JP2010225307A - Light source with polarization function, homogenizer, light source device using these, and local dimming backlight system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source with a polarization function capable of emitting light of all polarization components of random polarization emitted from a light-emitting means through polarization conversion aligning into one direction, so that, light utilization efficiency of a backlight for a liquid crystal display element is enhanced to be also able, as a result, to adapt to local dimming. <P>SOLUTION: At one of two positions to be symmetrical with respect to an optical axis as a center of a lens L0 on an anterior focal plane (a focal plane of a light incident side) or its vicinity of the lens L0 of a focal distance f0, a light-emitting means 10 (for example, one or plurality of organic LEDs) of random polarization is fitted, and a 1/4 wavelength film 14 and a mirror 12 reflecting light having passed through the film 14 are fitted at the other of the two positions. A light source with the polarization function 4 with a wire grid polarizer 16 arranged is fitted in the vicinity of a lens surface of the lens L0. Furthermore, a homogenizer 6 keeping polarization homogeneous angularly and spatially is arranged on an emission side of the light source with the polarization function 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light source with a change function that generates substantially all of the light from the light emitting means that emits randomly polarized light in one direction, and a homogenizer that forms a light source device such as a backlight for a liquid crystal display in combination therewith The present invention relates to a light source device such as a backlight including a light source with a polarization function and a homogenizer, and a local dimming backlight system using the light source device.

Liquid crystal displays are used as image display means in various electronic devices such as watches, still cameras, movie cameras, personal computers, television receivers, and various industrial equipment, and the amount and usage will continue to expand. It is.
By the way, illumination light is indispensable for a liquid crystal display. This is because the liquid crystal display element does not display by itself, but displays by the contrast between the portion through which light is transmitted and the portion through which light is not transmitted.

A general method for obtaining the illumination light is a transmissive type in which a backlight is disposed behind a liquid crystal display element and light from the backlight is used as illumination light for display (Patent Document 1: Japanese Patent Laid-Open No. 2007-2007). -264111).
The liquid crystal display requires a polarizer having a polarization direction different from each other by 90 ° on both the incident side and the emission side of the liquid crystal display element, or a polarizer having a parallel polarization direction. In the case of the mold type, an ordinary polarizer constituting a polarization means on the incident side is interposed between the light emitting means of the backlight and the liquid crystal display element (Patent Document 2: Japanese Patent Laid-Open No. 2008-197308).

By the way, due to requests for prevention of deterioration of the global environment, resource saving, suppression of carbon dioxide generation, etc., various electronic devices, industrial devices, etc. are required to have low power consumption. Electronic devices such as television receivers are no exception.
However, there is a demand for an increase in the size of the television receiver and the like, and the increase in size inevitably leads to an increase in power consumption. It is strongly requested.

Compared to a cathode ray tube type display, the power consumption of a liquid crystal display is remarkably low, but it cannot be neglected to reduce the power consumption of the liquid crystal display.
By the way, the power consumption of the backlight accounts for most of the power consumption of the liquid crystal display. For this reason, techniques such as using a light emitting diode having high luminous efficiency as the light emitting means of the backlight are advancing. Recently, however, techniques for reducing power consumption by local dimming have been actively developed.

  Local dimming means that the image has light and darkness, and the dark part weakens the light of the backlight to reduce wasteful power consumption. According to this technology, the power consumption of the backlight is reduced from statistical studies. It seems to be reduced to 30%. It can be said that it is groundbreaking in that respect.

JP 2007-264111 A JP 2008-197308 A

  By the way, the conventional backlight is provided with a polarizing plate or a polarizing film that allows only light polarized in one direction to pass on the incident side of the liquid crystal display element, and is generated from, for example, an organic light emitting diode (organic LED) used as a light emitting means. Of the randomly polarized light, only the light polarized in one direction acts as illumination light, and polarized light different from that direction by 90 ° is absorbed by the polarizing means and does not contribute to the illumination at all. This is nothing more than about half of the power consumption of the light emitting means is wasted.

  The present invention has been made to solve such problems, and a light source with a polarization function that can emit light after performing polarization conversion that aligns all polarization components of randomly polarized light emitted from the light emitting means in one direction. And a homogenizer capable of making spatially and angularly non-uniform light uniform on the incident side, and spatially and angularly uniform. An object of the present invention is to provide a light source device that is optimal for local dimming in combination, for example, a backlight, and further to provide a local dimming backlight system using the light source device including the light source with polarization function and a homogenizer. And

  The light source with a polarization function according to claim 1 has a front focal plane (focal plane on the light incident side) of a lens having a focal length f0 or one of two symmetrical positions around the optical axis of the lens in the vicinity thereof. Randomly polarized light emitting means, a quarter wavelength film and a mirror for reflecting light passing through the film are provided on the other side, and a wire grid polarizer is disposed in the vicinity of the lens surface of the lens.

The homogenizer according to claim 2 is configured such that the lens having the focal length f1 and the lens having the focal length f2 on the exit side thereof are substantially parallel to each other and the distance between the lens surfaces is substantially equal to the focal length f2 of the exit side lens. And a diffusion film having a diffusion characteristic independent of an incident angle is arranged in the vicinity of the main plane of each of the two lenses.
Here, the diffusion characteristic that does not depend on the incident angle refers to a diffusion characteristic in which the diffusion principal ray direction and the diffusion profile are almost the top hat even if the incident angle changes.
Specific examples of such a diffusion film were proposed by Japanese Patent Application No. 2006-2675 and Japanese Patent Application No. 2004-267170 by the applicant's university, and introduced in Japanese Patent Application Laid-Open Nos. 2007-183498 and 2006-84563. ing.

The homogenizer according to claim 3 is a homogenizer according to claim 2, wherein a diffusion film element in which diffusion is limited to only one direction is substantially the same as, for example, the vertical direction and the horizontal direction. By using an orthogonal stack, the spatial output pattern of the homogenizer is converted into a square pattern such as a square or rectangle, regardless of the spatial pattern incident on the homogenizer. And
In addition, in this specification and a claim, a "diffusion film element" means the individual diffusion film body which comprises a diffusion film by mutually laminating | stacking.

A homogenizer according to a fourth aspect of the present invention is the homogenizer according to the third aspect, wherein a micro optical diffusion film element in which a plurality of cylindrical lenses are integrated is used as the diffusion film element.
In addition, the micro optical system diffusion film described in JP 2007-183498 A is preferable as the micro optical system diffusion film.
The homogenizer according to claim 5 is the homogenizer according to claim 3, characterized in that an internal refractive index distribution diffusion film element is used as the film element.
As the internal refractive index distribution diffusion film, those introduced as a diffusion film in JP-A-2006-84563 are suitable.

A homogenizer according to claim 6 is the homogenizer according to claim 2, wherein a micro optical system diffusion film in which micro lenses extending in an optical axis direction are integrated is used as the diffusion film. The aperture pattern of the micro lens is a spatial pattern on the homogenizer emission side.
As the micro optical diffusion film, those introduced in Japanese Patent Application Laid-Open No. 2007-183498 are suitable.

The homogenizer according to claim 7 is the homogenizer according to claim 2, 3, 4, 5 or 6, wherein each diffusion film as a constituent element also has a property of maintaining polarized light. And
In addition, as a diffusion film having such polarization maintaining properties, those introduced as diffusion films in JP-A-2006-84563 and JP-A-2007-183498 are suitable.

The light source device according to claim 8 comprises the light source with polarization function according to claim 1 and the homogenizer according to claim 7 that receives light emitted from the light source with polarization function. To do.
The light source device according to claim 9 is the light source device according to claim 8, wherein there are a plurality of light sources with polarization function according to claim 1, and light from the plurality of light sources with polarization function is according to claim 7. It is made to inject into the homogenizer of this.

The light source with polarization function according to claim 10 is the light source with polarization function according to claim 1, wherein the light emitting means of random polarization is composed of a plurality of LEDs, LD (laser diode) or OLED (organic EL). And
The light source device according to claim 11 is a homogenizer according to claim 7, wherein the light source with polarization function according to claim 10 is single or plural, and the light emitted from the light source with polarization function is received. It is characterized by comprising.

