JP3685794B2 - Projection display - Google Patents

Description

  The present invention relates to a projection display apparatus that mainly enlarges and projects an optical image formed on a light valve on a screen.

  In order to obtain a large screen image, a method of forming an optical image corresponding to a video signal on a light valve, irradiating the optical image with light, and enlarging and projecting onto a screen by a projection lens is well known. If a reflective light valve is used as the light valve, both high resolution and high pixel aperture ratio can be achieved, and a high-luminance projection image with high light utilization efficiency can be displayed.

  FIG. 10 shows a configuration diagram of an optical system of a projection display apparatus according to a conventional example using a reflective light valve. The illumination optical system for condensing and illuminating the light emitted from the lamp 1 as the light source on the reflective light valve 6 is a quadrangular prism having a concave mirror 2 and a cross-section substantially the same aspect ratio as the effective display surface of the reflective light valve 6. Rod prism 3, condenser lens 4, and condenser mirror 5.

  The concave mirror 2 has an elliptical cross-sectional shape, and has a first focal point and a second focal point. The lamp 1 is arranged such that the center of the light emitter is located near the first focal point of the concave mirror 2, and the light incident surface of the rod prism 3 is located near the second focal point of the concave mirror 2. The concave mirror 2 is formed by forming an optical multilayer film that transmits infrared light and reflects visible light on the inner surface of a glass substrate.

  The light emitted from the lamp 1 is reflected and collected by the concave mirror 2, and forms a light emitter image of the lamp 1 at the second focal point of the concave mirror 2. The luminous body image of the lamp 1 is brightest in the vicinity of the center near the optical axis and tends to become darker as the periphery becomes darker. To solve this problem, the incident surface of the rod prism 3 is arranged in the vicinity of the second focal point, the incident light is multiply reflected on the side surface of the rod prism 3 to make the luminance uniform, and the output surface of the rod prism 3 is made the secondary surface. If an image is formed on the reflective light valve 6 by the condenser lens 4 and the condensing mirror 5 as a light source, the uniformity of the illumination light can be ensured.

  Here, the operation of the reflective light valve 6 will be described with reference to FIG. The reflection type light valve 6 controls the light traveling direction according to the video signal, and forms an optical image as a change in reflection angle. A mirror element 21 is formed in a matrix for each pixel, and each mirror element 21 has an ON signal for white display and an OFF signal for black display, respectively, with respect to a plane 22 perpendicular to the optical axis of the projection lens by ± θ °. Tilt. The illumination principal ray 24 is transmitted through the cover glass 23, is incident on and reflected by the mirror element 21, and is emitted from the cover glass 23 again.

  As shown in FIG. 11A, first, at the time of an ON signal, the incident angle of the illumination principal ray 24 is such that the ON light principal ray 25 is reflected and travels along the direction perpendicular to the plane 22, that is, along the optical axis of the projection lens. Set to. In this case, the angle formed by the illumination principal ray 24 and the ON light principal ray 25 is 2θ. Further, as shown in FIG. 11B, at the time of the OFF signal, the OFF light principal ray 26 is reflected and travels in a direction not incident on the projection lens, and the angle formed between the illumination principal ray 24 and the OFF light principal ray 26 is 6θ. Become.

  As shown in FIG. 10, the illumination light 8 incident on the reflective light valve 6 enters the projection lens 7 as the ON light 9 when the signal is ON, and falls outside the effective diameter of the projection lens 7 as the OFF light 10 when the signal is OFF. proceed. In this way, a projection image is formed on the screen by controlling the time distribution of the ON light 9 and the OFF light 10 according to the video signal.

  However, the reflected light generated at the interface between the cover glass 23 shown in FIG. 11 and the air of the external medium travels as unnecessary reflected light 11 which is a hatched portion in FIG. To do. Since the unnecessary reflected light 11 proceeds in the same way for both ON / OFF signals, there is a problem that the quality of black display particularly during the OFF progress is remarkably adversely affected and the contrast performance is deteriorated. .

  The present invention solves the conventional problems as described above, and provides a projection display device capable of improving the contrast performance while suppressing the necessary light and minimizing the decrease in brightness. The purpose is to provide.

In order to achieve the above object, a projection display device according to the present invention includes a light source, a reflective light valve having a mirror element formed for each pixel , and radiated light from the light source on the reflective light valve. An illumination optical system that condenses, a projection lens that enlarges and projects the light reflected by the mirror element of the reflective light valve onto the screen, and either the projection lens or the illumination optical system And a diaphragm that determines the size of the cross-sectional area of the light beam projected from the projection lens onto the screen, the diaphragm having a fixed diaphragm having an aperture, and the beam bundle at the aperture A part of the light shielding plate, and the light shielding plate is configured to be displaceable in a direction toward the optical axis of the illumination optical system or the optical axis of the projection lens. Yo Characterized in that to allow reducing the projection to the reflection type light of the unwanted light reflected by the front surface of the valve on the screen.

