JP4433930B2 - Optical device and projection display device - Google Patents

Description

  The present invention relates to an optical device and a projection display device used as an illumination device for a display device such as a liquid crystal projector.

A liquid crystal projector is a projector device using a spatial light modulator (hereinafter referred to as a liquid crystal panel) using a liquid crystal material.
In a liquid crystal projector, the liquid crystal panel itself does not emit light. Therefore, in a liquid crystal projector, a liquid crystal panel and a light source are combined to illuminate the liquid crystal panel with light.
Then, a video signal is applied to the liquid crystal panel, and an image formed by the liquid crystal panel is projected onto the screen by the projection lens.
With the liquid crystal projector having such a configuration, a small and efficient projector device can be realized.

By the way, some liquid crystal materials have a property (light application property) that changes the polarization of incident light according to an applied electric field.
Many liquid crystal panels perform light modulation using this property.
For this reason, light incident on the liquid crystal panel needs to be linearly polarized light in one direction (p-polarized light or s-polarized light). Then, the polarization direction of the light emitted from the liquid crystal panel is rotated according to the video signal applied to the liquid crystal panel.
Therefore, a polarizer is disposed as an analyzer on the emission side of the liquid crystal panel in order to perform light modulation.

In addition, as a liquid crystal projector employing a polarization conversion optical device, a projector having an aperture on / off mode switching has been proposed (for example, a patent) so that a display image that is more easily viewable can be obtained according to the environment where the screen is placed. Reference 1).
JP-A-8-106090

By the way, in a liquid crystal projector optical system that uses a polarization conversion optical system to improve the light source light utilization efficiency, the illumination light incident on the liquid crystal panel has a finite angular distribution according to the illumination design. Disturbs the contrast.
When the F number of the illumination optical system is increased, the incident angle to the liquid crystal panel becomes nearly vertical, so that the polarization characteristics work effectively and the contrast increases.
On the other hand, when the F number of the illumination optical system is increased, the optical path length becomes longer and the occupied volume of the illumination device increases. As a result, it has the disadvantages of increasing the set outer size and increasing the material cost.

Further, there is a limit to improving the performance of the projector having the aperture on / off mode switching.
Switch the lamp drive voltage to Lo mode during program playback with many dark scenes, such as movies, by switching the aperture on / off mode, and then turn the aperture on (eg, 20% shading rate) to achieve a black level. To improve contrast (modes such as Cinema Black Pro).
During viewing, the aperture is always on and part of the light is blocked. At the same time, the white level also decreases, so the brightness in bright scenes decreases accordingly. As a result of setting the shading ratio so that there is no sense of incongruity, the contrast is only improved by about 20% and no significant improvement can be expected.

  In general, an iris diaphragm uses a stepping motor because of its simple control method. However, if it is operated continuously and at a high speed according to the illuminance of the screen to be projected, it can be irritating during operation. Since it emits noise, it is unsuitable for use as a noise source in home projectors that require quietness.

  The present invention has been made in view of such circumstances, and its purpose is to suppress an increase in the set external size and an increase in material cost, and to improve the contrast. Further, the noise is small and quiet during the diaphragm operation. An object of the present invention is to provide an excellent optical device and a projection display device using the same.

In order to achieve the above object, an optical device according to a first aspect of the present invention includes a light source that emits illumination light, and an optical axis of the light source that equalizes illumination light emitted from the light source. A pair of first multi-lens array and second multi-lens array arranged with a predetermined interval so that the center of the optical axis coincides with its own center, and an aperture opening that opens and closes concentrically with respect to the optical axis includes a section have a variable aperture stop device that is disposed between the first multi-lens array and the second multi-lens array, the variable aperture stop device, the first multi-lens array and The first multi-lens array and the second multi-lens array are not adjacent to the second lens array, are equidistant from each of the first multi-lens array and the second multi-lens array, and the first multi-lens array and the second multi-lens array. Are arranged such that the opening centers of the central shaft and the throttle opening of the switch the lens array are matched, having the structure in which the opening ratio is not 0% when the throttle opening is fully closed.

According to a second aspect of the present invention, there is provided a projection type display apparatus comprising: a light modulating unit that modulates and emits incident illumination light based on input image information; and the illumination light from the light source to the light modulating unit. An illumination optical device to be incident and a projection optical system for projecting illumination light emitted from the light modulation means, and the illumination optical device includes a light source that emits illumination light, and illumination emitted from the light source equalizing the optical, optical axis center and its center first and a by matching the pair arranged at predetermined intervals in the multi-lens array and the second multi-lens of the light source on the optical axis of the light source an array, includes a throttle opening for opening and closing concentrically possess a variable aperture stop device that is disposed between the first multi-lens array and the second multi-lens array with respect to the optical axis The variable aperture stop device includes the first The multi-lens array and the second multi-lens array are not adjacent to the multi-lens array and are equidistant from each of the first multi-lens array and the second multi-lens array. Each central axis of the second multi-lens array and the aperture center of the aperture opening are arranged so as to coincide with each other, and the aperture ratio does not become 0% when the aperture aperture is fully closed. .

