JP2011034031A - Optical sheet, translucent screen, and rear projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet and translucent screen for improving the accuracy of detecting infrared light by improving the infrared transmittance without damaging the external light absorption function. <P>SOLUTION: The optical sheet 1 is used for the translucent screen for controlling video light projected from a video light source and making it come to an observer side. The optical sheet 1 includes a light transmission section 2 that has a plurality of unit light transmission sections 2a constituting part of a video light outgoing surface 1b of the optical sheet 1 and arranged along the sheet surface, and transmits the video light and infrared light, and a light absorption section 3 that constitutes part of the video light outgoing surface 1b of the optical sheet 1 and contains visible-light-absorption infrared transmission material 3b. The infrared transmittance of the optical sheet 1 is 70% or higher. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical sheet, a transmissive screen provided with the optical sheet, and a rear projection display device.

  2. Description of the Related Art In recent years, touch screens capable of operating a computer by touching a screen with a finger or a dedicated pen have been used. In addition, an electronic blackboard called an interactive board, which can input characters and figures drawn on a board as they are into a personal computer, and conversely project image information of the personal computer onto the board, has come to be used. ing.

  In such a touch screen or interactive board, the position can be detected by using infrared light or the like.

  On the other hand, a transmissive screen that emits and displays video light projected from a light source unit to an observer side is known. Various types of transmission screens have been proposed. For example, a transmission screen including an optical sheet having a lenticular lens and a light absorption layer has been proposed (see, for example, Patent Document 1).

  However, when such a transmission type screen is applied to an infrared light detection type touch screen or interactive board that detects a position by detecting infrared light, light for absorbing external light in the optical sheet is used. In the absorption part, infrared light is also absorbed. For this reason, there is a possibility that position detection by infrared light cannot be performed.

  In addition, when the light absorption part contains the light absorption particles, it may be possible to improve the infrared light transmittance by reducing the concentration of the light absorption particles, but when the concentration of the light absorption particles is decreased. The external light absorption function is significantly impaired.

JP 58-55921 A

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide an optical sheet and a transmission screen that can improve infrared light transmittance without impairing the external light absorption function and improve the detection accuracy of infrared light.

  According to one aspect of the present invention, there is provided an optical sheet used in a transmission screen that controls image light projected from an image light source and emits the image light to an observer side, and is an image sheet on the image light exit surface of the optical sheet. Comprising a plurality of unit light transmitting portions arranged along the sheet surface, and constituting a part of the image light emitting surface of the optical sheet and a light transmitting portion that transmits image light and infrared light. And an optical absorption part including a visible light absorbing infrared light transmitting material, and an infrared light transmittance of the optical sheet is 70% or more.

  According to another aspect of the present invention, there is provided a transmissive screen comprising the optical sheet described above and a Fresnel lens portion disposed on the image light incident side of the optical sheet.

  According to another aspect of the present invention, the transmissive screen, a video light source that projects video light onto the transmissive screen, an infrared light source that projects infrared light onto the transmissive screen, and the infrared light A rear projection type display device is provided, comprising an infrared light detector capable of detecting the light intensity.

  According to the optical sheet of one embodiment of the present invention, the transmissive screen and the rear display device of the other embodiment, the infrared light transmittance is improved without impairing the external light absorption function, and the infrared light detection accuracy is improved. Can be improved.

It is a typical sectional view of the optical sheet concerning a 1st embodiment. It is a typical structure figure of other optical sheets concerning a 1st embodiment. It is a figure which shows the other aspect of the visible light absorption infrared-light transmissive material which concerns on 1st Embodiment. It is a typical manufacturing process figure of the optical sheet which concerns on 1st Embodiment. 1 is a schematic structural diagram of a rear display device according to a first embodiment. It is a typical structure figure of the transmission type screen concerning a 1st embodiment. It is a typical sectional view of the optical sheet concerning a 2nd embodiment. It is typical sectional drawing of the optical sheet which concerns on 3rd Embodiment. It is the graph which showed the transmittance | permeability with respect to the wavelength of the optical sheet which concerns on an Example and a comparative example. It is the graph which showed the gain with respect to the viewing angle of the optical sheet which concerns on an Example and a comparative example.

