JP2008218154A - Light source device, and display device equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device capable of being thinned, and excelling in photosynthesis performance by solving a problem where a conventional light source device synthesizing incident light from a plurality of light sources by using a prism sheet is low in utilization efficiency of light rays; and a display device equipped it. <P>SOLUTION: This light source device is provided with a plurality of light sources different in light emission wavelength, and a prism sheet which has a plurality of minute prisms on one surface and of which the other surface is flat, and is structured such that incident light from the plurality of light sources entered at a predetermined angle from the incident surface side of the prism sheet is output from the emitting surface side of the prism sheet as emission light mixed in color by arranging the plurality of light sources on the incident surface side of the prism sheet by being tilted at the predetermined angle. The light source device is characterized in that a bandpass mirror transmitting light rays in a wavelength region emitted from the corresponding light source and reflecting light rays in the other wavelength regions is arranged between each light source and the prism sheet. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light source device that mixes and emits incident light from a plurality of light sources, and more particularly, to a light source device that can be reduced in size and thickness, and has improved light utilization efficiency, and a display device including the same.

  Conventionally, as a display device using a color light source, there are a color projector, a projection-type color television, a liquid crystal display device using a backlight, and the like. As a light source device used for these devices, for example, there is a method using a dichroic prism for a color projector or a projection type color television. (For example, refer to Patent Document 1.) Further, since this dichroic prism is an expensive member, the price of the apparatus is increased, and this method has a disadvantage that inherently causes a large light loss. As a method for solving the drawbacks, a light source device has been proposed in which a plurality of light beams are converted into a single light beam using a linear prism. (For example, refer to Patent Document 2.) Further, as a backlight of a liquid crystal display device or the like, a light source device has been proposed in which the light emitted from the LED light source is improved in luminance uniformity by using two prism sheets. (For example, see Patent Document 3.)

  Hereinafter, the structure of the light source device in the prior art will be described with reference to the drawings. 28 and 29 show the configuration of the color projector shown in Patent Document 2, FIG. 28 shows the configuration of the color projector, and FIG. 29 is a partial sectional view of the linear prism plate shown in FIG. In FIG. 29, reference numeral 50 denotes a linear prism plate. The upper surface constitutes an exit surface having a large number of prism rows, and the lower surface constitutes a flat entrance surface. The incident lights P51a and P51b that are incident on the incident surface 51 on the lower surface side of the linear prism plate 50 from two different oblique directions are refracted by the incident surface 51 and then refracted by the two exit surfaces 52 and 53 of the prism. Direction light P52 and P53.

  In other words, by appropriately designing the refractive index determined by the material of the linear prism plate 50 and the apex angle (tip angle) of the prism, two types of incident light incident from two directions orthogonal to the prism row are each 2 of the prism. The light is refracted at one emission surface and emitted in the same direction. Based on this principle, it is possible to emit as a single light obtained by combining incident light from two types of light sources. When the two types of light sources are different color lights, two colors can be emitted as mixed color light. Further, when it is desired to combine three or more types of light sources, it can be executed by repeating the combination using a plurality of linear prism plates 50.

  FIG. 28 shows a color projector including a light source device that synthesizes three color lights of red (hereinafter R), green (hereinafter G) and blue (hereinafter B) using two linear prism plates 50 shown in FIG. Reference numerals 50a and 50b denote linear prism plates having the same configuration as the linear prism plate 50. Reference numeral 55 denotes a projection lens, 56 denotes a projection screen, 57 denotes an R light source, 58 denotes a G light source, 59 denotes a B light source, and 61, 62, and 63 denote relay lenses for the R light source 57, the G light source 58, and the B light source 59, respectively. is there.

  In the above-described configuration, the R light and the G light emitted from the R light source 57 and the G light source 58 arranged at different angles of 45 ° with respect to the incident surface of the linear prism plate 50a are respectively connected to the relay lens 61. , 62 to be collimated and then incident on the incident surface of the linear prism plate 50a from different oblique directions of 45 °. The two incident lights of R light and G light are emitted in the vertical direction from the emission surface of the linear prism plate 50a as a single light synthesized by the linear prism plate 50a. The combined outgoing light from the linear prism plate 50a enters the incident surface of the linear prism plate 50b disposed at an angular position of 45 ° with respect to the linear prism plate 50a from an oblique direction of 45 °. .

  Further, after the B light emitted from the B light source 59 is converted into parallel rays through the relay lens 63, the linear prism is viewed from an oblique direction of 45 ° different from the single light synthesized from the R light and the G light. The light enters the incident surface of the plate 50b. As a result, the combined single light of the R light and the G light and the B light are combined by the linear prism plate 50b, and emitted from the linear prism plate 50b as a single light that combines the R light, the G light, and the B light. The light is emitted vertically from the surface.

  Next, the configuration of the surface light emitting device shown in the cited document 3 will be described with reference to FIGS. 30 and 31. 30 is an exploded perspective view of the surface light emitting device, and FIG. 31 is a partially enlarged side view showing a light emitting state of the light emitting substrate shown in FIG. In FIG. 30, reference numeral 70 denotes a surface light emitting device, which includes a plurality of LEDs 72 and a plurality of reflectors 73 on a lower side of two prism sheets 70 a and 70 b that are arranged so that the prism rows are orthogonal to each other. A configured light emitting substrate 75 is disposed. The liquid crystal unit 80 is arranged on the upper surface side of the surface light emitting device 70 to constitute a liquid crystal display device using the surface light emitting device 70 as a backlight.

  A plurality of LEDs 72 are arranged in a matrix, for example, on the light emitting substrate 75, and each reflector 73 is provided so as to collectively cover the LEDs 72 arranged in one row. As shown in FIG. 31, each reflector 73 has a first surface 73 a that faces the light emitting surface of the LED 72 and a second surface 73 b that covers the upper surface. The radiated light emitted from the LED 72 is reflected laterally by the first surface 73a of the reflector 73 and is incident on the adjacent reflector 73, and is reflected upward by the second surface 73b of the adjacent reflector 73 to be laminated. The light enters the arranged prism sheets 70a and 70b. The stacked prism sheets 70a and 70b arrange the optical path of the reflected light incident from the second surfaces 73b of the plurality of reflectors 73 provided on the light emitting substrate 75 and emit the light upward (in the direction of the liquid crystal unit 80). Have a role to let you.

  The surface light emitting device 70 having the above-described configuration emits white light as a backlight. Accordingly, white light is emitted from the light emitting substrate 75. White LEDs can be broadly divided into a type in which an LED having a specific emission wavelength and a phosphor are combined, and R, G, B in one package. There are three types of LEDs, and any type can be used. The plurality of LEDs 72 arranged on the light emitting substrate 75 are three kinds of LEDs of R, G, and B, and reflected so that these three colors of light are mixed by the first surface 73a and the second surface 73b of the reflector 73. By emitting the light, it is possible to realize a white light surface emitting device.

Japanese Patent Application Laid-Open No. 2002-244211 JP-A-63-132215 JP 2006-228710 A

  However, the light source device in the prior art has the following problems. In the light source device using the dichroic prism in Patent Document 1, since the dichroic prism is an expensive member, there is a problem that the price of the device is high and that this method has a substantial loss of light amount.

  Further, in the light source device using a plurality of linear prisms in Patent Document 2, for example, when combining light sources of R, G, B, and three color LEDs, an arrangement interval having a predetermined angle is provided in the two linear prisms. Since the arrangement space for the linear prism is widened, the shape of the light source device as a whole becomes large, which makes it difficult to reduce the thickness of the device. In addition, since the light beam incident on the linear prism is incident from an oblique direction, the light beam width when exiting from the linear prism is extended, resulting in a difference in the light beam width between the incident light and the light output and a change in the aspect ratio of the light beam. This amount of change increases with the number of oblique light incidences of the linear prism. That is, in the case of the light source device shown in FIG. 28, R light and G light are obliquely incident on the linear prism plate 50a and combined, and then the combined single light is obliquely incident on the linear prism plate 50b and B light is combined. Therefore, with respect to the R light and the G light, the oblique light incidence of the linear prism is performed twice, and the aspect ratio is twice different.

  Furthermore, in the light source device using the light emitting substrate with the reflector and the two prism sheets in Patent Document 3, the prism rows of the two prism sheets are stacked so as to be orthogonal to each other. The two prism sheets arranged in a stacked manner with the prism rows being orthogonal to each other are used only for the purpose of changing the optical path of the synthesized light.

(Object of invention)
The present invention has been made in view of the above problems, and by thinning the optical device by a combination of a prism sheet and a bandpass mirror, and by devising the incident direction of a plurality of light sources, the prism sheet performs a combining function. An object of the present invention is to provide a light source device that is inexpensive and can be reduced in size and thickness, has excellent photosynthetic performance, and has improved light utilization efficiency, and a display device including the light source device.