Preferably, the variable aperture stop device includes an actuator that drives the opening operation of the stop opening portion by an articulated link mechanism.

  Preferably, the actuator includes a galvanometer, and the galvanometer is disposed on the emission surface side with respect to the light source.

Preferably, the variable aperture stop device comprises a multiple aperture blades of the same shape in the iris opening, the plurality of diaphragm blades are synchronously opened and closed.

  Preferably, the surface of the diaphragm blade is gloss-plated, and a protrusion is formed in point contact with an overlapping region of the blade with an adjacent blade.

Preferably, it has a cooling structure for forcibly cooling at least the actuator of the variable aperture stop device.
Preferably, the apparatus has a cooling structure for forcibly cooling at least the actuator and the diaphragm blades of the variable aperture diaphragm apparatus.

  Preferably, the actuator is controlled to remove the operating stroke limit.

According to the present invention, the diaphragm device is disposed at a substantially equidistant position between the first multi-lens array and the second multi-lens array.
For example, when the level is high in accordance with the average luminance level of the video signal, the aperture device is continuously variable so that the aperture aperture ratio is large when the level is low and small so that the optimum aperture diameter is always obtained, and the illumination F number on the black side. Is controlled to be maximum.
Further, for example, the illumination F number is controlled to be minimum and the aperture ratio is 100% on the white side.
The structure is such that the aperture ratio does not become 0%, the surface of the diaphragm blades is brightly plated, and projections are provided on the blade surfaces so that point contact is possible in the region where the blades overlap each other. Actuators (for example, galvanometers) Is disposed on the exit surface side with respect to the light source, and thus the driving actuator is forcibly cooled. Therefore, the smooth opening / closing operation is realized, and malfunction of each part such as the drive actuator due to the influence of high heat is prevented.

According to the present invention, if the aperture device is installed at a predetermined location, the polarization efficiency can be improved without changing the optical design of the conventional illumination optical system, so that the image contrast projected on the screen can be greatly improved. .
The increase in the occupied volume of the illumination optical system by installing this diaphragm device is only in the vicinity of the diaphragm device mounting portion, and a significant improvement in performance can be achieved without impairing the merchantability.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a diagram showing in principle a preferred embodiment of a liquid crystal projector (projection type display device) employing an optical device according to the present invention.
FIG. 2 is a diagram showing a mounting form of a liquid crystal projector (projection display device) employing the optical device according to the present invention.

As shown in FIGS. 1 and 2, the liquid crystal projector 100 includes a light source unit 101, a collimator lens 102, an optical filter 103, a first multi-lens array (MLA) 104, an aperture device 105, a second MLA 106, and polarization conversion. Element 107, condenser lens 108, dichroic mirrors 110R, 110G, reflection mirrors 111, 112, 113, condenser lenses 120R, 120G, 120B, polarizing plates 121R, 121G, 121B, liquid crystal panels 122R, 122G, 122B, polarizing plate 123R , 123G, 123B, dichroic prism 124, projection optical system 125, relay lenses 130, 131, and the like.
The light source unit 101, the collimator lens 102, the optical filter 103, the first MLA 104, the diaphragm device 105, the second MLA 106, the polarization conversion element 107, and the condenser lens 108 constitute an illumination optical device 109.

The diaphragm 105, which is a feature of the present invention, is arranged in the middle of the optical path between the first MLA 105 and the second MLA 106, specifically, at a substantially central portion between the arrangement positions of the first MLA 105 and the second MLA 106. The variable aperture illumination stop device opens and closes concentrically with respect to the optical axis (solid line indicated as illumination light L).
Further, the diaphragm device 105 employs a galvanometer instead of a stepping motor as a driving device.
Hereinafter, the configuration and function of each component of the liquid crystal projector 100 will be described, then the specific configuration and function of the diaphragm device 105 will be described, and further the cooling structure of the liquid crystal projector will be described.

  The light source unit 101 includes a discharge lamp 101a and a reflective condenser mirror 101b. The light collected from the discharge lamp 101a is condensed by the reflective condenser mirror 101b and emitted toward the collimator lens 102.

  The collimator lens 102 emits the illumination light L emitted from the light source unit 101 toward the optical filter 103 as a parallel bundle.

  The optical filter 103 removes unnecessary light in the infrared region and the ultraviolet region that is emitted from the light source unit 101 and included in the illumination light L via the collimator lens 102.

The first MLA 104 divides the illumination light L from the light source unit 101 into a plurality of parts, and arranges these optical images in the vicinity of the light incident surface of the second MLA 106.
More specifically, in the first MLA 104, a plurality of lenses are arranged in an array, the illumination light L is divided into a plurality of images, the divided images are condensed, and a light spot of each divided image is determined in a predetermined manner. A layout is made at a position (near the light incident surface of the second MLA 106).