(First embodiment)
The first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of an optical sheet according to the present embodiment, FIG. 2 is a schematic sectional view of another optical sheet according to the present embodiment, and FIG. It is a figure which shows the other aspect of the visible light absorption infrared-light transmissive material which concerns.

  An optical sheet 1 shown in FIG. 1 is used for a transmission screen that controls image light projected from an image light source (not shown) and emits the light to an observer side. As shown in FIG. 1, the optical sheet 1 has an image light incident surface 1 a for incident image light and an image light exit surface 1 b for emitting image light. The light transmission part 2 to be diffused and the light absorption part 3 that absorbs external light, which is visible light incident mainly from the observer side, are formed. As shown in FIG. 2, the prism portion 4 may be provided on the image light incident side of the light transmitting portion 2.

  The light transmitting part 2 constitutes a part of the image light emitting surface 1b, and includes a plurality of unit light transmitting parts 2a arranged along the sheet surface. In the present embodiment, the unit light transmitting portion 2a has a substantially trapezoidal cross section. This trapezoid has an image light incident side as a lower base and an image light output side as an upper base.

  The light transmitting portion 2 is made of a light transmissive resin having a refractive index N1 and transmitting video light and infrared light. This is usually formed of, for example, epoxy acrylate having a characteristic of being cured by ionizing radiation, ultraviolet rays, or the like.

  The light absorbing portion 3 is formed so as to constitute a part of the image light emitting surface 1b. In the present embodiment, the cross-sectional shape formed by the unit light transmitting portions 2a adjacent to the light absorbing portion 3 is formed in a substantially triangular space. That is, the cross-sectional shape of the light absorbing portion 3 is a substantially triangular shape with the base of the image light emitting side in the thickness direction of the optical sheet 1.

  The light absorption part 3 can be comprised from the visible light absorption infrared-light transmissive material 3b etc. which were contained in the transparent resin 3a and the transparent resin 3a. The transparent resin 3a is preferably made of a material having a refractive index N2 smaller than the refractive index N1. Moreover, what is used as transparent resin 3a is not specifically limited, For example, the urethane acrylate etc. which have the characteristics hardened | cured by ionizing radiation, an ultraviolet-ray, etc. are mentioned.

  The visible light absorbing infrared light transmitting material 3b has a function of transmitting infrared light and absorbing external light that is visible light. Examples of the visible light absorbing infrared light transmitting material 3b include those made of ink mixed with a pigment or a dye. Examples of such pigments include perylene black pigment, aniline black pigment, format black (mixed pigment of yellow, magenta, cyan pigment), phthalocyanine blue, brilliant carmine 6B, and the like.

  Note that the visible light absorbing infrared light transmitting material 3b may be contained in the transparent resin 3a in the form of covering the surface of the core particle 3c as shown in FIG. Examples of the core particle 3c include plastic beads such as melamine beads, acrylic beads, acrylic-styrene beads, polycarbonate beads, polyethylene beads, and polystyrene beads. Among these, acrylic beads are preferable.

  From the viewpoint of detecting infrared light, the optical sheet 1 needs to have an infrared light transmittance of 70% or more. More specifically, it is preferable that the optical sheet 1 exhibits an infrared light transmittance of 70% or more in light having a wavelength of 830 to 900 nm. Here, “transmittance” was measured by placing an optical sheet so that light was incident from the image light incident surface side, with a value measured without placing the optical sheet on the spectral transmittance measuring instrument as a reference value. It means the ratio (%) of the value to the reference value. Shimadzu MPC-2200 can be used to measure the transmittance.