  The light source device of the present invention includes a plurality of light sources having different emission wavelengths, a prism sheet having a plurality of fine prisms on one surface and a flat surface on the other surface, and is provided on the incident surface side of the prism sheet. By arranging the plurality of light sources inclined at a predetermined angle, incident light from the plurality of light sources incident at a predetermined angle from the incident surface side of the prism sheet is mixed from the output surface side of the prism sheet. A light source device that outputs light, and a band pass mirror that transmits light in a wavelength region emitted from a corresponding light source and reflects light in another wavelength region is provided between each of the light sources and the prism sheet. It is characterized by.

  According to this, incident light from a light source incident at a predetermined angle from the incident surface side of the prism sheet is incident on one prism inclined surface or another prism inclined surface of the prism sheet, and is incident on one prism inclined surface. The light beam refracted and emitted from the exit surface of the prism sheet, the light beam incident on the other prism inclined surface is directed to the band pass mirror, reflected by the band pass mirror and incident on the incident surface of the prism sheet, The light is emitted from the emission surface of the prism sheet.

  Therefore, it is possible to provide a light source device in which the light beam is effectively used and the light beam utilization efficiency is improved. In addition, since the incident light from the plurality of light sources can be synthesized by the thin optical system using the prism sheet, it is possible to provide a light source device that is compact and thin in shape and optically has excellent optical synthesis performance.

  Incident light of each light source is incident toward a predetermined condensing point on the prism sheet.

  Each of the plurality of light sources includes a condensing lens in front of the light emitting surface.

  The lens may be a lens having different radii of curvature in the vertical and horizontal directions.

  According to the above configuration, incident light can be converted into parallel rays, and by using lenses having different radii of curvature in the vertical and horizontal directions, the spread of the light beam width of the outgoing light due to the incident light entering obliquely is suppressed. be able to.

  The band-pass mirror is a reflective film formed on the exit surface of the lens.

  The exit surface of the lens on which the reflective film is formed is a curved surface.

  According to the above configuration, the band-pass mirror can be formed on the exit surface of the lens, so there is no need to provide a special member for the band-pass mirror, the number of parts and the installation space are not required, and the band-pass depends on the lens shape. The light condensing property of the mirror can be adjusted.

  A plurality of the prism sheets are provided.

In this case, it is preferable that the prism sheet is composed of two prism sheets, and the two prism sheets are arranged so that each prism row intersects at a predetermined angle.

  According to this, a plurality of light sources are arranged dispersed in four zones formed by the intersection of each prism row in two stacked prism sheets, and the incident light of each light source is In this application, the light is incident along the center line of the prism sheet in the vicinity of the crossing angle of the prism rows, and all incident light of each light source is incident on a predetermined condensing point in the two stacked prism sheets. The light combining function can be performed on the two prism sheets arranged in a stacked manner by a peculiar incidence method of a plurality of light sources.

  When two prism sheets are stacked and arranged, each light source is distributed and arranged in four zones formed by the intersection of each prism row in the two stacked prism sheets.

  At this time, the incident light of each light source is incident along the vicinity of the center line of the intersection angle of each prism row in the two stacked prism sheets.

  Or the incident light of each said light source is incident toward the predetermined condensing point in two laminated | stacked prism sheets, It is characterized by the above-mentioned.

  As another aspect of the light source arrangement, each of the light sources is arranged point-symmetrically with respect to a predetermined condensing point in the two prism sheets.

  As another aspect of the further light source arrangement, the respective light sources are arranged symmetrically with respect to an axis passing through a predetermined condensing point in the two prism sheets.

  When a plurality of prism sheets are provided, or when two prism sheets are stacked, the plurality of light sources include R, G, and B LED light sources.

  Specifically, R, G, and B LED light sources are disposed at three locations on the incident surface side of the prism sheet, and a G / LED light source is disposed at one location.

  According to the above configuration, in the emission of white light by the color mixture of the R, G, and B LED light sources, the number of G / LED light sources that emit less light than the R and B LED light sources is increased. Good white light can be emitted.

  Alternatively, R, G, and B LED light sources are disposed at three locations on the incident surface side of the prism sheet, and BlueYAG / LED light sources are disposed at one location.

  Alternatively, R, G, and B LED light sources are disposed at three positions on the incident surface side of the prism sheet, and a reflecting mirror is disposed at one position.

  In particular, when two prism sheets are stacked, the light source is arranged in such a manner that R, G, and B LED light sources are arranged at three positions on the incident surface side of the two stacked prism sheets. The G • LED light source is disposed in the two, and the two G • LED light sources are disposed in adjacent zones.

  The prism sheet of the light source device is characterized in that an apex angle of the fine prism row is substantially a right angle.

  A liquid crystal display device including the light source device as a backlight of a liquid crystal cell is characterized in that a reflective polarization conversion element is provided between the liquid crystal cell and the light source device.

  According to this, the liquid crystal cell can be reused by reflecting invalid light toward the light source device, and the light use efficiency can be improved.

  In this case, the prism sheet has birefringence characteristics. According to this, it can be converted into light effective for the liquid crystal cell by the birefringence characteristic of the prism sheet.

  This effective conversion to light can also be achieved by disposing a retardation plate between the reflective polarization conversion element and the bandpass mirror.

  That is, the liquid crystal display device of the present invention can increase the light reuse rate by combining a reflective polarization conversion element and a prism sheet or retardation plate having birefringence characteristics as a backlight of the liquid crystal display device. Can provide a bright display device.

  As described above, in the light source device of the present invention, incident light from a plurality of light sources can be synthesized by a thin optical system using a prism sheet, and the light beam utilization efficiency can be enhanced by a bandpass mirror. It is possible to provide a light source device that is small in size and thin and optically excellent in photosynthesis performance, and a display device including the same.

  The light source device of the present embodiment includes a plurality of light sources having different emission wavelengths, and a prism sheet having a plurality of fine prisms on one surface and a flat surface on the other surface. The plurality of light sources are arranged at a predetermined angle on the incident surface side of the prism sheet.

The arrangement inclined at a predetermined angle is when incident light from a plurality of light sources incident at a predetermined angle from the incident surface side of the prism sheet is output as emitted light mixed from the output surface side of the prism sheet. The arrangement is such that the emitted light is emitted in the same direction, for example, directly above, and the light emitted from the light source is emitted toward a predetermined condensing point on the prism sheet.
For example, the refractive index of the prism sheet, the number of prism sheets to be arranged, the arrangement relationship of each prism sheet when a plurality of prism sheets are used, and any of the surface and plane of the prism sheet having fine prisms. It is determined by the entrance surface or the exit surface, or by the shape of the prism, the apex angle of the prism, or the like.

  Here, the light source device of the present embodiment is characterized in that a bandpass mirror that transmits light in a wavelength region emitted from a corresponding light source and reflects light in another wavelength region is provided between each light source and a prism sheet. It is in the point provided. For example, a bunt path mirror provided in a light source that emits red light transmits only light in a red wavelength region and reflects light in a wavelength region other than red.

Next, the operation of the light source device of this embodiment will be described. Light beams emitted from the respective light sources are incident at a predetermined angle from the incident surface side of the prism sheet via the band pass mirror. Of this incident light, the light beam incident on one prism slope of the prism sheet is refracted and emitted from the exit surface of the prism sheet, and is combined with the light beams of the other light sources to become combined light.
On the other hand, light rays incident on the other prism slopes are reflected from the prism sheet toward the bandpass mirror. Since the bunt path mirror provided in front of each light source reflects light in a wavelength region different from that of the corresponding light source, the light toward the bunt path mirror is reflected toward the prism sheet. The reflected light beam is incident on the incident surface of the prism sheet and emitted from the emission surface of the prism sheet, and is emitted as combined light together with the light incident on one slope. Thus, the light reflected by the incident surface of the prism sheet is again emitted toward the prism sheet and emitted from the emission surface. That is, conventionally, the invalid light reflected by the prism sheet can be converted into effective light, so that the light beam can be effectively used and the light source device can be provided with improved light beam utilization efficiency. Furthermore, since the light source device of the present embodiment can synthesize incident light from a plurality of light sources by an optical system with a thin configuration using a prism sheet, the light source is compact and thin in shape and has excellent optical synthesis performance. Equipment can be provided.

  This light source device will be described in detail using an example.

(First embodiment)
Embodiment 1 of the light source device of the present invention will be described below with reference to the drawings. 1 to 13 show a light source device according to a first embodiment of the present invention. FIG. 1 is an external perspective view of the light source device, and FIG. 2 is a top view and a side view showing the configuration of two prism sheets. FIG. 3 is a plan view showing the relationship between two prism sheets and a plurality of light sources.

