JP2010066351A - Projection type liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type liquid crystal display device that suppresses contrast degradation by a simple configuration. <P>SOLUTION: The projection type liquid crystal display device includes: a light source 3 that generates light emitted to a light valve 2; an integrator lens 4 that is disposed on an optical axis between the light source 3 and light valve 2 and that uniformizes an illumination distribution of light emitted to the light valve 2 from the light source 3; and a polarization conversion element 5 that is disposed on the optical axis and converts incident light to first straight polarization light. The polarization conversion element 5 includes: a λ/2 phase difference filter 5c that splits light emitted from the integrator lens 4, into first straight polarization light and second straight polarization light orthogonal to the first straight polarization light and a polarization axis, and that rotates the polarization axis of the second straight polarization light provided on an emission face for the second straight polarization light, through 90°; and a polarization film 60 that absorbs second straight polarization light provided on the emission face of the first straight polarization light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a projection type liquid crystal display device, and more particularly to a projection type liquid crystal display device using a liquid crystal light valve.

  In a conventional projection display device, light leakage and stray light (unnecessary light) occur in various optical elements that make up the optical system such as a guide optical system and a projection lens, and an image is projected onto a screen, particularly in a dark room For example, a dark video does not become dark enough, so there is a problem that a sufficient contrast cannot be obtained and a sense of reality is lacking.

  In particular, in a projection display device using a liquid crystal light valve, the liquid crystal light valve has a characteristic of blocking transmitted light according to the polarization characteristics of light, and cannot completely block transmitted light. Improvement of contrast is strongly desired.

  In a general guidance optical system (illumination optical system), light emitted from a light source is made uniform by an integrator lens and then irradiated to a liquid crystal light valve. In order to increase the amount of light irradiating the liquid crystal light valve, a polarization conversion element is arranged on the light path of the light source or the liquid crystal light valve, and the non-polarized light emitted from the light source is transmitted through the polarization conversion element. The liquid crystal light bulb is irradiated after being converted to. However, since the polarization conversion element has an incident angle dependency, it has been impossible to completely convert the polarization conversion element into predetermined linearly polarized light. Therefore, the light that has not been converted into the predetermined linearly polarized light after passing through the polarization conversion element becomes unnecessary light, which causes a decrease in contrast.

  As a countermeasure against such a problem, polarization separation that separates a light beam by transmitting the first linearly polarized light and reflecting the second linearly polarized light whose polarization direction is orthogonal to the polarization direction of the first linearly polarized light. The polarization direction of the first linearly polarized light emitted in the same direction and the reflective surface that emits the second linearly polarized light reflected by the polarization separation surface in the same direction as the first linearly polarized light. A polarization rotation element that aligns with the polarization direction of the other linearly polarized light, and the boundary between the two light fluxes on the exit surface of the two types of linearly polarized light conversion elements having the same polarization direction. An output shielding plate that shields the optical path is arranged (see, for example, Patent Document 1).

JP 2004-53703 A (page 4, FIG. 1) JP-A-10-335758

  In Patent Document 1, there is an effect of shielding a narrow area where two types of linearly polarized light are emitted, but there is no effect on a wide area emitted from the polarization conversion element, which causes a problem of a decrease in contrast.

  The present invention has been made to solve these problems, and an object thereof is to provide a projection type liquid crystal display device capable of suppressing a decrease in contrast with a simple configuration.

  In order to solve the above problems, a projection-type liquid crystal display device according to the present invention is disposed on a light valve, a light source that generates light to irradiate the light valve, and an optical path between the light source and the light valve. An integrator lens composed of a first lens array and a second lens array that equalizes the illuminance distribution of the light radiated from the light valve to the light valve, and is disposed on the optical path, and the incident light is converted into the first linearly polarized light. The polarization conversion element converts the light emitted from the integrator lens into a first linearly polarized light and a second linearly polarized light whose polarization axis is orthogonal to the first linearly polarized light. And a λ / 2 retardation film for rotating the polarization axis of the second linearly polarized light 90 degrees provided on the exit surface of the second linearly polarized light, and an exit surface of the first linearly polarized light The second provided in Characterized in that it comprises a polarizing film for absorbing or reflecting the linear polarized light.