  Such an optical sheet 1 can be manufactured, for example, by the following method. FIG. 4A and FIG. 4B are manufacturing process diagrams schematically showing manufacturing steps of the optical sheet according to the present embodiment.

  As shown in FIG. 4A, the resin serving as the light transmitting portion 2 is supplied onto the base material 11 by the resin supply device 12 while flowing the base material 11 such as polyethylene terephthalate. Next, the resin is irradiated with ultraviolet light by the ultraviolet light irradiation device 14 in a state where the resin serving as the light transmitting portion 2 is sandwiched between the base material 11 and the roll-shaped lens molding die 13 and cured. . Thereby, the light transmission part 2 is formed.

  After forming the light transmission part 2, as shown in FIG. 4 (b), visible light absorption infrared light is applied to the light transmission part 2 by the resin supply device 15 while flowing the base material 11 on which the light transmission part 2 is formed. A transparent resin 3a including a transmitting material 3b is supplied. Then, the molding surface of the light transmission part 2 is scraped with the doctor blade 16, and only the groove of the light transmission part 2 is filled with the transparent resin 3a. Finally, the ultraviolet light irradiation device 17 irradiates the transparent resin 3a with ultraviolet light to be cured. Thereby, the light absorption part 3 is formed between the unit light transmission parts 2a, and the optical sheet 1 shown by FIG. 1 is obtained.

  Next, a transmission screen and a rear display device using this optical sheet will be described. FIG. 5A shows a rear display device in which a transmissive screen is arranged in a substantially horizontal state, and FIG. 5B shows a rear display device in which a transmissive screen is arranged in an oblique state. FIG. 5C shows a rear display device in which transmission screens are arranged in a substantially vertical state. FIG. 6 is a schematic structural diagram of the transmission screen according to the present embodiment.

  As shown in FIGS. 5A to 5C, the rear display device 20 such as a touch screen or an interactive board includes, for example, a transmissive screen 30, a screen support 40 that supports the transmissive screen 30, An image light source 50 that projects image light onto the transmissive screen 30, an infrared light source 60 that projects infrared light onto the transmissive screen 30, an infrared light detector 70 such as a CCD camera capable of detecting infrared light, It is comprised from the housing 80 etc. which accommodates the image light source 50 grade | etc.,. The image light source 50, the infrared light source 60, and the infrared light detector 70 are disposed on the back side of the transmissive screen 30.

  As shown in FIG. 6, the screen 30 includes a transparent substrate 31, a Fresnel lens unit 32, the optical sheet 1, a light diffusion plate 33, etc., and irradiates image light from the back side of the transmissive screen 30. Image light is emitted from the front surface of the screen 30. When this screen 30 is applied to a touch screen or an interactive board, video light can be incident from the back side of the screen or the like, so that the display image is not obstructed when writing to the screen or the like.

  The transparent substrate 31 is for maintaining the strength of the screen 30, and the rigidity is determined by the thickness of the transparent substrate 31. That is, as the thickness of the transparent base material 31 is increased, the strength of the screen 30 against external force can be increased. The transparent substrate 31 is made of, for example, an acrylic plate.

  The Fresnel lens unit 32 converts the image light irradiated from the image light source 50 into parallel light. By applying the Fresnel lens portion 32 as the screen 30 such as a touch screen, it is possible to provide good image light on the screen 30 or the like even if an image light source is installed at a position closer to the screen 30 or the like. As a result, the installation space can be reduced as compared with a conventional touch screen or the like in which an image light source is installed on the front surface.

  In the present embodiment, the Fresnel lens unit 32 is arranged so that the lens surface is on the image light emitting side, but the Fresnel lens unit 32 may be arranged so that the lens surface is on the image light incident side. The Fresnel lens unit 32 is a refractive type Fresnel lens unit, but may be a total reflection type Fresnel lens unit or a hybrid type Fresnel lens unit. When the hybrid type Fresnel lens is applied, the distance from the screen to the video light source can be shortened, so that the interactive board or the like can be made compact.