The homogenizer according to claim 12 has diffusion characteristics that do not depend on an incident angle, respectively, in the vicinity of the main plane of the lens having a focal length f1 and in the position away from the main plane of the lens from the main plane to the exit side. A diffusion film having the following is arranged.
The homogenizer according to claim 13 is the homogenizer according to claim 12, wherein the diffusion film according to claim 3, 4 or 5 is installed as the diffusion film having diffusion characteristics independent of an incident angle. By doing so, the spatial output pattern of the homogenizer is converted into a substantially square pattern such as a square or a rectangle, regardless of the spatial pattern incident on the homogenizer.

The homogenizer according to claim 14 is the homogenizer according to claim 12, wherein the diffusion film according to claim 6 is installed as the diffusion film having diffusion characteristics independent of an incident angle. The spatial emission pattern of the homogenizer is converted into the opening pattern of the micro lens of the micro optical system diffusion film, regardless of the spatial pattern incident on the homogenizer.
The homogenizer according to claim 15 is the homogenizer according to claim 12, 13 or 14, characterized in that each of the diffusion films also has a property of maintaining polarized light.

A light source device according to a sixteenth aspect includes the homogenizer according to the fifteenth aspect and the light source with a polarization function according to the first or tenth aspect.
The light source device according to claim 17 is the light source device according to claim 16, comprising a plurality of light sources with polarization function.
A local dimming backlight system according to claim 18 is characterized in that a plurality of light source devices according to claim 8, 9, 16 or 17 are arranged in an array.
A local dimming backlight system according to a nineteenth aspect is the local dimming backlight system according to the eighteenth aspect, wherein a plurality of light source devices with a polarization function share a single diffusion film on the emission side of the homogenizer. The exit areas on the shared diffusion film on the homogenizer exit side of the adjacent light source device with polarization function are overlapped with each other.

The light source with polarization function according to claim 20 has a specific light emission color set to enable full color display by a color field sequential method in the light source with polarization function according to claim 1 or 10. It is characterized by that.
In the color field sequential method, multiple types of light sources with different emission colors, such as red, blue, and green, are provided, and full color display is performed without using color filters by switching and driving these multiple types of light sources. This method is introduced in, for example, Japanese Patent Application Laid-Open No. 2006-85156.
The light source with polarization function may have a plurality of types (for example, three types) of emission colors such as red, blue, and green. In addition, a plurality of types, for example, three types of light sources with a polarization function may correspond to the claims.

A light source device with a polarization function according to claim 21 has a plurality of light sources with a polarization function of substantially monochromatic light in the plurality of light sources with polarization function in the light source device with polarization function according to claim 9 or 17. The light source unit having a polarization function has a specific emission color set so as to enable full color display by a color field sequential method.
The local dimming backlight system according to claim 22 is the local dimming backlight system according to claim 18 or 19, wherein the light source device includes a plurality of types of light source devices with changing functions having different emission colors as display units. It has a liquid crystal display element without a color filter and has a function for full color display by a color field sequential method.

  According to the light source with a polarization function according to claim 1, the light emitted from the light emitting means is first emitted as it is with respect to the polarization component transmitted through the wire grid polarizer, and is polarized light reflected by the wire grid polarizer. The component, that is, the polarized light component transmitted through the wire grid polarizer and the polarized light component different in 90 ° direction is first linearly polarized by a quarter wavelength plate in which the polarization direction is shifted from the 45 ° major axis direction (delay axis direction). Becomes circularly polarized light, reaches the mirror, reflects, and passes through the quarter-wave plate again, the circularly polarized light becomes linearly polarized light having a polarization direction that is 90 ° different from the polarization direction of the linearly polarized light that is initially incident. Therefore, the polarized light is in the same direction as the polarized light transmitted through the wire grid polarizer. As a result, the light also passes through the wire grid polarizer.

That is, all the light from the light emitting means is converted into polarized light that is transmitted through the wire grid polarizer and emitted.
Therefore, the direction of polarization of the light from the light emitting means can be emitted in a unified manner, and the light utilization rate of the light emitting means for a device that uses light polarized in one direction can be increased to about twice that of the prior art. it can.
The homogenizer according to claim 2 is configured such that the lens having the focal length f1 and the lens having the focal length f2 on the exit side thereof are substantially parallel to each other and the distance between the lens surfaces is substantially the focal length f2 on the exit side. In this manner, a diffusion film having a diffusion characteristic independent of the incident angle is disposed in the vicinity of the main surface of each lens. According to such a homogenizer, incident light that is not spatially and angularly uniform is first angularly uniformed by the diffusion film having a top hat diffusion characteristic that does not depend on the incident angle.

Next, the lens having the focal length f1 that converts the angle information into the position information is spatially uniform in the vicinity of the lens having the focal length f2. Since it is angularly uniformed by a diffusion film having a diffusion characteristic that does not depend on the incident angle, which is disposed on the lens exit side of the focal length f2, even if spatially and angularly nonuniform on the entrance side, the exit side Can be made spatially and angularly uniform.
Further, the homogenizer according to claim 2 has a function of converting the angle information of the diffusion characteristic of the diffusion film on the incident side into position information in the vicinity of the lens having the focal length f2 by the lens having the focal length f1. Therefore, when two or more diffusing film elements having a top hat-like diffusing characteristic in which the diffusing characteristic of the diffusing film on the incident side diffuses in almost only one direction and the incident angle is independent are laminated so that the diffusing directions are almost orthogonal to each other. The spatial output pattern of the homogenizer can be converted into a rectangular pattern such as a rectangle or a square without depending on the incident light pattern.
This is important in making the pattern overlap of the local dimming backlight block division uniform depending on the location.
This is because the degree of overlap varies depending on the location, and uniform illumination becomes difficult if the shape is circular. Even when a lamp optical system homogenizer of a projection system is used, since the image display device has a square shape (Example 16: rectangle of 9), the square pattern output is important in order to increase the light utilization efficiency. Become.

The homogenizer according to claim 3 is a micro-optical system in which two or more diffusion film elements whose diffusion is limited to only one direction are laminated substantially orthogonally as in the vertical direction and the horizontal direction as a diffusion film. The spatial light emission pattern of the homogenizer is converted into a square pattern such as a square or a rectangle by using a diffusion film, regardless of the spatial pattern incident on the homogenizer. This is a homogenizer.
Therefore, according to such a homogenizer, since the spatial emission pattern is a square pattern such as a square or a rectangle, unlike the case where the spatial pattern is a circular pattern, the pattern of the block division of the local dimming backlight is divided. It is possible to make the overlap uniform from place to place.

  The homogenizer according to claim 4 is a micro-optical device according to claim 3, wherein cylindrical lenses are integrated as a plurality of diffusion film elements constituting the diffusion film and the diffusion direction is limited to a negative direction. According to such a homogenizer, since the spatial pattern on the exit side of the micro-optical system diffusing film is mainly quadrangular (square or rectangular), the spatial pattern is a circular pattern. Unlike the above, it is possible to make the pattern overlap of the block division of the local dimming backlight uniform depending on the location.

  The homogenizer according to claim 5 has a structure in which the internal refractive index distribution is a substantially unidirectional distribution as the diffusion film, and two or more internal refractive index distribution diffusing film elements having a diffusion direction limited to a substantially negative direction. The homogenizer according to claim 3 is configured using an internal refractive index distribution diffusion film having a structure in which the diffusion directions are substantially orthogonal to each other. According to such a homogenizer, the internal refractive index Since the spatial pattern on the output side of the distributed diffusion film is mainly square (square or rectangular), unlike the case where the spatial pattern is a circular pattern, the pattern overlap of the local dimming backlight block division is uniform depending on the location. It becomes possible to.

The homogenizer of claim 6 comprises the homogenizer of claim 2 using, for example, a micro optical diffusion film described in JP-A-2007-183498 as the diffusion film. According to the homogenizer, since the aperture pattern of the micro lens of the micro optical system becomes the two-dimensional diffusion characteristic of the micro optical system diffusion film, the angle information of the diffusion characteristic of the diffusion film on the incident side is expressed by the focal length f1. Due to the function of the lens converting into position information in the vicinity of the lens having the focal length f2, the minute lens opening pattern of the minute optical system diffusion film becomes the spatial pattern on the homogenizer emission side.
According to the homogenizers of claims 3, 4 and 5 described above, as described above, the spatial pattern is mainly a quadrangle (square or rectangle). For example, the degree of freedom and controllability of patterns such as hexagons and combinations of polygons can be enhanced.