  According to the present invention, the polarization conversion element separates the light emitted from the integrator lens into the first linearly polarized light and the second linearly polarized light whose polarization axis is orthogonal to the first linearly polarized light. A λ / 2 phase difference film for rotating the polarization axis of the second linearly polarized light by 90 degrees provided on the exit surface of the second linearly polarized light, and a first provided on the exit surface of the first linearly polarized light. 2 is provided with a polarizing film that absorbs or reflects the linearly polarized light, and thus a reduction in contrast can be suppressed with a simple configuration.

  Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1>
FIG. 1 is a configuration diagram of a projection type liquid crystal display device 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the projection type liquid crystal display device 1 includes a liquid crystal light valve 2 (light valve), a light source system 3 (light source) that generates light to irradiate the liquid crystal light valve 2, a light source system 3 and a liquid crystal light. The first lens array 4a and the second lens array 4b are arranged on the optical path between the bulb 2 and uniformize the illuminance distribution of light emitted from the light source system 3 to the liquid crystal light bulb 2. An integrator lens 4, a polarization conversion element 5 that is disposed on the optical path and converts incident light into one type of linearly polarized light (first linearly polarized light), and a condenser lens that is sequentially disposed downstream of the polarization conversion element 5. 6 and a field lens 7. Further, the first polarizing plate 8 that transmits one type of linearly polarized light (for example, p-polarized light) out of the light emitted from the condenser lens 6, and the reflection having the same transmission axis as the first polarizing plate 8. The first polarizing plate 9 transmits linearly polarized light (for example, s-polarized light) having a polarization axis different from the transmission axis of the first polarizing plate 8 out of light emitted from the liquid crystal light valve 2. 2 polarizing plates 10.

  A projection optical system 11 is disposed after the second polarizing plate 10, and light emitted from the projection optical system 11 is projected onto a screen (not shown).

  FIG. 1 shows the configuration of the projection type liquid crystal display device 1 relating to the optical path of light of one color, but the red, green, and blue colors have the same configuration as described above except for the projection optical system 11. The image light emitted from the second polarizing plate 10 provided for each color may be combined by a light combining element (not shown) and then projected from the projection optical system 11 onto the screen.

  As the liquid crystal light valve 2, a reflective liquid crystal light valve is used in the first embodiment. The liquid crystal light valve 2 has a large number (for example, hundreds of thousands) of liquid crystal display elements corresponding to each pixel of image light projected on a screen arranged in a plane, and each liquid crystal display element is arranged according to pixel information. By operating, the light incident on the liquid crystal light valve 2 is emitted as image light. Although the reflective liquid crystal light valve is used in the first embodiment, a transmissive liquid crystal light valve may be used. When the transmissive liquid crystal light valve is used, the reflective polarizing plate 9 in FIG. 1 is not necessary, and the second polarizing plate 10 and the projection optical system 11 are disposed on the optical axis C1 at the rear stage of the liquid crystal light valve 2. Become.

  The light source system 3 is provided to irradiate the liquid crystal light valve 2 with light, and includes a light source 3a and a reflecting mirror 3b that reflects the light emitted from the light source 3a and irradiates the integrator lens 4. Generally, a high pressure mercury lamp, a halogen lamp, or a xenon lamp is used as the light source 3a, but other light emitting devices such as an LED (Light Emitting Diode), a laser, and an electrodeless discharge lamp may be used.

  The reflecting mirror 3b is formed on a parabolic surface or an elliptical surface, but may have any shape and structure as long as the light can be condensed on the polarization conversion element 5, and is not particularly limited. . For example, in order to make the light incident on the integrator lens 4 substantially parallel to the optical axis C, when the shape of the reflecting mirror 3b is a paraboloid or an ellipsoid, as shown in FIG. A concave lens 70 for making the light substantially parallel may be disposed between the lens 3 and the integrator lens 4. FIG. 7 is a diagram showing a simulation of light emitted from the light source 3a when the reflecting mirror 3b is an ellipsoid. As shown in FIG. 7, the reflecting mirror 3 b has an elliptical surface, and the light emitted from the light source system 3 by the concave lens 70 is substantially parallel to the optical axis C. Generally, a bulb of the light source 3a exists in the vicinity of the optical axis C, and 71 in FIG. 7 indicates an opening portion by the bulb.

