JP2021060584A - Optical unit and projector provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical unit capable of improving usability while preventing a decrease in the amount of projected light. An internal total reflection prism P1 that reflects illumination light L1 on an illumination light reflecting surface 12 and an illumination light L1 formed by a plurality of prisms P21, P22, and P23 and reflected by the illumination light reflecting surface 12 are input and output surfaces. The internal total reflection prism P1 is provided with a color separation synthesis prism unit P2 that is incident from 21b and emits ON light L2 (projected light) from the input / output surface 21b, and the internal total reflection prism P1 is close to the input / output surface 21b and is close to the input / output surface 21b. The optical axis AX1 of the incident light L11 of the illumination light L1 incident on the illumination light reflecting surface 12 and the optical axis AX2 on the inlet / output surface 21b of the ON light L2 are the same. The entrance / exit surface 21b is arranged on the optical axis plane, which is the plane of the light, and satisfies a predetermined relationship with the incident light L11. [Selection diagram] Fig. 6

Description

The present invention relates to an optical unit in which illumination light is incident and the projected light reflected by the digital micromirror device is emitted, and a projector including the same.

A projector equipped with a conventional optical unit is disclosed in Patent Document 1. The projector is equipped with a light source, an optical unit, multiple Digital Micromirror Devices and a projection lens. The optical unit has a total reflection type optical separation prism and a cross dichroic prism. The total reflection type optical separation prism and the cross dichroic prism are arranged in this order from the projection side (emission side) toward the digital micromirror device.

A digital micromirror device is a reflective image display element having a rectangular shape in a plan view, and has an image display surface composed of a plurality of minute micromirrors. The digital micromirror device generates projected light by controlling the tilt of the surface of each micromirror ON / OFF and modulation the intensity of the illumination light to form an image. Each micromirror rotates about one rotation axis of the digital micromirror device, and the tilt angle of the micromirror in the ON state and the tilt angle of the micromirror in the OFF state are different.

The total reflection type light separation prism consists of two prisms, one prism has an injection surface, the other prism has an incident surface and a total reflection surface, and a protruding portion protruding in the emission direction with respect to the emission surface. Have. A part of the total reflection surface is provided on the protruding portion, and the white illumination light incident on the total reflection type light separation prism from the incident surface is totally reflected toward the cross dichroic prism. The ejection surface is arranged to face the projection lens and emits the projected light generated by the digital micromirror device toward the projection lens.

The cross dichroic prism has two dichroic coated surfaces that are orthogonal to each other, and the white illumination light totally reflected by the total reflection surface of the total reflection type light separation prism is decomposed into a red component, a green component, and a blue component for each digital. Lead to each micromirror device. In addition, the cross dichroic prism color-synthesizes the red, green, and blue ON light (projected light) reflected by the ON state micromirror of each digital micromirror device, and the color-synthesized ON light is totally reflected light separation. It emits toward the prism. The surface of the cross dichroic prism on the most emitting surface side is parallel to the emitting surface and perpendicular to the optical axis of the color-synthesized ON light.

In the projector having the above configuration, the white illumination light emitted from the light source and incident on the total reflection type light separation prism is totally reflected by the total reflection surface of the total reflection type light separation prism and then emitted from the total reflection type light separation prism. It is incident on the cross dichroic prism. The illumination light incident on the cross-dichroic prism is color-separated and emitted toward a digital micromirror device in which the red component, the green component, and the blue component of the illumination light are different from each other.

Then, the red, green, and blue ON lights reflected by the ON state micromirrors of each digital micromirror device are incident on the cross dichroic prism, color-synthesized, and emitted toward the total reflection type optical separation prism. .. The color-synthesized ON light is transmitted from the total reflection surface of the total reflection type light separation prism, then emitted from the emission surface, and is transmitted through the projection lens. As a result, a color image is projected.

Japanese Unexamined Patent Publication No. 2007-25287 (pages 5, 6, 6, 1 and 3)

Generally, in a projector, the projection position of a projected image is changed by moving the projection lens in the vertical direction or the horizontal direction. That is, in the projector, the projection lens is shifted up and down and left and right. However, according to the conventional optical unit, the total reflection type optical separation prism has a protruding portion protruding in the emission direction, and the projection lens is arranged in the vicinity of the side of the protruding portion. Therefore, the movement of the projection lens in the left-right direction is restricted, and the amount of left-right shift of the projection lens (distance that can be moved in the left-right direction) becomes small. Further, when the protruding portion of the total reflection type optical separation prism is arranged near the lower part of the projection lens, the vertical movement of the projection lens is restricted and the vertical shift amount of the projection lens (distance that can be moved in the vertical direction). ) Becomes smaller. Therefore, there is a problem that the usability of the optical unit and the projector is lowered.

On the other hand, when the protruding portion (total reflection surface) of the total reflection type optical separation prism is moved along the most emitting side surface of the cross dichroic prism in the direction away from the projection lens, the amount of left / right shift and the amount of vertical shift of the projection lens are increased. It can be made larger. However, in this case, among the luminous flux of the illumination light directed to the total reflection type light separation prism, the light beam on the cross dichroic prism side may not be incident on the incident surface. At this time, if the angle of incidence of the illumination light on the incident surface is changed in order to make the light beam of the illumination light on the cross dichroic prism side incident on the incident surface, some of the illumination light is transmitted on the total reflection surface without being totally reflected. As a result, the amount of illumination light totally reflected by the total reflection surface of the total reflection type light separation prism is reduced, and the amount of illumination light incident on the digital micromirror device is reduced, so that the amount of projected light is reduced. There was a problem.

An object of the present invention is to provide an optical unit capable of improving usability while preventing a decrease in the amount of projected light, and a projector provided with the optical unit.

In order to achieve the above object, the present invention emits illumination light toward a plurality of digital micromirror devices that generate projected light by modulating the illumination light on an image display surface according to an image signal, and at the same time, a plurality of illumination lights. In an optical unit that transmits and emits projected light generated by the digital micromirror device.
A reflective member having an illumination light reflecting surface that reflects illumination light,
A prism formed by a plurality of first prisms, in which the illumination light reflected by the illumination light reflecting surface is incident from the first surface formed on the first prism on the most emitting side, and the projected light is emitted from the first surface. With the unit
The reflective member is arranged so as to be close to the first surface and project from the first surface in the emission direction of the projected light.
The optical axis of the incident light of the illumination light incident on the illumination light reflecting surface and the optical axis of the projected light on the first surface are arranged on an optical axis plane which is the same plane.
When the outward first normal vector of the first surface is projected onto the optical axis plane, the first normal vector is arranged on the same side as the optical axis of the incident light with respect to the optical axis of the projected light. The first component vector projected onto the optical axis plane is characterized in that as it moves away from the first plane, it goes away from the optical axis of the projected light emitted from the first plane.

Further, in the present invention, in the optical unit having the above configuration, it is preferable that at least one of the first prisms has a dichroic coated surface, and the prism unit performs color separation of illumination light and color synthesis of projected light.

Further, in the optical unit having the above configuration, when the inward second normal vector of the facing surface facing the first surface of the first prism having the first surface is projected onto the optical axis plane. The second component vector, which is arranged on the same side as the optical axis of the incident light with respect to the optical axis of the projected light and projects the second normal vector onto the optical axis plane, becomes said as the distance from the facing surface increases. It is preferable that the projected light emitted from the first surface is directed away from the optical axis.

Further, in the present invention, in the optical unit having the above configuration, it is preferable that the illumination light reflecting surface is arranged outside the light flux of the projected light.

Further, in the optical unit having the above configuration, it is preferable that the reflecting member is formed of an internal total internal reflection prism and the illumination light reflection surface is formed of the total internal reflection surface of the internal total reflection prism.

Further, in the present invention, in the optical unit having the above configuration, it is preferable that the reflecting member is made of a mirror member and the illumination light reflecting surface is formed of the mirror surface of the mirror member.

Further, in the present invention, in the optical unit having the above configuration, the optical axis of the projected light is arranged in the normal direction and the second surface on which the projected light is emitted is provided, and the projected light emission direction side of the first surface is provided. The end portion of the light beam of the illumination light on the illumination light reflecting surface on the prism unit side is arranged on the same side as the prism unit with respect to the second surface. The intersection of the illumination light reflecting surface and the second surface is preferably arranged outside the light beam of the projected light on the second surface.

Further, in the optical unit having the above configuration, the emission side optical member is a second prism that injects projected light from an incident surface facing the first surface and emits projected light from the second surface. Is preferable.

Further, in the present invention, in the optical unit having the above configuration, a plurality of mounting portions for mounting the digital micromirror device are provided, and the mounting portions are arranged corresponding to the first prisms, respectively, and the digital micromirror device is mounted. It is preferable that the micromirror device forms an image by controlling the inclination of each surface of a plurality of micromirrors rotating about a rotation axis to ON / OFF and intensifying the illumination light.

Further, in the optical unit having the above configuration, each of the micromirrors has two rotation axes orthogonal to each other, and each of the micromirrors is driven with respect to the two rotation axes, and the projected light is projected. It is preferable that a plane including the optical axis on the first surface of the digital micromirror device and parallel to the lateral center of the digital micromirror device in the longitudinal direction is orthogonal to the illumination light reflecting surface.