  As shown in FIG. 1, the light source device 10 of the present embodiment includes two stacked prism sheets PS1 and PS2, and a light source K1 disposed at a predetermined angle on the incident surface side of the prism sheets PS1 and PS2. , K2, K3, and K4. Light emitted from the light sources K1, K2, K3, and K4 is incident on the incident surface of the prism sheet PS1, exits from the exit surface of the prism sheet PS2, and enters a liquid crystal display element (not shown). Yes.

  Each of the light sources K1, K2, K3, and K4 includes a light emitting diode (hereinafter referred to as an LED) 1 having a different emission color, a condenser lens 2 that collects the light from the light sources K1, K2, K3, and K4, and the LED 1 A case 3 for housing the optical lens 2 is provided. The light source K1 is provided with a red LED 1r (hereinafter referred to as R • LED), the light sources K2 and K3 are provided with a green LED 1g (hereinafter referred to as G • LED), and the light source K4 is a blue LED 1b (hereinafter referred to as B • LED). .) Is provided.

  Next, the arrangement relationship between the two prism sheets PS1 and PS2 and the four light sources K1, K2, K3, and K4 will be described with reference to FIGS. FIG. 2 is a top view and a side view showing the configuration of the two prism sheets PS1 and PS2, showing a top view of the prism sheets PS1 and PS2 stacked in the center, and a side view seen from the X-axis direction on the left side of the figure. The side view seen from the Y-axis direction is shown on the lower side of the figure. FIG. 3 shows the positional relationship of the four light sources K1, K2, K3, and K4 with respect to the top view of the stacked prism sheets PS1 and PS2 shown in FIG.

  As shown in FIG. 2, each of the prism sheets PS1 and PS2 has a plane as an entrance surface and a prism surface having a prism as an exit surface. In this embodiment, the ridges of symmetrical prism rows are formed in parallel, the pitch of each prism row is 1 μm to 100 μm, the prism apex angle is substantially right angle, and the refractive index n is 1.49 (PMMA). ) Made of prism sheet.

  The prism sheets PS1 and PS2 are stacked by intersecting prism rows substantially vertically. This crossing angle is determined by the material and shape of the prism sheet. In FIG. 2, the axis parallel to the prism row of the prism sheet PS1 is taken as the Y axis, and the axis parallel to the prism row of the prism sheet PS2 is taken as the X axis. The solid line parallel to the X-axis indicates the top and valley lines in the prism row of the upper prism sheet PS2, and the dotted line parallel to the Y-axis indicates the top and valley in the prism row of the lower prism sheet PS1. The solid line and the dotted line constitute an orthogonal grid. Although not shown, an axis perpendicular to the XY plane is defined as the Z axis.

  Next, the arrangement relationship of the four light sources K1, K2, K3, and K4 with respect to the two prism sheets PS1 and PS2 will be described with reference to FIG. Four zones formed by the intersection of the respective prism rows of the two prism sheets PS1 and PS2, that is, four zones S1 and S2 obtained by dividing the plane of the prism sheets PS1 and PS2 into the X axis and the Y axis, Four light sources K1, K2, K3, and K4 are distributed and arranged in S3 and S4. Accordingly, the incident light P1 emitted from the light source K1, the incident light P2 emitted from the light source K2, the incident light P3 emitted from the light source K3, and the incident light P4 emitted from the light source K4 are laminated two prism sheets PS1. , PS2 are incident along the vicinity of the center lines N, M of the crossing angles of the prism rows, and are intensively incident toward a predetermined focal point Po of the two prism sheets PS1, PS2. It has become. In this embodiment, a predetermined condensing point Po of the two prism sheets PS1 and PS2 is set as the upper center point of the upper prism sheet PS2.

As a result, as shown in FIG. 3, the light source K1, the light source K4, the light source K2, and the light source K3 are arranged at positions that are point-symmetric with respect to the condensing point Po, as shown in FIG. The light source K3 and the light source K2 and the light source K4 are arranged at positions symmetrical with respect to the X axis passing through the condensing point Po. The angles from the X axis of each light source are all the same, and this angle is determined by the refractive index and the prism apex angle depending on the material of the two prism sheets PS1 and PS2. In this embodiment, when viewed from the XY plane, all the light sources K1, K2, K3, and K4 are arranged at the same angle of 43.5 ° from the X axis. This is because the prism angle has +-, and therefore, the direction of the light beam differs in four directions depending on the contact surface, but the four directions are the same when viewed from the angle with the normal of the surface. That is, even if the directions of the light beams are different, the angles are the same. In order to emit the emitted light directly upward with the refractive index n of the prism sheets PS1 and PS2 being 1.49 and the prism apex angle being 90 °, the incident light Are incident at the same angle of ± 43.5 ° with respect to the X axis.
For the same reason, when viewed from the XZ plane, as shown in FIG. 12, all the light sources K1, K2, K3, K4 are arranged at the same angle of 38.4 ° from the Z axis.

  Next, the bunt path mirror 5, which is a feature of the present embodiment, will be described with reference to FIG. The vant-pass mirror 5 is provided between each light source K1, K2, K3, K4 and the prism sheet PS1, transmits light in the wavelength region emitted from the LED of each corresponding light source, and transmits light in the other wavelength region. It is a reflective mirror. In front of the light emitting surface of the light source K1, there is provided a band pass mirror 5r that transmits the wavelength region of red light (hereinafter referred to as R light) emitted from the corresponding R • LED 1r and reflects rays in other wavelength regions. Yes. In front of the light emitting surfaces of the light sources K2 and K3, there is provided a band pass mirror 5g that transmits the wavelength region of green light (hereinafter referred to as G light) emitted from the corresponding G • LED 1g and reflects light rays in other wavelength regions. It has been. In front of the light emitting surface of the light source K4, a band-pass mirror 5b that transmits only blue light (hereinafter referred to as B light) emitted from the B LED 1b and reflects light in other wavelength regions is provided. The bunt path mirror 5 may be provided by forming a reflective film on the exit surface of the condenser lens 2 provided in each light source.

  The incident conditions from each light source on the two prism sheets PS1 and PS2 stacked in the present invention will be described in detail later, but a basic photosynthesis (color mixing) operation will be described with reference to FIG. Here, one prism slope constituting the prism face of the prism sheet PS1 is L1, the other prism slope is L2, one prism slope constituting the prism face of the prism sheet PS2 is U1, and the other prism slope is U2. explain.

  Incident light from each light source arranged at the above position is incident obliquely toward the prism sheet PS1. That is, the light source device 10 makes incident light from each light source obliquely incident on the prism surface and obliquely uses the prism surface so that incident light from four directions can be refracted under the same conditions. Yes. As shown in FIG. 2, the incident light P1 emitted from the light source K1 passes through the prism slope L1 of the prism sheet PS1 and the prism slope U2 of the prism sheet PS2, and becomes emitted light. Incident light P2 emitted from the light source K2 passes through the prism inclined surface L2 of the prism sheet PS1 and the prism inclined surface U2 of the prism sheet PS2, and becomes emitted light. Incident light P3 emitted from the light source K3 passes through the prism inclined surface L1 of the prism sheet PS1 and the prism inclined surface U1 of the prism sheet PS2, and becomes emitted light. Incident light P4 emitted from the light source K4 passes through the prism inclined surface L2 of the prism sheet PS1 and the prism inclined surface U1 of the prism sheet PS2, and becomes emitted light.

  Incident light radiated from each light source having a wide area is incident on each inclined surface of a large number of prism rows formed on the two prism sheets PS1 and PS2, and refracts radiation. The pitch of each prism row is Since it is a fine pitch of 1 μm to 100 μm, it is not visually recognized as separate emitted light but is recognized as a single synthesized emitted light. Accordingly, when the light source K1 is R light, the light source K4 is B light, and the light sources K2 and K3 are G light, white light Pw in which R light, B light, and G light are mixed is emitted.

  Next, the optical path of the incident light from each light source with respect to the two prism sheets PS1 and PS2 will be described in detail with reference to FIGS. FIG. 4 is a partially enlarged view of the prism sheet PS2 shown in FIG. 2, and shows optical paths of incident lights that pass through the prism sheet PS2 while being refracted. FIG. 5 is a partially enlarged view of the prism sheet PS1 shown in FIG. 2, and shows the optical path of each incident light passing through the prism sheet PS1 while being refracted.

  In general, the method for obtaining the optical path of the prism is as follows. That is, when incident light is input from the incident surface side of one prism sheet and an emitted light is obtained in a direction directly above the prism sheet, a method of tracing the optical path of the light in the opposite direction is performed. For example, in the case of the prism sheet PS2 that is the upper prism sheet of FIG. 4, it is necessary to first emit the mixed white light Pw as the emitted light in the upward direction, so that the emitted light from each light source is reversed. The light is incident on the prism sheet from directly above the prism sheet. At this time, the Snell's law is applied to the incident light according to the difference in refractive index between air and acrylic, and a predetermined refraction angle is given at the boundary surface and proceeds in the prism sheet. Further, when the light is emitted from the incident surface of the prism sheet PS2 into the air, a predetermined refraction angle according to Snell's law is given to the boundary surface and the light is emitted into the air.

