JP4333355B2 - Spatial light modulator and projector - Google Patents

Description

  The present invention relates to a spatial light modulation device, particularly a liquid crystal type spatial light modulation device, and a projector including the spatial light modulation device.

  As a representative example of the spatial light modulator, for example, a liquid crystal panel is used. In the liquid crystal panel, various wirings such as data lines, scanning lines, and capacitor lines, and various electronic elements such as thin film transistors and thin film diodes are formed in the image display area. For this reason, in each pixel, a region where light contributing to image display can be transmitted or reflected is limited by the presence of various wirings, electronic elements, and the like. The aperture ratio of each pixel is defined by an area ratio of the area where each pixel area can transmit or reflect light contributing to image display, that is, the area ratio of the aperture area. Generally, the aperture ratio of a liquid crystal panel is about 70%. In addition, light from a light source incident on the liquid crystal panel is transmitted or reflected through an electro-optical material layer such as a liquid crystal layer in a substantially parallel light state. For this reason, when the liquid crystal panel is illuminated with substantially parallel light, only the amount of light corresponding to the aperture ratio of each pixel can be used out of the total amount of light. Light that is not used results in light loss.

  Therefore, conventionally, a microlens array including microlens elements corresponding to each pixel is formed on the counter substrate of the liquid crystal panel. The microlens element condenses illumination light from the light source toward the aperture region in units of pixels. The illumination light collected by the microlens element can efficiently pass through the aperture area of the pixel. For this reason, when a microlens array is used for the liquid crystal panel, the light use efficiency can be improved. Here, when the illumination light is condensed, the component that is perpendicularly incident on the substrate of the liquid crystal panel is reduced. For this reason, the contrast of an image will fall.

  For this reason, for example, Patent Document 1 proposes a configuration that improves contrast when a microlens array is used.

JP 2000-275627 A

  In some cases, an optical compensation film is used for a liquid crystal panel, particularly a twisted nematic (hereinafter referred to as “TN”) liquid crystal panel. If an optical compensation film is used for a TN display liquid crystal panel, the viewing angle can be widened. However, when the above-described microlens array is used for a TN display liquid crystal panel including an optical compensation film, there is a problem that the effect of improving the contrast cannot be obtained.

  The present invention has been made in view of the above, and a spatial light modulator provided with an optical compensation film, particularly a spatial light modulator capable of obtaining a high-contrast image with a wide viewing angle in a TN display liquid crystal panel, And it aims at providing a projector provided with the same.

  In order to solve the above-described problems and achieve the object, according to the first invention, an optical compensation film that gives a predetermined phase difference to incident light, and a modulation that emits light after modulating it according to an image signal And a refractive optical unit having a refracting surface for causing at least oblique incidence of light to the modulating unit.

  The spatial light modulator of the present invention, for example, a TN display liquid crystal spatial light modulator, has an optical compensation film. The optical compensation film has a function of compensating for the asymmetry of the polarization in the optical axis direction, that is, the direction in which light travels, caused by liquid crystal molecules with little movement near the alignment film when a voltage is applied in a TN display liquid crystal panel. For this reason, an observer can widen the viewing angle which can observe an image favorably. In the present invention, a refracting optical unit having a refracting surface for at least oblique incidence of light is further provided to the modulation unit. The modulation unit is a liquid crystal layer formed in a substantially parallel space between, for example, two parallel flat plates. The light refracted by the refracting optical unit is incident obliquely at a predetermined angle with respect to the normal line of the liquid crystal layer as the modulating unit. Thereby, the contrast of an image can be improved. In the present invention, it is most desirable to arrange the optical compensation film, the refractive optical section, and the modulation section in this order along the light traveling direction. However, the present invention is not limited to this, and the refractive optical unit, the optical compensation film, and the modulation unit are arranged in this order along the light traveling direction, or the refractive optical unit, the modulation unit, and the optical compensation film are arranged in this order. Any of these may be used.

  According to a preferred aspect of the first invention, the modulation section has a plurality of pixel openings, the refractive optical section includes a plurality of refractive optical elements, and the refractive optical element transmits incident light to the pixel openings. It is desirable to pass through the region of the part and at least obliquely enter. In a liquid crystal spatial light modulator for TN display, for example, a plurality of pixel openings are formed in a lattice shape that is substantially orthogonal. The refractive optical element is provided corresponding to each pixel opening. The refractive optical element allows incident light to pass through the corresponding pixel opening. Thereby, the utilization efficiency of light can be improved. Further, in this aspect, the refractive optical element causes incident light to pass through each aperture region and obliquely enter the modulation unit. Thereby, an image with high contrast can be obtained.