Further, according to the present invention, in the optical unit having the above configuration, a third prism is arranged between each of the digital micromirror devices and each of the first prisms, and the third prism is the digital micromirror. The projected light, which is the ON light reflected by the micromirror in the ON state of the device, is transmitted, and the unnecessary light, which is the OFF light reflected by the micromirror in the OFF state of the digital micromirror device, is reflected. It is preferable to have an OFF light reflecting surface.

Further, in the present invention, it is preferable that the optical unit having the above configuration satisfies the following conditional expression (1).
θ _OFF > sin ^-1 (1 / n)> θ _ON ... (1)
However,
θ _ON : The angle of incidence of the ON light ray having the largest incident angle on the OFF light reflecting surface on the OFF light reflecting surface,
θ _OFF : The angle of incidence of the OFF light ray having the smallest incident angle on the OFF light reflecting surface on the OFF light reflecting surface,
n: Refractive index of the third prism,
Is.

Further, the projector of the present invention is displayed on an optical unit having the above configuration, a light source, an illumination optical system that emits illumination light toward the reflection member, and the digital micromirror device attached to the attachment portion. It is characterized by having a projection optical system that magnifies and projects the image on the screen.

Further, according to the present invention, in the projector having the above configuration, the projection optical system is arranged so as to face the first surface of the optical unit, and the reflection member is from the optical axis of the projected light emitted from the first surface. Is also arranged below, and it is preferable that the projection optical system can move in the vertical direction.

According to the optical unit of the present invention, the optical axis of the incident light of the illumination light incident on the illumination light reflecting surface and the optical axis on the first surface of the projected light are arranged on the optical axis plane which is the same plane, and the first When the outward first normal vector of one surface is projected on the optical axis plane, the first normal vector is arranged on the same side as the optical axis of the incident light of the illumination light with respect to the optical axis of the projected light. The first component vector projected onto the axis plane tends to move away from the optical axis of the projected light emitted from the first plane as the distance from the first plane increases. As a result, while preventing a decrease in the amount of illumination light totally reflected by the illumination light reflecting surface, the optical axis of the projected light emitted from the first surface and near the first surface and the optical axis of the projected light of the reflecting member. The distance in the direction perpendicular to can be increased. Therefore, when the projection optical system is arranged so as to face the first surface of the optical unit, the amount of shift in the direction of the projection optical system toward the reflective member can be increased. Therefore, it is possible to improve the usability of the optical unit and the projector while preventing a decrease in the amount of projected light.

Schematic configuration diagram showing a projector including the optical unit according to the first embodiment of the present invention. Perspective view showing an optical unit according to the first embodiment of the present invention. An exploded perspective view showing an optical unit according to a first embodiment of the present invention. Top view showing the optical unit of the first embodiment of the present invention Side view showing the optical unit of the 1st Embodiment of this invention Side sectional view showing the optical unit of the first embodiment of the present invention. A perspective view showing a reference state, an ON state, and an OFF state of the micromirror of the digital micromirror device of the optical unit of the first embodiment of the present invention. A perspective view for explaining the operation of the digital micromirror device of the optical unit of the first embodiment of the present invention. Illumination light for the micromirror of the digital micromirror device of the optical unit of the first embodiment of the present invention, ON light reflected by the micromirror in the ON state, and OFF light reflected by the micromirror in the OFF state. Schematic diagram showing Side sectional view showing an optical unit of a comparative example A perspective view showing an optical unit according to a second embodiment of the present invention. Top view showing the optical unit of the second embodiment of the present invention Side view showing the optical unit of the 2nd Embodiment of this invention Side sectional view showing the optical unit of the second embodiment of the present invention. Perspective view showing an optical unit according to a third embodiment of the present invention. Top view showing the optical unit of the third embodiment of the present invention Side view showing the optical unit of the 3rd Embodiment of this invention Side sectional view showing an optical unit according to a third embodiment of the present invention. Perspective view showing an optical unit according to a fourth embodiment of the present invention. Side view showing the optical unit of the 4th Embodiment of this invention Side sectional view showing an optical unit according to a fourth embodiment of the present invention. A perspective view showing an optical unit according to a fifth embodiment of the present invention. Top view showing the optical unit of the fifth embodiment of the present invention A side view showing an optical unit according to a fifth embodiment of the present invention. Side sectional view showing an optical unit according to a fifth embodiment of the present invention. A perspective view for explaining the operation of the digital micromirror device of the optical unit of the fifth embodiment of the present invention. Perspective view showing the optical unit of the sixth embodiment of the present invention. Top view showing the optical unit of the sixth embodiment of the present invention Side sectional view showing the optical unit of the sixth embodiment of the present invention.

<First Embodiment>
An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a projector including the optical unit of the first embodiment. The 3-chip type (three-plate type) projector PJ includes a light source 1, an illumination optical system 2, an optical unit PU, a digital micromirror device DP1, DP2, DP3 (see also FIG. 4), a projection optical system LN, an actuator 4, and a control. The unit 3 is provided.

The light source 1 is composed of, for example, an LED and emits white light. The illumination optical system 2 has an integrator, a relay lens group, a reflection mirror, and the like (all not shown). The illumination optical system 2 collects the emitted light of the light source 1 and emits it as the illumination light L1 toward the optical unit PU.

FIG. 2 shows a perspective view of the optical unit PU. In FIG. 2, the X direction indicates the thickness direction of the color separation synthesis prism unit P2. The Z direction indicates the optical axis AX2 direction of the projected light reflected by the digital micromirror device DP2. The Y direction indicates a direction perpendicular to the X direction and the Z direction. The optical unit PU includes one internal total internal reflection prism P1 (reflection member), one color separation synthesis prism unit P2 (prism unit), one projection side prism P3 (second prism), and three OFF lights. It has a separation prism P4 (third prism). The color separation synthesis prism P2 includes a prism P21 (first prism), a prism P22 (first prism), and a prism P23 (first prism).

For example, glass can be used as the material of the internal total reflection prism P1, the prisms P21 to P23 of the color separation synthesis prism unit P2, the projection side prism P3, and the OFF light separation prism P4. In the present embodiment, the internal total reflection prism P1, the prisms P21, P22, P23, the projection side prism P3, and the OFF light separation prism P4 are formed of glass having the same refractive index.

The optical unit PU is supported in the projector PJ by a support member (not shown). The support member is arranged in contact with the upper and lower surfaces of the optical unit PU in FIG. 2, and sandwiches the optical unit PU. Further, the optical unit PU has three mounting portions (not shown) for mounting the digital micromirror devices DP1, DP2, and DP3 having a substantially rectangular plan view. The mounting portion is composed of, for example, a metal frame member, and is provided corresponding to the prisms P21, P22, and P23.

As will be described later, the optical unit PU incidents the illumination light L1 from the internal total reflection prism P1 and projects the projected light (ON light L2 described later) reflected by the digital micromirror devices DP1, DP2, and DP3 into the projection optical system LN. Eject toward. In the following description, the digital micromirror devices DP1 to DP3 may be collectively referred to as the "digital micromirror device DP". The details of the optical unit PU and the digital micromirror device DP will be described later.

The projection optical system LN has lenses 51, 52 (see FIG. 5) and the like, and magnifies and projects an image displayed on the digital micromirror device DP onto the screen SC. The actuator 4 moves the lenses 51 and 52 along the optical axis AX to perform, for example, zooming and focusing. Further, the actuator 4 can move the lenses 51 and 52 in the vertical direction in FIGS. 1 and 5 to change the position (projection position) of the projected image in the vertical direction. That is, the actuator 4 and the projection optical system LN shift the projected image up and down. The control unit 3 has a CPU and controls the entire projector PJ.

3 to 6 show an exploded perspective view, a top view, a side view, and a side sectional view of the optical unit PU, respectively. Note that FIG. 6 shows a cross-sectional view including the optical axis AX2 of the ON light L2 (projected light) that has passed through the digital micromirror device DP2 and is reflected by the digital micromirror device DP2. The optical axis AX2 of the ON light L2 reflected by the digital micromirror device DP2 coincides with the normal passing through the center of the digital micromirror device DP2. Further, the optical axis AX1 of the illumination light L1 coincides with the optical path of the light beam of the illumination light L1 incident on the center of the digital micromirror device DP.

The color separation synthesis prism unit P2 is arranged between the digital micromirror device DP2 and the internal total reflection prism P1. A wedge-shaped projection side prism P3 is arranged on the projection side (injection side) of the color separation synthesis prism unit P2.

Further, between the digital micromirror device DP1 and the color separation synthesis prism unit P2, between the digital micromirror device DP2 and the color separation synthesis prism unit P2, and between the digital micromirror device DP3 and the color separation synthesis prism unit P2. An OFF optical separation prism P4 is arranged between the prism unit P2 and the prism unit P2. That is, the OFF optical separation prism P4 is provided corresponding to each digital micromirror device DP.

Further, a cover glass CG (see FIG. 6) is provided between the digital micromirror device DP and the OFF optical separation prism P4. Note that the cover glass CG is not shown in FIGS. 2 to 5.

FIG. 7 is a perspective view showing a reference state, an ON state, and an OFF state of the micromirror MR of the digital micromirror device DP. FIG. 8 is a perspective view for explaining the operation of the digital micromirror device DP. The digital micromirror device DP has a plurality of minute micromirror MRs arranged in a matrix and having a substantially square plane view. The micromirror MR is mounted on the substrate SB, and the substrate SB is housed in a substantially rectangular housing (not shown).