  According to the present invention, since the shape of the light-shielding part shielded by the light-shielding means is non-rotationally symmetric with respect to the optical axis of the illumination optical system, the necessary light can be prevented from being shielded. Contrast performance can be improved while minimizing.

  According to the projection display device of the present invention, since it is possible to suppress the necessary light from being blocked, it is possible to improve the contrast performance while minimizing the decrease in brightness.

In the projection display device, it is preferable that a shape of the opening excluding a portion shielded by the light shielding plate in the opening is non-rotationally symmetric with respect to an optical axis of the illumination optical system or the projection lens. .
The light shielding means and further comprising a movable means of the light shielding means, the shape of the aperture of the diaphragm has a shape which is shielded by the shielding means, a shape which is shielded by the shielding means, the illumination optical It is preferably non-rotationally symmetric with respect to the optical axis of the system or the projection lens, and the movable means can displace the light shielding means to change the area of the opening. According to the projection display apparatus as described above, since the necessary light can be prevented from being blocked as compared with a diaphragm that shields light in a rotationally symmetrical manner, for example, a diaphragm that concentrically narrows the aperture, the reduction in brightness is minimized. Contrast performance can be improved while suppressing to a low level. Further, the contrast performance and the light output can be arbitrarily adjusted.

  It is preferable that the apparatus further includes a prism that reflects illumination light from the illumination optical system to the reflective light valve and transmits reflected light from the reflective light valve. According to the projection display apparatus as described above, the illumination optical system can be made compact, and unnecessary reflected light generated at the prism interface can be cut while minimizing the decrease in brightness.

  A first prism configured to reflect the illumination light from the illumination optical system to the reflection light valve and transmit the reflection light from the reflection light valve; A second prism that separates the illumination light into three primary color lights of red, blue, and green, and combines the reflected light from each of the reflection type light valves corresponding to the three primary color lights. It is preferable to provide. According to the projection display device as described above, it is possible to display a high-definition, full-color projection image, and it is possible to minimize a decrease in brightness of unnecessary reflected light generated at the interface between the first prism and the second prism. It is possible to cut while limiting to the limit.

  The reflection type light valve preferably includes an image forming surface and a transparent plate arranged in parallel with the image forming surface on the emission side of the image forming surface.

  In the reflection type light valve, it is preferable that a plurality of mirror elements that control the reflection direction of light according to a video signal are arranged in a matrix.

The illumination light from the illumination optical system is incident on the reflective light valve from an oblique direction,
When the position of the light shielding means where the outer periphery of the illumination light and the outer periphery of unnecessary reflected light from the reflective light valve are closest is a reference position,
The light shielding means can be moved in one direction from the reference position toward the optical axis by the movable means, and it is preferable that the light shielding area of the diaphragm increases as the movement in the one direction is continued. According to the projection display device as described above, unnecessary reflected light from the reflective light valve can be cut in order from the optical axis side.

  In addition, the shape of the aperture of the diaphragm is preferably circular in the open state.

  Moreover, it is preferable that the shape of the light-shielding part shielded by the light-shielding means is a substantially semicircular shape. According to the projection display device as described above, the shape of the light shielding portion that is non-rotationally symmetric with respect to the optical axis can be easily formed.

  Further, when the diaphragm is viewed in the planar direction, one side of the light shielding means is a straight line parallel to a horizontal line passing through a point on the optical axis, and the parallel straight line and an inner peripheral line of the aperture of the diaphragm It is preferable that the shape of the light-shielding part enclosed is a substantially semicircle shape.

  Moreover, it is preferable that the shape of the light-shielding part light-shielded by the said light-shielding means is a substantially crescent moon shape. According to the projection display device as described above, the shape of the light shielding portion that is non-rotationally symmetric with respect to the optical axis can be easily formed.

  Further, the light shielding means has a circular opening, the light shielding portion is formed by decentering the circular opening with respect to the aperture of the diaphragm, and an inner peripheral line of the opening of the light shielding means, It is preferable that the shape of the light shielding portion surrounded by the inner peripheral line of the aperture of the diaphragm is a substantially crescent shape.

  The shading means may have an inner diameter that is variable, and has an opening that is eccentric with respect to the aperture of the diaphragm, and the inner circumference of the opening of the shading means and the aperture of the aperture It is preferable that the shape of the light-shielding portion surrounded by the peripheral line is a substantially crescent shape, and the area of the light-shielding portion is changed by changing the inner diameter dimension of the opening of the light-shielding means.

  Further, when the diaphragm is viewed in a planar direction, when the upper side is an upper part and the lower side is a lower part with respect to a horizontal line passing through a point on the optical axis, the aperture of the diaphragm is It is preferable that the light shielding area is increased by the light shielding means sequentially shielding light from one side of the upper part or the lower part to the other side.