  According to a preferred aspect of the first invention, the refractive optical element is preferably a polygonal prism, a conical prism, or an aspheric lens. With these configurations, light can be obliquely incident on the modulation unit more efficiently.

  In addition, according to the second aspect of the invention, it is possible to provide a projector including a light source that supplies light, the above-described spatial light modulation device, and a projection lens that projects light from the spatial light modulation device. Since the present invention includes the above-described spatial light modulator, a high-contrast projection image can be obtained with a large viewing angle.

  Embodiments of a projector provided with a spatial light modulation device according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this Example.

(Explanation of the entire projector)
First, a schematic configuration of a projector according to Embodiment 1 of the present invention will be described with reference to FIG. Next, a characteristic configuration of the present embodiment will be described with reference to FIG. First, in FIG. 1, an ultra-high pressure mercury lamp 101 as a light source unit includes red light (hereinafter referred to as “R light”) as first color light and green light (hereinafter referred to as “G light”) as second color light. And blue light (hereinafter referred to as “B light”) which is the third color light. The integrator 104 uniformizes the illuminance distribution of the light from the ultrahigh pressure mercury lamp 101. The light whose illuminance distribution is made uniform is converted into polarized light having a specific vibration direction, for example, s-polarized light by the polarization conversion element 105. The light converted into the s-polarized light is incident on the R light transmitting dichroic mirror 106R constituting the color separation optical system. Hereinafter, the R light will be described. The R light transmitting dichroic mirror 106R transmits R light and reflects G light and B light. The R light transmitted through the R light transmitting dichroic mirror 106R is incident on the reflection mirror 107. The reflection mirror 107 bends the optical path of the R light by 90 degrees. The R light whose optical path is bent is incident on the optical compensation film 130R. The R light transmitted through the optical compensation film 130R is incident on the first color light spatial light modulator 110R that modulates the R light as the first color light according to the image signal. The spatial light modulator for first color light 110R is a transmissive TN display liquid crystal display device that modulates R light according to an image signal. Since the polarization direction of the light does not change even if it passes through the dichroic mirror, the R light incident on the first color light spatial light modulator 110R remains as s-polarized light.

  The first color light spatial light modulator 110R includes a λ / 2 phase difference plate 123R, a glass plate 124R, a first polarizing plate 121R, a liquid crystal panel 120R, and a second polarizing plate 122R. The detailed configuration of the liquid crystal panel 120R will be described later. The λ / 2 phase difference plate 123R and the first polarizing plate 121R are arranged in contact with a light-transmitting glass plate 124R that does not change the polarization direction. Thereby, the problem that the first polarizing plate 121R and the λ / 2 phase difference plate 123R are distorted by heat generation can be avoided. In FIG. 1, the second polarizing plate 122R is provided independently. However, the second polarizing plate 122R may be disposed in contact with the exit surface of the liquid crystal panel 120R or the entrance surface of the cross dichroic prism 112.

  The s-polarized light incident on the first color light spatial light modulator 110R is converted into p-polarized light by the λ / 2 phase difference plate 123R. The R light converted into p-polarized light passes through the glass plate 124R and the first polarizing plate 121R as it is and enters the liquid crystal panel 120R. The p-polarized light incident on the liquid crystal panel 120R is converted into s-polarized light by modulation according to the image signal. The R light converted into s-polarized light by the modulation of the liquid crystal panel 120R is emitted from the second polarizing plate 122R. In this way, the R light modulated by the first color light spatial light modulator 110R is incident on the cross dichroic prism 112 which is a color synthesis optical system.

(Optical compensation film)
Here, the optical compensation film 130R will be described. The liquid crystal panel 120R of the present embodiment is a TN display liquid crystal panel. A description will be given of an operation of modulating a light and displaying a gradation by using a normally white mode as an example for a TN display liquid crystal panel. In TN display, liquid crystal having positive dielectric anisotropy is aligned in parallel. Then, as will be described later, the alignment directions (hereinafter referred to as “rubbing directions”) of the alignment films of the two substrates sandwiching the liquid crystal layer are formed so as to be substantially orthogonal. With this configuration, the liquid crystal molecules are aligned 90 ° twisted. Then, when the polarization axes of the first polarizing plate 121R and the second polarizing plate 122R are aligned with the alignment direction of the alignment film, the light rotates in the liquid crystal layer. For this reason, the spatial light modulator for first color light 110R transmits and emits incident light under crossed Nicols. On the other hand, when a voltage is applied to the liquid crystal layer, the liquid crystal molecules rise and the twisted structure of the liquid crystal molecules disappears. For this reason, the incident light to the first color light spatial light modulator 110R is not transmitted under crossed Nicols. Therefore, when a voltage is applied to the liquid crystal layer, a dark display is obtained. Thus, in the normally white mode liquid crystal panel 120R with TN display, the transmittance for incident light decreases according to the voltage applied in units of pixels. Thus, gradation display can be performed by controlling the amount of transmitted light from the first color light spatial light modulator 110R. When the liquid crystal panel 120R is in the normally black mode, the transmittance for incident light increases according to the voltage applied in units of pixels. The entire spatial light modulator emits light having a contrast corresponding to the image signal.