The reference state of the micromirror MR is indicated by the reference plane MS1, the ON state of the micromirror MR is indicated by the reflection surface MS2, and the OFF state of the micromirror MR is indicated by the reflection surface MS3. The micromirror MR can rotate with respect to the second axis ax2 orthogonal to the first axis ax1 after being tilted with respect to the first axis ax1 from the reference state. As a result, in the digital micromirror device DP, each pixel reflection surface MS is ON / OFF controlled on the image display surface DS composed of a plurality of pixel reflection surface MSs, and the micromirror MR is in the image display state (ON state). It takes two angular states, an image non-display state (OFF state) and an image non-display state (OFF state). That is, the digital micromirror device DP drives the micromirror MR with respect to two orthogonal axes, and the micromirror MR can take a reference state, an ON state, and an OFF state. As a result, the digital micromirror device DP constitutes a reflective image display element that intensity-modulates the illumination light L1 to generate a desired image. That is, the digital micromirror device DP intensity-modulates the illumination light L1 to generate the projected light.

Since the drive of each micromirror MR is performed on two orthogonal axes (first axis ax1 and second axis ax2), the pixel reflection surface MS of the micromirror MR is inclined in different planes. In the digital micromirror device DP2 of the present embodiment, the tilted state in the YZ plane is the ON state, and the tilted state in the XZ plane is the OFF state. In the normally assumed ON / OFF control, when the pixel reflecting surface MS is in the ON state, the illumination light L1 incident on the micromirror MR is in the normal direction of the image display surface DS (normal of the digital micromirror device DP). It is reflected by the light and becomes ON light L2 (projected light). Further, when the pixel reflecting surface MS is in the OFF state, the illumination light L1 incident on the micromirror MR is reflected at a large angle from the normal direction of the image display surface DS, and becomes OFF light L3 (unnecessary light).

Therefore, as shown in FIG. 9, in the vicinity of the digital micromirror device DP2, each micromirror MR has the optical axis AX3 of the OFF light L3 as the optical axis AX2 of the ON light L2 and the optical axis AX1 of the illumination light L1. The OFF light L3 is reflected in a direction away from the optical axis plane AP including. Further, the normal of the image display surface DS (normal of the digital micromirror device DP) is parallel to the optical axis AX2 of the ON light L2 (projected light) in the vicinity of the digital micromirror device DP2. Similarly to the digital micromirror device DP2, each micromirror MR is turned off in the vicinity of the digital micromirror devices DP1 and DP3 in a direction away from the plane (not shown) including the optical axes AX1 and AX2. Reflects light L3.

In the present embodiment, the angle β formed by the normal of the micromirror MR in the ON state and the normal of the digital micromirror device DP is 17 °, and the normal of the micromirror MR in the OFF state and the digital micromirror MR. The angle γ formed by the normal of the micromirror device DP is 17 °. Therefore, the angle formed by the optical axis AX1 of the incident light (illumination light L1) of the digital micromirror device DP and the normal line of the digital micromirror device DP is 34 °.

As described above, on the image display surface DS of the digital micromirror device DP, a two-dimensional image is formed by the intensity modulation of the illumination light L1. The digital micromirror device DP expresses ON / OFF by driving the micromirror MR with respect to two orthogonal axes as described above.

Returning to FIGS. 2 to 6, the internal total reflection prism P1, the color separation synthesis prism unit P2, the projection side prism P3, and the OFF light separation prism P4 will be described. The internal total reflection prism P1 has an entrance surface 11, an illumination light reflection surface 12, and an emission surface 13 (see FIG. 3). The incident surface 11 is inclined in a direction approaching the projection optical system LN toward the screen SC, and the illumination light L1 emitted from the illumination optical system 2 is incident.

The illumination light reflecting surface 12 is composed of a total reflection surface formed on the internal total reflection prism P1, and is inclined in a direction closer to the color separation synthesis prism unit P2 as the distance from the incident surface 11 increases. The illumination light reflecting surface 12 totally reflects the illumination light L1 incident from the incident surface 11 toward the color separation synthesis prism unit P2.

The exit surface 13 is arranged so as to face the color separation synthesis prism unit P2, and is inclined in a direction away from the projection optical system LN toward the incident surface 11. The emission surface 13 emits the illumination light L1 totally reflected by the illumination light reflection surface 12 toward the color separation synthesis prism unit P2.

The color separation synthesis prism unit P2 having prisms P21, P22, and P23 is a so-called Phillips type dichroic prism unit, and the prisms P21, P23, and P22 are arranged in this order from the internal total reflection prism P1 toward the digital micromirror device DP2. Will be done.

The prisms P21, P22, and P23 have entrance / exit surfaces 21a, 22a, and 23a, respectively. The entrance / exit surfaces 21a, 22a, and 23a are close to each other and face the OFF optical separation prism P4. The entrance / exit surfaces 21a, 22a, and 23a are inclined in directions away from the digital micromirror devices DP1, DP2, and DP3, respectively, toward the OFF light emission surface 43 described later.

Further, in the color separation synthesis prism unit P2, the entrance / exit surface 21b (first surface) arranged on the injection side of the prism P21 on the most emission side (most projection optical system LN side) is the incident surface 11 of the internal total reflection prism P1. It tilts away from the projection optical system LN toward the side. In the present embodiment, the entrance / exit surface 21b is inclined by about 11 ° with respect to the XY plane.

The optical axis AX1 of the incident light L11 of the illumination light L1 incident on the illumination light reflecting surface 12 and the optical axis AX2 on the input / output surface 21b of the ON light L2 (projected light) are the same planes as the optical axis plane AP ( (See Fig. 9). The optical axis plane AP is the same plane as the paper surface of FIG. The outward first normal vector NV1 (see FIG. 2) of the entrance / exit surface 21b is projected onto the optical axis plane AP and arranged on the same side as the optical axis AX1 of the incident light L11 with respect to the optical axis AX2 of the ON light L2. The first component vector CV1 to be formed tends to move away from the optical axis AX2 of the ON light L2 emitted from the entrance / exit surface 21b as the distance from the entrance / exit surface 21b increases.

Further, the prisms P21 and P23 have total reflection surfaces 21t and 23t, respectively, and have a dichroic coated surface DR and a dichroic coated surface DB, respectively. The total reflection surface 21t is composed of an inner surface of the entrance / exit surface 21b. The dichroic coated surface DR is arranged to face the total reflection surface 21t, and the total reflection surface 23t is arranged to face the dichroic coat surface DR. The dichroic coated surface DB is arranged close to the prism P22 and opposed to the prism P22.

As shown in FIG. 4, the dichroic coated surface DR and the total reflection surface 23t are inclined toward the projection optical system LN as they move away from the digital micromirror device DP1 when viewed from the Y direction. The dichroic coated surface DB is inclined in the direction closer to the projection optical system LN as the distance from the digital micromirror device DP3 is increased when viewed from the Y direction. The entrance / exit surface 21b and the total reflection surface 21t are perpendicular to the normal line of the digital micromirror device DP2 when viewed from the Y direction. That is, the entrance / exit surface 21b and the total reflection surface 21t are perpendicular to the optical axis AX2 of the ON light L2 reflected by the digital micromirror device DP2 when viewed from the Y direction.

Further, the inward second normal vector NV2 (see FIG. 4) of the dichroic coated surface DR (opposing surface) facing the entrance / exit surface 21b is projected onto the optical axis plane AP with respect to the optical axis AX2 of the ON light L2. The second component vector CV2 (see FIG. 6) arranged on the same side as the optical axis AX1 of the incident light L11 is from the optical axis AX2 of the ON light L2 emitted from the input / output surface 21b as the distance from the dichroic coated surface DR increases. Head away.

Further, the inward third normal vector NV3 (see FIG. 4) of the dichroic coated surface DB is projected onto the optical axis plane AP, and the optical axis AX2 of the ON light L2 is on the same side as the optical axis AX1 of the incident light L11. The third component vector CV3 (see FIG. 6) arranged in the dichroic coated surface DB tends to move away from the optical axis AX2 of the ON light L2 emitted from the entrance / exit surface 21b as it moves away from the dichroic coated surface DB.

The dichroic coated surface DR reflects the red component of the illumination light L1 and transmits the green component and the blue component of the illumination light L1. The dichroic coated surface DB reflects the blue component of the illumination light L1 and transmits the green component of the illumination light L1. That is, the dichroic coated surface DR and the dichroic coated surface DB reflect the component of the illumination light L1 having a predetermined wavelength and transmit the component of the illumination light L1 other than the predetermined wavelength. As a result, the color separation synthesis prism unit P2 color-separates the illumination light L1 emitted from the internal total reflection prism P1 and emits the illumination light L1 to the digital micromirror device DP side, respectively.

Further, the dichroic coated surface DR reflects the red ON light L2 and transmits the green and blue ON light L2. The dichroic coated surface DB reflects the blue ON light L2 and transmits the green ON light L2. That is, the dichroic coated surface DR and the dichroic coated surface DB reflect the ON light L2 having a predetermined wavelength and transmit the ON light L2 other than the predetermined wavelength. As a result, the color separation synthesis prism unit P2 color-synthesizes the red, green, and blue ON lights L2 emitted from the digital micromirror devices DP1, DP2, and DP3, respectively, and moves them to the emission side via the input / output surface 21b. Exit.