  When the prism sheet PS2 is used as an actual light source device, if the incident light from each light source is incident at the angle of the emitted light emitted from the incident surface of the prism sheet PS2 into the air based on the above result, the prism sheet is used. The inner light travels at the same predetermined refraction angle, and outgoing light can be obtained in a direction directly above the outgoing surface of the prism sheet PS2.

Therefore, the light incident on the prism sheet from each light source of the light source device 10 to which the above-described method for obtaining the optical path is applied has an optical path as shown in FIGS.
In the case of the upper prism sheet PS2 shown in FIG. 4, the YZ plane is shown, and the incident light P1 from the light source K1 and the incident light P2 from the light source K2 shown in FIG. The light passing through U2 and the incident light P3 from the light source K3 and the incident light P4 from the light source K4 pass through the prism slope U1 on the right side of the prism sheet PS2 and are emitted in the direction immediately above. Accordingly, the incident light P1 and P2 are inclined to the left and the incident light P3 and P4 are inclined right and the incident direction is opposite, but the incident light travels at the same angle. It becomes an angle.

  At this time, the angles θ2 and γ2 with respect to the boundary surface normal (indicated by dotted lines) of the incident surface of the prism sheet PS2 in each incident light, and the boundary surface normals (indicated by dotted lines) of the prism slope of the prism sheet PS2 in each outgoing light And angles β2 and α2 are all the same. These angles use acrylic having a refractive index of 1.49, and in the prism sheet PS2 having a prism apex angle of 90 °, α2 = 45.0 °, β2 = 28.3 °, γ2 = 16.7 °, θ2 = 25.3 °.

  Next, in the case of the lower prism sheet PS1 shown in FIG. 5, the X axis-Z axis plane is shown, and the angle with the boundary surface normal (shown by the dotted line) of the incident surface of the prism sheet PS1 in each incident light. The angles β1 and α1 between θ1 and γ1 and the boundary normal line (shown by dotted lines) of the prism slope of the prism sheet PS1 in each outgoing light are all the same. These angles use acrylic having a refractive index of 1.49, and in the prism sheet PS1 having a prism apex angle of 90 °, α1 = 50.3 °, β1 = 31.1 °, γ1 = 24.6 °, θ1 = 38.4 °. In addition, although each output light P1-P4 from prism sheet PS1 in FIG. 5 is shown in figure so that it may radiate | emit in the directly upward direction on drawing, these output light has an inclination angle in the orthogonal | vertical direction with respect to a paper surface. This is because the tilt is not visible in the XZ plane of FIG. That is, the outgoing lights P1 and P2 have an inclination angle toward the back of the paper surface, and the outgoing lights P3 and P4 have an inclination angle toward the near side of the paper surface.

  That is, the inclination directions of the outgoing lights P1 to P4 are reversed, but the inclination angles are all the same, and the inclination angle is 25.3 ° with respect to the Z axis. The inclination is 50.3 ° with reference to the boundary normal of the prism slope. Accordingly, each of the outgoing lights P1 to P4 of the lower prism sheet PS1 having an inclination of 25.3 ° with respect to the Z axis is 25.3 ° with respect to the boundary normal to the lower surface of the upper prism sheet PS2. Incident light having an incident angle, that is, an incident angle of θ2, is refracted inside the prism sheet PS2 and is emitted in a direction directly above the upper surface. 4 and 5 show a state in which the incident light P1 and the incident light P2 and the incident light P3 and the incident light P4 are incident on different prism inclined surfaces for easy understanding. Are simultaneously incident on the same prism slope and synthesized.

  FIG. 6 schematically shows a traveling state of an optical path through which incident light continuously passes through two prism sheets PS1 and PS2, and only incident light P1 is representatively shown. That is, from the point f1 of the incident surface of the lower prism sheet PS1, the incident light P1 is at an angle in the XY plane direction of 43.5 ° from the X axis with respect to the prism row and 38.4 from the boundary normal to the lower surface. When incident at an angle (θ1) in the Z-axis direction of °, after being refracted in the prism sheet PS1, it is emitted into the air from the point f2 of the prism slope L1. The emitted incident light P1 is incident at an angle (θ2) in the Z-axis direction of 25.3 ° from the boundary surface normal from the point f3 of the incident surface of the upper prism sheet PS2, and is refracted in the prism sheet PS2. After that, the light is emitted into the air in the direction directly above the point f4 of the prism slope U2. Although not shown, incident light P2, P3, and P4 are also emitted in the same manner according to the optical paths shown in FIGS. Note that FIG. 6 shows the two prism sheets PS1 and PS2 a little apart from each other for easy understanding, and corresponds to the X axis as a virtual axis for easy understanding of the arrangement position of the prism sheet PS2. An X ′ axis is provided.

  In this way, incident light is incident on each prism row in the two prism sheets arranged in a stacked manner by crossing the prism rows from an oblique direction having an angle in the XY plane direction and an angle in the Z-axis direction. The prism slope is used diagonally. As a result, under the same optical conditions, incident light from four directions can be simultaneously incident and combined, and the prism sheet PS2 can be synthesized as a single white light Pw that combines the R light, the G light, and the B light. The light is emitted in a direction directly above the emission surface.

  By the way, in the light source device 10, among the light rays incident on the prism sheet from each light source next, there are effective rays emitted to the emission surface side of the prism sheet and invalid rays not emitted to the emission surface side of the prism sheet. The reason why the invalid light beam is generated will be described with reference to FIG. FIG. 7 is a partial cross-sectional view of the lower prism sheet PS1. As an example, the incident light P4 from the light source K4 in FIG. 5 is incident on the prism surface of the prism sheet PS1. As shown in FIG. 7, the incident light P4 from the light source K4 is left inclined incident light, and the light incident on the left inclined prism inclined surface L2 of the prism sheet PS1 is emitted as effective light. An effective prism slope is formed, and the right sloped prism slope L1 is a non-effective prism slope.

  When incident light P4 having a certain width from the light source K4 is incident from the incident surface side of the prism sheet PS1 based on the above premise, most of the light beams indicated by the black arrows pass through the prism inclined surface L2 which is an effective prism inclined surface as effective light P4a. Emitted. However, part of the incident light indicated by the white arrow is reflected by the prism inclined surface L1, which is an ineffective prism inclined surface, travels through the prism, refracts and exits the prism inclined surface L2. Further, the light travels in the air, refracts by being hit by the prism inclined surface L1 of the adjacent prism, and again travels in the prism and is reflected by hitting the prism inclined surface L2, thereby being emitted as ineffective light P4b to the incident surface side of the prism sheet PS1. The

  That is, when the effective light indicated by the black arrow hits the prism slope L2, the light ray is refracted and transmitted because it hits at an angle smaller than the critical angle. On the other hand, when the ineffective light indicated by the white arrow hits the prism slope L1, the light beam is reflected because it hits at an angle larger than the critical angle. The ineffective light reflected by the prism inclined surface L1 is then transmitted and reflected according to the relationship with the critical angle, and proceeds in the direction opposite to that at the time of incidence. In the case of the prism sheet PS1 in this embodiment, the optical path of the ineffective light is the same as the incident angle to the lower surface of the first prism sheet PS1 and the outgoing angle from the lower surface of the last prism sheet PS1.

  Next, the principle of converting the ineffective light into effective light will be described with reference to FIG. FIG. 8 is a partial sectional view of a prism sheet and a light source showing a configuration for converting ineffective light emitted from the light source K4 into effective light by the band-pass mirror 5r of the light source K1, and in FIG. Are arranged at opposite positions as shown in FIG. As shown in FIG. 7, the emitted light P4 from the light source K4 includes effective light P4a and non-effective light P4b, and the effective light P4a indicated by the black arrow passes directly through the prism slope L2 of the lower prism sheet PS1. Emitted in the direction. Further, the ineffective light P4b indicated by the white arrow enters the prism inclined surface L1, is repeatedly reflected and refracted, and is emitted to the lower surface side of the prism sheet PS1.

  What should be noted here is the traveling direction of the ineffective light P4b. As described with reference to FIG. 7, the ineffective light P4b has the same angle of incidence on the incident surface of the first prism sheet PS1 and the same angle of emission from the incident surface of the last prism sheet PS1. As a result, the ineffective light P4b emitted from the incident surface side of the prism sheet PS1 is reflected by the band-pass mirror 5r of the light source K1 disposed at the opposite position, thereby being converted into effective light P4a. In other words, the reflected effective light P4a is incident on the prism sheet PS1 from the incident surface side as incident light having a right inclination, and passes through the prism inclined surface L1 and is emitted in the directly upward direction. This ineffective light P4b can be converted into effective light P4a because the incident angle of the optical path of the ineffective light P4b to the lower surface of the first prism sheet PS1 and the exit angle from the lower surface of the last prism sheet PS1 are the same. It is.