  Here, in many cases, the alignment direction of the liquid crystal molecules existing in the vicinity of the alignment film is not properly controlled according to the applied voltage. Specifically, the alignment direction of the liquid crystal molecules in the vicinity of the alignment film hardly changes depending on the applied voltage. For this reason, for example, transmitted light (leakage light) is generated even when dark display, that is, all black display is desired on the normally white mode liquid crystal panel 120R. Thereby, the visual field which an observer can recognize a dark display will be limited. That is, in the TN display liquid crystal panel, a viewing angle at which an observer can observe an image with an appropriate contrast is limited. The optical compensation film 130R has a function of further widening and widening the viewing angle of the liquid crystal panel 120R for TN display. As described above, the optical compensation film 130R compensates for the asymmetry of the polarization in the optical axis direction, that is, the direction in which the light travels, due to the liquid crystal molecules with little movement near the alignment film when a voltage is applied. As the optical compensation film 130R, a hybrid film of a discotic liquid crystal compound and then crosslinked, for example, a WV film (manufactured by Fuji Photo Film Co., Ltd.) can be used. By using the optical compensation film 130R, an observer can observe a projected image with a larger viewing angle than when the optical compensation film 130R is not provided.

  Next, the G light will be described. The light paths of the G light and the B light reflected by the R light transmitting dichroic mirror 106R are bent by 90 degrees. The G light and the B light whose optical paths are bent enter the B light transmitting dichroic mirror 106G. The B light transmitting dichroic mirror 106G reflects the G light and transmits the B light. The G light reflected by the B light transmitting dichroic mirror 106G enters the optical compensation film 130G. The G light emitted through the optical compensation film 130G is incident on the second color light spatial light modulator 110G that modulates the G light according to the image signal. The spatial light modulator for second color light 110G is a transmissive liquid crystal display device that modulates G light according to an image signal. The second color light spatial light modulator 110G includes a liquid crystal panel 120G, a first polarizing plate 121G, and a second polarizing plate 122G. Details of the liquid crystal panel 120G will be described later.

  The G light incident on the second color light spatial light modulator 110G is converted into s-polarized light. The s-polarized light incident on the second color light spatial light modulator 110G passes through the first polarizing plate 121G as it is and enters the liquid crystal panel 120G. The s-polarized light incident on the liquid crystal panel 120G is converted into p-polarized light by modulation according to the image signal. The G light converted into p-polarized light by the modulation of the liquid crystal panel 120G is emitted from the second polarizing plate 122G. Thus, the G light modulated by the second color light spatial light modulator 110G enters the cross dichroic prism 112, which is a color synthesis optical system.

  Next, the B light will be described. The B light transmitted through the B light transmitting dichroic mirror 106G enters the optical compensation film 130B via the two relay lenses 108 and the two reflection mirrors 107. The B light emitted through the optical compensation film 130B is incident on the third color light spatial light modulator 110B that modulates the B light in accordance with the image signal. The spatial light modulator for third color light 110B is a transmissive liquid crystal display device that modulates B light according to an image signal.

  The reason why the B light passes through the relay lens 108 is that the optical path length of the B light is longer than the optical path lengths of the R light and the G light. By using the relay lens 108, it is possible to guide the B light transmitted through the B light transmitting dichroic mirror 106G directly to the third color light spatial light modulator 110B. The spatial light modulator for third color light 110B includes a λ / 2 phase difference plate 123B, a glass plate 124B, a first polarizing plate 121B, a liquid crystal panel 120B, and a second polarizing plate 122B. Note that the configuration of the spatial light modulation device 110B for the third color light is the same as the configuration of the spatial light modulation device 110R for the first color light described above, and thus detailed description thereof is omitted.

  The B light incident on the spatial light modulator for third color light 110B is converted into s-polarized light. The s-polarized light incident on the third color light spatial light modulator 110B is converted into p-polarized light by the λ / 2 phase difference plate 123B. The B light converted into p-polarized light passes through the glass plate 124B and the first polarizing plate 121B as it is, and enters the liquid crystal panel 120B. The p-polarized light incident on the liquid crystal panel 120B is converted into s-polarized light by modulation according to the image signal. The B light converted into the s-polarized light by the modulation of the liquid crystal panel 120B is emitted from the second polarizing plate 122B. The B light modulated by the third color light spatial light modulator 110B is incident on the cross dichroic prism 112 which is a color synthesis optical system. As described above, the R light transmitting dichroic mirror 106R and the B light transmitting dichroic mirror 106G constituting the color separation optical system convert the light supplied from the ultrahigh pressure mercury lamp 101 into the R light that is the first color light, the second light, and the second light. The light is separated into G light, which is colored light, and B light, which is third color light.