Therefore, the pattern overlap of the block division of the local dimming backlight is more improved by the homogenizer of claim 6 than in the case of the overlap of only the square by the homogenizer of claims 3, 4 and 5. Can be more effectively made uniform depending on the location.
That is, for example, it becomes important as a local dimming backlight that emphasizes uniformity, such as hexagonal overlap in the delta arrangement block division, and the microlens array of the micro-optical system diffusion film is the closest density of regular hexagon (honeycomb) pattern A packed arrangement is also possible.
Even when the lamp optical system homogenizer of the projection system is used, the image display device is rectangular (eg, a rectangle of Example 16: 9), so that light can be obtained by using a micro-optical system diffusing film with a square aperture micro-lens. In order to increase the use efficiency of the pattern, the square pattern output is also important.

The homogenizer according to claim 7 is the homogenizer according to claim 2, 3, 4, 5 or 6, but each diffusion film as a component also has a property of maintaining polarized light. As the diffusion film having such polarization maintaining characteristics, those introduced as diffusion films in JP-A-2006-84563 and JP-A-2007-183498 are suitable.
The present invention polarizes almost all of the light emitted from the light emitting means of random polarization by the light source with polarization function in one direction and applies light to an element (liquid crystal or the like) for displaying an image using the polarized light. The purpose is to improve utilization efficiency. However, even if the light source with polarization function of the present invention can realize the function of aligning random polarized light into unidirectional polarized light, the polarized light aligned in one direction is disturbed to random polarized light by diffusion of the diffusion film of the homogenizer. If this happens, the light use efficiency cannot be improved.
Therefore, the homogenizer according to claim 7 having a polarization maintaining function is indispensable for improving the light utilization efficiency.

According to the light source device of claims 8 and 9, almost all of the light emitted from the randomly polarized light emitting means by the light source with polarization function is polarized in one direction, and the homogenization is performed while maintaining the polarization state. It can be made spatially and angularly uniform by the kneader.
According to the light source with a polarization function according to claim 10, since the light emitting means is composed of a plurality of LEDs (: light emitting diodes) LD (: laser diodes) and OLEDs (: organic LEDs), each LED, LD, OLED Even if there are variations in characteristics, the characteristics of one light emitting means are characteristics obtained by averaging the characteristics of a plurality of LEDs, LDs, and OLEDs.
Therefore, variation in the characteristics of the light emitting means can be reduced.
The light source device according to claim 11 is a homogenizer according to claim 7, wherein the light source with polarization function according to claim 10 is single or plural, and the light emitted from the light source with polarization function is received. The output light of the light source with a polarization function that achieves uniform characteristics variation by a plurality of light emitting means, and the output light of the light sources with a plurality of polarization functions, while maintaining the polarization state, also from an angle Also, it is possible to control the emission side light pattern by making the space uniform.

According to the homogenizer of claim 12, 13 or 14, the incident angles are respectively near the principal plane of the lens having the focal length f1 and at a position away from the lens principal plane to the emission side by the approximate focal length f1. Because a diffusion film having diffusion characteristics that does not depend on the angle is arranged, incident light that is not spatially or angularly uniform is first angularly uniform by the diffusion film having top hat diffusion characteristics that do not depend on the incident angle. It becomes.
Next, since the angle information is converted into the position information in the rear focal plane away from f1 by the lens having the focal length f1 that converts the angle information into the position information, it is spatially uniform in the vicinity of the rear focal plane. It will be. However, since it is still non-uniform in angle, it is possible to achieve uniformity in angle by installing a diffusion film having a top-hat diffusion characteristic that does not depend on the incident angle on the rear focal plane. Therefore, even if it is spatially and angularly nonuniform on the incident side, it can be made spatially and angularly uniform on the outgoing side.

  Not only can the number of lenses used be reduced, but there is no exit-side lens, which makes it easy to overlap the exit areas of these homogenizers, which is an important function when applied to a local dimming backlight system. . Furthermore, when applied to a local dimming backlight system, the homogenizer emission side pattern control is important for uniform overlap, so that the diffusion film having diffusion characteristics independent of the incident angle used for this homogenizer By installing the diffusing film according to claim 3, 4 and 5, the spatial output pattern of the homogenizer is substantially rectangular, such as a square or a rectangle, regardless of the spatial pattern incident on the homogenizer. The spatial emission pattern of the homogenizer can be converted into a micro-optical system without depending on the spatial pattern incident on the homogenizer by converting the pattern to the above pattern or by installing the diffusion film according to claim 6. It can convert into the opening pattern of the micro lens of a diffusion film.

According to the homogenizer according to claim 15, in the homogenizer according to claim 12, 13 or 14, since each of the diffusion films also has a property of holding polarized light, for example, by a light source with a polarization function, etc. When polarized light is input, it can be made spatially and angularly uniform on the exit side while maintaining polarization, even if spatially and angularly nonuniform on the incident side. .
Since the light source device according to claims 16 and 17 comprises the homogenizer according to claim 15 and the light source with polarization function according to claim 1 or 10, a light source device for local dimming is provided. can do.

According to the local dimming backlight system according to claim 18, when the light source device according to claim 8, 9, 16 or 17 is arranged in a plurality of arrays, a polarization maintaining diffusion film is used for a large area. Is capable of providing light that is polarized and spatially and angularly uniform to, for example, a liquid crystal display element and the like, and that can achieve a low power consumption and high performance local dimming backlight system.
According to the local dimming backlight system of claim 19, in the local dimming backlight system of claim 18, a plurality of light source devices with polarization function share one diffusion film on the homogenizer emission side. Since the exit areas on the shared diffusion film on the homogenizer exit side of the adjacent polarization function light source device overlap each other, it is possible to emit light with uniform light characteristics over a wide area. As a result, high-quality local dimming characteristics can be obtained.

According to the light source with polarization function according to claim 20, full color can be obtained by switching a combination of colors (for example, red, green, and blue) that becomes almost white by additive color mixture as the emission color of the light emitting means at high speed in time. A full-color display that does not require a color filter by a color field sequential method in which an image of one frame is displayed by, for example, a 3 × speed or 6 × speed red field, green field, and blue field temporally high-speed sequential display can be realized.
According to the light source device with a polarization function according to claim 21, in the light source device with a polarization function according to claim 9 or 17, a plurality of light sources with a polarization function of each substantially monochromatic light are provided. Realization of full color display by color field sequential method in units of light source with polarization function (for example, light source with polarization function of red, light source with polarization function of green, light source with polarization function of blue) can do.

According to the local dimming backlight system of the twenty-second aspect, it is possible to eliminate the color filter that greatly reduces the light use efficiency in the liquid crystal display. For example, if light in red, green, and blue filters is not absorbed, even if the color filter is ideal, it can be expected that the light utilization efficiency is increased by about 3 times. Actually, since the color filter transmittance is not 100% even with respect to the selected wavelength, the light utilization efficiency can be increased by about 4 times.
Therefore, by combining a plurality of types of light sources with polarization function of different light emission colors according to claims 20 and 21, or a combination of a light source device with polarization function and a liquid crystal display element without a color filter, the local dimming is approximately doubled in polarization conversion. Therefore, the efficiency of the invention can be said to be very great because the efficiency of light use can be expected to be increased by about 24 times in total.