  Further, the effective light P4a reflected by the bandpass mirror 5r can be incident on the prism inclined surface L1 of the prism sheet PS1 with respect to the size of the prism, with respect to the size of the bandpass mirror and the distance from the prism surface to the bandpass mirror. This is because it is significantly different. In other words, the pitch of the prism row is as fine as 1 μm to 100 μm, but the size of the bandpass mirror and the distance from the prism are 5 to 20 mm, which are different by about two digits. There will be some fluctuation due to the influence of accuracy. Therefore, the effective light P4a reflected by the bandpass mirror 5r does not return to the original position accurately, but returns to the prism inclined surface L1 having a wide incident angle with a slight fluctuation. As a result, most of the reflected light passes through the prism slope L1 and is emitted in the upward direction, so that the ineffective light is converted into effective light.

  Next, a configuration for converting the non-effective light P4b into effective light P4a will be described with reference to FIGS. FIG. 9 is a sectional view of a prism sheet and a light source showing a configuration for converting ineffective light P4b of the emitted light P4 of the light source K4 into effective light P4a by the bandpass mirror 5r of the light source K1, and FIG. It is sectional drawing of the prism sheet and light source which show the structure which converts the non-effective light P1b into the effective light P1a with the band pass mirror 5b of the light source K4. 9 and 10, thick arrows indicate a light bundle having a predetermined area, and effective light is indicated by white arrows and ineffective light is indicated by black arrows. In FIG. 9, the light source K4 and the light source K1 are disposed at the opposing positions as described in FIG. 8, and the emitted light P4 from the light source K4 includes effective light P4a and ineffective light P4b. The beam bundle of effective light P4a indicated by a white arrow passes through a large number of prism inclined surfaces L2 of the lower prism sheet PS1 and is emitted directly upward, and the beam bundle of non-effective light P4b indicated by a black arrow indicates a large number of beam bundles. After entering the prism slope L1, it is reflected and refracted repeatedly and emitted to the exit surface side of the prism sheet PS1.

  The beam bundle of the ineffective light P4b emitted from the emission side of the prism sheet PS1 is converted into the beam bundle of the effective light P4a by being reflected by the bandpass mirror 5r of the light source K1 disposed at the opposite position. Is done. That is, the reflected light beam of the effective light P4a is incident on the lower surface side of the prism sheet PS1 as right-angled incident light, passes through a large number of prism inclined surfaces L1, and is emitted directly upward.

  The role of the bandpass mirror in this conversion operation is as follows. First, since the band-pass mirror 5b in the light source K4 passes only light in the wavelength region of B light and reflects light in the other wavelength regions, the emitted light P4 of B light emitted from the light source K4 is the band-pass mirror 5b. And enters the prism sheet PS1. Further, since the bandpass mirror 5r in the light source K1 transmits only the light in the wavelength region of the R light and reflects the light in the other wavelength region, the incident light P4b of the B light incident from the prism sheet PS1 is reflected and is reflected in the prism sheet PS1. Will re-enter the beam. That is, the band-pass mirror 5 has a function of converting the ineffective light of the emitted light from the other light sources into effective light by passing the emitted light from the corresponding light sources and reflecting the emitted light from the other light sources. I have it.

  FIG. 10 is a cross-sectional view of the prism sheet and the light source showing the configuration for converting the ineffective light P1b of the emitted light P1 of the light source K1 into the effective light P1a by the bandpass mirror 5b of the light source K4. This shows the relationship. That is, the outgoing light P1 emitted from the light source K1 includes effective light P1a and ineffective light P1b. The light beam of the effective light P1a indicated by the white arrow passes through a large number of prism inclined surfaces L1 of the lower prism sheet PS1 and is emitted directly upward, and the light beam of the non-effective light P1b indicated by the black arrow indicates a large number of light beams. After entering the prism slope L2, it is repeatedly reflected and refracted and emitted to the incident surface side of the prism sheet PS1.

  The beam bundle of the non-effective light P1b emitted from the incident surface side of the prism sheet PS1 is reflected by the bandpass mirror 5b of the light source K4 arranged at the opposite position to be converted into the beam bundle of the effective light P1a. Converted. That is, the reflected light beam of the effective light P1a is incident on the lower surface side of the prism sheet PS1 as incident light having a left inclination, passes through a large number of prism inclined surfaces L2, and is emitted directly upward.

  The role of the bandpass mirror in this conversion operation is as follows. First, since the bandpass mirror 5r in the light source K1 passes only light rays in the wavelength region of R light and reflects light rays in other wavelength regions, the emission light P1 of R light emitted from the light source K1 is the bandpass mirror 5r. And enters the prism sheet PS1. Further, since the bandpass mirror 5b in the light source K4 passes only light in the wavelength region of B light and reflects light in the other wavelength regions, the incident light P1b of R light incident from the prism sheet PS1 is reflected and is reflected in the prism sheet PS1. Will re-enter the beam.

  That is, the light source K4 and the light source K1 have a function of converting each other's non-effective light into effective light by the respective band pass mirrors. These two conversion operations are performed simultaneously. Furthermore, since the light sources K3 and K2 arranged opposite to each other perform the same interchange function, the ineffective light of all the light sources is converted into effective light.

  This mutual exchange function is not performed only by the prism sheet PS1, but also by the upper prism sheet PS2. That is, when the effective light P4a and P1a emitted from the lower prism sheet PS1 are also incident from the incident surface side of the prism sheet PS2, they are divided into ineffective light and effective light as in the prism sheet PS1. For example, the light P4a emitted from the light source K4 shown in FIG. 9 will be described. When the light P4a emitted from the prism sheet PS1 is incident from the lower surface side of the prism sheet PS2, it is inclined right as shown by the incident light P4 in FIG. Therefore, the prism slope U1 in the prism sheet PS2 becomes an effective prism slope, and the prism slope U2 becomes an ineffective prism slope.

  As a result, most of the incident light P4a incident on the prism sheet PS2 passes through the prism inclined surface U2 and is emitted in the directly upward direction. However, the light beam hitting the prism inclined surface U1 is repeatedly reflected and refracted to enter the prism sheet PS2. The light is emitted from the surface side and returned to the prism sheet PS1. The light beam incident on the prism sheet PS1 from the prism sheet PS2 passes through the prism sheet PS1 after being divided into two parts in order to equally hit the two prism slopes of the prism sheet PS1, that is, the prism slope L1 and the prism slope L2. Reflected by the bandpass mirror of each light source. Then, after being converted from the ineffective light to the effective light by this reflection, the light passes through the prism sheets PS1 and PS2 again and is emitted directly upward. As described above, the above interchange function is performed simultaneously for the light rays emitted from all the light sources.

  FIG. 11 is a plan view showing the relationship between the incident light from the light source K4 shown in FIG. 9 and the reflected light from the two prism sheets PS1 and PS2 stacked on the XY plane. In FIG. 11, the four zones with respect to the XY axes correspond to the light source arrangement shown in FIGS. 2 and 3, P4 is the incident light from the light source K4 in zone S4, P4b1 is the reflected light toward zone S1, and the prism The amount of light is the sum of half reflected light from the sheet PS1 and half reflected light from the prism sheet PS2. Further, the incident light P4b2 is reflected light toward the zone S2, and is half the amount of light reflected from the prism sheet PS2. Further, in the case of incident light from the light source K4, there is no reflected light toward the zone S3, and the light beam direction is indicated by a dotted line.

  In the XY plane, all the light beam directions are 43.5 ° from the X axis, and most of the incident light P4 from the light quantity K4 is emitted directly above. A portion of the reflected light is reflected and refracted by the prism sheet PS1 and travels toward the zone S1, and the reflected light that is reflected and refracted by the prism sheet PS2 is divided into two by the prism surface of the prism sheet PS1 and halved to the zones S1 and S2. I will go. Although the above description has been made with respect to the light emitted from the light source K4 in the zone S4, the same operation is performed for the light emitted from each light source in the zones S1, S2, and S3.

  Next, the spread of light rays in the light source device of the present invention will be described. FIG. 12 is a side view showing the spread of rays when incident light P1 and P4 are incident on the lower surface of the lower prism sheet PS1. When this light source device is an illuminating device, the direction parallel to the Z axis is the outgoing optical axis of the illuminating device, and the direction inclined by θ1 (38.4 °) from the Z axis is the incident optical axis from the light sources K1 and K4. The horizontal axis is an axis rotated 43.5 ° from the X axis of the prism sheet PS1. Considering a case where incident light P1 having a light flux width H from the light source K1 is incident on the lower surface of the prism sheet PS1, a light beam having a width is incident from an oblique direction toward the horizontal plane, and therefore the width of the light beam on the incident surface is It spreads and is emitted as a light beam having a width of 1.28H. Further, the incident light P4 from the light source K4 is also incident from a symmetrical position under the same conditions as the incident light P1 of the light source K1, and has the same spread.