  The integrator optical system 4 includes a first lens array 4a and a second lens array 4b. In addition, the first lens array 4a and the second lens array 4b include a rectangular convex lens (a lens cell or a cell) having a long side in the x-axis direction and a short side in the y-axis direction. The configuration is arranged in a matrix form. Each of the plurality of convex lenses constituting the first lens array 4a and each of the plurality of convex lenses constituting the second lens array 4b are opposed to each other and are disposed to face each other in the z-axis direction.

  The general polarization conversion element 5 converts the light incident on the polarization conversion element 5 into one kind of linearly polarized light and emits it, and is arranged arbitrarily separated in the x-axis direction. FIG. 2 is a configuration diagram of a general polarization conversion element 5. As shown in FIG. 2, the polarization conversion element 5 includes a plurality of polarization separation films 5 a arranged with an inclination (for example, 45 degrees) with respect to the z-axis direction (the direction of the optical axis C), and the polarization separation film 5 a. And a plurality of reflective films 5b arranged to be inclined (for example, 45 degrees) with respect to the z-axis direction, and a portion on the emission surface of the polarization conversion element 5 where light transmitted through the polarization separation film 5a is emitted. And a λ / 2 retardation film 5c.

  The light incident on the polarization conversion element 5 is separated into s-polarized light and p-polarized light by the polarization separation film 5a. That is, p-polarized light is transmitted through the polarization separation film 5a, and s-polarized light is reflected from the polarization separation film 5a. The p-polarized light transmitted through the polarization separation film 5a is emitted from the polarization conversion element 5 after being converted into s-polarized light by the λ / 2 retardation film 5c. On the other hand, the s-polarized light reflected from the polarization separation film 5a is emitted from the polarization conversion element 5 after being reflected from the reflection film 5b. Thus, the light emitted from the polarization conversion element 5 is substantially s-polarized light. In order to make the light emitted from the polarization conversion element 5 substantially p-polarized light, the λ / 2 retardation film 5c is not disposed on the exit surface of the p-polarized light that has passed through the polarization separation film 5a, and the reflection film A λ / 2 retardation film 5c may be disposed on the exit surface of the s-polarized light reflected from 5b. The polarization conversion element 5 according to Embodiment 1 will be described in detail later.

  FIG. 3 is a diagram illustrating the operation of the first polarizing plate 8, the reflective polarizing plate 9, the liquid crystal light valve 2, and the second polarizing plate 10 according to Embodiment 1 of the present invention. Other components are as shown in FIG. 1, but are omitted here for convenience. In FIG. 3, a case where non-polarized light that is not linearly polarized light is incident on the first polarizing plate 8 will be described. Note that the polarization axes of p-polarized light and s-polarized light in FIG. 2 are parallel to the x-axis and y-axis, respectively. However, with respect to the stage subsequent to the condenser lens 6, the polarization axes of p-polarized light and s-polarized light are respectively y-axis. Will be described as being parallel to the x-axis. Further, when the polarization separation film 5a of FIG. 2 is used as a reference reflecting surface, the axis parallel to the zx plane becomes the polarization axis of the p-polarized light, and therefore the polarization axis of the p-polarized light emitted from the polarization conversion element 5 is the x-axis. Become. Further, in FIG. 1, when the reflective polarizing plate 9 is used as a reference reflecting surface, the axis parallel to the yz plane is the polarization axis of p-polarized light, and therefore the polarization axis of p-polarized light is the y-axis. That is, unnecessary light (s-polarized light) that enters the first polarizing plate 8 described later indicates p-polarized light that exits the polarization conversion element 5.