The prism P21 and the prism P23 may be interchanged and arranged. That is, the prism P23 may be arranged on the injection side of the prism P21. Further, instead of the so-called Philips type dichroic prism unit, the color separation synthesis prism unit P2 may be formed by the cross dichroic prism unit.

The projection side prism P3 (injection side optical member) is arranged on the emission side (injection side) of the prism P21 of the color separation synthesis prism unit P2 and on the opposite side (upper side in FIG. 2) of the incident surface 11 of the internal total reflection prism P1. It has an incident surface 31 and an exit surface 32 (second surface, ejection surface). The “injection surface” refers to a surface on which the ON light L2 is emitted from the optical unit PU toward the projection optical system LN. The incident surface 31 is inclined in a direction closer to the projection optical system LN as it is separated from the internal total reflection prism P1 when viewed from the X direction. The incident surface 31 is incident with ON light L2 (projected light after color synthesis) emitted from the input / output surface 21b.

The exit surface 32 is arranged to face the projection optical system LN, and emits the ON light L2 so that the optical axis AX2 of the ON light L2 coincides with the normal direction of the exit surface 32. Distortion of the image projected on the screen SC by the projection side prism P3 can be reduced. Further, the end portion of the internal total reflection prism P1 on the projection optical system LN side projects in the injection direction (Z direction) with respect to the emission surface 32 of the projection side prism P3.

The OFF optical separation prisms P4 are arranged close to and facing the entrance / exit surfaces 21a, 22a, and 23a, respectively. Each OFF light separation prism P4 has an entrance / exit surface 41, an OFF light reflection surface 42, and an OFF light emission surface 43. The entrance / exit surfaces 41 are arranged so as to face each other in the vicinity of the digital micromirror devices DP1, DP2, and DP3, and the optical axis AX2 of the ON optical L2 in the vicinity of the digital micromirror devices DP1, DP2, and DP3 is inserted, respectively. It coincides with the normal direction of the exit surface 41.

The OFF light emitting surface 43 is composed of an end surface (end surface in the Y direction, upper surface in FIG. 2) opposite to the incident surface 11 of the internal total internal reflection prism P1 with respect to the optical axis AX2 of the ON light L2. The OFF light reflecting surfaces 42 arranged in the vicinity of the digital micromirror devices DP1, DP2, and DP3 are separated from the digital micromirror devices DP1, DP2, and DP3 as they move toward the OFF light emitting surface 43, respectively. It is inclined to. The OFF light reflecting surface 42 totally reflects the OFF light L3 reflected by the micro mirror MR in the OFF state and transmits the ON light L2 reflected by the micro mirror MR in the ON state. The OFF light emitting surface 43 emits the OFF light L3 totally reflected by the OFF light reflecting surface 42 toward the outside of the optical unit PU.

Further, the light absorbing member PM is provided so as to face each of the OFF light emitting surfaces 43 apart from each other. The light absorbing member PM is formed of, for example, a black-treated metal plate and absorbs the OFF light L3 emitted from the OFF light emitting surface 43. This makes it possible to prevent thermal deformation of other members in the projector PJ due to the OFF light L3 emitted from the optical unit PU.

Further, between the internal total reflection prism P1 and the color separation synthesis prism unit P2, between the color separation synthesis prism unit P2 and the projection side prism P3, and between the color separation synthesis prism unit P2 and the OFF light separation prism P4. An air layer (air gap, not shown) is provided. Further, in the color separation synthesis prism unit P2, an air layer is provided between the prism P21 and the prism 23, and also between the prism P23 and the prism 22.

In the projector PJ having the above configuration, when white light is emitted from the light source 1 (see FIG. 1), it is condensed by the illumination optical system 2 (see FIG. 1) and the white illumination light L1 is emitted toward the optical unit PU. Will be done.

The white illumination light L1 is totally reflected by the illumination light reflection surface 12 after being incident on the incident surface 11 of the internal total reflection prism P1. The white illumination light L1 totally reflected by the illumination light reflecting surface 12 is emitted from the exit surface 13 and then is incident on the entrance / exit surface 21b of the prism 21 of the color separation synthesis prism unit P2.

The white illumination light L1 incident on the prism P21 of the color separation synthesis prism unit P2 is incident on the dichroic coated surface DR, and the red component of the illumination light L1 is reflected and the green component and the blue component are transmitted. The green component and blue component of the illumination light L1 transmitted through the dichroic coated surface DR are incident on the prism P23, the blue component is reflected by the dichroic coated surface DB, and the green component is transmitted through the dichroic coated surface DB and incident on the prism P22. ..

The red component of the illumination light L1 reflected by the dichroic coat surface DR, the blue component of the illumination light L1 reflected by the dichroic coat surface DB, and the green component of the illumination light L1 transmitted through the dichroic coat surface DR and the DB are the entrance / exit surfaces 21a, respectively. , 23a, 22a, and incident on the OFF light separation prism P4, respectively. The red component, green component, and blue component of the illumination light L1 transmitted through each OFF light separation prism P4 are emitted from the input / output surface 41, and are transmitted through the cover glass CG to the digital micromirror devices DP1, DP3, and DP2, respectively. Incident. As a result, the color separation synthesis prism unit P2 color-separates the illumination light L1 totally reflected by the illumination light reflecting surface 12 and emits it to the digital micromirror devices DP1, DP2, and DP3, respectively.

The red, green, and blue ON lights L2 reflected by the ON-state micromirror MRs of the digital micromirror devices DP1 to DP3 are incident on the OFF light separation prism P4 from the inlet / output surface 41, respectively, and the OFF light reflection surface 42. Is incident on the prisms P21, P22, and P23 of the color separation synthesis prism unit P2 from the entrance / exit surfaces 21a, 22a, and 23a, respectively.

The red ON light L2 is totally reflected by the total reflection surface 21t of the prism P21 and then reflected by the dichroic coated surface DR and heads toward the entrance / exit surface 21b. The green ON light L2 passes through the prism P22 and then passes through the dichroic coated surface DB and the DR in this order toward the entrance / exit surface 21b. The blue ON light L2 is totally reflected by the total reflection surface 23t of the prism P23, then reflected by the dichroic coat surface DB, passes through the dichroic coat surface DR, and heads toward the entrance / exit surface 21b. At this time, the red, green, and blue ON lights L2 are color-synthesized while passing through the color-separation synthesis prism unit P2, and the color-synthesized ON light L2 is emitted from the inlet / output surface 21b to the emission side.

The ON light L2 (projected light after color synthesis) emitted from the input / output surface 21b is incident on the projection side prism P3 via the incident surface 31. The ON light L2 incident on the projection side prism P3 passes through the projection side prism P3 and is emitted from the emission surface 32 toward the projection optical system LN.

At this time, as shown in FIG. 6, the illumination light reflecting surface 12 is arranged outside the light flux of the ON light L2. That is, the ON light L2 does not enter the illumination light reflecting surface 12. As a result, the luminous flux of the illumination light L1 within the Z-direction distance D1 (about 85 mm in this embodiment) between the entrance / exit surface 41 and the exit surface 32 of the OFF light separation prism P4 corresponding to the digital micromirror device DP2. The light flux of the ON light L2 can be separated.

Further, the end portion of the light beam of the illumination light L1 on the illumination light reflecting surface 12 on the color separation synthesis prism unit P2 side is arranged on the same side as the color separation synthesis prism unit P2 with respect to the emission surface 32. That is, the end LE (see FIG. 6) on the P2 side of the color separation synthesis prism unit P2 in the region where the luminous flux of the illumination light L1 on the illumination light reflection surface 12 is projected onto the optical axis plane AP is color separation synthesis with respect to the emission surface 32. It is arranged on the same side as the prism unit P2. Further, the line of intersection NL between the illumination light reflecting surface 12 and the emitting surface 32 is arranged outside the light flux of the ON light L2 on the emitting surface 32. As a result, the luminous flux of the ON light L2 on the emission surface 32 and the luminous flux of the illumination light L1 on the illumination light reflection surface 12 do not overlap. The "intersection line NL between the illumination light reflecting surface 12 and the emission surface 32" indicates the intersection line between the surface parallel to the emission surface 32 including the emission surface 32 and the illumination light reflection surface 12.

Further, a plane that includes the optical axis AX2 of the ON light L2 emitted from the entrance / exit surface 21b, passes through the center of the digital micromirror device DP2 in the longitudinal direction, and is parallel to the lateral direction (in the present embodiment, the optical axis plane AP). (Same plane as) is orthogonal to the illumination light reflecting surface 12.

The ON light L2 incident on the projection optical system LN is projected onto the screen SC (see FIG. 1). As a result, the color image displayed on the digital micromirror device DP is projected on the screen SC. At this time, the actuator 4 performs zooming and focusing. Further, the projection side prism P3 emits ON light L2 from the emission surface 32 so that the optical axis AX2 coincides with the normal direction of the emission surface 32. As a result, it is possible to reduce the distortion of the image enlarged and projected on the screen SC.