FIG. 1 shows a light source device according to a first embodiment (first embodiment) of the present invention, in which FIG. 1A is a cross-sectional view, and FIG. 1B is a configuration diagram showing an arrangement of lenses for explaining light diffusion. , (C) is a relationship diagram between an incident angle and light intensity, and (D) is a relationship diagram between an emission angle and light intensity. It is a figure which shows the optical path of the light from which the said incident direction differs in + (theta) 1, optical axis direction, and-(theta) 1 of the said Example (: Example 1), and spreading | diffusion. (A) to (C) are the first modification (: Modification 1) of the homogenizer lens portion of the above embodiment (: Embodiment 1) or the diffusion film having an incident angle independent top hat diffusion characteristic. (A) is a block diagram showing the arrangement of lenses for explaining the light diffusion, (B) is a diagram showing the relationship between the incident angle and the light intensity, and (C) is the outgoing angle. FIG. It is a figure which shows the optical path of the light from which the incident direction of + (theta) 1 of the said 1st modification, an optical axis direction, and-(theta) 1 differs, and spreading | diffusion. (A) to (C) are the second modification example of the homogenizer lens portion of the first embodiment (Example 1) or the diffusion film having an incident angle-independent top hat diffusion characteristic (: (A) is a block diagram showing the arrangement of lenses for explaining the light diffusion, (B) is a diagram showing the relationship between the incident angle and the light intensity, and (C) is an outgoing angle and light. It is a relationship diagram of intensity. It is a figure which shows the optical path and diffusion of the light from which the incident directions differ in -theta3,-(theta3 + theta4) / 2, -theta4 in the said 2nd modification (: modification 2). (A)-(C) show the third modification (: modification 3) of the lens part of the homogenizer of the above embodiment or the diffusion film principle diagram of the incident-hat-independent top hat diffusion characteristics. (A) is a block diagram showing the arrangement of lenses for explaining the light diffusion, (B) is a relationship diagram between the incident angle and the light intensity, (C) is a relationship diagram between the emission angle and the light intensity. is there. It is sectional drawing which shows the structure of the light source device of 2nd Example (: Example 2) of this invention. It is a perspective view which shows the light source device of 3rd Example (: Example 3) of this invention. It is a perspective view which shows the 4th Example (: Example 4) of this invention. FIG. 11 is a perspective view showing a fifth embodiment (embodiment 5) of the present invention. It is a perspective view which shows an example (Example 6) of the light source apparatus for 1 block corresponding to the color [R (red), G (green), B (blue) three primary colors] concerning this invention. An example (Example 7) of the backlight for local dimming arrange | positioned in the aspect which shares one output side diffusion film by carrying out the delta arrangement | sequence of the several light source device is shown. It is a perspective view which shows another example (: Example 8) of the backlight for local dimming. It is a circuit block diagram which shows an example (: Example 9) of each local dimming system using the backlight which consists of a several light source device.

The present invention basically converts a randomly polarized light emitted from a light emitting means into a polarized light in one direction regardless of the polarization direction by using a wire grid polarizer as a light source with a polarization function. The one that can be used is used. As the light emitting means, for example, LED, organic LED, organic EL, LD and the like are suitable, and one light emitting means may be constituted by one semiconductor element in one semiconductor chip.
However, if one light emitting means is constituted by a plurality of semiconductor elements in a single semiconductor chip or a plurality of semiconductor chips, variations in the optical characteristics of the semiconductor elements can be averaged. There is an advantage that the optical characteristics can be made more uniform.

As a homogenizer, using two or one lens, and further using a diffusion film, particularly one having diffusion characteristics that do not depend on the incident angle, spatially and angularly nonuniform light is used as incident light. Even if the light is received, it is possible to emit light that is spatially and angularly uniform.
Note that the above-described characteristics that do not depend on the incident angle refer to characteristics in which the diffusion principal ray direction and the diffusion profile have diffusion characteristics such as a top hat even when the incident angle changes. As such a diffusion film, specifically, the University of the Applicant has been proposed by Japanese Patent Application Nos. 2006-2675 and 2004-267170, and introduced by Japanese Patent Application Laid-Open Nos. 2007-183498 and 2006-84563. It is recommended to use a diffusion film. This is because this diffusion film not only has a characteristic that does not depend on the incident angle, but also has a characteristic of maintaining polarized light.

In addition, the present invention can employ a color field sequential method, thereby further reducing power consumption.
That is, according to the present invention, the light use efficiency can be increased about twice in the liquid crystal display device using polarized light by the polarization conversion function and the polarization holding diffusion function, and further, the local dimming function can be increased three times. Furthermore, the color field sequential method can be further increased by a factor of 4 and the total can be increased by about 24 times.

Hereinafter, the details of the present invention will be described based on illustrated embodiments.
Example 1
1 (A) to 1 (C) and FIGS. 2 (A) and 2 (B) show the light source device of the first embodiment (Example 1) of the present invention, and FIG. (B) is a block diagram showing the arrangement of lenses for explaining light diffusion, (C) is a diagram showing the relationship between the incident angle and the light intensity, and (D) is a diagram showing the relationship between the emission angle and the light intensity. 2 (A) to (C) are diagrams showing light paths and diffusion of light having different incident directions of + θ1 (A), an optical axis direction (B), and −θ1 (C).
First, the structure of the light source device will be described with reference to FIG.

In the figure, reference numeral 2 denotes a light source device, which includes a light source 4 with a polarization function and a homogenizer 6.
The light source 4 with a polarizing function includes a lens L0 having a focal length f0, a light emitting unit 10 of random polarization disposed on the incident side of the lens L0, and a collimating lens 11 formed on the surface of the light emitting unit 10, and also on the incident side. It comprises a mirror 12 disposed, a quarter-wave film 14 on the mirror 12, and a wire grid polarizer 16 disposed on or near the lens surface on the exit side of the lens L0.
The light emitting means 10, the mirror 10 and the quarter wavelength film 14 are symmetrical about the optical axis of the lens L0 and are positioned on the focal plane on the incident side of the lens L0.

Therefore, the light incident on the lens L0 out of the light emitted from the light emitting means 10 passes through the polarizer 16 as it is for the component light polarized in the direction passing through the wire grid polarizer 16, but All of the component light polarized at an angle of 90 ° is reflected toward the mirror 12 by the wire grid polarizer 16.
Then, before the light reflected toward the mirror 12 reaches the mirror 12, the linearly polarized light is first circularly polarized by the quarter wavelength plate whose polarization direction and 45 ° major axis direction (delay axis direction) are shifted. When the light reaches the mirror, is reflected, and is transmitted through the quarter-wave plate again, the circularly polarized light becomes linearly polarized light having a polarization direction different by 90 ° from the polarization direction of the linearly polarized light that is first incident.
As a result, the polarized light of the component reflected by the wire grid polarizer 16 toward the mirror 12 and having a polarization direction different from that of the light passing through the wire grid polarizer 16 by 90 ° is the ¼ wavelength film 14. When the 90 [deg.] Polarization direction is changed in the process of reciprocating, the polarization direction becomes the same as the light that has passed through the wire grid polarizer 16, and the light passes through the polarizer 16.
Therefore, according to the light source 4 with the polarization function, all of the light emitted from the light emitting means 10 toward the lens L0 can be polarized and converted so as to be aligned in one polarization direction and emitted to the homogenizer 6. It can be done.

Therefore, the utilization efficiency of the light emitted from the light emitting means 10 can be increased to about twice the conventional efficiency.
This is in addition to the fact that the power consumption of the light emitting means 10 required to emit the same amount of light to the homogenizer 6 can be reduced to about one half, as well as the light source device 2 and a backlight or other light source using the same. This greatly contributes to reduction of power consumption of the apparatus.

The homogenizer 6 includes a diffusion film 18 arranged on the incident side of the lens L1 having the focal length f1, a lens L1 having the focal length f1, and a focal length f2 arranged on the exit side of the lens L1. The lens L2 and the diffusion film 20 arranged on the exit side of the lens L2 are configured.
The diffusing film 18 is disposed so as to be located in the vicinity of the main plane of the lens L1, and is required to have a diffusing characteristic that does not depend on an incident angle. desirable. In this example, as the diffusion films 18 and 20, as described above, the diffusion films disclosed by JP2007-183498A and JP2006-84563A are used. In addition to the diffusion characteristic that does not depend on the light, it also has a high polarization holding characteristic for holding polarized light.

The lens L1 and the lens L2 have principal planes (both of their diameters are d) that are parallel to each other, and the distance between the principal planes is set to be substantially the same as the focal length f2 of the lens L2 that is a lens on the exit side. Yes.
However, there are various types of variations (modifications) in the relationship between the focal lengths f1 and f2 of the lenses L1 and L2, and in this embodiment, f1 = f2.
The diffusion film 20 is disposed so as to be positioned in the vicinity of the main plane of the lens L2, and is required to have a diffusion characteristic that does not depend on the incident angle.