  The light diffusion plate 33 is for further diffusing the image light diffused by the optical sheet 1. As the light diffusing plate 33, those conventionally known in the screen field can be used. For example, as the light diffusing plate 33, a material obtained by adding fine particles to a base material can be used.

  Examples of the substrate include a transparent resin film, a transparent resin plate, a transparent resin sheet, and transparent glass. As transparent resin film, triacetate cellulose (TAC) film, polyethylene terephthalate (PET) film, diacetyl cellulose film, acetate butyrate cellulose film, polyethersulfone film, polyacrylic resin film, polyurethane resin film, polyester film, A polycarbonate film, a polysulfone film, a polyether film, a polymethylpentene film, a polyether ketone film, a (meth) acrylonitrile film, or the like can be suitably used.

  As the fine particles, organic fillers such as plastic beads are preferable, and those having high transparency are particularly preferable. Examples of the plastic beads include melamine beads, acrylic beads, acrylic-styrene beads, polycarbonate beads, polyethylene beads, polystyrene beads, and polyvinyl chloride beads. Among these, acrylic beads are preferable.

  The image light emitted from the image light source 50 enters the Fresnel lens unit 32 through the transparent substrate 31. The image light converted into parallel light by the Fresnel lens unit 32 enters from the image light incident surface 1a of the optical sheet 1 and exits from the light transmitting unit 2 of the image light exit surface 1b. In addition, when the refractive index of the transparent resin 3a is made smaller than the refractive index of the constituent material of the light transmission part 2, it is diffused by being totally reflected at the boundary surface between the light transmission part 2 and the light absorption part 3, and light Video light is emitted from the transmission unit 2. The emitted image light is further diffused by the light diffusion plate 33, and the image light is emitted from the front surface of the screen 30. In addition, external light and stray light are absorbed by the light absorption unit 3. Thereby, there is no reflection of external light on the transmissive screen 30, an excellent visibility, a good contrast, and a sharp image can be realized.

  On the other hand, infrared light emitted from the infrared light source 60 passes through the transparent base material 31, the Fresnel lens portion 32, the optical sheet 1, and the light diffusion plate 33. Thereby, for example, when a finger is brought into contact with the front surface of the screen 30, infrared light is reflected by the finger, so that the infrared light detector 70 can detect the position information of the finger.

  According to the present embodiment, since the visible light absorbing infrared light transmitting material 3b is included in the light absorbing portion 3, the transmittance of infrared light is reduced without deteriorating the function of absorbing external light and stray light. Can be improved. Accordingly, it is possible to provide the optical sheet 1 that can be used as a part of a rear display device such as an infrared light detection touch screen or an interactive board.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described. In the present embodiment, an optical sheet having a structure different from that of the optical sheet of the first embodiment will be described. FIG. 7 is a schematic cross-sectional view of the optical sheet according to the present embodiment.

  As shown in FIG. 7, the optical sheet 91 has an image light incident surface 91 a and an image light exit surface 91 b, similar to the optical sheet 1, and mainly includes a light transmission unit 92 and a light absorption unit 93. Etc. Moreover, the light absorption part 93 is comprised from the transparent resin 93a and the visible light absorption infrared-light transmissive material 93b similarly to the light absorption part 3. FIG. In addition, since the structure of each member, material, etc. are the same as that of the 1st Embodiment except being demonstrated below, description shall be abbreviate | omitted.

  The unit light transmitting portion 92a of the light transmitting portion 92 is a spherical lens, and this spherical lens is arranged for one layer along the sheet surface. The light transmitting portion 92 is configured to refract light incident from the image light incident surface 91a and emit image light from a region 92b near the apex of each spherical lens on the image light exit side.