  The cross dichroic prism 112, which is a color synthesis optical system, is configured by arranging two dichroic films 112a and 112b perpendicularly to an X shape. The dichroic film 112a reflects B light and transmits R light and G light. The dichroic film 112b reflects R light and transmits B light and G light. As described above, the cross dichroic prism 112 has the R light and G light modulated by the first color light spatial light modulation device 110R, the second color light spatial light modulation device 110G, and the third color light spatial light modulation device 110B, respectively. And B light. The projection lens 114 projects the light combined by the cross dichroic prism 112 onto the screen 116. Thereby, a full color image can be obtained on the screen 116.

  As described above, the light incident on the cross dichroic prism 112 from the first color light spatial light modulator 110R and the third color light spatial light modulator 110B is set to be s-polarized light. The light incident on the cross dichroic prism 112 from the second color light spatial light modulator 110G is set to be p-polarized light. In this way, by changing the polarization direction of the light incident on the cross dichroic prism 112, the light emitted from the spatial light modulators for the respective color lights in the cross dichroic prism 112 can be effectively combined. The dichroic films 112a and 112b are usually excellent in the reflection characteristics of s-polarized light. For this reason, R light and B light reflected by the dichroic films 112a and 112b are s-polarized light, and G light transmitted through the dichroic films 112a and 112b is p-polarized light.

(Configuration of LCD panel)
Next, details of the liquid crystal panel will be described with reference to FIG. The projector 100 described with reference to FIG. 1 includes three liquid crystal panels 120R, 120G, and 120B. These three liquid crystal panels 120R, 120G, and 120B differ only in the wavelength region of light to be modulated, and have the same basic configuration. Therefore, the following description will be made with the liquid crystal panel 120R as a representative example.

  FIG. 2 is a perspective sectional view of a part of the configuration of the liquid crystal panel 120R. The liquid crystal panel 120R is arranged in a lattice shape in which a plurality of opening areas AP are substantially orthogonal. The opening area AP is a rectangular opening formed in the black matrix 205 having a light shielding function. The opening area AP corresponds to one pixel. FIG. 2 shows only a portion of one opening area AP among the plurality of opening areas AP of the liquid crystal panel 120R. The configuration of the liquid crystal panel 120R corresponding to the other opening regions is the same as the configuration shown in FIG. The R light from the ultrahigh pressure mercury lamp 101 enters the liquid crystal panel 120R from the upper side in FIG. 2 and exits from the lower side toward the screen 116. Inside the incident-side dust-proof transparent plate 201 (exit side), a microlens element 203 that is a refractive optical element is formed by a microlens array substrate 202 and an optically transparent adhesive layer 204. The detailed configuration and operation of the microlens element 203 will be described later with reference to FIG. One microlens element 203 is provided corresponding to one corresponding opening area AP. Looking at the entire liquid crystal panel 120R, a plurality of microlens elements 203 are arranged on a plane corresponding to the plurality of aperture regions AP to form a microlens array that is a refractive optical unit.

  A counter substrate 206 having a transparent electrode 207 made of an ITO film or the like is formed on the inner side (outgoing side) of the microlens element 203. Further, a black matrix 205 serving as a light shielding portion is formed between the counter substrate 206 and the transparent electrode 207. As described above, the black matrix 205 is provided with the rectangular opening area AP corresponding to the pixel. Furthermore, an alignment film 208 that has been subjected to a predetermined alignment process such as a rubbing process is provided on the emission side of the transparent electrode 207. The alignment film 208 is made of, for example, a transparent organic film such as a polyimide film.

  A TFT substrate 212 is formed on the inner side (incident side) of the emission-side dust-proof transparent plate 213. Inside the TFT substrate 212, a transparent electrode and a TFT (thin film transistor) forming layer 211 are provided. An alignment film 210 is provided further inside (incident side) of the TFT formation layer 211. The rubbing direction of the alignment film 208 and the rubbing direction of the alignment film 210 are arranged so as to be substantially orthogonal. Then, the incident side dustproof transparent plate 201 and the emission side dustproof transparent plate 213 are bonded together with the counter substrate 206 and the TFT substrate 212 facing each other. A liquid crystal layer 209 for image display is sealed between the counter substrate 206 and the TFT substrate 212.