  The surface of the light shielding means is preferably formed of a metal or dielectric multilayer film that reflects incident light with a reflectance of 80% or more. According to the projection display apparatus as described above, the amount of light absorption can be suppressed, the temperature of the surface of the light shielding portion becomes high, and the surrounding optical components can be prevented from being damaged by radiant heat.

  In addition, a control unit that controls a displacement amount of the light shielding unit by the movable unit is provided, and the light shielding amount of the diaphragm is controlled by the control unit so as to change according to a level of an input video signal. It is preferable. According to the projection display device as described above, for example, if the dark scene is controlled so that the contrast and the black level are emphasized, and the bright scene is controlled so that the white level is emphasized, the contrast is higher. Display performance can be obtained.

  Further, it is preferable that the light shielding amount of the diaphragm can be controlled from the outside of the apparatus. According to the projection display device as described above, it is possible to arbitrarily select a brightness-oriented projection image and a contrast-oriented projection image according to the intended use.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a schematic configuration of a projection display apparatus according to Embodiment 1 of the present invention. In the figure, 1 is a lamp as a light source, 31 is a stop, 6 is a reflection type light valve, and 7 is a projection lens. An optical system constituted by the concave mirror 2, the rod prism 3, the condenser lens 4, and the condenser mirror 5 is collectively referred to as an illumination optical system. Reference numeral 12 denotes an optical axis of the illumination optical system.

  As described with reference to FIG. 10, the reflective light valve 6 that is an image forming unit has mirror elements 21 formed in a matrix for each pixel, and controls the light traveling direction according to the video signal to change the reflection angle. An optical image is formed. The concave mirror 2 is an ellipsoidal mirror in which the cross-sectional shape of the reflecting surface is an ellipse, and has a first focal point and a second focal point.

  A xenon lamp is used as the lamp 1 and is arranged so that the center of the light emitter is located near the first focal point of the concave mirror 2, and the light incident surface of the rod prism 3 is located near the second focal point of the concave mirror 2. Has been placed. The concave mirror 2 is formed by forming an optical multilayer film that transmits visible light and reflects visible light on the inner surface of a glass substrate.

  The rod prism 3 is a quadrangular prism whose light entrance surface and light exit surface have the same aspect ratio as the effective display surface of the reflective light valve 6, and is disposed at a location where the emitted light from the lamp 1 is collected. The material is made of quartz glass with excellent heat resistance. A luminous body image of the lamp 1 collected by the concave mirror 2 is formed near the incident surface of the rod prism 3. The luminous body image of the lamp 1 collected by the concave mirror 2 is brightest in the vicinity of the center near the optical axis 12 and tends to darken rapidly toward the periphery, so that uneven brightness remains in the plane.

  On the other hand, since the light beam incident on the rod prism 3 is multiple-reflected on the side surface of the rod prism 3 and the illuminant image is subdivided and superimposed as many times as the number of reflections, it is illuminated on the exit surface of the rod prism 3. The brightness is made uniform. Thus, due to the subdivision and superimposing effect of the lamp illuminant image, the greater the number of reflections within the rod prism 3, the better the uniformity. For this reason, the degree of uniformity depends on the length of the rod prism 3. In the present embodiment, the length of the rod prism 3 is set so that the peripheral illuminance on the screen is 90% or more with respect to the central illuminance.

  The exit surface of the rod prism 3 with uniform luminance is used as a secondary surface light source, and the effective display area of the reflective light valve 6 is matched by the condenser lens 4 and the condenser mirror 5 disposed thereafter. If the image is formed at such a magnification, it is possible to achieve both ensuring of light collection efficiency and improvement of uniformity. The light emitted from the lamp 1 is collected by the illumination optical system, and the illumination light 32 enters the reflective light valve 6.

  Of the illumination light 32 incident on the reflective light valve 6, the ON light 33 corresponding to white display is incident on the projection lens 7 and enlarged and projected on the screen (not shown). On the other hand, the OFF light 34 corresponding to black display travels outside the effective diameter of the projection lens 7 and does not reach the screen.

Hereinafter, the positional relationship of each optical member will be described more specifically with reference to FIG.
The projection display apparatus shown in FIG. 2 is developed so that the optical axes are on the same line in the configuration shown in FIG. 1 in order to facilitate understanding of the positional relationship between the optical members.

  That is, in the configuration shown in FIG. 1, the condensing mirror 5 that is a reflective element is replaced with a lens 5a that is a transmissive element, and the reflective light valve 6 that is a reflective element is replaced with a light valve 6a that is a transmissive element. It is. In FIG. 2, the light beam indicated by oblique lines is the on-axis light beam 90, and 91 and 92 are off-axis light beams.

  The luminous body image of the lamp 1 is formed on the incident surface of the rod prism 3 by the ellipsoidal mirror 2. The light passing through the rod prism 3 repeats multiple reflections on the inner surface of the rod prism 3, and the luminance is made uniform on the exit surface side.