  The light absorbing portion 93 is formed so as to cover a region excluding the region 92b near the apex of each spherical lens on the image light emitting side. Also in this embodiment, since the visible light absorbing infrared light transmitting material 93b is included in the light absorbing portion 93, the same effect as that of the first embodiment can be obtained.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described. In the present embodiment, an optical sheet having a structure different from that of the optical sheet of the first embodiment will be described. FIG. 8 is a schematic cross-sectional view of the optical sheet according to the present embodiment.

  As shown in FIG. 8, the optical sheet 101 has an image light incident surface 101 a and an image light exit surface 101 b, similar to the optical sheet 1, and mainly includes a light transmission unit 102 and a light absorption unit 103. Etc. Similarly to the light absorbing unit 3, the light absorbing unit 103 includes a transparent resin 103a and a visible light absorbing infrared light transmitting material 103b. In addition, since the structure of each member, material, etc. are the same as that of the 1st Embodiment except being demonstrated below, description shall be abbreviate | omitted.

  The unit light transmitting portion 102a of the light transmitting portion 102 is a convex cylindrical lens formed on the image light incident side. The light transmitting portion 102 is configured to refract light incident from the image light incident surface 101a and emit image light from the flat portion 102b positioned on the image light emitting side. Between the unit light transmitting portions 102a, a protruding portion 102c protruding from the flat portion 102b to the image light emitting side is formed. The flat portions 102b and the protruding portions 102c are alternately arranged.

  The light absorbing portion 103 is formed on the protruding portion 102c. Also in the present embodiment, since the visible light absorbing infrared light transmitting material 103b is included in the light absorbing portion 103, the same effects as those of the first embodiment can be obtained.

  Examples will be described below. In this example, the optical sheet described in the above embodiment was manufactured, the spectral transmittance of the optical sheet was measured, and the gain with respect to the viewing angle of the optical sheet was measured. For comparison with the present example, an optical sheet not including a visible light absorbing infrared light transmitting material was produced, and the spectral transmittance and the gain with respect to the viewing angle were measured in the same manner as the optical sheet of the example.

Sample (Example)
First, an ultraviolet curable resin serving as a light transmission portion was supplied onto the base material while flowing the base material. Next, with the ultraviolet curable resin sandwiched between the substrate and the roll-shaped lens molding die, the resin is irradiated with ultraviolet light by an ultraviolet light irradiation device and cured to form a light transmitting portion. did.

  After forming the light transmission part, as a transparent resin containing visible light absorption infrared light transmission ink as a visible light absorption infrared light transmission material on the light transmission part while flowing the base material on which the light transmission part is formed UV curable resin was supplied.

  Next, the molding surface of the light transmitting portion was scraped with a doctor blade, and only the groove of the light transmitting portion was filled with an ultraviolet curable resin containing visible light absorbing infrared light transmitting ink. Finally, the ultraviolet curable resin was irradiated with ultraviolet light by an ultraviolet light irradiation device and cured to form a light absorbing portion. Thus, an optical sheet according to the example was obtained.

(Comparative example)
An optical sheet was produced in the same manner as in Example except that colored acrylic beads as light absorbing particles were used instead of visible light absorbing infrared light transmitting ink.

Spectral transmittance measurement The optical sheets of Examples and Comparative Examples thus obtained were irradiated with light from the image light incident surface side, and the spectral transmittance of the optical sheet was measured. For measurement of the spectral transmittance, MPC-2200 manufactured by Shimadzu Corporation was used.

  FIG. 9 is a graph showing the transmittance with respect to the wavelength of the optical sheet according to the example and the comparative example. When the spectral transmittances of the optical sheet of the example and the optical sheet of the comparative example are compared, the transmittance of the optical sheet of the example is higher than that of the optical sheet of the comparative example in the visible light region as shown in FIG. Was low. In the infrared region, the optical sheet of the example had a higher transmittance than the optical sheet of the comparative example at a wavelength of 780 nm or more.