  In the configuration shown in FIG. 1, the first polarizing plate 121R and the second polarizing plate 122R are provided separately from the liquid crystal panel 120R. However, instead of this, a polarizing plate may be provided between the incident-side dustproof transparent plate 201 and the counter substrate 206, between the emission-side dustproof transparent plate 213 and the TFT substrate 212, and the like.

  Next, the configuration and operation of the microlens element 203 will be described with reference to FIG. FIG. 3A illustrates a schematic configuration from the incident-side dust-proof transparent plate 201 to the liquid crystal layer 209 of the liquid crystal panel 120R. Other configurations of the liquid crystal panel 120R are omitted. An optically transparent microlens array substrate 202 and an optically transparent adhesive layer 204 constitute a microlens element 203 that is a refractive optical element. Incident light that is a substantially parallel light beam is refracted at the interface between the microlens array substrate 202 and the adhesive layer 204. Here, the microlens element 203 is an aspherical lens including a lens portion LA in the vicinity of the optical axis AX and an inclined surface portion LB formed around the lens portion. The inclined surface portion LB is formed at an inclination angle θ with respect to the parallel surface of the incident-side dust-proof transparent plate 201 that is a parallel plate. The light beam LAR incident on the lens portion LA is condensed so as to pass through the opening area AP of the black matrix 205 by the condensing function of the lens. Further, the light beam LBR incident on the inclined surface portion LB passes through the aperture region AP and is incident obliquely on the liquid crystal layer 209 due to the refractive action of the inclined surface. The light beam LBR refracted by the slope portion LB is incident obliquely on the liquid crystal layer 209 at an incident angle α. The shape of the microlens element 203, the refractive index of the microlens array substrate 202, and the refractive index of the adhesive layer 204 are appropriately set so that the condensed light and the refracted light can efficiently pass through the aperture region AP. .

  FIG. 3-2 shows a state in which the microlens element 203 is projected onto the surface of the counter substrate 206. A region where the slope portion LB is projected is indicated by hatching. As can be seen from FIG. 3-2, most of the microlens element 203 is composed of the inclined surface portion LB. As a result, of the light incident on the microlens element 203, a proportion of the light proportional to the area of the inclined surface portion LB is obliquely incident on the liquid crystal layer 209.

  Next, the improvement of the contrast of the projected image by the microlens element 203 will be described. FIG. 4 shows an incident angle α (horizontal axis, unit: degree) of a light beam to the liquid crystal layer 209 for three types of inclination angles θ = 0 °, 40 °, and 60 ° of the inclined surface portion LB of the microlens element 203. The relationship with the total amount of light (vertical axis, unit: W) is shown. In the case of the inclination angle θ = 0 °, the microlens element 203 is in the same state as a simple plane portion. In this case, the peak value of the light amount distribution is in the vicinity of the incident angle α = 4 °. On the other hand, as the tilt angle θ is increased from 40 ° to 60 °, the peak value of the light amount distribution shifts to the vicinity of the incident angle α = 7 °. Further, as the tilt angle θ increases, the component that obliquely enters the liquid crystal layer 209 also increases.

  FIG. 5 shows the relationship between the contrast (vertical axis) of the projected image and the tilt angle θ (horizontal axis). Two microlens elements 203 having different manufacturing methods are used for one inclination angle θ. Therefore, six pieces of contrast data are plotted for three types of inclination angles θ = 0 °, 40 °, and 60 °. Further, the contrast of the projected image is evaluated in two cases, when the optical compensation films 130R, 130G, and 103B are provided and when they are not provided.

  First, the case where the optical compensation films 130R, 130G, and 130B are not provided will be described. When the tilt angle θ = 0 °, that is, when the microlens element 203 is non-powered in the same state as a parallel plate, if the tilt angle θ is changed from 0 ° to 60 °, the contrast of the projected image becomes about 250 to 300: 1. . On the other hand, when the optical compensation films 130R, 130G, and 130B are provided as in this embodiment, the contrast of the projected image is about 250: when the tilt angle θ = 0 °. When the tilt angle θ = 60 °, the contrast is improved to about 510: 1. When the tilt angle θ = 40 °, the contrast exhibits an intermediate characteristic between the tilt angles θ = 0 ° and 60 °.

  4 and 5, when the inclination angle θ of the inclined surface portion LB of the microlens element 203 is 60 ° and the incident angle α of the light beam to the liquid crystal layer 209 is about 7 °, a high-contrast projection image is obtained. It turns out that it is obtained. Next, the reason why a high-contrast projected image can be obtained in this state will be described with reference to FIGS.