The aperture device 105 is arranged between the first MLA 104 and the second MLA 106 of the illumination optical device 109 and at substantially the intermediate position between them, and opens and closes concentrically with respect to the optical axis.
The diaphragm device 105 is continuously variable so that the diaphragm aperture ratio is large when the level is high and small when the level is high, and small when the level is high, and always the optimum diaphragm aperture.
The aperture device 105 is controlled so that the illumination F number is maximized on the black side.
The diaphragm device 105 is controlled so that the illumination F number is minimum and the diaphragm aperture ratio is 100% on the white side.
The aperture device 105 has a structure so that the aperture ratio is not 0%.
The diaphragm device 105 has six or more diaphragm blades having the same shape, and these diaphragm blades are opened and closed synchronously. The surface of the diaphragm blade has a bright plating finish, and projections are provided so that point contact can be made in a region where the blades overlap each other on the blade surface.
The diaphragm device 105 has a structure in which a drive actuator and a blade opening position detection sensor are heat-insulated, and the drive actuator is disposed on the light exit surface side with respect to the light source unit 101.
Further, the diaphragm device 105 has a structure for forcibly cooling the driving actuator, and has a structure for forcibly cooling the blades of the illumination diaphragm device and its periphery.
Further, the expansion device 105 is configured not to use the actuator operation stroke limit (mechanical end position).
A specific configuration and function of the diaphragm 105 having the above features will be described in detail later.

The second MLA 106 causes the split light source image obtained by the first MLA 104 to be incident on the polarization conversion element 107 so as to be incident as illumination light for the liquid crystal panels 122R, 122G, and 122B.
In the second MLA 106, a plurality of levels corresponding to a plurality of light spots collected by the first MLA 104 are arranged, and the divided images are superimposed and combined by the first MLA 104 by each lens and emitted.

  The polarization conversion element 107 includes, for example, a polarization beam splitter arranged in a strip shape and a phase difference plate provided intermittently corresponding to the polarization beam splitter. The p polarization component of the incident illumination light L is converted into an s polarization component. The illumination light having the same polarization direction and including many s-polarized light components as a whole is output.

  The condensing lens 108 condenses the illumination light L that has passed through the polarization conversion element 107 so as to be superimposed on the liquid crystal panels 122R, 122G, and 122B.

The dichroic mirror 110R is inclined 45 degrees with respect to the optical axis of the illumination light L having the polarization direction aligned after passing through the condenser lens 108, and the light LR in the red wavelength region of the illumination light L.
Only reflects toward the reflecting mirror 111 and transmits light LGB in other wavelength regions.

  The reflection mirror 111 is inclined 45 degrees with respect to the optical axis of the light LR reflected by the dichroic mirror 110R, and reflects the light LR toward the condenser lens 120R.

  The dichroic mirror 110G is inclined 45 degrees with respect to the optical axis of the light LGB transmitted through the dichroic mirror 110R, and only the light LG in the green wavelength region of the light LGB transmitted through the dichroic mirror 110R is transmitted to the condenser lens 120G. The light is reflected toward and transmits the light LB in the other wavelength region (blue wavelength region).

The relay lenses 130 and 131 are provided to re-image the blue light LB in the middle of the optical path because the optical path length from the dichroic mirror 110G of the light LB in the blue wavelength range to the liquid crystal panel 122B is relatively long.
The blue light LB that has passed through the dichroic mirror 110G passes through the relay lenses 130 and 131 and is reflected by the reflecting mirror 113 toward the condenser lens 120G.

Each of the condensing lenses 120R, 120G, 120B and the liquid crystal panels 122R, 122G, 122B are respectively arranged at predetermined positions with respect to the three side surfaces of the cubic dichroic prism 124.
Further, polarizing plates 121R, 121G, and 121B as polarizers and polarizing plates 123R, 123G, and 123B as analyzers are arranged in parallel on the incident side and the exit side of the liquid crystal panels 122R, 122G, and 122B, respectively. .
The polarizing plates 121R, 121G, and 121B are fixed to the emission side of the condenser lenses 120R, 120G, and 120B, respectively, and the polarizing plates 123R, 123G, and 123B are fixed to the three surfaces on the incident side of the dichroic prism 124, respectively. .

The liquid crystal panels 122R, 122G, and 122B modulate the intensities of the color lights LR, LG, and LB incident through the condenser lenses 120R, 120G, and 120B according to the applied video signals corresponding to the three primary colors of red, green, and blue.
That is, the color light LR having a predetermined polarization direction transmitted through the polarizing plates 121R, 121G, and 121B.
, LG, LB rotate the planes of polarization based on the video signals applied to the liquid crystal panels 122R, 122G, 122B.
A predetermined polarization component of the light subjected to the rotation of the polarization plane is transmitted through the polarizing plates 123R, 123G, and 123B and is incident on the dichroic prism 124.

The dichroic prism 124 is formed by, for example, joining a plurality of glass prisms, and interference filters 124a and 124b having predetermined optical characteristics are formed on the joining surfaces of the glass prisms.
The interference filter 124a reflects the blue light LB and transmits the red light LR and the green light LG. The interference filter 124b reflects the red light LR and transmits the green light LG and the blue light LB.
Therefore, each color light LR modulated by the liquid crystal panels 122R, 122G, 122B.
, LG and LB are combined and enter the projection optical system 125.