(Basic type)
Next, referring to FIG. 1 (A), (B), (C), (D) and FIG. It will be explained that the kniter 6 can be made uniform both spatially and angularly. First, the diffusion film 18 on the incident side of the homogenizer 6 is a diffusion film having top hat-like diffusion characteristics that are independent of the incident angle. Therefore, if the incident angle range of this diffusion film is + θ1 to −θ1 as shown in FIG. 1C, the light incident in the range of + θ1 to −θ1 is incident angle as shown in FIG. Without depending on the above, it diffuses uniformly in the range of + θ1 to −θ1 like a top hat. Therefore, the angular uniformity is realized by the incident side diffusion film 18 of the homogenizer 6. The lens L1 of the homogenizer 6 functions to convert angle information into position information. The lens L2 functions to align the direction of the principal chief ray on the exit side of the lens L2.

In this example, since the focal lengths f1 and f2 of the lens L1 and the lens L2 are equal as described above, ± θ1 [θ1 = tan−1 d / () with respect to the optical axes of the two lenses L1 and L2. Only light incident at an incident angle within the range of 2f1)] can enter the lens L2 and become light emitted from the lens L2.
In FIG. 1B, light incident on the lens L1 at an angle of + θ1 with respect to the optical axis is indicated by a solid line arrow, light incident at an angle parallel to the optical axis is indicated by a broken line arrow, and −θ1 Light incident at an angle is indicated by a one-dot chain line.

  As is clear from FIGS. 1B and 2, the incident light to the lens L1 in the range of incident angles + θ1 to −θ1 has the same incident angle regardless of the incident angle. Even if they are different from each other, they enter the same position on the main plane of the lens L2, so that the incident angle information is converted into position information on the main plane of the lens L2 by the lens L1. Since the light incident on the lens L1 is angularly uniformized by the diffusion film 18 on the lens L1 incident side, it is spatially uniformized on the main plane of the lens L2. Since the lens L1 is installed on the front focal plane of the lens L2, the diffusion characteristics of the emitted light from the lens L2 are substantially the same, and are diffused within a range of ± θ1 (2θ1). Although the diffused light emitted from the lens L2 is spatially uniform, it is not yet uniform in terms of angle.

Therefore, the diffusion film 20 is installed on the exit side of the lens L2. The diffusion film 20 has the same characteristics as the diffusion film 18 and uniforms the light intensity that varies angularly within the range of + θ1 to −θ1 by the top hat diffusion characteristics independent of the incident angle. Therefore, on the emission side of the homogenizer 6, uniform light can be emitted both in terms of angle and space. Since the diffusion films 18 and 20 have a function of maintaining the polarization state of light even when diffused, the homogenizer 6 is a spatial and angular homogenizer having a polarization maintaining function.
According to the light source device 2, light polarized in one direction by the light source 4 with a polarization function can be emitted with uniform angular and spatial light while maintaining the polarization.

(Modification 1)
FIGS. 3A to 3C and FIG. 4 show a first modified example (modified example 1) of the lens portion of the homogenizer of the above embodiment, and FIG. 3A explains the light diffusion. FIG. 4 is a configuration diagram showing the arrangement of lenses for the above, (B) is a diagram showing the relationship between the incident angle and the light intensity, (C) is a diagram showing the relationship between the exit angle and the light intensity, and FIG. It is a figure which shows the optical path and the spreading | diffusion of the light from which an incident angle differs in the direction (B) and-(theta) 1 (C).
The lens portion of the homogenizer of this modification (Modification 1) is different from the homogenizer 6 of the embodiment shown in FIGS. 1 and 2 in terms of the focal length f2 of the exit-side lens L2 and the entrance-side lens L1. The difference is only in that the focal length is smaller than the focal length f1. The distance between the principal planes of the lens L1 and the lens L2 is also set to the focal length f2 of the exit side lens L2. The incident angle range and the outgoing diffusion angle range of the incident side diffusion film 18 are in the range of + θ1 to −θ1, and the incident angle range and outgoing diffusion angle range of the output side diffusion film 20 are in the range of + θ2 to −θ2. In FIG. 3, the diffusion films 18 and 20 are omitted.

The reason why the focal length f2 of the exit-side lens L2 is made smaller than the focal length f1 of the entrance-side lens L1 is to increase the exit-side diffusion angle range (NA).
Light of each angle incident on the lens L1 in the incident angle range of ± θ1 is collected at the position of the incident angle on the plane P (on the front side) closer to the emission side than the main plane of the lens L2. The lens L2 is transmitted when it reaches the plane P, and the action of the lens L2 is stronger than in the embodiment of FIG. 1, and the diffusion range is ± θ2 (θ2 = tan−1 [d / (2f2)]. Note that a relationship of tan θ2 = f1 · tan θ1 / f2 is established between tan θ2 and tan θ1.
Θ1 = tan−1d / (2f1), d: the diameter of the main plane of the lenses L1 and L2.

Therefore, as shown in FIG. 3B, even if the incident angle / light intensity distribution is biased to a certain incident angle −θa (−θ1 <−θa <0 °), the emission angle / light intensity distribution on the output side. Becomes uniform in the range of + θ2 to −θ2 as shown in FIG.
Thus, in order to increase the diffusion range on the exit side, a focal length f2 as the exit side lens L2 and a focal length f2 (f1> f2) smaller than the focal length f1 of the entrance lens L1 can be used. Good.

(Modification 2)
FIGS. 5A to 5C and FIG. 6 show a second modified example (Modified Example 2) of the lens portion of the homogenizer of the above embodiment, and FIG. 5A shows the light diffusion. It is a block diagram which shows arrangement | positioning of the lens for demonstrating, (B) is a related figure of an incident angle and light intensity, (C) is a relational figure of an output angle and light intensity, FIG. ) Is a diagram showing the optical path and diffusion of light having different incident directions of -θ3 (A),-(θ3 + θ4) / 2 (B), and -θ4 (C).
The present modification (Modification 2) is a homogenizer that is different from the lens portion of the homogenizer 6 of the embodiment (basic type, Modification 1) shown in FIGS. Further, as the exit side lens L2, a virtual lens L2 ′ having a diameter approximately 2d2 that is substantially larger than the diameter d of the entrance side lens L1 and having the same axis as that of the lens L1 (focal length is f2; in this example, the lens L1). For example, the upper end portion of the lens L1 and the same area as the lens L1 (diameter of about d) is used (the lens L2 portion of the virtual lens L2 ′). Is different.

Secondly, the entire direction of the incident light is different from the optical axis of the lens L1 so that the incident light basically enters the lens L1 from, for example, obliquely below, and the emitted light enters the lens L2. It is different in that it becomes.
By deforming in this way, in Modification 2, it is possible to fix the emission diffusion angle range and independently control only the incident angle range.
The incident angle of the light indicated by the solid line is −θ3, the incident angle of the light indicated by the broken line is − (θ3 + θ4 / 2, the incident angle of the light indicated by the alternate long and short dash line is −θ4, and a range of −θ3 to −θ4 with respect to the lens L1. The light of the incident angle enters the lens L2 and becomes outgoing light.

Here, θ3 = tan−1d1 / f2 and θ4 = tan−1d2 / f2. In FIG. 5, θ2 = tan−1d / 2f2 = θ1 = tan−1d / 2f1. Here, d1 is the distance between the optical axes of the lenses L1 and L2 (virtual lens L2 ′) and the position on the main plane of the lens L2 where the light incident on the lens L1 gathers at an angle of −θ3, and d2 is the lens. This is the distance between the optical axes of L1 and L2 and the position on the main plane of the lens L2 where light incident at an angle of −θ4 gathers.
In this modification, the incident angle range and the outgoing diffusion angle range of the incident side diffusion film 18 are in the range of −θ3 to −θ4, and the incident angle range and the outgoing diffusion angle range of the outgoing side diffusion film 20 are + θ2 to −θ2. Range. In FIG. 5, the diffusion films 18 and 20 are omitted. In this modification of the homogenizer 6, even if the incident angle / light intensity distribution to the homogenizer 6 is biased to a certain angle −θb (−θ3 <−θb <−θ4) as shown in FIG. Even if there is unevenness in the space, the exit angle and light intensity distribution on the exit side are uniform in the range of + θ1 to −θ1 and spatially uniform as shown in FIG. Become. In addition, the polarization characteristics are almost maintained.