  When the exit surface of the rod prism 3 is a secondary planar light source image, this light source image is formed on the light valve 6a by the lenses 4a and 5a, and further formed on the screen (not shown) by the projection lens 7. That is, the relationship between the exit surface of the rod prism 3 and the optical image forming surface of the light valve 6a is conjugated with each other, and the relationship between the optical image forming surface of the light valve 6a and the screen surface is also conjugated with each other. .

  On the other hand, the stop 31a is a stop corresponding to the stop 31 of FIG. 1, is disposed in the optical path of the illumination optical system, and is between the lens 4a and the lens 5a. The diaphragm 93 is disposed in the projection lens 7. The stop 31a and the stop 93 are aperture stops that determine the size of the beam bundle cross-sectional areas of the on-axis beam bundle 90, the off-axis beam bundle 91, and the off-axis beam bundle 92. The diaphragm 93 is disposed at the position of the entrance pupil of the projection lens 7, and the diaphragm 31 a is disposed at a position substantially conjugate with the diaphragm 93.

  1 and FIG. 5 and subsequent configurations according to each embodiment are not the same in the optical axis, but the conjugate relationship is the same as the configuration in FIG. Further, in each of these drawings, the illustration of the off-axis ray bundle is omitted in order to explain the action of unnecessary light.

  FIG. 3 shows a specific example of the diaphragm 31 shown in FIG. In each figure, the fixed stop 36 has an opening through which light is transmitted, and the arrangement position and the opening shape are fixed. The diaphragm is configured by a combination of the fixed diaphragm 36 and a light shielding plate 37a, 37b or 37c which is a light shielding means.

  The light shielding means according to the present embodiment can be displaced by the movable means, and the light shielding area can be varied by this displacement. The displacement of the light shielding means includes the movement of the position of the light shielding means and the shape change of the light shielding means itself such as the change in the opening area of the light shielding means.

  The diaphragm 31a shown in FIG. 3A includes a fixed diaphragm 36 and a light shielding plate 37a that is a light shielding means. In this figure, a part of the opening of the fixed diaphragm 36 is shielded from light by a light shielding plate 37a. The shaded portion is a light-shielding portion (for example, a portion indicated by reference numeral 38a in the right end view; the same applies to reference numerals 38b and 38c in FIGS.

  As shown in this figure, the light shielding area increases as the light shielding plate 37a moves downward. The light shielding plate 37a has a side 37d which is a straight line parallel to a horizontal line 39 passing through the center 36a of the opening of the fixed aperture 36 (a point on the optical axis 12 in FIG. 1). For this reason, the shape of the light-shielding portion surrounded by the side 37d and the inner peripheral line of the opening of the fixed diaphragm is a substantially semicircular shape. This is the same even when the light shielding plate 37a is moved downward. If the side 37d and the horizontal line 39 coincide with each other, the light shielding portion becomes a complete semicircular shape.

  In the diaphragm 31b shown in FIG. 3B, an opening is formed in the light shielding plate 37b which is a light shielding means. Also in the example shown in this figure, as in the example shown in FIG. 3A, the light shielding area changes as the light shielding plate 37b moves downward. That is, as the amount of eccentricity between the opening of the light shielding plate 37b and the opening of the fixed diaphragm 36 increases, the light shielding area increases. In the example shown in the figure, the shape of the light shielding part surrounded by the inner peripheral line of the opening of the light shielding plate 37b and the inner peripheral line of the opening of the fixed diaphragm 36 is a substantially crescent shape.

  In the diaphragm 31c shown in FIG. 3C, an opening is formed in the light shielding plate 37c which is a light shielding means. The opening of the light shielding plate 37c can change the opening diameter, and the light shielding area can be varied. That is, as shown in the figure, the light shielding area increases as the opening diameter of the light shielding plate 37c decreases. Further, in the example of this figure, similarly to the example of FIG. 3B, the shape of the light shielding portion surrounded by the inner peripheral line of the opening of the light shielding plate 37c and the inner peripheral line of the opening of the fixed diaphragm 36 becomes a substantially crescent shape. Yes.

  Here, taking the diaphragm 31a shown in FIG. 3A as an example, when the side 37d of the light shielding plate 37a is located above the opening of the fixed diaphragm 36, the light shielding area is zero. In this state, in FIG. 1, the illumination light 32 and the unnecessary reflected light 35 generated at the cover glass interface of the reflective light valve 6 are in the closest state. That is, in this state, the amount of unnecessary reflected light that enters the projection lens 7 also increases.