  For example, the projection optical system 125 projects the image light incident from the dichroic prism 124 onto a projection surface such as a screen. A color image is projected on the screen.

  Hereinafter, a specific configuration and function of the diaphragm device 105 will be described with reference to the drawings.

  FIG. 3 is a front view illustrating a configuration example of the diaphragm device according to the present embodiment. FIG. 4 is a perspective view showing a configuration example of the diaphragm device according to the present embodiment.

The aperture device 105 has a circular opening 201 at the center, a main body 200 formed of a heat-resistant resin such as PPS, and one surface of the main body 200 (incident illumination light L in front of the figure). A plurality of (6 in this embodiment) diaphragm blades 301 to 306, one end of which is rotatably attached to the outer peripheral edge portion on the surface) side, and the right central portion of the main body 200 in the drawing. A galvanometer 400 as a drive actuator attached to the attachment portion 202 on the light emitting surface side of the illumination light of the main body portion 200 and having the first swing arm 401 attached to the rotation shaft, and a circle of the attachment portion 202 of the main body portion 200 A hole formed in an arc shape and having one end attached to the first swing arm 401 on the incident surface side of the illumination light L of the main body 200 through a restricting portion 203 that restricts the movement range of the first swing arm 401. 2 shakes An arm 500.
Also, screw mounting pieces 204 and 205 are extended on the near side (incident side of the illumination light L) in the substantially central portion of the main body 200 in the drawing. When the diaphragm device 105 is inserted into a predetermined setting position, the screw mounting pieces 204 and 205 abut against the mounting housing as shown in FIG. 2 and can be screwed at that position. Further, the mounting pieces 204 and 205 are simply brought into contact with the mounting housing, so that the optical axis of the diaphragm device 105 and the optical axis of the optical device 109 substantially coincide with each other.

Near the other end of the diaphragm blades 301 to 306 (the end portion that can be positioned in the opening 201) has an overlapping area, and this area is formed so as to make point contact with the adjacent diaphragm blade. Protruding portions 301a to 306a are formed. As a result, the frictional resistance at the time of opening and closing is reduced, and a smooth opening and closing operation is realized.
In addition, guided shafts 301b to 306b are formed at one end portions of the diaphragm blades 301 to 306 (near the rotating shaft).

The second swing arm 500 includes a mounted portion 501 that is linear and has one end portion attached to the first swing arm 401, and a circular portion 502 that is circularly formed on the attached portion 501 from the other end side. Have. The second swing arm 500 is made of sheet metal, for example.
The circular portion 502 of the second swing arm 500 is formed with a circular opening 503 having a slightly larger diameter than the opening 201 of the main body 200, and the opening 503 and the opening 201 of the main body 200 are substantially aligned. In this way, it is attached to the main body 200 so as to be movable left and right in FIG. In this case, the diameter of the opening 503 is set so as not to block the opening 201 of the main body 200 even if the second swing arm 500 moves left and right.
A plurality of (six in this embodiment) long holes 504 to 509 are formed in the circular portion 502 along the circumferential direction. In these long holes 504 to 509, guided shafts 301 b formed at predetermined positions of the diaphragm blades 301 to 306, specifically, positions corresponding to the positions where the long holes 504 to 509 are formed in the state of being attached to the main body 200. ˜306b is locked.
Accordingly, the second swing arm 500 moves in the predetermined range from side to side in the drawing in accordance with the movement of the first swing arm 401 that rotates in the predetermined range as the galvanometer 400 is driven. The guided shafts 301b to 306b of 301 to 306 are fitted into the long holes 504 to 509 of the second swing arm 500, respectively, and the aperture blades 301 to 306 are opened and closed.

  The diaphragm device 105 having such a configuration has the following characteristics.

The illumination optical device 109 is disposed between the first MLA 104 and the second MLA 106 and substantially at an intermediate position therebetween.
Since the aperture opening shape is approximated to a circle, the aperture blades have the same shape, and have an aperture shape that approximates the most perfect circle at the minimum aperture diameter.
In the present embodiment, six are selected as the optimum number of aperture blades 301 to 306.

<Optimal number of aperture blades: 6>
If the number of blades is reduced, the aperture shape is not circular, and the uniformity of the illumination light quantity distribution on the liquid crystal panel is impaired.
The number of blades that can be approximated to a perfect circle with respect to the aperture diameter change of the diaphragm is selected. If the number exceeds six, the cost increases and the complexity of the system increases to compensate for the increased driving frictional resistance.
There is an effect of increasing the F number of the light beam condensed on the liquid crystal panel. Since the angle component of the incident light beam to each cell of the liquid crystal panel is reduced, the polarization efficiency is improved and it works effectively for improving the contrast.