Further, the actuator 4 can move the projection lenses 51 and 52 of the projection optical system LN in the Y direction, and the projection position of the projected image can be changed in the Y direction. For example, when the projector PJ is attached to the ceiling surface in the living room (not shown), the projection lenses 51 and 52 are moved to the internal total reflection prism P1 side (downward in FIG. 5). As a result, the projector PJ can project an image on the screen SC at a position away from the ceiling.

At this time, as the first component vector CV1 moves away from the entrance / exit surface 21b, the first component vector CV1 moves away from the optical axis AX2 of the ON light L2 emitted from the entrance / exit surface 21b. As a result, even if the distance D2 between the optical axis AX2 on the emission surface 32 of the ON light L2 and the intersection line NL is increased, the color separation synthesis prism unit P2 side of the light beam of the illumination light L1 toward the internal total internal reflection prism P1. The light beam of the illumination light L1 can also be incident on the incident surface 11 and totally reflected by the illumination light reflecting surface 12.

On the other hand, the OFF light L3 reflected by the micromirror MR in the OFF state of the digital micromirror devices DP1, DP2, and DP3 is totally reflected by the OFF light reflecting surface 42 after being incident on the OFF light separation prism P4 from the input / output surface 41. , OFF The light is discharged to the outside of the optical unit PU from the light emitting surface 43. Then, the OFF light L3 discharged from the optical unit PU is absorbed by the light absorbing member PM. As a result, it is possible to prevent the OFF light L3 from being incident on the projection optical system LN. Therefore, it is possible to prevent a decrease in the contrast of the projected image.

At this time, the light absorbing member PM is provided away from the OFF light emitting surface 43. As a result, it is possible to reduce the heat transfer of the light absorbing member PM that has absorbed the OFF light L3 to the optical unit PU. Therefore, it is possible to suppress the temperature rise of the optical unit PU and prevent thermal deformation of the optical unit PU. As a result, the life of the optical unit PU and the projector PJ can be extended.

The illumination light L1 (flat light) reflected by the micromirror MR transitioning from one of the ON state and the OFF state to the other is in the direction opposite to the incident light of the illumination light L1 with respect to the normal direction of the micromirror MR. Be reflected. The flat light and the reflected light of the illumination light L1 on the cover glass CG are also emitted from the OFF light emitting surface 43 after being incident on the OFF light separation prism P4. As a result, it is possible to prevent the flat light and the reflected light of the illumination light L1 from the cover glass CG from being incident on the projection optical system LN. Therefore, it is possible to further prevent a decrease in the contrast of the projected image.

_{Here, in each OFF light separation prism P4, the incident angle θ ON} of the light of the ON light L2 having the largest incident angle on the OFF light reflecting surface 42 on the OFF light reflecting surface 42 and the incident on the OFF light reflecting surface 42 _{When the incident angle θ OFF} of the light beam of the OFF light L3 having the smallest angle on the OFF light reflecting surface 42 satisfies the following conditional expression (1), the OFF light reflecting surface 42 passes through the ON light L2 and the OFF light L3. Is preferable because it can reflect almost all of the light.

θ _OFF > sin ^-1 (1 / n)> θ _ON ... (1)
However,
θ _ON : The angle of incidence of the light rays of the ON light L2 having the largest incident angle on the OFF light reflecting surface 42 on the OFF light reflecting surface 42,
θ _OFF : The angle of incidence of the light rays of the OFF light L2, which has the smallest angle of incidence on the OFF light reflecting surface 42, on the OFF light reflecting surface 42.
n: Refractive index of OFF optical separation prism P4,
Is.

For example, when the refractive index n of the OFF light separation prism P4 is 1.5168, the incident angle θ _{ON is set} to 36.5 ° and the incident angle θ _{OFF is set} to 43.7 ° to satisfy the conditional equation (1). The OFF light reflecting surface 42 can transmit the ON light L2 and substantially totally reflect the OFF light L3.

The vertical shift amount (shift amount in the Y direction) of the projection optical system LN was compared between the projector PJ using the optical unit PU of the present embodiment and the projector using the optical unit of the comparative example.

FIG. 10 shows a side sectional view of the optical unit of the comparative example. For convenience of explanation, the same parts as those of the optical unit PU of this embodiment are designated by the same reference numerals. In the comparative example, the entrance / exit surface 21b of the prism P21 of the color separation synthesis prism unit P2 is perpendicular to the optical axis AX2 of the color-synthesized ON light L2. Further, in the comparative example, the projection side prism P3 is omitted. Therefore, the injection surface of the present embodiment coincides with the exit surface 32 of the projection side prism P3, and the injection surface of the comparative example coincides with the entrance / exit surface 21b of the prism P21. Other configurations of the comparative example are the same as those of the optical unit PU of the present embodiment. The vertical shift amount was set to the distance D2 between the optical axis AX2 of the ON light L2 on the injection surface and the line of intersection NL (see FIGS. 6 and 10). The distance D1 between the entrance / exit surface 41 and the exit surface 32 facing the digital micromirror device DP2 in the Z direction is 85 mm in the present embodiment and the comparative example. Further, the inclination angle of the illumination light reflecting surface 12 of the present embodiment and the comparative example with respect to the XZ plane is the same.

The vertical shift amount of the projection optical system LN of the projector PJ of the present embodiment was 26.6 mm, whereas the vertical shift amount of the projection optical system of the projector of the comparative example was 19.0 mm. Therefore, when the optical unit PU of the present embodiment is used, the vertical shift amount is 7.6 mm longer than that of the comparative example. Therefore, the vertical shift amount of the projection optical system LN of the projector PJ provided with the optical unit PU of the present embodiment can be made longer than in the case of the comparative example. In the present embodiment and the comparative example, the F number of the illumination light L1 was substantially the same, and the brightness of the projected image was also substantially the same.

According to this embodiment, when the outward first normal vector NV1 of the entrance / exit surface 21b is projected onto the optical axis plane AP, the optical axis AX2 of the ON light L2 is on the same side as the optical axis AX1 of the incident light L11. The first component vector C1 obtained by projecting the first normal vector NV1 onto the optical axis plane AP is in the direction away from the optical axis AX2 of the ON light L2 emitted from the entrance / exit surface 21b as the distance from the entrance / exit surface 21b increases. Head to. As a result, even if the distance D2 between the optical axis AX2 on the emission surface 32 (injection surface) of the ON light L2 and the intersection line NL is increased, the light rays of the illumination light L1 toward the internal total internal reflection prism P1 are color-resolved and synthesized. The light beam of the illumination light L1 on the prism unit P2 side can also be incident on the incident surface 11 and totally reflected by the illumination light reflecting surface 12. Therefore, when the projection optical system LN is arranged, the optical unit PU is used by increasing the shift amount of the projection optical system LN in the Y direction while preventing a decrease in the amount of emitted ON light L2 (projected light). The sex can be improved.

Further, the prism P21 (first prism) and the prism P23 (first prism) have a dichroic coated surface DR and DB, respectively, and the color separation synthesis prism unit P2 (prism unit) is the color separation of the illumination light L1 and the ON light. Color synthesis of L2 (projected light) is performed. As a result, the white illumination light can be easily color-separated, and the projected light of each color can be easily color-synthesized.

Further, when the inward second normal vector NV2 of the dichroic coated surface DR (opposing surface) facing the entrance / exit surface 21b of the prism P21 (first prism) having the entrance / exit surface 21b is projected onto the optical axis plane AP. The second component vector CV2, which is arranged on the same side as the optical axis AX1 of the incident light L11 with respect to the optical axis AX2 and projects the second normal vector NV2 onto the optical axis plane AP, becomes as the distance from the dichroic coated surface DR increases. The ON light L2 emitted from the entrance / exit surface 21b is directed away from the optical axis AX2. As a result, it is possible to secure a sufficient length of the prism P21 in the Z direction while inclining the entrance / exit surface 21b, and it is possible to further prevent a decrease in the amount of illumination light L1 guided by the digital micromirror device DP. it can.

Further, the illumination light reflecting surface 12 is arranged outside the light flux of the ON light L2. As a result, the luminous flux of the illumination light L1 and the luminous flux of the ON light L2 can be separated at a distance D1 in the Z direction between the entrance / exit surface 41 and the exit surface 32 facing the digital micromirror device DP2. Therefore, since the ON light L2 does not pass through the illumination light reflecting surface 12, the air layer (air gap) through which the ON light L2 passes is compared with the configuration in which the projection side prism P3 is arranged close to and facing the illumination light reflecting surface 12. The number of is reduced. Therefore, the transmittance of the ON light L2 in the optical unit PU can be improved, and the image quality of the projected image can be improved.

Further, the illumination light reflecting surface 12 is formed by the total reflection surface of the internal total reflection prism P1 (reflection member). As a result, the cross section of the light beam of the illumination light L1 on the illumination light reflecting surface 12 is smaller than the cross section of the light beam of the illumination light L1 before being incident on the incident surface 11, so that the enlargement of the illumination light reflecting surface 12 is suppressed. However, it is possible to further prevent a decrease in the amount of light of the ON light L2. Further, the reflection efficiency of the illumination light L1 on the illumination light reflecting surface 12 can be improved, and the decrease in the amount of the ON light L2 can be further prevented.