  At the time of light shielding, the light shielding area of the light shielding plate 37a varies while moving in the arrow 40 direction. That is, assuming that the position of the light shielding means where the outer periphery of the illumination light 32 and the outer periphery of the reflected light 35 are closest is the reference position, the lower side 37d starts to move in the direction from the reference position toward the optical axis 12, and thereafter this movement If it continues to move in the same direction as the direction, the light shielding area continues to increase, and the opening of the fixed aperture 36 is shielded from the top in order. If the lower side 37d is moved in the direction opposite to the direction of the arrow 40 in the state where the light shielding portion is formed, the light shielding area is reduced, and the opening of the fixed aperture 36 is opened in one direction.

  Due to the movement in the direction of the arrow 40, the unnecessary reflected light 35 in FIG. 1 is sequentially cut from the optical axis side. That is, the movement of the position of the lower side 37d of the light shielding plate 37a in the direction of the arrow 40 increases the light shielding area, but the shape of the light shielding portion is non-rotationally symmetric with respect to the optical axis. It becomes larger in order from above, and the lower part of the opening of the fixed diaphragm 36 remains open.

  Therefore, compared with a diaphragm that varies the light-shielding area in a rotationally symmetrical manner, for example, a diaphragm that narrows the aperture concentrically, the necessary light can be blocked, so contrast performance is minimized while minimizing the decrease in brightness. Can be improved.

  As the movable means for moving the light shielding plate, for example, a structure in which the light shielding plate is attached to the rotation shaft of the motor via a gear and the position of the light shielding plate is displaced in conjunction with the rotation of the motor may be used. In this case, it is only necessary to control the amount of rotation of the rotating shaft so that the light shielding plate is stopped at an arbitrary position so that the light shielding area can be controlled.

  3A and 3B show an example in which the entire light shielding plate moves and the light shielding area increases, but in the example of FIG. 3C, the light shielding plate 37c remains fixed and the opening area of the light shielding plate 37c is increased. Is changed to increase the light shielding area. As the mechanism of the light shielding plate 37c and the movable means that can change the opening area, for example, a mechanism similar to an iris diaphragm may be used.

  Moreover, the material of the light shielding plates 37a to 37c shown in FIG. 3 is preferably one having a surface reflectance of 80% or more. Since high energy light is incident on the light-shielding part, if the light absorption amount on the surface of the light-shielding part increases, the temperature of the light-shielding part increases as the light-shielding area increases, and in some cases, the radiant heat damages surrounding optical components. Because there is a fear of doing.

  In the present embodiment, an aluminum plate having a mirror finished surface and a reflectance of about 88% is used. However, the present invention is not limited to this, and a metal mirror finished product such as stainless steel or a mirror element in which a dielectric multilayer film is formed on the surface of the substrate may be used.

  FIG. 4 is a graph showing the relationship between the amount of aperture light shielding and the projected image performance of the projection display apparatus according to this embodiment. 4A shows the relationship between the aperture light shielding amount (horizontal axis S) and the contrast ratio (vertical axis C), and FIG. 4B shows the relationship between the aperture light shielding amount (horizontal axis S) and the light output relative value (vertical axis P). It is a thing. As shown in the graph, as the aperture light shielding amount S increases, the contrast ratio C increases while the light output P decreases. That is, the relationship between the contrast ratio of the projected image and the light output with respect to the aperture light shielding amount is a reciprocal relationship.

  Therefore, an input unit is provided outside the apparatus, and the light shielding area of the diaphragm may be controlled by remote control from the outside of the apparatus by a control unit that controls the displacement amount of the movable unit. According to this configuration, the balance between contrast and light output can be arbitrarily set as necessary.

  For example, in the example of FIG. 3A, if the light shielding plate 37a is moved in the direction of the arrow 40, the light shielding area is increased and the light output is reduced, but the contrast can be improved. If the lens is moved in the opposite direction, the amount of opening of the diaphragm increases and the contrast decreases, but the light output can be improved. According to this configuration, it is possible to arbitrarily select a projected image that emphasizes brightness and a projected image that emphasizes contrast according to the intended use.

  Furthermore, the light shielding area of the diaphragm may be automatically controlled according to the level of the video signal using the control means as described above. For example, display performance with higher contrast can be obtained by controlling the contrast and the black level to be lower for dark scenes and the white level to be higher for bright scenes.

(Embodiment 2)
FIG. 5 shows a schematic configuration of a projection display apparatus according to Embodiment 2 of the present invention. In the figure, a lamp 1 as a light source, a reflective light valve 6 and a projection lens 7 are the same as those shown in FIG. An optical system constituted by the concave mirror 2, the rod prism 3, the condenser lens 4, the reflection mirror 42, the field lens 43, and the total reflection prism 44 is collectively referred to as an illumination optical system.

  The operations of the concave mirror 2, the rod prism 3, and the condenser lens 4 are the same as those in the embodiment described with reference to FIG. In the present embodiment, the light after exiting the condenser lens 4 is configured to enter the total reflection prism 44 via the reflection mirror 42 and the field lens 43.