The diaphragm device 105 is not installed adjacent to the first MLA 104 surface.
The first MLA 104 has a substantially conjugate relationship with the liquid crystal panel, and the uniformity of the in-plane illuminance of the light source light that has passed through the cells near the opening edge boundary of the diaphragm blades 301 to 306 forms an image on the liquid crystal panel. It is because it reduces.

Further, the diaphragm 105 is not installed adjacent to the second MLA 106 surface.
Since the light source light that has passed through each cell lens of the first MLA 104 is condensed on the corresponding cell lens of each second MLA surface, the illuminance distribution is discrete on the second MLA 106 surface. This is because in a single aperture aperture device centered on the optical axis of the lamp light source 101, the relationship between the aperture diameter and the aperture light quantity becomes a saw-shaped distribution, and the linearity deteriorates.
As described above, when an experiment was performed on the installation position of the diaphragm device 105, it was possible to obtain optimum uniformity and linearity of change in light amount when the distance was approximately equal from the first MLA 104 and the second MLA 106.

The diaphragm device 105 is designed and manufactured so that the outer shape and the aperture center of the diaphragm blades 301 to 306 coincide.
The aperture device 105 is installed and fixed between the first MLA 104 and the second MLA 106 so that the optical axis coincides with the central axis of the aperture device.
When the outer shape of the aperture device 105 is stored as a guide in the aperture device storage section on the illumination optical unit side, the optical axis center of the illumination light source unit 101 and the aperture center of the aperture device 105 coincide with each other without special positioning. ing.
A first swing arm 401 is fixed to the output shaft of the galvanometer 400 and swings as the galvanometer shaft swings.
A driving pin is fixed to the distal end portion of the first swing arm 401 and is engaged with the sliding guide groove (the restricting portion 203) of the second swing arm 500.
The second swing arm 500 is rotatable about the illumination optical axis along the rotation direction guide (the long holes 504 to 509) formed in the diaphragm main body 200 via the first swing arm 401. Guided.
On the second swing arm 500, engagement pins for synchronously opening and closing each blade of the diaphragm device are arranged and fixed on the circumference.
The output shaft of the galvanometer 400 and the diaphragm blade are mechanically connected. When a control voltage for obtaining a predetermined aperture opening is applied to the galvanometer 400, the galvanometer output shaft → first swing arm → second swing Displacement is transmitted in the order of arm → aperture blade, and an arbitrary aperture opening can be obtained by a control voltage value from the outside (in this case, the control side of the projector).

FIG. 5 is a circuit diagram showing an example of a galvanometer according to the present embodiment. FIG. 6 is a diagram showing control characteristics of the galvanometer according to the present embodiment.
As shown in FIG. 5, the galvanometer 400 includes a Hall element 410, a braking coil 411, a drive coil 412, operational amplifiers 413 to 415, resistance elements R1 to R19, and capacitors C1 to C5. The resistance elements R9 and R14 are variable resistance elements.

When a target aperture diameter position signal is input as a control signal for the galvanometer 400, a current flows through the drive coil 412, and the output shaft of the galvanometer rotates.
Along with the rotation of the shaft, a rotation position signal is output from the Hall element 410 installed in the galvanometer 400, and the output shaft stops when it is in equilibrium with the input control signal.
The brake coil 411 functions as a pickup sensor for the drive coil 412, and always feeds back to maintain an equilibrium state so as to act as a brake for sudden changes.
In order to eliminate individual differences (variations) in control voltage and swing angle mainly due to individual differences of the Hall elements 410 constituting the galvanometer 400, initialization is performed by a control microcomputer (microcomputer) (not shown) provided on the projector side when the power is turned on. I do.
The voltage at the open end and the closed end is sampled according to the output voltage of the Hall element 410, and the absolute amount of the output voltage to the open end and the close end of the diaphragm 105 is stored in a memory prepared on the control side.
From the maximum swing angle of the galvanometer 400 and the absolute amount of the output voltage, the relationship between the swing angle and the output voltage is known, and the absolute rotation angle of the output shaft can be positioned at an arbitrary angle.

Next, the reason why the galvanometer 400 is used as a drive source will be described.
The galvanometer 400 is capable of high-speed operation (about 50 to 70 ms from fully open to fully closed) with very little noise during operation and close to silence.
The aperture device 105 needs to position the blades 301 to 306 at the target position with a predetermined speed and accuracy.
In general, an iris diaphragm uses a simple stepping motor because of its simple control method. However, when it is operated continuously and at a high speed according to the illuminance of the projected screen, an irritating excitation noise is generated during operation. Therefore, a home projector that requires quietness becomes a noise source and is unsuitable for use.
On the other hand, the galvanometer 400 can suppress mechanical noise by being driven only by a connecting link without a gear serving as a noise source. The values of the currents flowing through the drive coil 412 and the braking coil 411 are optimized, the acceleration curves at the start and stop are optimized, and control is performed so as not to generate an impact sound due to mechanism inertia and backlash during acceleration / deceleration.
A mechanical collision noise is generated at the mechanical end position of the output shaft of the galvanometer 400. In actual control, it is used on the inner side of the end position which is the swing limit, and control is performed so as not to make a collision sound at the end position.