  FIG. 6 shows the relationship between the light amount (vertical axis, unit: arbitrary) of the projected image and the tilt angle θ (horizontal axis) when displaying all white. Two microlens elements 203 having different manufacturing methods are used for one inclination angle θ. When the optical compensation film 130R or the like is provided for each of the three types of inclination angles θ = 0 °, 40 °, and 60 ° (shown in white), and when the optical compensation film 130R is not provided (shown with diagonal lines). The amount of light is shown as a bar graph. As can be seen from FIG. 6, when displaying all white, the light amount when the optical compensation film 130R is provided and the light amount when the optical compensation film 130R is not provided in any of the inclination angles θ = 0 °, 40 °, and 60 °. Is almost equal.

  FIG. 7 shows the amount of light when displaying all black as in FIG. When the inclination angle θ = 0 ° and 40 °, the light amount when the optical compensation film 130R and the like are provided is approximately equal to the light amount when the optical compensation film 130R is not provided. On the other hand, when the tilt angle θ = 60 °, the amount of light when not provided is larger than the amount of light when the optical compensation film 130R or the like is provided (the portion surrounded by a circle in FIG. 7). ). When displaying all black, the light reaching the screen 116 (see FIG. 1) is ideally zero. That is, in the optical system provided with the optical compensation film 130R and the like, the amount of light transmitted to the screen 116 can be reduced by setting the inclination angle θ of the microlens element 203 to 60 °. A small amount of light transmitted through the liquid crystal panel 120R or the like means that it is close to an ideal all black display. For this reason, when the tilt angle θ is 60 °, it is possible to obtain a more ideal all-black display, so that the contrast of the projected image can be improved.

  In this embodiment, optical compensation films 130R, 130G, and 130B are used. Therefore, the liquid crystal panel 120R can greatly widen the viewing angle as compared with the conventional TN display liquid crystal panel. As described with reference to FIGS. 4, 5, 6, and 7, the light beam is incident on the liquid crystal layer 209 at an incident angle α = 7 ° with the inclination angle θ = 60 ° of the inclined surface portion LB of the microlens element 203. , The contrast of the projected image can be further improved with a large viewing angle. The inclination angle θ is preferably in the range of 45 ° <θ <80 °. More preferably, the range is 55 ° <θ <80 °. When the tilt angle θ is within these ranges, a high-contrast projected image can be obtained.

  In this embodiment, the optical compensation film 130R, the microlens element 203 serving as a refractive optical element, and the liquid crystal layer 209 serving as a modulator are sequentially formed from the ultrahigh pressure mercury lamp 101 side. However, the configuration is not limited to this, and the optical compensation film 130R is disposed between the microlens element 203 and the liquid crystal layer 209, or the optical compensation film 130R is closer to the projection lens 114 than the microlens element 203 and the liquid crystal layer 209. Any arrangement may be used.

  A spatial light modulation device according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 8 illustrates a perspective configuration of the liquid crystal panel 820R in the spatial light modulation device according to the second embodiment. The present embodiment is different from the first embodiment described above in that a microprism element 803 is used instead of the microlens element. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 8 shows only a portion of one opening area AP among the plurality of opening areas AP of the liquid crystal panel 820R. Since the configuration of the liquid crystal panel 820R corresponding to the other opening regions is the same as the configuration shown in FIG. The R light from the ultra-high pressure mercury lamp 101 is incident on the liquid crystal panel 820R from the upper side in FIG. 8 and is emitted from the lower side toward the screen 116. Inside the incident-side dust-proof transparent plate 201, a microprism array substrate 802 and a microprism element 803 that is a refractive optical element are formed. The detailed configuration and operation of the microprism element 803 will be described later with reference to FIG. One microprism element 803 is provided on a cover glass 804 that is a parallel plate corresponding to one corresponding opening area AP. Looking at the entire liquid crystal panel 820R, a plurality of microprism elements 803 are arranged on a plane corresponding to the plurality of aperture areas AP to constitute a microprism array which is an optical refraction part.

  FIG. 9 shows a perspective configuration of the microprism element 803. The microprism element 803 has a polygonal pyramid shape, for example, a quadrangular pyramid shape formed on a substantially square cover glass 804. For this reason, the microprism element 803 has four inclined surface portions LB1, LB2, LB3, and LB4.

  Next, the configuration and operation of the microprism element 803 will be described with reference to FIG. FIG. 10 shows a schematic configuration from the incident side dust-proof transparent plate 201 to the liquid crystal layer 209 of the liquid crystal panel 820R. Other configurations of the liquid crystal panel 120R are omitted. A cover glass 804 facing the optically transparent microprism array substrate 802 is filled with an optically transparent adhesive layer 803a to form a microprism element 803 as a refractive optical part. Incident light of a substantially parallel light beam is refracted at the interface between the microprism array substrate 802 and the adhesive layer 803a. Here, the slope portions LB1, LB2, LB3, and LB4 of the microprism element 803 are formed at an inclination angle θ with respect to the parallel surface of the incident-side dustproof transparent plate 201 that is a parallel plate. For example, the light beam LBR incident on the inclined surface portion LB1 passes through the aperture region AP and is incident obliquely on the liquid crystal layer 209 at an incident angle α due to the refractive action of the inclined surface LB1. The shape of the microprism element 803, the refractive index of the microprism array substrate 802, and the refractive index of the adhesive layer 803a are set as appropriate so that the refracted light can efficiently pass through the aperture region AP.