(Modification 3)
FIGS. 7A to 7C show a third modification (modification 3) of the homogenizer of the above-described embodiment. FIG. 7A shows a lens arrangement for explaining the light diffusion. (B) is a diagram showing the relationship between the incident angle and the light intensity, and (C) is a diagram showing the relationship between the exit angle and the light intensity, and the light ray incident at the + θ1 incident angle with respect to the lens L1 is shown by a solid line. The light incident parallel to the optical axis is indicated by a broken line, and the light incident at −θ1 is indicated by a one-dot chain line. In FIG. 7, unlike FIG. 1 and the like, the angle of incidence from diagonally upward to diagonally downward is −θ, and the angle of incidence from diagonally downward to diagonally upward is + θ.
The lens part of the homogenizer of this modification (Modification 3) is the same as the lens part of the homogenizer 6 of the embodiment shown in FIGS. 1 and 2, first, as the exit side lens L2. For example, a virtual lens L2 ″ (having a focal length of f2 and equal to the focal length f1 of the lens L1 in this example) having a diameter approximately twice the diameter d of the lens L1 of the lens L1 is approximately the same as the lens L1 in the lower half. (The portion excluding the lens L2 and the substantially upper half of the virtual lens L2 ″ are not present) are used. This difference is that the optical axes of the lens L1 and the lens L2 are shifted by a distance a, which makes it possible to independently control the emission diffusion angle range by fixing the incident angle range. Between the parallel principal planes of the lens L1 and the lens L2 Away it is also set to the focal length f2 of the lens L2 on the exit side.

In the present modification (Modification 3), incident light in an incident angle range of ± θ1 (θ1 = tan-1d / 2 · f1) is incident on the lens L2, and an emission angle in a range of θ6 to θ5. The light having
Θ5 = tan−1 [(a / f2) −tan θ1], θ6 = tan−1 [(a / f2) + tan θ1], a: the distance between the optical axis of the lens L1 and the optical axis of the virtual lens L2 ″ In this modification, the incident angle range and the outgoing diffusion angle range of the incident side diffusion film 18 are in the range of −θ1 to −θ1, and the incident angle range and the outgoing diffusion angle range of the output side diffusion film 20 are in the range of θ5 to θ6. 7, the diffusion films 18 and 20 are omitted, and in the modification of the homogenizer 6, the incident angle / light intensity distribution of incident light on the lens L1 to the homogenizer 6 is shown. As shown in FIG. 7 (B), the emission angle / light intensity distribution on the emission side is shown in the figure regardless of whether it is biased at a certain angle, for example, −θb (0>−θb> −θ1) or spatially uneven. 7 (C), in the range of θ6 to θ5 Becomes one, and also to be uniform in spatial. Moreover it retains substantially polarization characteristics.

As described above, the homogenizer of the embodiment shown in FIGS. 1 and 2 can have various modifications.
With these modifications, in the control of the incident angle range and the outgoing diffusion angle range of the basic homogenizer 6, independent control of the sizes of the incident angle range and the outgoing diffusion angle range is performed in the first modification, and the outgoing control is performed in the second modification. Independent control of the direction of the incident angle range with the diffusion angle range fixed, and in Modification 3, the incident angle range is fixed to enable independent control of the direction of the output diffusion angle range. Therefore, by combining the basic type, the first modification, the second modification, and the third modification, the incident angle range and the emission diffusion angle range can be freely controlled.

(Example 2)
FIG. 8 is a cross-sectional view showing the light source device 2a of the second embodiment (embodiment 2) of the present invention.
The light source device 2a of this embodiment differs from the light source device 2 of the first embodiment in that the homogenizer 6a does not use the lens L2 used in the homogenizer 6, but has the focal length f1 of the lens L1. The difference is that the diffusion film 20 is arranged in parallel with the main plane of the lens L1, but the other points are common.
The diffusion film 20 (and the diffusion film 18) is, for example, a diffusion film disclosed by Japanese Patent Application Laid-Open No. 2007-183498 and Japanese Patent Application Laid-Open No. 2006-84563, that is, a film that is uniform in angle and space and maintains polarized light. It is good to use the same as in the case of the first embodiment.

  Also with this light source device 2 a, incident light having an incident angle in the range of + θ1 to −θ1 is incident on the diffusion film 20 at a position corresponding to the incident angle of the incident light and diffused by the diffusion film 20. Therefore, the uniformity of the emission angle and light intensity distribution of the emitted light is high. It is also spatially uniform. However, the incident angle range and the outgoing diffusion angle range of the diffusion film 20 need to be larger because the lens L2 is omitted. This angle is + θ7 to −θ7 (θ7 = tan−1d / f1).

Example 3
FIG. 9 is a perspective view showing a light source device 2b of a third embodiment (Example 3) of the present invention.
The present embodiment (: embodiment 3) is separated from the focal length f1 in the light source device (see FIG. 8, having the homogenizer of claim z11) 2a of the second embodiment (: embodiment 2). In place of the arranged diffusion films 18 and 20, by installing orthogonal two-layer laminated micro cylindrical lens diffusion films 18a and 18a having the principle and structure of the diffusion film introduced by JP 2007-183498A, The homogenizer emission pattern can be output as a square pattern regardless of the homogenizer incidence pattern.

In FIG. 9, 10 is a light emitting means, 11 is a collimating lens provided on the surface of the light emitting means 10, 12 is a mirror, 14 is a quarter wavelength plate, L0 is a lens with a focal length f0, and 16 is a wire grid polarizer. , 18a is the diffusion film, more specifically, an orthogonal two-layer laminated micro cylindrical lens diffusion film.
The cross-sectional structure of the diffusion film 18a is shown in an enlarged portion of the corner.
The diffusion film 18a is formed by laminating diffusion film elements 40 and 50 each having a cylindrical element connected in a direction in which the directions of the cylindrical elements are orthogonal to each other, and 42, 42, ... and 44, 44, Are the cylindrical lens elements on both sides of the diffusion film element 40, the focal length f3 of the incident side cylindrical elements 42, 42,..., And the focal length f4 of the outgoing side cylindrical elements 44, 44,. Are the same (f3 = f4), and the distance between both surfaces on which the cylindrical elements are formed is also f3 (= f4).

52, 52,... And 54, 54,... Are cylindrical lens elements on both sides of the diffusion film element 50, the focal length f5 of the incident side cylindrical elements 52, 52,. The focal length f6 of 54, 54,... Is the same (f5 = f6), and the distance between both surfaces on which the cylindrical elements are formed is also f5 (= f6).
Reference numeral 20a denotes an orthogonal two-layer laminated micro cylindrical lens diffusing film having the same structure as the diffusing film 18a. However, the focal lengths are not necessarily the same, but the relationship between the focal lengths f3 and f4 and the relationship between f5 and f6 also holds for the diffusion film 20a.

That is, the focal length f7 of the incident side cylindrical element and the focal length f8 of the emission side cylindrical element of the incident side diffusion film element (a diffusion film element corresponding to the diffusion film element 40 of the diffusion film 18a) of the diffusion film 20a are the same ( f7 = f8), and the focal length f7 (= f8) is equal to the distance between both surfaces on which the cylindrical elements are formed.
In addition, the focal length f9 of the incident-side cylindrical element and the focal length f10 of the emitting-side cylindrical element of the output-side cylindrical element connecting body (a diffusion film element corresponding to the diffusion film element 50 of the diffusion film 18) are the same (f9 = f10), and its focal length f9 (= f10) is equal to the distance between both surfaces on which the cylindrical elements are formed.