Next, the aperture diameter will be described.
FIG. 7 is a diagram illustrating a state in which the aperture stop according to the present embodiment is turned off (fully opened: 0% light shielding).
FIG. 8 is a diagram illustrating a state in which the aperture stop according to the present embodiment is on (50% light shielding: fixed mode).
FIG. 9 is a diagram illustrating a state in which the diaphragm device according to the present embodiment is turned on (fully closed: 80% light shielding).

The diaphragm device 105 of the present embodiment dynamically changes the aperture diameter of the diaphragm as shown in FIGS. 7 to 8 according to APL (average picture level) fluctuation.
The control system on the projector side has three kinds of setting modes of aperture on (ON) / off (OFF) / automatic (AUTO).
In the aperture-off mode, the light-shielding rate is 0% when the aperture is fully opened, the light-shielding rate is 50% when the aperture is ON, and the aperture is variably controlled so that the optimum aperture aperture is between 0 and 80% when the aperture is AUTO.

Here, a method for controlling the aperture ratio in the AUTO mode will be described.
In the liquid crystal panel drive circuit, in order to convert the input signal format into a screen size, video signal timing, resolution and the like corresponding to the output format, at least one frame is temporarily stored in the frame buffer and then output from the panel driver.
The microcomputer for controlling the diaphragm device takes in APL information included in one frame before output and recognizes the value.
Digital-to-analog (DA) conversion into a control signal for obtaining an optimum aperture opening based on the recognized APL information.
In synchronization with the image signal output to the liquid crystal panel, this control signal optimized from the APL information is applied to the diaphragm drive circuit to obtain an optimum diaphragm aperture.
The microcomputer for controlling the diaphragm device compares the APL fluctuations of the front and rear frames and recognizes the difference.
When the APL fluctuation between frames exceeds a preset threshold value, a rapid change of the aperture opening is suppressed by driving the aperture device by multiplying the control signal by a coefficient of 1 or less.
The human eye as a viewer is insensitive to the absolute value of the brightness against a sudden change in brightness. For example, generally when a sudden movement from a dark place to a bright place takes about 40 seconds for the eyes to get used to the surrounding brightness.
Based on these eye characteristics, a coefficient is calculated so that the viewer does not feel uncomfortable, and various parameters related to driving of the diaphragm device are determined.

The diaphragm device 105 of the present embodiment is limited to about 80% instead of 100%, even in the fully closed state.
The minimum aperture diameter is determined on the assumption that the uniformity is within the target standard and that system troubles such as smoke and ignition due to abnormal temperature rise on the blade surface are assumed.
As the aperture diameter decreases, the superposition effect of the so-called integrator optical system is reduced, and the non-uniformity of the light quantity distribution of each cell lens tends to appear on the liquid crystal panel.
Since the light source lamp is always lit, all of the light energy from the lamp light source transmitted through the first MLA 104 reaches the diaphragm blades 301 to 306 in a 100% light-shielded state, and the temperature rise due to heat absorption on the blade surface is significant. . Even if the forced cooling of the diaphragm device is stopped due to some system abnormality, a part of the light source light (illumination light L) is transmitted, so that it can be avoided from the danger of extremely high temperature.

  Next, heat resistance measures for the expansion device 105 in this embodiment will be described.

FIG. 10 is a diagram showing a cooling structure of the liquid crystal projector 100 according to the present embodiment.
As shown in FIG. 10, the cooling structure 600 includes a sirocco fan 601 dedicated to cooling the lamp ballast and diaphragm, a sirocco fan 602 dedicated to cooling the prism and diaphragm, a lamp ballast 603, a duct 604 for cooling the diaphragm, and an air outlet for prism cooling. 605, a galvanometer cooling air outlet 606, a diaphragm blade cooling air outlet 607, a second MLA cooling air outlet 608, and a polarization conversion element cooling air outlet 609.

As shown in FIG. 5, a Hall element 410 and a peripheral circuit board are built in the main body of the galvanometer 400. In order to prevent the detection accuracy from being deteriorated due to the temperature drift of the Hall element, the inside of the galvanometer 400 needs to be controlled to a temperature not exceeding 60 ° C.
The main body of the diaphragm 105 becomes high temperature (about 95 ° C.) due to absorption of light energy from the illumination light source.
In order to insulate the galvanometer 400 and the expansion device 105 main body, as described above, the expansion device main body 200 is made of a heat-resistant resin such as PPS.
The galvanometer 400 is fixed to the mounting portion 202 of the expansion device main body 200 with two resin bosses having the minimum diameter for heat insulation with the expansion device main body 200 that becomes high temperature, and the other portions use air as a heat insulation layer. The structure keeps a spatial distance.
Contact between the first oscillating arm 401 and the second oscillating arm 500 of the galvanometer 400 is limited to only the drive pin, and the heat conduction between them is minimized.
In order to prevent the temperature of the galvanometer 400 from rising, forced air cooling is performed by the galvanometer cooling air outlet 606. As shown in FIG. 10, this air cooling also serves as ballast cooling for driving the lamp, and therefore does not lead to an increase in cost.
By the above cooling measures, the surface temperatures of the galvanometer 400 and the Hall element 410 are reliably managed within 60 ° C.