  FIG. 13 is a plan view showing the spread of light rays when incident light is incident from four directions onto the two prism sheets PS1 and PS2 stacked in the light source device shown in FIG. 12 by four light sources K1 to K4. It is. In FIG. 13, the dotted line is an axis rotated by 43.5 ° from the X axis. S14 is illumination light composed of the light sources K1 and K4, and S23 is illumination light composed of the light sources K2 and K3. Each of the short axes has a width H of incident light and the long axis has a width of 1.28H of outgoing light. It is oval. The two elliptical illumination lights S14 and S23 are overlapped with a common center point. As a result, the two elliptical overlapping portions indicated by diagonal lines are the combined illumination light S of the four light sources K1 to K4. Available as That is, when the four light sources K1 to K4 are R light, B light, G light, and G light, they can be used as white light Pw in which the illumination light S is mixed.

(Second embodiment)
Next, a light source device according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 14 is a side view showing the spread of light when incident light P1 and P4 are incident from the light sources K1 and K4 on the lower surface of the lower prism sheet PS1, and corresponds to FIG. 12 in the light source device of the first embodiment. Is. Therefore, the same elements as those in the light source device of FIG. The light source device of FIG. 14 differs from the light source device of FIG. 12 in that a lens having a different radius of curvature is provided as an optical device in the optical path between the light source K1 and the light source K4 and the lower surface of the prism sheet PS1. In this embodiment, the anamorphic lens 12 is provided.

  Next, the spreading state of the light beam will be described with reference to FIGS. Considering the case where incident light P1 having a circular shape with a diameter H as shown in FIG. 15A is radiated from the light source K1, the incident light P1 passes through the anamorphic lens 12 to be vertically and horizontally. By receiving different optical changes, the incident light P1 becomes an elliptical light beam shape having a major axis in the horizontal direction H and a minor axis in the vertical direction Hs as shown in FIG. Incident on the lower surface of the sheet PS1. As a result, the incident light P1 incident from the oblique direction toward the horizontal plane has a light beam width Hs widened to H by the increase in the vertical width of the light beam on the incident surface, and the diameter shown in FIG. The light beam having a circular shape is restored and emitted. That is, by using the anamorphic lens 12 to reduce the incident light P1 in advance by an amount corresponding to the incident oblique light, outgoing light having the same shape as the incident light is obtained.

  FIG. 16 shows a light source device having the anamorphic lens 12 shown in FIG. 14, in which incident light is incident on four stacked prism sheets PS1 and PS2 from four directions by four light sources K1 to K4. It is a top view which shows a breadth, and respond | corresponds to FIG. 13 in the light source device of 1st Example. 16 differs from FIG. 13 in that both the illumination light S14 composed of the light sources K1 and K4 and the illumination light S23 composed of the light sources K2 and K3 have a circular shape with a diameter of H. It becomes a circle with a diameter of H. Accordingly, the illumination lights S14, S23, and S are all in one circle indicated by diagonal lines. That is, since the light source device in the second embodiment can use all incident light as illumination light, it becomes an efficient illumination device. In the light source device of FIG. 14, the configuration in which the anamorphic lens 12 is provided in the optical path of the light source device of the first embodiment shown in FIG. 7 is not limited to this, and is provided in each light source K. An anamorphic lens 12 may be provided instead of the condensing lens 2. In addition, a reflective film may be formed on the exit surface of the anamorphic lens 12 to provide the function of a band pass mirror.

(Third embodiment)
Next, a light source device according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 17 is a perspective view of the light source device according to the third embodiment, and the basic configuration is the same as that of the light source device according to the first embodiment shown in FIG. Omitted. In FIG. 17, reference numeral 20 denotes a light source device, which is different from the light source device 10 of FIG. 1 in that a BlueYAG • LED 1 by is arranged instead of G • LED as the light emitting means of the light source K 3.

  Next, the configuration of the BlueYAG • LED1by will be described. FIG. 18 is a cross-sectional view of a BlueYAG • LED which is a phosphor-mixed white light emitting device. Reference numeral 1by denotes a BlueYAG • LED, and a B • LED 1b is connected to a substrate 33 having electrodes 31 and 32, and the B • LED 1b is molded with a transparent resin 36 mixed with YAG-based fluorescent particles 35.

  In the operation of the BlueYAG • LED 1by, when a drive voltage is applied to the electrodes 31 and 32, the B • LED 1b emits blue light Pb. When the blue light Pb collides with the fluorescent particles 35 mixed in the transparent resin 36, the fluorescent particles 35 are excited to perform wavelength conversion, and yellow light Pe is emitted from the fluorescent particles 35. As a result, the blue YAG • LED 1by mixes the blue light Pb emitted from the B • LED 1b and output without colliding with the fluorescent particles 35, and the yellow light Pe that has collided with the fluorescent particles 35 and is wavelength-converted. The fluorescent white light Pwy is emitted.

  As shown in FIG. 17, the light source device 20 performs color mixing by arranging R / LED 1r for the light source K1, G / LED 1g for the light source K2, BlueYAG / LED 1by for the light source K3, and B / LED 1b for the light source K4. Therefore, in addition to the color mixture by the R, G, and B LEDs, the bright white light Pwy by the BlueYAG • LED1by is mixed, thereby realizing a bright illumination device with good color rendering.

(Fourth embodiment)
Next, a light source device according to a fourth embodiment of the present invention will be described with reference to FIGS. 19 is a perspective view of a light source device according to the fourth embodiment of the present invention, and FIG. 20 is a relationship between incident light from each light source similar to FIG. 11 and reflected light from two stacked prism sheets PS1 and PS2. FIG. 20A shows incident light from the light source K3 in the zone S3, FIG. 20B shows incident light from the light source K4 in the zone S4, and FIG. Represents incident light from the light source K1 in the zone S1, and (d) represents incident light from the light source K2 in the zone S2. FIG. 21 shows the relationship between the incident light from the light source K3 and the reflected light from the two stacked prism sheets PS1 and PS2 in the XY plane in the light source device 10 of the first embodiment of the present invention shown in FIG. FIG. 22 is a plan view showing the relationship between the incident light from the light source K3 and the reflected light from the two prism sheets PS1 and PS2 stacked in the light source device of the fourth embodiment of the present invention shown in FIG. It is a top view shown by an XY plane.

  In FIG. 19, reference numeral 30 denotes a light source device, and the basic configuration is the same as that of the light source device 10 of FIG. 1. The light source device 30 is different from the light source device 10 in that the light source K2 and the light source K4 are replaced. In the light source device 10, the light source K4 is disposed in the zone S4 and the light source K2 is disposed in the zone S2. In the apparatus 30, the light source K2 is arranged in the zone S4, and the light source K4 is arranged in the zone S2. By doing so, the conversion efficiency of ineffective light, which is reflected light, into effective light is increased.

  The reason will be described below. FIG. 20 is a plan view showing the relationship between incident light from each light source and reflected light from the two stacked prism sheets PS1 and PS2 in the XY plane, and FIG. 20A shows the zone S3. (B) shows the incident light from the light source K4 in the zone S4, (c) shows the incident light from the light source K1 in the zone S1, and (d) shows the light source in the zone S2. It shows the incident light from K2. That is, as described in FIG. 11, the relationship between the reflected light from the two prism sheets PS1 and PS2 with respect to the incident light from each light source is that a large amount of reflected light is present in the zone facing the zone where the light source exists. As described above, a small amount of reflected light is directed to the other zone and there is no reflected light in the remaining zones. The zones where no reflected light exists with respect to the incident light from each zone are as shown in FIGS. 20A to 20D, and as shown in FIG. 20A, the incident light from the light source K3 in the zone S3 In contrast, no reflected light is present in the zone S4, and no incident light is present in the zone S3 with respect to incident light from the light source K4 in the zone S4 in (b), and the light source K1 in the zone S1 in (c). It can be seen that there is no reflected light in the zone S2 with respect to the incident light from, and no reflected light in the zone S1 with respect to the incident light from the light source K2 in the zone S2 in (d).