  From these results, it is considered that the detection accuracy can be improved when the optical sheet according to the example is used for an infrared light detection type interactive board or a touch screen.

The gain measurement optical sheet was irradiated with visible light, and the gains of the optical sheets of Examples and Comparative Examples were measured while changing the viewing angle. The gain is the ratio between the brightness (illuminance) on the image light incident side of the optical sheet and the brightness (luminance) on the image light exit side, p is the proportionality constant, and the brightness (unit solid of light emitted in a certain direction) A value expressed by G = p × (K / I) where K is an amount of light flux per corner, I is an illuminance (amount of light flux incident on a unit area), and G is a gain. is there. For measuring the gain with respect to the viewing angle, a GP-500 screen optical property evaluation apparatus manufactured by Murakami Color Research Laboratory, which is a declination luminance measuring device, was used.

  FIG. 10 is a graph showing the gain with respect to the viewing angle of the optical sheets according to the example and the comparative example. As shown in FIG. 10, in the optical sheet of the comparative example, the gain when the viewing angle is 0 ° is about 0.325, and the viewing angle when the gain value is ½ is around 12 °. It was. On the other hand, in the optical sheet of the example, the gain when the viewing angle was 0 ° was about 0.27, and the viewing angle when the gain value was ½ was around 12 °.

  From these results, since the viewing angles were the same, it was confirmed that the optical sheet of the example exhibited the same performance as that of the comparative example in the visible light region.

  DESCRIPTION OF SYMBOLS 1, 91, 101 ... Optical sheet, 1a, 91a, 101a ... Image light incident surface, 1b, 91b, 101b ... Image light emission surface, 2, 92, 102 ... Light transmission part, 2a, 92a, 102a ... Unit light transmission 3, 93, 103... Light absorbing portion, 3 b, 93 b, 103 b... Visible light absorbing infrared light transmitting material, 20... Rear display device, 30. , 60 ... an infrared light source, 70 ... an infrared light detector.

Claims (9)

An optical sheet used in a transmission screen that controls the image light projected from the image light source and emits the image light to the viewer side,
A part of the image light emitting surface of the optical sheet, comprising a plurality of unit light transmitting portions arranged along the sheet surface, and a light transmitting portion that transmits image light and infrared light;
A part of the image light exit surface of the optical sheet, and a light absorbing part including a visible light absorbing infrared light transmitting material, wherein the infrared light transmittance of the optical sheet is 70% or more. An optical sheet.   The optical sheet according to claim 1, wherein the optical sheet has a transmittance of 70% or more in light having a wavelength of 830 to 900 nm.   The optical according to claim 1 or 2, wherein the light absorbing portion further includes a transparent resin, the visible light absorbing infrared light transmitting material is made of an ink containing a pigment or a dye, and is contained in the transparent resin. Sheet.   The cross-sectional shape of the unit light transmission part of the light transmission part is a substantially trapezoid with the image light emission side as the upper base and the image light incident side as the lower base, and the light absorption part is formed between the unit light transmission parts. The optical sheet according to any one of claims 1 to 3.   The optical sheet according to claim 4, further comprising a prism portion formed on the image light incident surface side of the light transmitting portion.   The unit light transmission part of the said light transmission part is a spherical lens, The said light absorption part is formed on the area | region except the area | region of the vertex vicinity of the image light emission side of each said spherical lens. The optical sheet according to any one of the above.   The unit light transmission part of the said light transmission part is a cylindrical lens formed in the image light incident side, The said light absorption part is formed in any one of the said unit light transmission part. The optical sheet according to 1. The optical sheet according to any one of claims 1 to 7,
A transmissive screen comprising: a Fresnel lens portion disposed on the image light incident side of the optical sheet. The transmissive screen according to claim 8,
An image light source that projects image light onto the transmissive screen;
An infrared light source that projects infrared light onto the transmission screen;
An infrared light detector capable of detecting the infrared light;
A rear projection type display device comprising:

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