  In FIG. 3A, when the first polarizing plate 8 transmits the p-polarized light, the reflection-type polarizing plate 9 also transmits the p-polarized light because the transmission axis is the same as that of the first polarizing plate 8, so The p-polarized light transmitted through the plate 9 reaches the liquid crystal light valve 2. The p-polarized light reaching the liquid crystal light valve 2 is reflected by the liquid crystal light valve 2 and then passes through the reflective polarizing plate 9 (arrow 30) when the polarization axis is not rotated by the liquid crystal light valve 2. On the other hand, when the polarization axis of the liquid crystal light valve 2 is rotated by 90 degrees, the light is reflected by the reflective polarizing plate 9 after being reflected by the liquid crystal light valve 2, and the transmission axis of the first polarizing plate 8 is 90 degrees. After passing through a different second polarizing plate 10, it reaches the projection optical system 11 (arrow 31). FIG. 3B is a diagram illustrating the transmission axes of the first polarizing plate 8 and the second polarizing plate 10. Since the reflective polarizing plate 9 transmits part of the s-polarized light, in order to improve the contrast, the polarization characteristics of the light incident on the first polarizing plate 8 (p-polarized light and s-polarized light Ratio) and the absorption performance of s-polarized light in the first polarizing plate 8 are important.

  FIG. 4 is a diagram showing the operation of the first polarizing plate 8, the reflective polarizing plate 9, the liquid crystal light valve 2, and the second polarizing plate 10 according to Embodiment 1 of the present invention. Other components are as shown in FIG. 1, but are omitted here for convenience. As shown in FIG. 4, arrows 40 to 45 indicate polarized light. In Tables 1 and 2, the first polarizing plate 8 has a p-polarized light transmittance of 92%, an s-polarized light transmittance of 0.5%, and the reflective polarizing plate 9 has a p-polarized light transmittance of 90%. The s-polarized light transmittance is 0.5%, the p-polarized light reflectance is 3%, the s-polarized light reflectance is 92%, the p-polarized light transmittance of the second polarizing plate 10 is 0.1%, and s-polarized light. The extinction ratio (the light amount of the white arrow 45 / the light amount of the black arrow 45) when the light transmittance is 88% is shown. Here, the extinction ratio represents the contrast at the arrow 45 through the components shown in FIG. When the liquid crystal light valve 2 is in the white state, the polarization axis of the polarized light indicated by the arrow 42 is rotated by 90 degrees to reflect 100%, and in the black state, the polarization axis of the polarized light indicated by the arrow 42 is changed. Assume that 100% reflection occurs without rotation.

  In Table 1, the p-polarized light component in the black state 1 indicated by the arrow 45 shown in FIG. 4 is represented by the following equation (1), and the s-polarized light component in the black state 1 is represented by the following equation (2). expressed. In the white state 1, the polarization axis of the polarized light indicated by the arrow 42 shown in FIG. 4 is rotated by 90 degrees, so that the polarized light components indicated by the arrows 42 and 43 are reversed between the p-polarized light and the s-polarized light. Become.

0.5 * 0.92 * 0.9 * 0.03 * 0.001 = 1.24E-05 (1)
0.5 * 0.005 * 0.005 * 0.92 * 0.88 = 1.01E-05 (2)
In Table 1, when the polarized light component of the arrow 40 incident on the first polarizing plate 8 is p-polarized light 0.5 and s-polarized light 0.5, that is, the polarization components of p-polarized light and s-polarized light. The case where the ratio is equal is shown. On the other hand, Table 2 shows the case of p-polarized light 0.8 and s-polarized light 0.2, that is, the case where the ratio of polarized light having a polarization axis equal to the transmission axis of the reflective polarizing plate 9 is high. From Table 1 and Table 2, when the ratio of polarized light incident on the first polarizing plate 8 is p-polarized light 0.8 and s-polarized light 0.2, p-polarized light 0.5 and s-polarized light are used. It can be confirmed that the extinction ratio is higher than that when the light is 0.5.