The surface temperature of the diaphragm blades 301 to 306 increases to 300 to 400 ° C. in the case of no cooling.
The blade material is a metal such as stainless steel or SK material, which is subjected to bright chrome plating to increase reflectivity and suppress heat absorption.
If the blade is deformed due to the temperature difference between the front and back of the blade, the sliding resistance may increase and the operation may become unstable.
Dots are formed on the blade surface. The blades are point-contacted to suppress an increase in sliding resistance.
A diaphragm blade cooling air blowing port 607 for forced air cooling of the blades is provided in a portion of the illumination optical unit that houses the diaphragm device.
An air duct is arranged so that cooling air flows along the blades from the cooling blade cooling air outlet 607 for cooling, and forced cooling is performed. The blade has a thickness of about 0.1 mm, has a very small heat capacity, and a remarkable air cooling effect appears.
Since the duct for cooling the blades is also used for cooling the polarization changing element, the cost rise is only the cost of die processing at the time of forming the duct.

FIG. 11 is a view showing the temperature around the diaphragm device of the illumination optical device 109 according to this embodiment.
In the figure, UT indicates an illumination optical unit (housing).
In FIG. 11, the horizontal axis represents time and the vertical axis represents temperature.
In FIG. 11, the curve indicated by A is the temperature outside the galvanometer 400, the curve indicated by B is the exit / inside temperature at the UT surface, the curve indicated by C is the exit / outside temperature at the UT surface, and D The curve shown is the entrance / external temperature on the UT surface, the curve shown by E is the exit surface temperature on the blade surface, the curve shown by F is the exit side temperature of the atmosphere, and the curve shown by G is the entrance side of the atmosphere The curve indicated by H indicates the temperature on the incident side on the UT surface, and the curve indicated by I indicates the temperature on the output side on the UT surface.

  As can be seen from FIG. 11, the illumination optical device 109 of the liquid crystal projector 100 of the present embodiment can maintain the temperature of each part at 60 ° or less due to the cooling effect by the cooling device 600.

  As described above, according to the present embodiment, the diaphragm device 105 that opens and closes concentrically with respect to the optical axis is disposed between the first MLA 104 and the second MLA 106 of the illumination optical device 109 and at a substantially intermediate position between both. The aperture device 105 operates continuously and continuously so that the aperture aperture ratio is large when the level is high and small when the level is high, and small when the level is low, and always has the optimum aperture diameter, and the illumination F number on the black side. Is controlled so that the illumination F number is minimized and the aperture aperture ratio is 100% on the white side, and the aperture ratio is not 0%. The surface of the aperture blade is brightly plated. A structure in which a projection is provided so that point contact is possible in a region where the blades overlap each other on the blade surface, and the galvanometer 400 and the blade opening position detection sensor are heat-insulated. It has, since the galvanometer 400 is disposed on the exit surface side with respect to the light source unit 101 can obtain the following effects.

If the illumination stop device 105 according to the present embodiment is installed at a predetermined place, the polarization efficiency can be improved without changing the optical design of the conventional illumination optical system, so that the image contrast projected on the screen can be greatly improved. .
The increase in the occupied volume of the illumination optical system by installing this diaphragm device 105 is only in the vicinity of the diaphragm device mounting portion, and a significant performance improvement can be achieved without impairing the merchantability.
By controlling so that the illumination F number is maximized on the black side, a further increase in contrast can be expected.
Further, since the diaphragm device 105 has a structure for forcibly cooling the driving actuator and has a structure for forcibly cooling the blades of the illumination diaphragm device and its peripheral portion, each part of the drive actuator and the like malfunctions due to the influence of high heat. Can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing in principle an embodiment of a liquid crystal projector (projection display device) employing an optical device according to the present invention. It is a figure which shows the mounting form of the liquid crystal projector (projection type display apparatus) which employ | adopted the optical apparatus which concerns on this invention. It is a front view which shows the structural example of the aperture_diaphragm | restriction apparatus which concerns on this embodiment. It is a perspective view which shows the structural example of the aperture_diaphragm | restriction apparatus which concerns on this embodiment. It is a circuit diagram which shows an example of the galvanometer which concerns on this embodiment. It is a figure which shows the control characteristic of the galvanometer which concerns on this embodiment. It is a figure which shows the mode at the time of diaphragm | throttle-off (full opening: 0% light shielding) of the aperture_diaphragm | restriction apparatus which concerns on this embodiment. It is a figure which shows the mode at the time of the aperture stop (50% light-shielding: fixed mode) of the aperture_diaphragm | restriction apparatus which concerns on this embodiment. It is a figure which shows the mode at the time of diaphragm | throttle ON (full closing: 80% light shielding) of the aperture_diaphragm | restriction apparatus which concerns on this embodiment. It is a figure which shows the cooling structure of the liquid crystal projector which concerns on this embodiment. It is a figure which shows the temperature of the aperture device periphery of the illumination optical apparatus which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Liquid crystal projector, 101 ... Light source part, 102 ... Collimator lens, 103 ... Optical filter, 104 ... 1st multi lens array (MLA), 105 ... Aperture device, 106 ... 2nd MLA, 107 ... Polarization conversion element, DESCRIPTION OF SYMBOLS 108 ... Condensing lens, 109 ... Illumination optical apparatus, 110R, 110G ... Dichroic mirror, 111, 112, 113 ... Reflection mirror, 120R, 120G, 120B ... Condensing lens, 121R, 121G, 121B ... Polarizing plate, 122R, 122G 122B ... Liquid crystal panel, 123R, 123G, 123B ... Polarizing plate, 124 ... Dichroic prism, 125 ... Projection optical system, 130, 131 ... Relay lens, 200 ... Diaphragm body, 201 ... Opening, 202 ... Mounting part, 301 -306 ... diaphragm blades, 40 ... galvanometer, 401 ... First swing arm 500 ... second swing arm, the long holes 504 to 509.