Further, the optical axis AX2 of the ON light L2 (projected light) is arranged in the normal direction, and the ON light L2 of the entrance / exit surface 21b has an exit surface 32 (second surface) from which the ON light L2 is emitted. A projection side prism P3 (injection side optical member) arranged on the emission direction side is provided. Thereby, the distortion of the projected image can be reduced. The end of the light beam of the illumination light L1 on the illumination light reflecting surface 12 on the color separation synthesis prism unit P2 (prism unit) side is arranged on the same side as the color separation synthesis prism unit P2 with respect to the emission surface 32. The intersection line NL between the illumination light reflecting surface 12 and the emitting surface 32 is arranged outside the light beam of the ON light L2 on the emitting surface 32. As a result, the shift amount of the projection optical system LN in the Y direction can be more reliably secured.

Further, a plurality of mounting portions for mounting the digital micromirror device DP are provided, and each mounting portion is arranged corresponding to the prisms P21, P22, and P23, respectively. The digital micromirror device DP forms an image by controlling the inclination of each surface of a plurality of micromirror MRs rotating about a rotation axis to be ON / OFF and intensity-modulating the illumination light L1. Thereby, the digital micromirror device DP can be easily attached to the optical unit PU, and the optical unit PU capable of emitting the projected light generated by the digital micromirror device DP can be easily realized.

Each micromirror MR has two rotation axes orthogonal to each other, and each micromirror MR is driven with respect to the two rotation axes. Thereby, the brightness of the projected image can be improved. Then, the optical axis AX2 of the ON light L2 emitted from the entrance / exit surface 21b is included, and the digital micromirror device DP2 (one digital micromirror device DP) passes through the center in the longitudinal direction and is parallel to the lateral direction. The plane is orthogonal to the illumination light reflecting surface 12. As a result, the cross section of the luminous flux of the illumination light L1 can be made smaller, so that the luminous flux of the illumination light L1 can be more reliably guided to the illumination light reflecting surface 12.

Further, an OFF optical separation prism P4 (third prism) is arranged between the digital micromirror devices DP1, DP2, DP3 and the prisms P21, P22, P23, respectively. The OFF optical separation prism P4 transmits the ON light L2 (projected light) reflected by the ON state micromirror MR of the digital micromirror device DP, and also transmits the ON light L2 (projected light) of the digital micromirror device DP in the OFF state. It has an OFF light reflecting surface 42 that reflects the OFF light L3 (unnecessary light) reflected by. As a result, the OFF light L3 can be discharged to the outside of the optical unit PU without being incident on the color separation synthesis prism unit P2. Therefore, it is possible to prevent the OFF light L3 from being incident on the projection lenses 51 and 52 of the projection optical system LN. As a result, the generation of stray light can be prevented and the contrast of the projected image can be improved.

Further, when the conditional expression (1) is satisfied, the OFF light reflecting surface 42 can transmit the ON light L2 and substantially totally reflect the OFF light L3.

Further, the projector PJ includes an optical unit PU, a light source 1, an illumination optical system 2 that emits illumination light L1 toward an internal total internal reflection prism P1 (reflection member), and a digital micromirror attached to an attachment portion. It includes a projection optical system LN that magnifies and projects the image displayed on the device DP onto the screen SC. Thereby, the projector PJ provided with the optical unit PU can be easily realized.

Further, the projection optical system LN is arranged so as to face the entrance / exit surface 21b of the optical unit PU, and the internal total reflection prism P1 is arranged below the optical axis AX2 of the ON light L2 emitted from the entrance / exit surface 21b. Ru. Then, the projection optical system LN can move in the vertical direction. This makes it possible to easily realize a projector PJ capable of shifting up and down.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. 11 to 14 show a perspective view, a top view, a side view, and a side sectional view of the optical unit PU of the second embodiment, respectively. For convenience of explanation, the same parts as those in the first embodiment shown in FIGS. 1 to 9 are designated by the same reference numerals. In the present embodiment, the configuration of the entrance / exit surface 21b (first surface) of the color separation synthesis prism unit P2 is different from that of the first embodiment. Other parts are the same as those in the first embodiment.

The entrance / exit surface 21b of the prism P21 of the color separation synthesis prism unit P2 of the present embodiment is inclined in the direction away from the projection optical system LN as the distance from the digital micromirror device DP1 increases when viewed from the Y direction. Further, the projection side prism P3 has a triangular shape when viewed from the Y direction.

The operation of the projector PJ provided with the optical unit PU having the above configuration is the same as that of the first embodiment.

The vertical shift amount (shift amount in the Y direction) of the projection optical system LN was compared between the projector PJ using the optical unit PU of the present embodiment and the projector using the optical unit of the comparative example. In the comparative example, as in FIG. 10, the first component vector CV1 is parallel to the optical axis AX2 of the ON light L2 emitted from the entrance / exit surface 21b. Further, the injection surface of the present embodiment and the comparative example coincides with the emission surface 32 of the projection side prism P3. Other configurations of the comparative example were the same as those of the optical unit PU of the present embodiment. Further, the measurement of the vertical shift amount was performed in the same manner as in the case of the first embodiment. The distance D1 between the entrance / exit surface 41 and the exit surface 32 facing the digital micromirror device DP2 in the Z direction is 85 mm in the present embodiment and the comparative example. Further, the inclination angle of the illumination light reflecting surface 12 of the present embodiment and the comparative example with respect to the XZ plane is the same.

The vertical shift amount of the projection optical system LN of the projector PJ using the optical unit PU of the present embodiment was 31.5 mm, whereas the vertical shift amount of the projection optical system of the projector using the optical unit of the comparative example was 31.5 mm. It was 27.6 mm. Therefore, when the optical unit PU of the present embodiment is used, the vertical shift amount is 3.9 mm longer than that of the comparative example. Therefore, the vertical shift amount of the projection optical system LN of the projector PJ provided with the optical unit PU of the present embodiment can be made longer than in the case of the comparative example. In the present embodiment and the comparative example, the F number of the illumination light L1 was substantially the same, and the brightness of the projected image was also substantially the same.

The same effect as that of the first embodiment can be obtained in this embodiment as well.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. 15 to 18 show a perspective view, a top view, a side view, and a side sectional view of the optical unit PU of the third embodiment, respectively. For convenience of explanation, the same parts as those in the first embodiment shown in FIGS. 1 to 9 are designated by the same reference numerals. In the present embodiment, the configuration of the color separation synthesis prism unit P2 is different from that of the first embodiment. Other parts are the same as those in the first embodiment.

The color separation synthesis prism unit P2 of the present embodiment is composed of prisms P21 and P22, and the prism P23 is omitted from the color separation synthesis prism unit P2 of the first embodiment. Also, the digital micromirror device DP3 corresponding to the prism P23 is omitted. The light source 1 is composed of a UHP lamp, and a color wheel (not shown) is arranged between the light source 1 and the illumination optical system 2.

The operation of the projector PJ provided with the optical unit PU having the above configuration is the same as that of the first embodiment after the illumination light L1 is incident on the incident surface 11. In the present embodiment, the red component of the illumination light L1 is incident on the digital micromirror device DP1, and the green component and the blue component of the illumination light L1 that has passed through the color wheel are incident on the digital micromirror device DP2. Alternately incident.

The vertical shift amount (shift amount in the Y direction) of the projection optical system LN was compared between the projector PJ using the optical unit PU of the present embodiment and the projector using the optical unit of the comparative example. In the comparative example, the entrance / exit surface 21b of the prism P21 of the color separation synthesis prism unit P2 is perpendicular to the optical axis AX2 of the color-synthesized ON light L2 as in the configuration shown in FIG. Further, in the comparative example, the projection side prism P3 is omitted. Therefore, the injection surface of the present embodiment coincides with the exit surface 32 of the projection side prism P3, and the injection surface of the comparative example coincides with the entrance / exit surface 21b of the prism P21. Other configurations of the comparative example were the same as those of the optical unit PU of the present embodiment. Further, the measurement of the vertical shift amount was performed in the same manner as in the case of the first embodiment. The distance D1 between the entrance / exit surface 41 and the exit surface 32 facing the digital micromirror device DP2 in the Z direction is 85 mm in the present embodiment and the comparative example. Further, the inclination angle of the illumination light reflecting surface 12 of the present embodiment and the comparative example with respect to the XZ plane is the same.

The vertical shift amount of the projection optical system LN of the projector PJ using the optical unit PU of the present embodiment was 30.5 mm, whereas the vertical shift amount of the projection optical system of the projector using the optical unit of the comparative example was 30.5 mm. It was 19.0 mm. Therefore, when the optical unit PU of the present embodiment is used, the vertical shift amount is 11.5 mm longer than that of the comparative example. Therefore, the vertical shift amount of the projection optical system LN of the projector PJ provided with the optical unit PU of the present embodiment can be made longer than in the case of the comparative example. In the present embodiment and the comparative example, the F number of the illumination light L1 was substantially the same, and the brightness of the projected image was also substantially the same.

The same effect as that of the first embodiment can be obtained in this embodiment as well. In addition, the number of expensive digital micromirror device DPs can be reduced as compared with the first embodiment.

<Fourth Embodiment>
Next, a fourth embodiment of the present invention will be described. 19 to 21 show a perspective view, a side view, and a side sectional view of the optical unit PU of the fourth embodiment. For convenience of explanation, the same parts as those in the first embodiment shown in FIGS. 1 to 9 are designated by the same reference numerals. In this embodiment, the configuration of the illumination light reflecting surface 12 is different from that in the first embodiment. Other parts are the same as those in the first embodiment.