  When the ratio of the s-polarized light incident on the first polarizing plate 8 is high, the s-polarized light is slightly contained in the polarized light transmitted through the first polarizing plate 8, and a part of the s-polarized light is further included. Will pass through the reflective polarizing plate 9. The s-polarized light transmitted through the reflective polarizer 9 is reflected by the liquid crystal light valve 2 and then reflected by the reflective polarizer 9 toward the second polarizer 10 with a high reflectivity. 10 is transmitted with a high transmittance, resulting in a low extinction ratio. Therefore, an ideal extinction ratio (contrast) can be obtained by setting the ratio of the polarized light component indicated by the arrow 40 to p-polarized light 1 and s-polarized light 0.

  The polarized light component indicated by the arrow 40 incident on the first polarizing plate 8 is generally determined by the polarization conversion element 5. Therefore, it is necessary to increase the proportion of one type of linearly polarized light emitted from the polarization conversion element 5. FIG. 5 is a diagram illustrating a polarized light component with respect to an incident angle in a general polarization conversion element 5. As shown in FIG. 5, arrows 50p, 51p, and 52p indicate p-polarized light emitted from the s-polarized light path when incident at 0 degrees, −5 degrees, and 5 degrees with respect to the x-axis direction, respectively, and arrows 50s. , 51 s and 52 s indicate s-polarized light emitted from the p-polarized light path when incident at 0 degrees, −5 degrees, and 5 degrees with respect to the x-axis direction, respectively. Further, Table 3 shows transmittance measurement data of arrows 50p to 52p and arrows 50s to 52s.

  As shown in Table 3, it can be confirmed that the transmittance of the p-polarized light (polarized component that should not be transmitted originally) emitted from the s-polarized light path when the light is incident at the arrow 52p, that is, 5 degrees, is the highest. The polarization conversion element 5 is easily affected by obliquely incident light, and in particular, the proportion of p-polarized light that is incident from an angle in the + direction with respect to the x-axis shown in FIG. 5 is high from the s-polarized light path. Therefore, it is possible to improve the extinction ratio at the arrow 45 in FIG. 4 by reducing the proportion of the p-polarized light emitted from the s-polarized light path.

  FIG. 6 is a configuration diagram of the polarization conversion element 5 according to Embodiment 1 of the present invention. As illustrated in FIG. 6, the polarization conversion element 5 according to the first embodiment converts light emitted from the second lens array 4 b of the integrator optical system 4 (integrator lens) into s-polarized light (first linearly polarized light). ) And p-polarized light (second linearly polarized light) whose polarization axes are orthogonal to each other by the polarization separation film 5a, and the polarization axis of the p-polarized light provided on the exit surface of the p-polarized light Λ / 2 phase difference film 5c rotated by 90 degrees, and a polarizing film 60 that absorbs p-polarized light provided on the exit surface of the s-polarized light. That is, the polarization conversion element 5 according to Embodiment 1 shown in FIG. 6 further includes a polarizing film 60 that absorbs p-polarized light on the exit surface of the s-polarized light of the conventional polarization conversion element 5 shown in FIG. In addition, λ / 2 retardation films 5c and polarizing films 60 are alternately arranged on the exit surface of the polarization conversion element 5.

  As described above, since the ratio of the p-polarized light emitted from the s-polarized light path is higher than the ratio of the s-polarized light emitted from the p-polarized light path, the p-polarized light is emitted on the exit surface of the s-polarized light of the polarization conversion element 5. By providing a polarizing film 60 that absorbs light (the absorption axis is parallel to the p-polarized light), the transmission of the p-polarized light emitted from the polarization conversion element 5 is suppressed, and the extinction ratio at the arrow 45 in FIG. 4 is improved. It becomes possible to make it. In particular, when the liquid crystal light valve 2 is a reflective liquid crystal light valve, the ratio of the polarization component emitted from the polarization conversion element 5 affects the contrast, so the polarization conversion element 5 is configured as shown in FIG. This is effective in improving the contrast.

