as the green light source.   2. The optical engine according to claim 1, wherein the green light source is composed of light from a yellow-green light emitting diode and light from a cyan light emitting diode by a dichroic mirror.   The optical engine according to claim 2, wherein the dichroic mirror has its reflection and transmission characteristics switched around a wavelength of 530 nm at an incident angle of 45 °. Each color light source has a light emitting diode and a polarization conversion element,
The optical engine according to any one of claims 1 to 3, wherein a unit obtained by combining each of the light emitting diode and the polarization conversion element is arranged in a check pattern.   The optical engine according to claim 4, wherein a corner cube prism sheet is provided on a non-incident surface on the light emitting diode side of the polarization conversion panel. The video display means has a video display element,
6. The optical according to claim 1, wherein a corner cube prism sheet is provided around the video display element so as to surround the video display element and substantially parallel to the video display element surface. engine.

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