  In the first embodiment, the lens unit LA of the microlens element 203 collects the light beam LAR. Further, the inclined surface portion LB refracts the light beam LBR. Thus, the liquid crystal layer 209 contains a mixture of light that is refracted and incident obliquely and light that is collected and incident. In contrast, in this embodiment, the microprism element 803 refracts the incident light beam LBR so as to pass through the aperture region AP. As a result, all the light that has passed through the microprism element 803 enters the liquid crystal layer 209 at an incident angle α. The incident angle α is approximately 7 °, for example, as in the first embodiment. Thereby, a high-contrast projection image can be obtained in a wide viewing angle. Like the microprism element 803, when the refracting surface is formed only by the slope without providing a lens portion, the light from the ultrahigh pressure mercury lamp 101 can be easily converted into predetermined oblique incident light. For this reason, an even higher contrast projection image can be obtained in a wide viewing angle by the optical compensation film 130R. The microprism element 803 is not limited to a polygonal pyramid shape, and may be a conical shape.

  In Examples 1 and 2, optical compensation films 130R, 130G, and 130B are provided in the optical paths of the three colored lights, respectively. However, the configuration is not limited to this. For example, if the rubbing directions of the alignment films of the liquid crystal panels 120R, 120G, and 120G for each color are matched, the light from the light path of the three colors, for example, the light from the ultra-high pressure mercury lamp 101 is color-separated. Alternatively, a configuration in which one optical compensation film is disposed in the optical path before the start is possible.

Next, a method for manufacturing a liquid crystal panel 120R including the microlens element 203 of Example 1 will be described with reference to FIGS. This manufacturing method is a method using a gray scale lithography technique. FIG. 11A shows the configuration of the gray scale mask and the amount of transmitted light. The gray scale mask 1100 is configured such that the transmittance increases stepwise from the center to the periphery. For example, the transmittance at the center is 0%, the transmittance at the periphery is 100%, and the middle is formed so as to have a desired transmittance. As the gray scale mask 1100, an area gradation mask or a gray scale mask using photosensitive glass can be used. And in the area | region which forms the slope part LB, it sets so that the transmittance | permeability may change substantially linearly. The amount of light 1101 that passes through the grayscale mask 1100 of FIG. First, a photoresist layer 1102 is formed on a microlens array substrate 202 that is a glass substrate. Then, the photoresist layer 1101 is exposed using the gray scale mask 1100. After the exposure, an etching process is performed. As a result, a shape corresponding to the transmittance of the gray scale mask 1100 is formed in the photoresist layer 1102 as shown in FIG. Next, a dry etching process is performed using a fluorine-based gas such as C ₄ F ₈ . By dry etching, the shape of the photoresist layer 1101 can be transferred to the microlens array substrate 202 as shown in FIG. Then, as shown in FIG. 11-4, the microlens array substrate 202 and the counter substrate 206 are fixed with an optically transparent adhesive layer 204. The refractive index n of the adhesive layer 204 is, for example, about n = 1.56. Next, as shown in FIG. 11-5, the black matrix 205 is patterned on the counter substrate 206. Further, a transparent electrode 207 such as an ITO film is formed. Since the manufacturing process following these processes is the same as the manufacturing method of a well-known liquid crystal panel, description is abbreviate | omitted. According to this manufacturing method, the microlens element 203 having an arbitrary shape can be manufactured by controlling the transmittance of the grayscale mask 1100.

Next, another manufacturing method of the liquid crystal panel 120R including the microlens element 203 of Example 1 will be described with reference to FIGS. First, an HTO film 1201 and a chromium mask 1202 serving as a mask are formed on the microlens array substrate 202 in order from the substrate side. An opening AP2 is provided in the center of the chrome mask 1202. Further, a photoresist layer 1203 is applied and patterned. Then, as shown in FIG. 12A, reactive ion etching (hereinafter referred to as “RIE”) is performed using a fluorine-based gas G such as C ₄ F ₈ together. This RIE functions as a pre-etch. When the pre-etching is completed, as shown in FIG. 12B, a portion that is a vertex of the lens portion LA (see FIG. 3A) is formed at the center of the microlens array substrate 202. Then, wet etching is performed on the substrate after pre-etching using a hydrofluoric acid solution. When the wet etching is completed, a concave lens shape can be formed on the microlens array substrate 202 as shown in FIG. Then, the microlens element 203, the black matrix 205, and the like are formed by the same procedure as described in FIGS. 11-4 and 11-5. Even when the HTO film 1201 is not used, the microlens element 203 having the slope portion LB can be formed.