  In the case where the λ / 2 retardation film 5c is provided on the exit surface of the s-polarized light, the effect can be obtained by providing a polarizing film that absorbs the s-polarized light on the exit surface of the p-polarized light. However, if a polarizing film that absorbs p-polarized light is provided on the exit surface of the λ / 2 retardation film 5c in FIG. 6, the absorption characteristics of the polarizing film may deteriorate due to thermal strain or the like. It is preferable not to provide a film. In addition, the polarizing film having a transmittance of transmitted light of 95% or more has a longer life because the amount of accumulated heat is smaller than that of a polarizing film having a transmittance of 95% or less.

  From the above, by providing the polarization conversion element 5 with the polarizing film 60, the ratio of the unnecessary light emitted from the polarization conversion element 5 is reduced, and the reduction in contrast can be suppressed.

  In addition, although the polarizing film 60 in this Embodiment 1 has the characteristic which absorbs predetermined polarized light, even if it has the characteristic which reflects predetermined polarized light like a reflective polarizing plate, it is the same An effect is obtained. In addition, by reflecting predetermined polarized light, heat accumulation is reduced and the influence of thermal strain is less likely.

  In the first embodiment, the λ / 2 retardation film 5c and the polarizing film 60 are generally formed of an organic material. However, the film may be formed of a thin film using an inorganic material. (For example, refer to Patent Document 2). By forming using an inorganic material, it becomes difficult to be affected by thermal strain, and the lifetime is longer than when an organic material is used. Moreover, you may provide the polarizing film 60 which absorbs or reflects p polarized light in the output surface of the phase difference film 5c in FIG. 6 by using an inorganic material.

  As shown in Tables 1 and 2, in the present invention, the projection display device using the reflective polarizing plate 9 and the reflective liquid crystal light valve is used to align the polarization components of the polarized light emitted from the polarization conversion element 5. 1 is particularly effective in improving the contrast.

<Embodiment 2>
FIG. 8 is a configuration diagram of the projection type liquid crystal display device 1 according to the second embodiment of the present invention. In Embodiment 2 of the present invention, the polarizing plate 5d is provided so as to be separated from the exit surface side of the polarization conversion element 5, and a polarizing film that absorbs p-polarized light is provided at a predetermined position of the polarizing plate 5d. It is characterized by being. Other configurations and operations are the same as those in the first embodiment, and thus description thereof is omitted here. As in the first embodiment, the polarization axes of the p-polarized light and the s-polarized light are parallel to the x-axis and the y-axis, respectively, with respect to the stage before the condenser lens 6, but the p-polarized light with respect to the stage after the condenser lens 6. It is assumed that the polarization axes of light and s-polarized light are parallel to the y-axis and the x-axis, respectively.

  In the case of the configuration of a general polarization conversion element 5 as shown in FIG. 2, p-polarized light is converted to s-polarized light by the λ / 2 retardation film 5c. However, due to the characteristics of the λ / 2 retardation film 5c, s In some cases, the ratio of the p-polarized light emitted from the p-polarized light path is larger than the ratio of the p-polarized light emitted from the polarized light path. That is, according to the polarization separation characteristics of the polarization conversion element 5, the proportion of s-polarized light that is unnecessary light is smaller in the p-polarized light path than in Table 3, but it is preferable to consider the λ / 2 retardation film 5c. There are cases where the optical path is preferred. Since the polarization rotation rate (ratio of converting p-polarized light to s-polarized light) of the general λ / 2 retardation film 5c is about 96%, p is larger than the ratio of s-polarized light emitted from the s-polarized light path. The ratio of s-polarized light emitted from the polarization optical path is smaller. As a countermeasure against such a problem, a polarizing plate 5d provided with a polarizing film 90 that absorbs p-polarized light as shown in FIG. 9B may be disposed on the exit surface side of the p-polarized light path. Thus, by disposing the polarizing plate 5d, the proportion of p-polarized light can be reduced, and the extinction ratio at the arrow 45 shown in FIG. 4 can be improved.