Example 4
FIG. 10 is a perspective view showing a fourth embodiment (Example 4) of the present invention. The present embodiment (: embodiment 3) is separated from the focal length f1 in the light source device (see FIG. 8, having the homogenizer of claim z11) 2a of the second embodiment (: embodiment 2). Instead of the diffusion films 18 and 20 arranged, by installing the orthogonal two-layer laminated internal refractive index distribution diffusion films 18b and 20b, the principle and structure of the diffusion film introduced by JP 2006-84563 A, The homogenizer emission pattern can be output as a square pattern regardless of the homogenizer incidence pattern.
The present embodiment differs from the embodiment shown in FIG. 9 only in that the diffusion films 18a and 20a are replaced with the diffusion films 18b and 18b. Since it has already been described, it will be omitted, and a specific description of the configuration will be made only on the different points.

Reference numeral 60 denotes a diffusion film element for vertical diffusion of the orthogonal two-layer laminated internal refractive index distribution diffusion film 18b, and a layer 64 having a refractive index n1 (for example, n1 = 1.55) extending in a substantially horizontal direction and a refractive index n2 (for example, n2). = Approximately 1.51) and layers 66 extending in a substantially horizontal direction are alternately arranged along the vertical direction, and the spacing between the layers 64 and 66 is 2 to 4 μm, and the refraction of the layer boundary portion Rate is a gradient index.
62 is a diffusion film element for diffusing in the left-right direction of the orthogonal two-layer laminated internal refractive index distribution diffusion film 18b. The layers 70 extending in the vertical direction are alternately arranged along the left-right direction, the interval between the layers 68 and 70 is 2 to 4 μm, and the layer boundary is a gradient index.
Since the configuration of the orthogonal two-layer laminated internal refractive index distribution diffusion film 20b is exactly the same as the configuration of the diffusion film 18b, illustration and description of the cross-sectional structure are omitted.

(Example 5)
FIG. 11 is a perspective view showing a fifth embodiment (embodiment 5) of the present invention. In this embodiment (: Embodiment 5), in the light source device 2a of the second embodiment (: Embodiment 2) of the present invention shown in FIG. Instead of the diffusion film 18 on the incident side, the principle and structure of the diffusion film introduced in Japanese Patent Application Laid-Open No. 2007-183498 is replaced with a hexagonal aperture microlens close-packed array (honeycomb lens array) diffusion film. By installing 18c, the homogenizer emission pattern can be output as a hexagonal pattern irrespective of the homogenizer incidence pattern.
Further, instead of the diffusion film 20 on the emission side, a diffusion film 20c designed so that the diffusion characteristic on the homogenizer output side becomes a square two-dimensional diffusion characteristic is used.

The structure of these diffusion films 18c and 20c will be described as follows. First, the diffusion film 18c has a microlens array structure in which a large number of microlenses 72 having hexagonal openings are arranged in a honeycomb shape 72, 72,. When the focal length of the incident side portion of each micro lens 72 is f3 and the focal length of the exit side portion is f4, the distance between the entrance side portion and the exit side portion is, for example, f4, for example, f3 = f4.
Next, the diffusion film 20 has a microlens array structure in which a large number of square aperture microlenses 74 are arranged 74, 74,. When the focal length of the incident side portion of each microlens 74 is f5 and the focal length of the exit side portion is f6, the distance between the entrance side portion and the exit side portion is, for example, f6, for example, f6 = f5.

Example 6
FIG. 12 is a perspective view showing an example (Example 6) 2a of the light source device for one block corresponding to the colors [R (red), G (green), B (blue) three primary colors] according to the present invention.
The light source device of one block has, as light emitting means, a randomly polarized light emitting means 10r that generates red light, a randomly polarized light emitting means 10g that generates green light, and a random polarized light emitting means 10b that generates blue light. A combination of the mirror 12 and the quarter-wave film 14 is arranged corresponding to each light emitting means 10r, 10g, 10b. However, one combination appears in FIG.

  Further, lenses L0r, L0g, and L0b are provided corresponding to the light emitting units 10r, 10g, and 10b, and one wire grid polarizer 16 is disposed behind the lenses L0r, L0g, and L0b. Since the wire grid polarizer only needs to be behind the lenses L0r, L0g, and L0b, the wire grid polarizer 16 having the area of the lens L1 is provided in FIG. 12, but the small area lenses L0r, L0g, Three wire grid polarizers having an area of L0b may be installed behind the lenses L0r, L0g, and L0b, respectively. This is effective when the wire grid polarizer is expensive. A diffusion film 18 is installed after the wire grid polarizer 16 of FIG. 12. One lens L1 is disposed in front of the diffusion film, and the focal length f1 of the lens L1 is placed on the exit side for diffusion. A film 20 is disposed. In this example, the lens L2 is not provided, but the sixth embodiment can be applied to a type having the lens L2. In this case, the distance between the lenses L1 and L2 is set to the focal length f2 of the lens L2.

  The relationship between each light emitting means 10r, 10g, 10b, mirrors 12, 12, 12 and quarter-wave films 14, 14, 14, and lenses L0r, L0g, L0b is the first shown in FIGS. In this embodiment, the light emitting means 10, the mirror 12, the quarter wavelength film 14, and the lens L0 are the same. The quarter-wave film 14 is more preferably a film designed as a dedicated achromatic quarter-wave film in a band centered on the respective main wavelengths for red, green, and blue.

Accordingly, when attention is paid to the red light generated from the randomly polarized light emitting means 10r, the polarized light component passing through the wire grid polarizer 16 of the red light is transmitted through the polarizer 16 as it is.
On the other hand, the polarization component in the direction perpendicular to the polarization component is reflected by the wire grid polarizer 16 and is directed to the mirror 12 by the lens L0r, but in front of it, the polarization direction and the 45 ° major axis direction (delay axis direction). First, linearly polarized light becomes circularly polarized light by the shifted quarter wave plate, reaches the mirror, reflects, and passes through the quarter wave plate again. Directional linear polarization. Accordingly, the polarization direction becomes a polarization component in a direction passing through the wire grid polarizer 16 and is transmitted through the wire grid polarizer 16.

Accordingly, the red light incident on the lens L0r is emitted from the polarizer 16 with all the polarization directions unified through the wire grid polarizer 16 regardless of the direction of the polarization. For example, it reaches the diffusion film 20 via L1. The diffusion films 18 and 20 are, for example, diffusion films disclosed by JP 2007-183498 A and JP 2006-84563 A, that is, top hat-like uniform diffusion characteristics independent of incident angles, and As in the case of the first embodiment, it is preferable to use a diffusion film having characteristics that can substantially maintain the polarization state in spite of diffusion.
This is exactly the same for green light and blue light generated from the randomly polarized light emitting means 10g, 10b.

(Example 7)
FIG. 13 shows an example (seventh example: example 7) of a backlight for local dimming in which a plurality of light source devices are arranged in a mode of sharing one emission side diffusion film.
2a, 2a,... Are light sources for one block (excluding the exit side diffusion film), and 20 is one exit film on the exit side (the one used in Example 1 is preferred). Yes, shared by all light source devices 2a, 2a,.
Each of the light source devices 2a, 2a,... Basically has a different area of the diffusion film 20 as an irradiation area, but is arranged in an array so that adjacent areas partially overlap each other. . In order to make the overlap overlap the same everywhere, the pattern on the emission side of each light source device must be square as shown in the figure. This function is realized when the hexagonal aperture microlens array diffusion film of Example 3, Example 4 and Example 5 is a square aperture microlens array diffusion film.

  The purpose of overlapping is to make the non-uniformity of illumination of each block uniform by overlapping with neighboring blocks, and to make the end portion of the block area inconspicuous. A hatched area in FIG. 13 is an irradiation area of the light source device 2a ', and a rectangular portion having an area of a center 1/4 in the hatched area 22a' is an area in charge of the light source device 2a '. Therefore, in this case, the illumination from the adjacent eight blocks overlaps.

(Example 8)
FIG. 14 is a perspective view showing another example (Example 8) of a backlight for local dimming. In the present embodiment, a plurality of light source devices (in FIG. 14, the light source device 21 and six light source devices 22, 23, 24, and 25 centering on the light source device shown in the fifth embodiment (Example 5)). , 26, and 27) are arranged in a delta arrangement so as to share the one exit side diffusion film 20d.