  FIG. 21 is a plan view showing the relationship between incident light from the light source K3 in the light source device 10 of the first embodiment shown in FIG. 1 and reflected light from the two stacked prism sheets PS1 and PS2 in the XY plane. In view of the direction of the reflected light shown in FIG. 20, the conversion efficiency of ineffective light, which is reflected light, into effective light is examined. In other words, the light source device 10 emits R, B, and G light emitted in a mixed color, and the current LED emits light from the G / LED compared to the R / LED and B / LED. Since there are few G * LEDs, as shown in FIG. 21, R * LED is arranged in zone S1, G * LED is arranged in zone S2, G * LED is arranged in zone S3, and B * LED is arranged in zone S4.

In this configuration, since two G • LEDs are arranged in the opposing zones S2 and S3, the arrangement is optimal as a color mixing condition. However, in terms of conversion efficiency from ineffective light that is reflected light to effective light. From the point of view, it decreases slightly. That is, as described above, each light source is provided with a band-pass mirror, but the light source K2 having two G • LEDs and the light source K3 transmit the same wavelength region of G light as the band-pass mirror. A path mirror 5g (shown by diagonal lines) is provided. As a result, the reflected light P3b of the incident light P3 emitted from the light source K3 is directed to the zone S2, but the bandpass mirror 5g provided in the light source K2 cannot reflect P3b which is G light and transmits it. End up. As a result, the conversion efficiency is reduced by the amount that the reflected light P3b is reflected and cannot be converted into effective light.

  FIG. 22 is a plan view showing the relationship between incident light from the light source K3 and reflected light from the two stacked prism sheets PS1 and PS2 in the XY plane in the light source device 30 of the fourth embodiment shown in FIG. In the light source device 30, the light source K2 having G · LED is arranged in the zone S4, and the light source K4 having B · LED is arranged in the zone S2. As a result, the reflected light P3b of the incident light P3 emitted from the light source K3 is directed to the zone S2, but the light source K4 is disposed in the zone S2, and is reflected by the bandpass mirror 5b provided in the light source K4 and effective. Converted to light. That is, the light source K2 provided with the band-pass mirror 5g that transmits the reflected light P3b can be arranged in the zone S4 where the reflected light of the light source K3 does not exist, so that the conversion efficiency to effective light can be increased.

  As described above, the light emission sources of the same color may be arranged in adjacent zones where the reflected light does not exist without being arranged in the opposed zones. The arrangement of the light emission sources of the same color is the zone shown in FIG. It can be seen that other zones than S3 and S4 may be arranged in the zones S1 and S2.

(5th Example)
Next, a light source device according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 23 is a perspective view of a light source device according to a fifth embodiment of the present invention. In FIG. 23, reference numeral 40 denotes a light source device, and the basic configuration is the same as that of the light source device 10 of FIG. 1, and the same elements are denoted by the same reference numerals and redundant description is omitted. The light source device 40 is different from the light source device 10 in that the light source K3 arranged in the zone S3 is replaced with a simple reflection mirror 6. That is, in the light source device 40, three light sources, an R light source K1, a G light source K2, and a B light source K4, are used as light sources, and the reflection mirror 6 disposed in the zone S3 is simply reflected from each light source. All the light is reflected and only the function of converting from ineffective light to effective light is performed. In this configuration, as the G • LED provided in the light source K2, the drive current is increased to increase the amount of light, or by increasing the number of mounted G • LEDs, It is desirable to balance the amount of light.

(Sixth embodiment)
Next, a light source of the light source device according to the sixth embodiment of the present invention will be described. FIG. 24 is a sectional view of a light source in the light source device according to the sixth embodiment of the present invention. In the figure, K is a light source, in which an LED 1 and two lenses 2a and 2b are incorporated in a case 3, and a film of a bandpass mirror 5 is formed on the exit surface of the second lens 2b. That is, the light source K in the present embodiment uses two condenser lenses to make the light emission of the LED 1 sufficiently parallel and to form a band pass mirror 5 on the exit surface of the second lens 2b. The mirror 5 is integrated, and the exit surface of the second lens 2b is a concave lens, so that the light collecting property of reflected light is improved.

  Note that the exit surface of the second lens 2b forming the film of the bandpass mirror 5 is not limited to a concave lens (concave mirror), but may be a convex lens (convex mirror) or a planar lens. It is desirable to determine appropriately according to the state. That is, in the case where the LED is a light source having a spread such as multi-surface light emission, a concave lens having a function of focusing reflected light is good, and in the case of point light emission in which the LED has intensity at the center, a convex lens having a function of spreading reflected light. Is desirable.

(Seventh embodiment)
Next, a light source device according to a seventh embodiment of the present invention will be described with reference to FIG. FIG. 25 is a perspective view of a light source device in a seventh embodiment of the present invention. In FIG. 25, 60 is a light source device, and a basic structure is one part of the light source device 10 of FIG. The difference between the light source device 60 and the light source device 10 is that only one prism sheet PS1 is used as a prism sheet, and two light sources, a light source K1 having R • LED and a light source K4 having B • LED, are also used as light sources. The emitted light from the prism sheet PS1 becomes color light Pc in which the R light from the light source K1 and the B light from the light source K4 are mixed. That is, the light source device 60 in the present embodiment is configured to mix two light sources with one prism sheet and convert ineffective light into effective light with a bandpass mirror. The conversion operation of non-effective light into effective light is as described with reference to FIGS. In addition, the light source to arrange | position can be arbitrarily set according to the color of the target color light Pc.

  In the case of this one prism sheet, the light from the two light sources can be synthesized by making the incident light from the two light sources obliquely incident on the prism row of the prism sheet. Since the light source device 60 in the present embodiment can perform color mixing with high conversion efficiency by a simple configuration combining one prism sheet and two light sources, it can be used as monochromatic light that is efficiently mixed, Use of color lighting devices and the like can be expected.

(Eighth embodiment)
Next, a configuration of a liquid crystal display device using the light source device of the present invention as a backlight will be described. FIG. 26 is a cross-sectional view schematically showing a liquid crystal display device using the light source device of the present invention as a backlight. Reference numeral 10 denotes the light source device of the present invention shown in FIG. 1, and four band-pass mirrors 5r, 5g, 5b. 5g shows a built-in state. A liquid crystal display element 7 includes an upper polarizing plate 11 and a lower polarizing plate 12. 8 is a reflection type polarization conversion element disposed between the liquid crystal display element 7 and the light source device 10, and 9 is a position disposed between the reflection type polarization conversion element 8 and the bandpass mirror 5 provided in the light source device 10. It is a phase difference plate. The liquid crystal display element 7, the reflective polarization conversion element 8, and the phase difference plate 9 constitute a liquid crystal display device, and the light source device 10 constitutes a backlight. The light source device may be any of the light source devices described above.

  Next, the action of illumination light in the liquid crystal display device of the present invention will be described. In FIG. 26, Pw indicated by a lattice pattern is light emitted from the light source device 10, Pp indicated by oblique lines is a light beam that passes through the reflective polarization conversion element 8 (for example, P-wave light beam), and Ps indicated by a satin pattern is a reflective polarization conversion element. 8 is a light ray reflected at 8 (for example, an S wave ray). First, outgoing light Pw emitted from the light source device 10 passes through the phase difference plate 9 and travels toward the reflective polarization conversion element 8. In the reflective polarization conversion element 8, the P-wave light beam Pp of the outgoing light Pw passes through the reflective polarization conversion element 8 and illuminates the liquid crystal display element 7. However, the S wave ray Ps is reflected by the reflective polarization conversion element 8, passes through the phase difference plate 9, and returns to the light source device 10.

  As described later, the S-wave light beam Ps incident on the light source device 10 is dispersed in four directions by the stacked prism sheets, and is reflected by the four band-pass mirrors 5r, 5g, 5b, and 5g, and again the light source device. 10 is emitted. The re-emitted S wave ray Ps is converted into a P wave ray Pp by passing through the phase difference plate 9, and this time passes through the reflective polarization conversion element 8 to illuminate the liquid crystal display element 7. The retardation of the phase difference plate 9 in this embodiment is set so that the S wave ray is converted into the P wave ray by passing through the phase difference plate twice.

  FIG. 27 shows the state of light rays reflected by the reflective polarization conversion element 8 and incident back to the light source device 10. FIG. 27 shows, as an example, a state of a back-incident light beam having an R light component emitted from the light source K1 in the zone S1, and the back-incident light beam is divided into four equal parts to obtain four band-pass mirrors 5r, 5g, Head for 5b, 5g. The light beam having the R light component is reflected by the bandpass mirrors 5g and 5b as indicated by the hatched arrows, but is not reflected because it is transmitted through the light-emitting bandpass mirror 5r. However, as shown by the thin line arrows, some of the light rays that have passed through the bandpass mirror 5r strike the LED element mounting surface and are reflected.