The optical unit PU of the present embodiment includes a mirror member 80 (reflection member) having a mirror surface 80a formed on a glass substrate 81 instead of the internal total reflection prism P1. The illumination light reflecting surface 12 is formed by the mirror surface 80a. The mirror surface 80a is formed by coating a metal (for example, aluminum, silver, etc.) or a dielectric multilayer film on a glass substrate 81 polished with high precision by a vacuum vapor deposition apparatus.

In the projector PJ provided with the optical unit PU having the above configuration, the white illumination light L1 emitted from the illumination optical system 2 is incident on the mirror surface 80a of the mirror member 80. The illumination light L1 incident on the mirror surface 80a is reflected by the mirror surface 80a and then is incident on the color separation synthesis prism unit P2 from the input / output surface 21b. Subsequent operations of the projector PJ of this embodiment are the same as those of the first embodiment.

In the projector PJ using the optical unit PU of the present embodiment and the projector using the optical unit of the comparative example, the vertical shift amount (shift amount in the Y direction) of the projection optical system LN was compared. In the comparative example, the entrance / exit surface 21b of the prism P21 of the color separation synthesis prism unit P2 is perpendicular to the optical axis AX2 of the color-synthesized ON light L2 as in the configuration shown in FIG. Further, in the comparative example, the projection side prism P3 is omitted. Therefore, the injection surface of the present embodiment coincides with the exit surface 32 of the projection side prism P3, and the injection surface of the comparative example coincides with the entrance / exit surface 21b of the prism P21. Other configurations of the comparative example are the same as those of the optical unit PU of the present embodiment. Further, the measurement of the vertical shift amount is the same as in the case of the first embodiment. The distance D1 between the entrance / exit surface 41 and the exit surface 32 facing the digital micromirror device DP2 in the Z direction is 85 mm in the present embodiment and the comparative example. Further, the inclination angle of the illumination light reflecting surface 12 of the present embodiment and the comparative example with respect to the XZ plane is the same.

The vertical shift amount of the projection optical system LN of the projector PJ using the optical unit PU of the present embodiment was 30.4 mm, whereas the vertical shift amount of the projection optical system of the projector using the optical unit of the comparative example was 30.4 mm. It was 18.0 mm. Therefore, when the optical unit PU of the present embodiment is used, the vertical shift amount is 12.4 mm longer than that of the comparative example. Therefore, the vertical shift amount of the projection optical system LN of the projector PJ provided with the optical unit PU of the present embodiment can be made longer than in the case of the comparative example. In the present embodiment and the comparative example, the F number of the illumination light L1 was substantially the same, and the brightness of the projected image was also substantially the same.

Even if the illumination light reflecting surface 12 is formed by the mirror surface 80a of the mirror member 80 as in the present embodiment, the same effect as in the first embodiment can be obtained.

<Fifth Embodiment>
Next, a fifth embodiment of the present invention will be described. 22 to 25 show a perspective view, a top view, a side view, and a side sectional view of the optical unit PU of the fifth embodiment, respectively. For convenience of explanation, the same parts as those in the first embodiment shown in FIGS. 1 to 9 are designated by the same reference numerals. In this embodiment, the configuration of the digital micromirror device DP is different from that in the first embodiment. Other parts are the same as those in the first embodiment.

The incident surface 31 of the projection side prism P3 of the present embodiment includes a surface 31a that is close to and faces the entrance / exit surface 21b, and a surface 31b that is close to and faces the illumination light reflection surface 12. The surfaces 31a and 31b are adjacent to each other in the Y direction. Further, the end portion of the exit surface 21 on the internal total reflection prism P1 side is close to the illumination light reflection surface 12.

FIG. 26 shows a perspective view of the micromirror MR in the ON state and the OFF state of the digital micromirror device DP of the present embodiment. The digital micromirror device DP of the present embodiment is the first embodiment in which the micromirror MR rotates with respect to two orthogonal axes at a point where the micromirror MR rotates with respect to one rotation axis RA. It is different from the Digital Micromirror Device DP. Others are the same as those of the digital micromirror device DP of the first embodiment.

The angle β and the angle γ are each 12 °. As a result, the micromirror MR is turned on by -12 ° around the rotation axis RA from the reference state (the state in which the normal direction of the micromirror MR coincides with the Z direction), and is turned on by + 12 °. It moves and turns off. As a result, the digital micromirror device DP expresses ON / OFF by driving the micromirror MR with respect to the uniaxial rotation axis RA. Further, in the vicinity of the digital micromirror device DP, the optical axis AX1 of the illumination light L1, the optical axis AX2 of the ON light L2, and the optical axis AX3 of the OFF light L3 are arranged on the same plane.

In the projector PJ provided with the optical unit PU having the above configuration, when the white illumination light L1 is emitted from the illumination optical system 2, ON light L2 (projected light) is emitted from the optical unit PU as in the first embodiment. The light. As a result, the projected image is projected on the screen SC.

At this time, a part of the ON light L2 emitted from the inlet / output surface 21b of the prism P21 is incident on the internal total reflection prism P1 from the exit surface 13, is transmitted through the illumination light reflection surface 12, and then is incident on the projection side prism P3. After that, the ON light L2 is emitted from the exit surface 32 of the projection side prism P3.

In the first embodiment and the fifth embodiment, the optical axis AX1 of the incident light of the digital micromirror device DP and the optical axis AX2 of the ON light L2 (reflected light) reflected by the micromirror MR in the ON state are formed. The angles θ (not shown) are 34 ° and 24 °, respectively. That is, the angle θ of the fifth embodiment is smaller than the angle θ of the first embodiment. Therefore, within the same distance D1 as in the first embodiment, the ON light L2 and the illumination light L1 cannot be completely separated, and unlike the first embodiment, the ON light L2 has an illumination light reflecting surface 12 Is transparent.

On the other hand, the OFF light L3 (unnecessary light) reflected by the OFF state micromirror MR of the digital micromirror devices DP1, DP2, and DP3 is opposite to the incident surface 11 in the Y direction on the upper surfaces of the prisms P21, P22, and P23, respectively. It is discharged to the outside of the optical unit PU from the upper end surface) and the entrance / exit surface 21b.

The vertical shift amount (shift amount in the Y direction) of the projection optical system LN was compared between the projector PJ using the optical unit PU of the present embodiment and the projector using the optical unit of the comparative example. In the comparative example, the entrance / exit surface 21b of the prism P21 of the color separation synthesis prism unit P2 is perpendicular to the optical axis AX2 of the color-synthesized ON light L2, as in the configuration shown in FIG. The injection surface of the present embodiment and the comparative example coincides with the emission surface 32 of the projection side prism P3. Other configurations of the comparative example were the same as those of the optical unit PU of the present embodiment. Further, the measurement of the vertical shift amount is the same as in the case of the first embodiment. The distance D1 between the entrance / exit surface 41 and the exit surface 32 facing the digital micromirror device DP2 in the Z direction is 86 mm in the present embodiment and the comparative example. Further, the inclination angle of the illumination light reflecting surface 12 of the present embodiment and the comparative example with respect to the XZ plane is the same.

The vertical shift amount of the projection optical system LN of the projector PJ of the present embodiment was 38.2 mm, whereas the vertical shift amount of the projection optical system of the projector using the optical unit of the comparative example was 25.1 mm. .. Therefore, when the optical unit PU of the present embodiment is used, the vertical shift amount is 13.1 mm longer than that of the comparative example. Therefore, the vertical shift amount of the projection optical system LN of the projector PJ provided with the optical unit PU of the present embodiment can be made longer than in the case of the comparative example. In the present embodiment and the comparative example, the F number of the illumination light L1 was substantially the same, and the brightness of the projected image was also substantially the same.

The same effect as that of the first embodiment can be obtained in this embodiment as well.

<Sixth Embodiment>
Next, a sixth embodiment of the present invention will be described. 27 to 29 show a perspective view, a top view, and a side sectional view of the optical unit PU of the sixth embodiment, respectively. For convenience of explanation, the same parts as those in the fifth embodiment shown in FIGS. 22 to 26 are designated by the same reference numerals. In the present embodiment, the configuration of the color separation synthesis prism unit P2 is different from that in the fifth embodiment. Other parts are the same as those in the fifth embodiment.

The color separation synthesis prism unit P2 of the present embodiment is composed of prisms P21 and P22, and the prism P23 is omitted from the color separation synthesis prism unit P2 of the fifth embodiment. Similar to the third embodiment, the color-separated illumination light L1 is guided by the digital micromirror devices DP1 and DP2, and the color-synthesized ON light L2 is emitted from the exit surface 32. Further, also in the present embodiment, as in the fifth embodiment, the ON light L2 transmits the illumination light reflecting surface 12.

The vertical shift amount (shift amount in the Y direction) of the projection optical system LN was compared between the projector PJ using the optical unit PU of the present embodiment and the projector using the optical unit of the comparative example. In the comparative example, the entrance / exit surface 21b of the prism P21 of the color separation synthesis prism unit P2 is perpendicular to the optical axis AX2 of the color-synthesized ON light L2, as in the configuration shown in FIG. The injection surface of the present embodiment and the comparative example coincides with the emission surface 32 of the projection side prism P3. Other configurations of the comparative example were the same as those of the optical unit PU of the present embodiment. Further, the measurement of the vertical shift amount is the same as in the case of the first embodiment. The distance D1 between the entrance / exit surface 41 and the exit surface 32 facing the digital micromirror device DP2 in the Z direction is 86 mm in the present embodiment and the comparative example. Further, the inclination angle of the illumination light reflecting surface 12 of the present embodiment and the comparative example with respect to the XZ plane is the same.