FIG. 15 is a circuit block diagram showing an example of a local dimming system using the backlight 28 according to the present invention composed of a plurality of light source devices.
2a, 2a,... Are light source devices that are controlled by the light emitting means 10r, 10g, 10b (or 10) independently of each other, and share one emission side diffusion film 20, and thereby the backlight 28 Is configured.
30 is a liquid crystal display element that receives illumination light from the backlight, 32 is a drive circuit that drives the liquid crystal display element 30, 34 is an image circuit that supplies image signals to the liquid crystal display element 30 through the drive circuit 32, and 36 is a local circuit. In the dimming circuit, the output of the image circuit 34 analyzes the image signal, and the light emission means of each light source device 2a, 2a,... It is possible to avoid wasteful power consumption by emitting light of the amount of light.

According to such a local dimming system, since not only the polarized light component in one direction of light output from the light emitting means but also the polarized light component different from the 90 ° direction is used for illumination of the liquid crystal display element. Compared with the local dimming technology in which only a polarized light component in one direction out of the light from the conventional randomly polarized light emitting means is received by the polarizer and used for illumination of the liquid crystal display element, the light use efficiency can be increased approximately twice. it can.
This means that the power consumption required for the light source can be substantially halved, and greatly contributes to the reduction of power consumption of electronic devices using liquid crystal display elements.

  The above system can be expected to increase the light utilization efficiency by about 2 times by polarization conversion and increase the efficiency by about 3 times by local dimming. If the color field sequential technology to be removed is used in combination, the efficiency can be further increased by about 4 times. As a method for realizing this, when the light emitting means is a semiconductor red, green, blue multi-light emitting chip (LED, LD, etc.) or multi-OLED, or when the light source device is a red, green, blue multi Since it is only necessary to realize red, green, and blue field lighting at 3 times the speed of one frame, it can be easily applied to the present invention. Specifically, this can be realized by sequentially lighting red, green, and blue light source device units at a high speed in the apparatus of the sixth embodiment shown in FIG.

A liquid crystal mode (liquid crystal display element) that can be used in this color field sequential method is suitable for a liquid crystal mode capable of high-speed response. In recent years, the speed-up technology of liquid crystals has advanced considerably, and among them, the nematic liquid crystal mode includes an OCB (Optically Compensated Bend) method, and the fast response liquid crystal includes a ferroelectric liquid crystal (FLC). In these liquid crystal modes, 3 × speed and 6 × speed color field sequential systems have already been realized and there is no technical problem. Therefore, the color field sequential method combined with the light source device and the backlight system of the present invention increases the efficiency by about 2 times in polarization conversion, about 3 times in local dimming, and about 4 times in the color field sequential method. About 24 times higher light utilization efficiency can be expected.
This means that the power consumption required for the light source can be greatly reduced, and greatly contributes to the reduction of power consumption of electronic devices using liquid crystal display elements.

  The present invention relates to a light source that generates substantially all of light from a light emitting means that emits randomly polarized light in one direction, and a polarization maintaining homogenizer that is combined with the light source device to form a light source device such as a backlight for a liquid crystal display. There is a wide industrial applicability to a light source device including a light source with a polarization function and a polarization maintaining homogenizer and a local dimming backlight system using the light source device.

2, 2a ... light source device, 4 ... light source with polarization function, 6 ... homogenizer,
10, 10r, 10g, 10b ... light emitting means (organic LED), 12 ... mirror,
14 ... 1/4 wavelength film, 16 ... wire grid polarizer,
18, 18a, 18c, 20, 20a, 20b, 20c ... diffusion film,
28 ... Backlight (light source device),
30 ... Liquid crystal display element, 32 ... Drive circuit, 34 ... Image circuit,
36: Local dimming circuit, 40, 50, 60, 62 ... Diffusion film element.

Claims (22)

Randomly polarized light emitting means is arranged at one of two positions symmetrical about the optical axis of the front focal plane (focal plane on the light incident side) of the lens at the focal length f0 or in the vicinity thereof, and 1/4 on the other side. Provide a wavelength film and a mirror that reflects the light passing through this film,
A light source with a polarization function, wherein a wire grid polarizer is disposed in the vicinity of the lens surface of the lens. A lens having a focal length f1 and a lens having a focal length f2 on the exit side thereof are arranged so that the principal plane is substantially parallel and the distance between the lens surfaces is substantially the focal length f2 on the exit side;
A homogenizer comprising a diffusion film having a diffusion characteristic independent of an incident angle in the vicinity of a main plane of each of the two lenses. The homogenizer according to claim 2,
As a diffusion film, by using a plurality of diffusion film elements in which diffusion is limited to only one direction, laminated so that the diffusion directions are orthogonal to each other, regardless of the spatial pattern incident on the homogenizer, A homogenizer characterized by converting the spatial emission pattern of the homogenizer into a square pattern such as a square or rectangle. The homogenizer according to claim 3,
As the diffusion film element, a micro optical system diffusion film element in which a plurality of cylindrical lenses are integrated is used. The homogenizer according to claim 3,
A homogenizer characterized by using an internal refractive index distribution diffusion film child as the film child. The homogenizer according to claim 2,
As the diffusion film, a micro optical system diffusion film in which micro lenses extending in the optical axis direction are integrated, and the aperture pattern of the micro lens of the micro optical system is used as a spatial pattern on the homogenizer emission side. Homogenizer. The homogenizer according to claim 2, 3, 4, 5 or 6,
The homogenizer characterized in that each of the diffusion films also has a property of maintaining polarized light. A light source with polarization function according to claim 1;
The homogenizer according to claim 7 that receives light emitted from the light source with polarization function,
A light source device comprising: The light source device according to claim 8,
A light source device comprising: a plurality of light sources with polarization function according to claim 1, wherein light from the plurality of light sources with polarization function is incident on the homogenizer according to claim 7. The light source with polarization function according to claim 1,
A light source with a polarization function, wherein the randomly polarized light emitting means comprises a plurality of LEDs, LDs (laser diodes) or OLEDs (organic EL). One or more light sources with polarization function according to claim 10;
The homogenizer according to claim 7 that receives light emitted from the light source with polarization function,
A light source device comprising: A diffusion film having diffusion characteristics that do not depend on the incident angle is disposed in the vicinity of the main plane of the lens having the focal length f1 and at a position that is approximately the focal length f1 away from the main plane of the lens to the exit side. A featured homogenizer. The homogenizer of claim 12,
By installing the diffusing film according to claim 3, 4 or 5 as the diffusing film which does not depend on the incident angle, the homogenizer can be used regardless of the spatial pattern incident on the homogenizer. A homogenizer characterized by converting the space emission pattern of a nizer into a substantially square pattern such as a square or rectangle. The homogenizer of claim 12,
By installing the diffusing film according to claim 6 as the diffusing film that does not depend on each incident angle, the spatial emission of the homogenizer is not dependent on the spatial pattern incident on the homogenizer. A homogenizer that converts a pattern into an aperture pattern of a micro lens of a micro optical diffusion film. The homogenizer according to claim 12, 13 or 14,
The homogenizer characterized in that each of the diffusion films also has a property of maintaining polarized light. The homogenizer of claim 15;
A light source with a polarization function according to claim 1 or 10,
A light source device comprising: The light source device according to claim 16, wherein
A light source device comprising a plurality of light sources with a polarization function. A local dimming backlight system, wherein a plurality of light source devices according to claim 8, 9, 16, or 17 are arranged in an array. The local dimming backlight system according to claim 18,
A plurality of light source devices with a polarizing function are shared by one diffusion film on the homogenizer emission side,
A local dimming backlight system characterized in that the exit areas on the shared diffusion film on the homogenizer exit side of the light source device with an adjacent polarization function overlap each other. The light source with polarization function according to claim 1 or 10,
A light source with a polarization function, characterized by having a specific emission color set so that full color display by a color field sequential method is possible. The light source device with polarization function according to claim 9 or 17, wherein the plurality of light sources with polarization function each have a plurality of light sources with polarization function of substantially monochromatic light, and full color by a color field sequential method for each light source with polarization function. A light source device with a polarization function, characterized in that it has a specific emission color set so that display is possible. The local dimming backlight system according to claim 18 or 19,
As a light source device, it has a plurality of types of light source devices with polarization function having different emission colors,
It has a liquid crystal display element without a color filter as a display means,
A local dimming backlight system characterized by a full-color display function using a color field sequential method.

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