  Here, the operation of the total reflection prism 44 will be described. The total reflection prism 44 is composed of two prisms, and a very thin air layer 45 is formed on the adjacent surfaces of the prisms. When the illumination light 46 is incident on the air layer 45, the air layer 45 is incident at an angle greater than the critical angle and is totally reflected and incident on the reflective light valve 6 from an oblique direction. The angle is set so that the light enters and passes through the air layer 45 at an angle less than the critical angle and enters the projection lens 7. Thus, by providing the total reflection prism 44 in the optical path of the illumination optical system, the illumination optical system can be made compact.

  Of the illumination light 46 incident on the reflective light valve 6, the ON light 47 corresponding to white display is transmitted through the total reflection prism 44 and the projection lens 7 and enlarged and projected on the screen (not shown). On the other hand, the OFF light 48 corresponding to black display travels outside the effective diameter of the projection lens 7 and does not reach the screen.

  In the case of this embodiment, in addition to the first unnecessary reflected light 49 generated at the cover glass interface of the reflective light valve 6, the second unnecessary reflected light generated at the interface of the total reflection prism 44 on the reflective light valve 6 side. 50 all affect the contrast performance of the projected image. Also in this case, the degree of influence of the first unnecessary reflected light 49 and the second unnecessary reflected light 50 incident on the projection lens 7 can be arbitrarily changed by the diaphragm 41 that can change the area of the light shielding portion.

  The aperture shape of the diaphragm 41 can be varied by using the one illustrated in FIG. 3 as in the first embodiment. The diaphragm or opening by changing the light shielding part is the same as in the first embodiment, and the light shielding means starts to move in the direction from the reference position toward the optical axis 12, and thereafter moves in the same direction as this movement start direction. By continuing, the light shielding area increases, and the aperture of the aperture 41 is shielded in order from one side. When the light shielding portion is formed and moved in the opposite direction, the light shielding area decreases, and the aperture of the diaphragm 41 opens in one direction.

  FIG. 6 shows a schematic configuration diagram of a projection display apparatus according to a comparative example of the embodiment shown in FIG. In the comparative example shown in FIG. 6, the diaphragm 41 is not arranged, or the opening of the diaphragm 41 is in an open state. In this case, the illumination light 51 is incident on the reflection type light valve 6, and then the ON light 52 corresponding to white display is transmitted through the total reflection prism 44 and the projection lens 7 and is enlarged and projected on the screen (not shown). The On the other hand, the OFF light 53 corresponding to black display travels outside the effective diameter of the projection lens 7 and does not reach the screen.

  Further, the first unnecessary reflected light 54 and the second unnecessary reflected light 55 are factors that degrade the contrast performance of the projected image. Comparing the embodiment of FIG. 5 with the comparative example of FIG. 6, in FIG. 5, a part of the opening of the fixed diaphragm is shielded by using the diaphragm 41, so that the first unnecessary reflection shown in FIG. 5 is performed. The light bundles of the light 49 and the second unnecessary reflected light 50 are thinner than the light bundles of the first unnecessary reflected light 54 and the second unnecessary reflected light 55 shown in FIG. I understand.

  As described above, in the embodiment of FIG. 5, both the first unnecessary reflected light 49 and the second unnecessary reflected light 50 are efficiently cut by the diaphragm 41 as compared with the comparative example shown in FIG. 6. be able to. In other words, compared to a diaphragm that varies the light shielding area in a rotationally symmetric manner, for example, a diaphragm that concentrically narrows the aperture, it can suppress the necessary light shielding, so contrast performance is minimized while minimizing the decrease in brightness. Can be improved.

  The arrangement of the diaphragm 41 and the material of the light shielding plate are the same as those in the first embodiment. Further, as in the first embodiment, it is preferable that the light shielding area of the diaphragm can be controlled by remote control from the outside of the set, and that the light shielding area can be controlled according to the video signal. In addition, although the example in which the light shielding unit is moved has been described as changing the light shielding area of the diaphragm 41, a configuration in which the opening of the light shielding unit is variable as illustrated in FIG. 3C may be used.

(Embodiment 3)
FIG. 7 shows a schematic configuration of a projection display apparatus according to Embodiment 3 of the present invention. In the figure, a lamp 1 as a light source, a reflective light valve 6 and a projection lens 7 are the same as those shown in FIG. Similarly to FIG. 5, a system constituted by the concave mirror 2, the rod prism 3, the condenser lens 4, the reflection mirror 42, the field lens 43, and the total reflection prism 44 is collectively referred to as an illumination optical system.

  The operations of the concave mirror 2, the rod prism 3, and the condenser lens 4 are the same as those in the embodiment described with reference to FIG. In this embodiment, the color separation / combination prism 62 is disposed between the total reflection prism 44 and the reflection type light valve 6, and three reflection type light valves 6 are used.