Claims (16)

A light source that emits illumination light;
A pair of first multi-lenses that uniformize the illumination light emitted from the light source and are arranged on the optical axis of the light source so that the optical axis center of the light source coincides with the center of the light source at a predetermined interval. An array and a second multi-lens array;
Includes a throttle opening for opening and closing concentrically possess a variable aperture stop device that is disposed between the first multi-lens array and the second multi-lens array with respect to the optical axis,
The variable aperture stop device is
The first multi-lens array and the second multi-lens array are not adjacent to the first multi-lens array and the second lens array, and are equidistant from each of the first multi-lens array and the second multi-lens array. The lens array and the second multi-lens array are arranged so that the central axes of the lens array and the second multi-lens array coincide with the aperture center of the aperture opening,
An optical device having a structure in which the aperture ratio does not become 0% when the aperture opening is fully closed . The variable aperture stop device, optical device according to claim 1, further comprising an actuator which is driven by the diaphragm articulated linkage the opening operation of the opening. The optical device according to claim 2 , wherein the actuator includes a galvanometer, and the galvanometer is disposed on an emission surface side with respect to the light source. The variable aperture stop device, the iris opening comprises multiple aperture blades of the same shape, optical device according to any one of claims 1 to 3 in which the plurality of diaphragm blades are synchronously opened and closed. The optical device according to claim 4 , wherein the surface of the diaphragm blade is gloss-plated, and a protrusion that makes point contact with an overlapping region of the blade with an adjacent blade is formed. The optical apparatus according to claim 2, further comprising a cooling structure that forcibly cools at least the actuator of the variable aperture stop device. The optical apparatus according to claim 6, further comprising a cooling structure that forcibly cools at least the actuator and the diaphragm blades of the variable aperture diaphragm apparatus. The actuator is an optical device according to claim 2, wherein you operate to exclude working stroke limit. Light modulating means for modulating and emitting incident illumination light based on input image information;
An illumination optical device that causes illumination light from the light source to enter the light modulation unit;
A projection optical system for projecting illumination light emitted from the light modulation means,
The illumination optical device includes:
A light source that emits illumination light;
A pair of first multi-lenses that uniformize the illumination light emitted from the light source and are arranged on the optical axis of the light source so that the optical axis center of the light source coincides with the center of the light source at a predetermined interval. An array and a second multi-lens array;
Includes a throttle opening for opening and closing concentrically possess a variable aperture stop device that is disposed between the first multi-lens array and the second multi-lens array with respect to the optical axis,
The variable aperture stop device is
The first multi-lens array and the second multi-lens array are not adjacent to the first multi-lens array and the second lens array, and are equidistant from each of the first multi-lens array and the second multi-lens array. The lens array and the second multi-lens array are arranged so that the central axes of the lens array and the second multi-lens array coincide with the aperture center of the aperture opening,
A projection display device having a structure in which the aperture ratio does not become 0% when the aperture opening is fully closed . The projection display device according to claim 9 , wherein the variable aperture stop device includes an actuator that drives an opening operation of the stop opening portion by a connecting link mechanism. The projection display device according to claim 10 , wherein the actuator includes a galvanometer, and the galvanometer is disposed on an emission surface side with respect to the light source. The variable aperture stop device, the iris opening comprises multiple aperture blades of the same shape, projection display according to any one of claims 9 to 11 in which the plurality of diaphragm blades are synchronously opened and closed apparatus. The projection display device according to claim 12, wherein a surface of the diaphragm blade is gloss-plated, and a protrusion that makes point contact is formed in an overlapping region of the blade with an adjacent blade. The projection display device according to claim 10, further comprising a cooling structure that forcibly cools at least the actuator of the variable aperture stop device. The projection display device according to claim 14, further comprising a cooling structure that forcibly cools at least the actuator and the diaphragm blades of the variable aperture diaphragm device. The actuator is a projection type display apparatus according to claim 10, wherein you operate to exclude working stroke limit.

Images