  FIG. 9A shows an example of the configuration of the polarization conversion element 5, and FIG. 9B shows an example of the configuration of the polarizing plate 5d. As shown in FIGS. 9A and 9B, the polarizing film 90 of the polarizing plate 5 d is disposed so as to face the λ / 2 retardation film 5 c provided on the polarization conversion element 5. In addition, the polarizing film 90 has a longer lifetime because the amount of heat accumulated is less when the transmittance of transmitted light is 95% or more than that of a polarizing film with a transmittance of 95% or less. The polarizing film 90 may be provided on either the polarization conversion element 5 side or the condenser lens 6 side of the polarizing plate 5d, and the width of the polarizing film 90 in the x-axis direction is the x-axis of the λ / 2 retardation film 5c. It may be wider than the width in the direction. This is because the polarizing plate 5d is arranged on the exit surface side of the polarization conversion element 5, and the width of the polarizing film 90 in the x-axis direction is λ / 2 phase difference in consideration of the spread of the light emitted from the polarization conversion element 5. This is because it is preferable that the width of the film 5c is slightly wider than the width in the x-axis direction.

  Further, as another configuration of the polarizing plate 5d, as shown in FIG. 10, polarizing films 100 may be provided at predetermined both ends of the polarizing plate 5d. With the configuration as shown in FIG. 10, the light at both ends in the x-axis direction of the polarizing plate 5d is absorbed by the polarizing film 100, so that the amount of light having a large incident angle is reduced. It is possible to reduce the influence of the incident angle characteristic of the image, and it is possible to project a high-contrast image on the screen.

  FIG. 11 is a diagram showing the relationship between the incident angle and the relative light quantity ratio in the liquid crystal light valve 2 according to Embodiment 2 of the present invention, and a comparison between the case where the polarizing plate 5d of FIG. 10 is used and the case where it is not used. I am doing. Here, 0 degree on the y-axis in FIG. 10 is assumed to be + in the θ direction centering on the y-axis. In FIG. 11, the vertical axis represents the relative light quantity ratio, and the horizontal axis represents the incident angle from the θ direction with the y-axis being 0 degree. A solid line 110 indicates a curve when the polarizing plate 5d is not used, and a broken line 111 indicates a curve when the polarizing plate 5d is used. In a region 112 in FIG. 11, it can be confirmed that the relative light quantity ratio at a large incident angle is decreased. From this, it is possible to suppress a decrease in contrast due to the influence of the incident angle characteristic on the liquid crystal light valve 2 and to increase the ratio of the predetermined polarized light emitted from the polarization conversion element 5.

  Further, in order to reduce the relative light quantity ratio of light incident on the liquid crystal light valve 2 at a large incident angle from the direction with the x axis as the rotation center, as shown in FIG. 12, polarizing films 120 and 121 are attached to the polarizing plate 5d. It may be provided. As a result, the relative light quantity ratio of the light incident on the liquid crystal light valve 2 at a large incident angle with respect to the optical axis C1 can be reduced. In addition, if the shape of a polarizing film is provided in the position away from not only the polarizing films 120 and 121 but the optical axis C1, the same effect will be acquired.

  In addition, although the polarizing films 100, 120, and 121 in the second embodiment have a characteristic of absorbing predetermined polarized light, they have a characteristic of reflecting predetermined polarized light like a reflective polarizing plate. However, the same effect can be obtained. In addition, by reflecting predetermined polarized light, heat accumulation is reduced and the influence of thermal strain is less likely.

  In the second embodiment, the λ / 2 retardation film 5c and the polarizing films 100, 120, and 121 are generally formed of an organic material, but even if the film is formed of a thin film using an inorganic material. It does not matter (see, for example, Patent Document 2). By forming using an inorganic material, it becomes difficult to be affected by thermal strain, and the lifetime is longer than when an organic material is used.

  As shown in Tables 1 and 2, in the present invention, a projection type liquid crystal display using a reflection type polarizing plate 9 and a reflection type liquid crystal light valve in order to align the polarization components of the polarized light emitted from the polarization conversion element 5. This is particularly effective for improving the contrast of the apparatus 1.