  Here, the configuration and operation of the color separation / combination prism 62 will be described below with reference to FIG. FIG. 8 is a horizontal sectional view of the color separation / combination prism 62 shown in FIG. The color separation / combination prism 62 includes three prisms, and a first dichroic mirror 71 and a second dichroic mirror 72 are formed on the adjacent surfaces of the prisms. In the case of the color separation / combination prism 62 used in the present embodiment, the light 73 incident from the total reflection prism 44 is first reflected only by the blue light by the first dichroic mirror 71 to become the blue light 74, and the blue reflective light valve. 6B is incident.

  Next, only the red light is reflected by the second dichroic mirror 72 to become red light 75, which enters the red reflective light valve 6R. The green light 76 that has passed through both the first dichroic mirror 71 and the second dichroic mirror 72 is incident on the green reflective light valve 6G. The three colors of light are reflected by the corresponding reflective light valves 6B, 6R, and 6G, and then are combined again by the first dichroic mirror 71 and the second dichroic mirror 72, and enter the total reflection prism 44. To do.

  In this way, white light is decomposed and synthesized into the three primary colors of red, blue, and green, and three reflective light valves 6B, 6R, and 6G corresponding to the respective video signals are used, so that high-definition and full-color projection is performed. An image can be displayed. Of the illumination light 63 incident on the reflective light valve 6 shown in FIG. 7, the ON light 64 corresponding to white display is transmitted through the color separation / combination prism 62, the total reflection prism 44, and the projection lens 7 on the screen (not shown). Without zooming in). On the other hand, the OFF light 65 corresponding to black display travels outside the effective diameter of the projection lens 7 and does not reach the screen.

  In the case of the present embodiment, unnecessary reflected light generated at the cover glass interface of the reflection type light valve 6 as shown in FIGS. 1 and 5, or the reflection type light valve 6 side interface of the total reflection prism 44 shown in FIG. (Neither is shown in FIG. 7), but unnecessary reflected light 66 generated at the interface of the color separation / combination prism also affects the contrast performance of the projected image.

Even in this case, the degree of influence of the unnecessary reflected light 66 incident on the projection lens 7 can be arbitrarily varied by the diaphragm 61 whose light-shielding area can be varied. The aperture shape of the diaphragm 61 is varied by using the one illustrated in FIG. 3 as in the first embodiment, and the diaphragm or opening by varying the light shielding portion is the same as in the first embodiment, and the light shielding means is provided. By starting to move in the direction from the reference position toward the optical axis 12 and then continuing to move in the same direction as the movement starting direction, the light shielding area increases, and the aperture of the diaphragm 61 is shielded in order from one side. become. When the light shielding portion is formed and moved in the opposite direction, the light shielding area decreases, and the aperture of the diaphragm 61 opens in one direction.

  FIG. 9 shows a schematic configuration diagram of a projection display apparatus according to a comparative example of the embodiment shown in FIG. In the comparative example shown in FIG. 9, the diaphragm 61 is not arranged, or the diaphragm opening is in an open state. In this case, after the illumination light 81 is incident on the reflection type light valve 6, the ON light 82 corresponding to white display is transmitted through the color separation / combination prism 62, the total reflection prism 44, and the projection lens 7 on the screen (not shown). ) Is magnified and projected.

  On the other hand, the OFF light 83 corresponding to black display travels outside the effective diameter of the projection lens 7 and does not reach the screen. Further, the unnecessary reflected light 84 is a factor that degrades the contrast performance of the projected image.

  Although not shown in the drawing, unnecessary reflected light generated at the cover glass interface of the reflective light valve 6 and unnecessary reflected light generated at the interface of the total reflection prism 44 are the same as those shown in FIGS. Has the same effect.

The embodiment of FIG. 7, when comparing the comparative example of FIG. 9, FIG. 7, since the shielding part of the opening of the fixed throttle with a throttle 61, the undesirable reflection 66 shown in FIG. 7 It can be seen that the thickness of the light beam is thinner than that of the unnecessary reflected light 84 shown in FIG.

  As described above, in the embodiment of FIG. 7, the unnecessary reflected light 66 can be efficiently cut by the diaphragm 61 as compared with the comparative example shown in FIG. In other words, compared to a diaphragm that varies the light shielding area in a rotationally symmetric manner, for example, a diaphragm that concentrically narrows the aperture, it can suppress the necessary light shielding, so contrast performance is minimized while minimizing the decrease in brightness. Can be improved.

  Further, the arrangement of the diaphragm 61 and the material of the light shielding plate are the same as those in the first embodiment. Furthermore, it is preferable that the light shielding area of the diaphragm can be controlled by remote control from the outside of the set, and that the light shielding area can be controlled according to the video signal is the same as in the first embodiment. Further, although the example in which the light shielding area of the diaphragm 61 is changed has been described by moving the light shielding means, a configuration in which the opening of the light shielding means is variable as shown in FIG. 3C may be used.