The vertical shift amount of the projection optical system LN of the projector PJ using the optical unit PU of the present embodiment was 38.2 mm, whereas the vertical shift amount of the projection optical system of the projector using the optical unit of the comparative example was 38.2 mm. It was 25.1 mm. Therefore, when the optical unit PU of the present embodiment is used, the vertical shift amount is 13.1 mm longer than that of the comparative example. Therefore, the vertical shift amount of the projection optical system LN of the projector PJ provided with the optical unit PU of the present embodiment can be made longer than in the case of the comparative example. In the present embodiment and the comparative example, the F number of the illumination light L1 was substantially the same, and the brightness of the projected image was also substantially the same.

The same effect as that of the first embodiment can be obtained in this embodiment as well.

The present invention can be applied to an optical unit in which illumination light is incident and projected light reflected by a digital micromirror device is emitted, and a projector including the same.

PJ Projector LN Projection Optical System PU Optical Unit PM Light Absorbing Member DP, DP1, DP2, DP3 Digital Micromirror Device DS Image Display Surface MR Micro Mirror MS Pixel Reflection Surface CG Cover Glass P1 Internal Total Internal Reflection Prism (Reflective Member)
P2 color separation synthesis prism unit (prism unit)
P21-P23 prism (first prism)
P3 Projection side prism (second prism)
P4 OFF light separation prism (third prism)
L1 Illumination light L2 ON light (projected light)
L3 OFF light (unnecessary light)
AX optical axis AX1 optical axis of illumination light AX2 optical axis of projected light (ON light) AX3 optical axis of OFF light MS2 ON reflective surface MS3 OFF reflective surface SC screen DR, DB dichroic coated surface 1 light source 2 illumination optical system 3 control unit 4 Actuator 11 Incident surface 12 Illumination light reflection surface 13 Exit surface 21a, 22a, 23a Input / exit surface 21b Input / exit surface (first surface)
21t, 23t Total internal reflection surface 31 Incident surface 32 Exit surface (second surface)
51, 52 projection lens

In order to achieve the above object, the present invention emits illumination light toward a plurality of digital micromirror devices that generate projected light by modulating the illumination light on an image display surface according to an image signal, and at the same time, a plurality of illumination lights. In an optical unit that transmits and emits projected light generated by the digital micromirror device.
A prism unit formed by a plurality of first prisms and emitting projected light from a first surface formed on the first prism on the most emitting side,
A second prism arranged close to the first prism is provided.
The second prism is formed with a second surface on which the projected light is incident and a second surface B which is arranged perpendicular to the projected optical axis and emits the projected light.
The second prism has a wedge shape in which the second A plane and the second B plane are not parallel to each other.
The second A surface of the second prism is close to the first surface of the first prism, and is arranged so as to project in the direction in which the projected light is emitted from the first surface.
The projected light emitted from the first surface of the first prism is incident on the second A surface of the second prism, and is emitted from the second B surface of the second prism.
The second prism is characterized in that no illumination light is incident on it.
Further, the present invention emits illumination light toward a plurality of digital micromirror devices that generate projected light by modulating the illumination light according to an image signal on an image display surface, and the plurality of digital micromirrors. In an optical unit that transmits and emits projected light generated by a device
A reflective member having an illumination light reflecting surface that reflects illumination light,
A prism formed by a plurality of first prisms, in which the illumination light reflected by the illumination light reflecting surface is incident from the first surface formed on the first prism on the most emitting side, and the projected light is emitted from the first surface. With the unit
The reflective member is arranged so as to be close to the first surface and project from the first surface in the emission direction of the projected light.
The optical axis of the incident light of the illumination light incident on the illumination light reflecting surface and the optical axis of the projected light on the first surface are arranged on an optical axis plane which is the same plane.
When the outward first normal vector of the first surface is projected onto the optical axis plane, the first normal vector is arranged on the same side as the optical axis of the incident light with respect to the optical axis of the projected light. The first component vector projected onto the optical axis plane is characterized in that as it moves away from the first plane, it goes away from the optical axis of the projected light emitted from the first plane.

Claims (14)

Illumination light is emitted toward a plurality of digital micromirror devices that generate projected light by modulating the illumination light according to an image signal on an image display surface, and is generated by the plurality of digital micromirror devices. In an optical unit that transmits projected light and emits it
A reflective member having an illumination light reflecting surface that reflects illumination light,
A prism formed by a plurality of first prisms, in which the illumination light reflected by the illumination light reflecting surface is incident from the first surface formed on the first prism on the most emitting side, and the projected light is emitted from the first surface. With the unit
The reflective member is arranged so as to be close to the first surface and project from the first surface in the emission direction of the projected light.
The optical axis of the incident light of the illumination light incident on the illumination light reflecting surface and the optical axis of the projected light on the first surface are arranged on an optical axis plane which is the same plane.
When the outward first normal vector of the first surface is projected onto the optical axis plane, the first normal vector is arranged on the same side as the optical axis of the incident light with respect to the optical axis of the projected light. The first component vector projected onto the optical axis plane is an optical unit characterized in that as it moves away from the first plane, it goes away from the optical axis of the projected light emitted from the first plane. The optical unit according to claim 1, wherein at least one of the first prisms has a dichroic coated surface, and the prism unit performs color separation of illumination light and color synthesis of projected light. When the inward second normal vector of the facing surface of the first prism having the first surface facing the first surface is projected onto the optical axis plane, the incident light with respect to the optical axis of the projected light The second component vector, which is arranged on the same side as the optical axis of the above and projects the second normal vector onto the optical axis plane, is from the optical axis of the projected light emitted from the first surface as the distance from the facing surface increases. The optical unit according to claim 1 or 2, wherein the optical unit moves away from the optical unit. The optical unit according to any one of claims 1 to 3, wherein the illumination light reflecting surface is arranged outside the light flux of the projected light. The optical unit according to any one of claims 1 to 4, wherein the reflecting member is composed of an internal total reflection prism, and the illumination light reflecting surface is formed by the total reflection surface of the internal total reflection prism. .. The optical unit according to any one of claims 1 to 4, wherein the reflecting member is made of a mirror member, and the illumination light reflecting surface is formed by a mirror surface of the mirror member. An emission side optical member having a second surface on which the optical axis of the projected light is arranged in the normal direction and the projected light is emitted and arranged on the emission direction side of the projected light on the first surface is provided.
The end portion of the luminous flux of the illumination light on the illumination light reflecting surface on the prism unit side is arranged on the same side as the prism unit with respect to the second surface.
The method according to any one of claims 1 to 6, wherein the line of intersection between the illumination light reflecting surface and the second surface is arranged outside the luminous flux of the projected light on the second surface. Optical unit. The optics according to claim 7, wherein the injection-side optical member is a second prism that injects projected light from an incident surface facing the first surface and emits projected light from the second surface. unit. A plurality of mounting parts for mounting the digital micromirror device are provided.
Each of the mounting portions is arranged corresponding to each of the first prisms.
The digital micromirror device is characterized in that the inclination of each surface of a plurality of micromirrors rotating about a rotation axis is controlled to be ON / OFF and an image is formed by intensity-modulating the illumination light. The optical unit according to any one of claims 1 to 8. Each of the micromirrors has two axes of rotation that are orthogonal to each other.
The drive of each of the micromirrors is carried out with respect to the two rotation axes.
A plane that includes the optical axis of the projected light emitted from the first surface, passes through the center of the longitudinal direction of one of the digital micromirror devices, and is parallel to the lateral direction is orthogonal to the illumination light reflecting surface. The optical unit according to claim 9. A third prism is arranged between each of the digital micromirror devices and each of the first prisms.
The third prism transmits the projected light, which is the ON light reflected by the micromirror in the ON state of the digital micromirror device, and is reflected by the micromirror in the OFF state of the digital micromirror device. The optical unit according to claim 10, further comprising an OFF light reflecting surface that reflects unnecessary light that is the OFF light. The optical unit according to claim 11, wherein the optical unit satisfies the following conditional expression (1).
θ _OFF > sin ^-1 (1 / n)> θ _ON ... (1)
However,
θ _ON : The angle of incidence of the ON light ray having the largest incident angle on the OFF light reflecting surface on the OFF light reflecting surface,
θ _OFF : The angle of incidence of the OFF light ray having the smallest incident angle on the OFF light reflecting surface on the OFF light reflecting surface,
n: Refractive index of the third prism,
Is. The optical unit according to any one of claims 9 to 12, a light source, an illumination optical system that emits illumination light toward the reflection member of the optical unit, and a digital device attached to the attachment portion. A projector characterized by having a projection optical system that magnifies and projects an image displayed on a micromirror device onto a screen. The projection optical system is arranged so as to face the first surface of the optical unit, and the projection optical system is arranged so as to face the first surface of the optical unit.
The reflecting member is arranged below the optical axis of the projected light emitted from the first surface.
The projector according to claim 13, wherein the projection optical system can move in the vertical direction.

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