It is a block diagram of the projection type liquid crystal display device by Embodiment 1 of this invention. It is a block diagram of a general polarization conversion element. It is a figure which shows the effect | action of the 1st polarizing plate by Embodiment 1 of this invention, a reflection type polarizing plate, a liquid crystal light valve, and a 2nd polarizing plate. It is a figure which shows the effect | action of the 1st polarizing plate by Embodiment 1 of this invention, a reflection type polarizing plate, a liquid crystal light valve, and a 2nd polarizing plate. It is a figure which shows the polarized light component with respect to the incident angle in a general polarization conversion element. It is a block diagram of the polarization conversion element by Embodiment 1 of this invention. It is a figure which shows the simulation of the light radiate | emitted from a light source in case the reflective mirror by Embodiment 1 of this invention is an ellipse. It is a block diagram of the projection type liquid crystal display device by Embodiment 2 of this invention. It is a figure which shows an example of a structure of the polarization conversion element and polarizing plate by Embodiment 2 of this invention. It is a block diagram of the polarizing plate by Embodiment 2 of this invention. It is a figure which shows the relationship between the incident angle and relative light quantity ratio in the liquid crystal light valve by Embodiment 2 of this invention. It is a figure which shows an example of a structure of the polarizing plate by Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Projection type liquid crystal display device, 2 Liquid crystal light valve, 3 Optical system, 3a light source, 3b Reflective mirror, 4 Integrator optical system, 4a 1st lens array, 4b 2nd lens array, 5 Polarization conversion element, 5a Polarization separation Film, 5b reflective film, 5c λ / 2 retardation film, 5d polarizing plate, 6 condenser lens, 7 field lens, 8 first polarizing plate, 9 reflective polarizing plate, 10 second polarizing plate, 11 projection optical system 60 polarizing film, 70 concave lens, 71 opening, 90 polarizing film, 100 polarizing film.

Claims (6)

A light valve,
A light source that generates light to irradiate the light valve;
A first lens array and a second lens array are arranged on an optical path between the light source and the light valve, and uniformize an illuminance distribution of light emitted from the light source to the light valve. An integrator lens,
A polarization conversion element disposed on the optical path for converting incident light into first linearly polarized light;
With
The polarization conversion element separates the light emitted from the integrator lens into the first linearly polarized light and the second linearly polarized light whose polarization axis is orthogonal to the first linearly polarized light, A λ / 2 phase difference film that rotates the polarization axis of the second linearly polarized light 90 degrees provided on the exit surface of the second linearly polarized light, and an exit surface of the first linearly polarized light. And a polarizing film that absorbs or reflects the second linearly polarized light. A light valve,
A light source that generates light to irradiate the light valve;
A first lens array and a second lens array are arranged on an optical path between the light source and the light valve, and uniformize an illuminance distribution of light emitted from the light source to the light valve. An integrator lens,
A polarization conversion element disposed on the optical path for converting incident light into first linearly polarized light;
A polarizing plate disposed on the exit surface side of the polarization conversion element, and
With
The polarization conversion element separates the light emitted from the integrator lens into the first linearly polarized light and the second linearly polarized light whose polarization axis is orthogonal to the first linearly polarized light, A λ / 2 retardation film that rotates the polarization axis of the second linearly polarized light 90 degrees provided on the exit surface of the second linearly polarized light;
A projection type liquid crystal display device, wherein a polarizing film that absorbs or reflects the second linearly polarized light is provided at a predetermined position of the polarizing plate.   The projection type liquid crystal display device according to claim 2, wherein the polarizing film is disposed to face the λ / 2 retardation film provided in the polarization conversion element.   The projection type liquid crystal display device according to claim 2, wherein the polarizing film is provided at predetermined both ends of the polarizing plate.   5. The projection type liquid crystal display device according to claim 1, wherein the λ / 2 retardation film and the polarizing film are formed of a thin film of an inorganic material.   6. The light valve according to claim 1, wherein the light valve is a reflective liquid crystal light valve, and a reflective polarizing plate is provided on the optical path between the integrator lens and the reflective liquid crystal light valve. Any one of the projection type liquid crystal display devices.

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