  As described above, in the combination of the light source device of the present invention and the liquid crystal display element, it is possible to efficiently recycle the reflective polarization conversion element without using a member that enhances diffusibility in the optical path of the backlight. Therefore, the efficiency can be further increased by combining the phase difference plate. In this embodiment, the phase difference plate 9 is disposed between the liquid crystal display element 7 and the light source device 10, but a prism sheet having a birefringence characteristic that provides a desired retardation is formed on the prism sheet constituting the light source device. By using this, the phase difference plate 9 can be omitted, and a thin and low-cost backlight can be realized.

  As described above, in each of the embodiments, the lamination of the single prism sheet and the two prism sheets has been described as the configuration of the light source device. However, the present invention is not limited to this, and the light source device shown in FIG. Even in a configuration in which two or three prism sheets are arbitrarily arranged to combine a plurality of light sources, the same object can be achieved by providing a bandpass mirror in front of each light source.

  As described above, according to the present invention, incident light from a plurality of light sources can be efficiently synthesized by a thin optical system using a prism sheet, so that the shape is small and thin, and optical synthesis performance is excellent. A light source device can be provided. Its application range is wide, and it can be used not only for general illumination but also for light sources for projectors and the like. In addition, a display device with high light use efficiency can be realized by using the backlight for the display device.

It is an external appearance perspective view of the light source device in 1st Example of this invention. It is the top view and side view which show the structure of the two prism sheets shown in FIG. FIG. 3 is a plan view showing a relationship between two prism sheets shown in FIG. 2 and a plurality of light sources. It is the elements on larger scale of prism sheet PS2 shown in FIG. It is the elements on larger scale of prism sheet PS1 shown in FIG. FIG. 3 is a perspective view schematically illustrating a passing optical path of incident light in two prism sheets illustrated in FIG. 2. It is the elements on larger scale of prism sheet PS1 shown in FIG. 2, and shows the state of effective light and non-effective light. It is the elements on larger scale of prism sheet PS1 shown in FIG. 2, and shows the state of effective light and non-effective light. It is a fragmentary sectional view of a prism sheet and a light source showing a configuration for converting non-effective light of light emitted from a light source K4 into effective light by a bandpass mirror of the light source K1. It is a fragmentary sectional view of a prism sheet and a light source showing a configuration for converting non-effective light of light emitted from a light source K1 into effective light by a bandpass mirror of a light source K4. It is a top view which shows the relationship between the incident light from the light source K4, and the reflected light from two laminated | stacked prism sheets in an XY plane. It is a side view which shows the breadth of a light ray when incident light inclines into the prism sheet of this invention. It is a top view of the light ray which injected into the prism sheet shown in FIG. 12 from four light sources. It is a side view which shows the breadth of a light ray when incident light inclines into the prism sheet of the light source device in 2nd Example of this invention. It is a top view of the incident light to the prism sheet shown in FIG. It is a top view of the light ray which injected into the prism sheet shown in FIG. 14 from 4 light sources. It is an external appearance perspective view of the light source device in 3rd Example of this invention. It is sectional drawing of BlueYAG * LED shown in FIG. It is a perspective view of the light source device in 4th Example of this invention. It is a top view which shows the relationship of the incident light from each light source in FIG. 19, and the reflected light from two laminated | stacked prism sheets in an XY plane. It is a top view which shows the relationship between the incident light from the light source K3 in FIG. 19, and the reflected light from two laminated | stacked prism sheets in an XY plane. It is a top view which shows the relationship between the incident light from the light source K3 in the light source device of FIG. 19, and the reflected light from two laminated | stacked prism sheets in an XY plane. It is a perspective view of the light source device in 5th Example of this invention. It is sectional drawing of the light source in the light source device of 6th Example of this invention. It is a perspective view of the light source device in 7th Example of this invention. It is sectional drawing which shows typically the liquid crystal display device which uses the light source device of this invention as a backlight. FIG. 27 is a plan view showing a state of light rays reflected by the reflective polarization conversion element 8 shown in FIG. It is a block diagram of the conventional color projector. FIG. 29 is a partial cross-sectional view of the linear prism plate shown in FIG. 28. It is a disassembled perspective view of the conventional surface emitting device. FIG. 31 is a partially enlarged side view of the light emitting substrate shown in FIG. 30.

Explanation of symbols

1 LED
1r red LED
1b Blue LED
1g green LED
1by BlueYAG ・ LED
2, 2a, 2b Condensing lens 3 Case 5, 5r, 5g, 5b Band pass mirror 6 Reflection mirror 7 Liquid crystal display element 8 Reflection type polarization conversion element 9 Phase difference plate 10, 20, 30, 40, 60 Light source device 12 Anamorphic Lens 13 Upper polarizing plate 14 Lower polarizing plate PS1, PS2 Prism sheets K1, K2, K3, K4 Light sources P1, P2, P3, P4 Incident light L1, L2, U1, U2 Prism slopes S1, S2, S3, S4 Zone Po Collection Light spot S, S14, S23 Illumination light 31, 32 Electrode 33 Substrate 35 Fluorescent particle 36 Transparent resin Pb Blue light Pe Yellow light Pwy, Pw White light

Claims (23)

A plurality of light sources having different emission wavelengths; a prism sheet having a plurality of fine prisms on one surface and a flat surface on the other surface; and the plurality of light sources on the incident surface side of the prism sheet. A light source device that outputs incident light from a plurality of light sources incident at a predetermined angle from the incident surface side of the prism sheet as emitted light obtained by mixing colors from the output surface side of the prism sheet. There,
A light source device characterized in that a band pass mirror is provided between each of the light sources and the prism sheet so as to transmit light in a wavelength region emitted from the corresponding light source and reflect light in another wavelength region.   Incident light from a light source incident at a predetermined angle from the incident surface side of the prism sheet is incident on one prism inclined surface or another prism inclined surface of the prism sheet, and a light beam incident on one prism inclined surface is refracted. The light beam emitted from the exit surface of the prism sheet and incident on the other prism slope is reflected and directed to the band pass mirror, reflected by the bunt pass mirror and incident on the entrance surface of the prism sheet, The light source device according to claim 1, wherein the light source device emits light from an exit surface of the prism sheet.   3. The light source device according to claim 1, wherein incident light of each of the light sources is incident toward a predetermined condensing point in the prism sheet.   4. The light source device according to claim 1, further comprising a condensing lens in front of the light emitting surfaces of the plurality of light sources. 5.   The light source device according to claim 4, wherein the lens is a lens having different curvature radii in length and width.   The light source device according to claim 4, wherein the band-pass mirror is a reflective film formed on an exit surface of the lens.   The light source device according to claim 6, wherein an exit surface of the lens on which the reflective film is formed is a curved surface.   The light source device according to claim 1, wherein a plurality of the prism sheets are provided.   9. The prism sheet according to claim 1, wherein the prism sheet is composed of two prism sheets, and the two prism sheets are stacked so that each prism row intersects at a predetermined angle. The light source device according to Item 1.   10. The light source device according to claim 9, wherein the light sources are distributed and arranged in four zones formed by crossing of the prism rows in the two stacked prism sheets.   The light source device according to claim 9 or 10, wherein the incident light of each light source is incident along the vicinity of the center line of the crossing angle of each prism row in the two stacked prism sheets.   12. The light source device according to claim 9, wherein the incident light of each light source is incident toward a predetermined condensing point in the two stacked prism sheets.   The light source device according to claim 12, wherein each of the light sources is arranged point-symmetrically with respect to a predetermined condensing point in the two prism sheets.   13. The light source device according to claim 12, wherein each of the light sources is arranged symmetrically with respect to an axis passing through a predetermined condensing point in the two prism sheets.   The light source device according to claim 8, wherein the plurality of light sources include R, G, and B LED light sources.   16. The light source device according to claim 15, wherein R, G, and B LED light sources are disposed at three locations on the incident surface side of the prism sheet, and a G / LED light source is disposed at one location.   R, G, B LED light sources are arranged at three locations on the incident surface side of the two prism sheets stacked, and G / LED light sources are arranged at one location. The light source device according to claim 9, wherein the light sources are arranged in adjacent zones.   16. The light source device according to claim 15, wherein R, G, and B LED light sources are arranged at three locations on the incident surface side of the prism sheet, and BlueYAG / LED light sources are arranged at one location. .   16. The light source device according to claim 15, wherein R, G, and B LED light sources are disposed at three locations on the incident surface side of the prism sheet, and reflecting mirrors are disposed at one location.   The light source device according to claim 1, wherein an apex angle of the fine prism row is substantially a right angle.   A liquid crystal display device comprising the light source device according to any one of claims 1 to 20 as a backlight of a liquid crystal cell, wherein a reflective polarization conversion element is provided between the liquid crystal cell and the light source device. A liquid crystal display device characterized by comprising:   The liquid crystal display device according to claim 21, wherein the prism sheet has birefringence characteristics. The liquid crystal display device according to claim 21, wherein a phase difference plate is disposed between the reflective polarization conversion element and the bandpass mirror.

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