  In each of the embodiments described above, the contrast performance and the light output can be arbitrarily adjusted so that the light-shielding area of the diaphragm can be varied. However, the diaphragm has a fixed aperture and has a desired contrast. You may use it fixed to performance. In this configuration, there is no need for movable means, and the shape of the opening in this case is the shape of the remaining opening obtained by removing the light-shielding portion (shaded portion) from the opening in the open state in the example of FIG. .

  That is, the shape of the fixed opening is the same as the shape in which the non-rotationally symmetric part is shielded with respect to the optical axis such as a substantially semicircular shape or a substantially crescent shape with respect to the opening corresponding to the open state. In this case, since the portion corresponding to the shape of the light shielding portion is non-rotational symmetric with respect to the optical axis, the shape of the fixed opening is also non-rotational symmetric with respect to the optical axis.

  In each of the above embodiments, the position of the stop is set to a position substantially conjugate with the entrance pupil of the projection lens in the optical path of the illumination optical system. It is done.

  Further, the diaphragm used in each of the above embodiments is most similar to the light valve in which an optical image is formed by controlling the traveling direction of light according to the video signal, like the reflective light valve shown in FIG. Demonstrate great effect. However, the present invention is not limited to such a reflection type light valve. If the reflection type light valve has transparent glass or plastic on the emission side of the image forming surface, an effect of reducing unnecessary reflected light can be obtained. It is done. For example, a light valve of a type that forms an optical image as a change in the polarization state, diffraction state, or scattering state of light using liquid crystal or the like as a modulation material may be used.

  As described above, according to the present invention, since the shape of the light-shielding portion shielded by the light-shielding means is non-rotationally symmetric with respect to the optical axis of the illumination optical system, the necessary light can be prevented from being shielded. The contrast performance can be improved while minimizing the decrease in height, and can be used in a projection display apparatus that enlarges and projects an optical image formed on a light valve on a screen.

1 is a schematic configuration diagram of a projection display apparatus according to Embodiment 1 of the present invention. The schematic block diagram explaining the aperture position which concerns on one Embodiment of this invention. The schematic block diagram of the aperture_diaphragm | restriction which concerns on the 1st Embodiment of this invention. The schematic block diagram of the aperture_diaphragm | restriction which concerns on the 2nd Embodiment of this invention. The schematic block diagram of the aperture_diaphragm | restriction which concerns on the 3rd Embodiment of this invention. The figure which shows the relationship between the aperture light-shielding amount and contrast ratio of the projection type display apparatus which concerns on one Embodiment of this invention. The figure which shows the relationship between the aperture light-shielding amount of the projection type display apparatus which concerns on one Embodiment of this invention, and light output. FIG. 5 is a schematic configuration diagram of a projection display device according to a second embodiment of the invention. The schematic block diagram of the projection type display apparatus which concerns on the comparative example which is not provided with the aperture_diaphragm | restriction. FIG. 5 is a schematic configuration diagram of a projection display device according to a third embodiment of the invention. FIG. 6 is a configuration diagram of a color separation / synthesis prism according to a third embodiment of the present invention. The schematic block diagram of the projection type display apparatus which concerns on the comparative example which is not provided with the aperture_diaphragm | restriction. 1 is a schematic configuration diagram of an example of a conventional projection display device. Operation | movement explanatory drawing of the reflection type light valve at the time of ON signal. Operation | movement explanatory drawing of the reflection type light valve at the time of OFF signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lamp 2 Concave mirror 3 Rod prism 4 Condenser lens 6 Reflection type light valve 7 Projection lens 12 Optical axis 31, 41, 61 Aperture 33, 47, 52, 64, 82 ON light 34, 48, 53, 65, 83 OFF light 35 , 49, 50, 54, 55, 66, 84 Unnecessary reflected light 44 Total reflection prism 62 Color separation / combination prism

Claims (2)

A light source;
A reflective light valve having a mirror element formed for each pixel ;
An illumination optical system for collecting the emitted light from the light source on the reflective light valve;
A projection lens for enlarging and projecting the light reflected on the screen by the emitted light is the mirror element of the reflection type light valve,
A diaphragm that is arranged at any position in the projection lens or the illumination optical system, and that determines a size of a cross-sectional area of a light bundle of light projected on the screen from the projection lens,
The diaphragm is composed of a fixed diaphragm having an opening and a light shielding plate capable of shielding a part of the light beam in the opening,
A screen for unnecessary reflected light reflected on the front surface of the reflective light valve by the displacement of the light shielding plate, wherein the light shielding plate is configured to be displaceable in a direction toward the optical axis of the illumination optical system or the optical axis of the projection lens. A projection display device characterized in that projection on the top can be reduced . 2. The projection display device according to claim 1, wherein a shape of the opening excluding a portion shielded by the light shielding plate in the opening is non-rotationally symmetric with respect to an optical axis of the illumination optical system or the projection lens.

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