  The present invention is not limited to a projector, but can be widely applied to a device including a TN display liquid crystal panel, such as a direct-view image display device.

  As described above, the spatial light modulation device according to the present invention is particularly useful for a TN display liquid crystal panel.

1 is a schematic configuration diagram of a projector according to a first embodiment of the invention. 1 is a schematic configuration diagram of a liquid crystal panel of Example 1. FIG. FIG. 2 is a schematic view of the vicinity of a microlens element of Example 1. The projection figure of a micro lens element. The figure which shows the relationship between incident angle (alpha) and light quantity. The figure explaining the contrast of an image. Light intensity comparison diagram when displaying all white. Light intensity comparison diagram when displaying all black. FIG. 3 is a schematic configuration diagram of a liquid crystal panel of Example 2. The block diagram of a microprism element. FIG. 6 is a schematic view of the vicinity of a microprism element of Example 2. The figure which shows the outline and transmitted light amount of a gray scale mask. Explanatory drawing of the manufacturing method of a micro lens element. Other explanatory drawing of the manufacturing method of a micro lens element. Still another explanatory view of the method of manufacturing the microlens element. Explanatory drawing of the manufacturing method of a micro lens element. Explanatory drawing of another manufacturing method of a micro lens element. Other explanatory drawing of another manufacturing method of a micro lens element. Still another explanatory view of another method of manufacturing a microlens element. Explanatory drawing of another manufacturing method of a micro lens element.

Explanation of symbols

  100 projector, 101 super high pressure mercury lamp, 104 integrator, 105 polarization conversion element, 106R, 106G dichroic mirror, 107 reflecting mirror, 108 relay lens, 110R, 110G, 110B spatial light modulator for each color light, 112 cross dichroic prism, 112a , 112b Dichroic film, 114 projection lens, 116 screen, 120R, 120G, 120B liquid crystal panel, 121R, 121G, 121B polarizing plate, 122R, 122G, 122B polarizing plate, 123R, 123G, 123B retardation plate, 124R, 124B glass plate , 130B, 130G, 130B optical compensation film, 201 incident-side dustproof transparent plate, 202 microlens array substrate, 203 microlens element, 204 Adhesive layer, 205 Black matrix, 206 Counter substrate, 207 Transparent electrode, 208 Alignment film, 209 Liquid crystal layer, 210 Alignment film, 211 TFT formation layer, 212 TFT substrate, 213 Ejection side dustproof transparent plate, 802 Micro prism array substrate , 803 micro prism element, 803a adhesive layer, 804 cover glass, 820R liquid crystal panel, 1100 gray scale mask, 1101 transmitted light amount, 1102 photoresist layer, 1201 HTO film, 1202 chromium mask, 1203 photoresist layer, AP opening region, AP2 aperture, AX optical axis, LA lens, LAR ray, LB, LB1-LB4 slope, LBR ray, α incident angle, θ tilt angle

Claims (5)

An optical compensation film that gives a predetermined phase difference to incident light; and
A modulator that modulates and emits light according to an image signal;
A refracting optical unit having a refracting surface for at least oblique incidence of light with respect to the modulating unit;
I have a,
The modulation unit is a liquid crystal panel,
The refractive optical part has a lens part near the optical axis and a slope part formed around the lens part, and the slope part has an inclination angle θ with respect to the incident surface of the liquid crystal panel. The inclination angle θ satisfies 45 ° <θ <80 °,
The light collected by the lens unit converges at a position after passing through the liquid crystal layer of the liquid crystal panel,
The spatial light modulation device according to claim 1, wherein the light beam refracted at the inclined surface is obliquely incident on the liquid crystal layer at an incident angle α so as to converge at a position after passing through the liquid crystal layer of the liquid crystal panel . The modulation unit has a plurality of pixel openings,
The refractive optical part is composed of a plurality of refractive optical elements,
The spatial light modulation device according to claim 1, wherein the refractive optical element causes incident light to pass through the pixel opening and at least obliquely incident. The spatial light modulation device according to claim 1 , wherein the inclination angle θ is 60 ° .   The spatial light modulator according to claim 1, wherein the incident angle α is 7 °. A light source for supplying light;
The spatial light modulation device according to any one of claims 1 to 4 ,
A projector comprising: a projection lens that projects light from the spatial light modulator.

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