JP2008209691A - Image forming apparatus, and image display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of achieving downsizing of an apparatus, and to provide an image display device. <P>SOLUTION: Light emitted from each light source device 3 is reflected by a mirror 20 and projected on a screen or the like through a projection lens 4 in a period where the mirror 20 in the selected line located on the corresponding column is in an on-state. Consequently, light (line light) by the amount of one line is projected in every selection period, when finishing selecting all the lines (y1 to ym), line light for the portion of m-lines, that is, for the portion of one screen is projected. This control is performed with high-speed frame frequency (e.g. 60 Hz) in the projector 1, the rays of line light are combined by an afterimage effect, then, viewed as a two-dimensional image composed of m×n pixels. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image based on an input image signal, and an image display apparatus using the image forming apparatus.

The projector includes a light source (such as an arc tube) that emits light, an electro-optic modulator that modulates light emitted from the light source according to an image signal, and forms an image, and projection optics that projects the formed image. System. As the electro-optic modulation device, a transmissive or reflective liquid crystal display device or a micro mirror type modulation device is generally used (for example, see Patent Document 1).
The liquid crystal display device forms an image in screen units by changing the polarization direction of the light source light for each of a large number of pixel electrodes (pixels) arranged in a matrix based on an input image signal. The micromirror type modulation device changes the reflection angle of the light source light for each of a large number of micromirrors (pixels) arranged in a matrix based on an input image signal, thereby forming an image in units of screens.

Japanese Patent Laid-Open No. 2005-115070

  However, in the projector as described above, a predetermined optical path length is ensured between the light source and the electro-optic modulation device, such as an integrator optical system for making the light irradiated to the electro-optic modulation device substantially uniform. Therefore, there is a limit to downsizing the equipment.

  The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus and an image display apparatus capable of downsizing the apparatus.

  The image forming apparatus of the present invention emits parallel light along a mirror type modulation device in which a plurality of movable mirrors are arranged in an attitude such that their reflecting surfaces are substantially on the same plane. A light source device and the plurality of mirrors are sequentially selected, and the selected mirrors are tilted based on an input image signal, and the parallel light is reflected in a predetermined angle direction by the tilted mirrors. And a mirror driving unit.

  According to this image forming apparatus, parallel light is sequentially reflected by a plurality of mirrors to form an image, so that the distribution of irradiation luminance is made uniform as compared with the case where light is applied to the entire image forming surface of the modulator. Therefore, the means (integrator optical system) can be omitted or simplified, and the apparatus can be downsized.

  In this image forming apparatus, the mirrors are arranged in a matrix composed of a plurality of rows and a plurality of columns, and the light source device emits the parallel light along one of the rows and the columns, and The mirror driving unit may select the mirror in the other unit of the row and the column.

  According to this image forming apparatus, since an image is formed by the mirrors arranged in a matrix, a two-dimensional image can be easily generated.

  In this image forming apparatus, it is preferable that the light source device emits strip-shaped parallel light that covers the plurality of mirrors arranged in a matrix.

  According to this image forming apparatus, since the light source device emits strip-shaped parallel light, it is not necessary to provide the number of light source devices corresponding to the columns, and the configuration can be simplified and the cost can be reduced. .

  In this image forming apparatus, a plurality of the parallel lights are emitted in parallel with each other, the mirror-type modulation device in which a plurality of the mirrors formed in a strip shape are arranged in parallel with each other, and substantially perpendicular to the longitudinal direction of the mirror. And a light source control unit that controls the light emission states of the plurality of light source devices in conjunction with the selection of the mirror based on an input image signal. It may be.

  According to this image forming apparatus, a plurality of parallel lights whose emission states are controlled based on image signals are reflected by a sequentially selected belt-shaped mirror to form an image, so that a two-dimensional image is easily generated. It becomes possible to do.

  In this image forming apparatus, the mirror inclined by the mirror driving unit may bend the optical path of the parallel light at an obtuse angle.

  According to this image forming apparatus, since the mirror is configured to bend the optical path of the parallel light at an obtuse angle, the tilt angle of the mirror can be reduced. For this reason, it becomes possible to easily manufacture the mirror type modulation device.

  An image display apparatus according to the present invention includes the above-described image forming apparatus.

  According to this image display device, it is possible to have the same effect as the above image forming device.

Hereinafter, as an embodiment of an image display device according to the present invention, a projector that modulates light emitted from a light source in accordance with an image signal and enlarges and projects the modulated light on an external screen or the like will be described. .
FIG. 1 is a diagram illustrating a schematic configuration of a projector according to the present embodiment, where (a) is a side view of the projector and (b) is a front view thereof.
As shown in FIGS. 1A and 1B, the projector 1 includes a mirror type modulation device 2, a plurality of light source devices 3, a projection lens 4 (not shown in FIG. 1B), And a drive circuit 40.

  The mirror type modulation device 2 is an electronic device in which a large number of movable mirrors 20 are formed on a semiconductor substrate 10, and each mirror 20 receives an image signal input from the outside as light emitted from the light source device 3. An image is formed by selective reflection according to the above. The mirror type modulation device 2 is arranged such that the mirror forming surface 2a on which the mirror 20 is formed is opposed to the projection lens 4, and is in a posture perpendicular to the + Z direction as the image projection direction, that is, the XY plane. It is fixed in a posture parallel to Each mirror 20 is in a matrix shape with m rows (y1 to ym) in the Y direction and n columns (x1 to xn) in the X direction, with the respective reflecting surfaces 20a facing the + Z direction and substantially in the same plane. The postures are individually controlled by a drive circuit 40 formed integrally with the mirror type modulation device 2.

  Above the mirror type modulation device 2 (−Y direction), n light source devices 3 are provided so as to correspond to the respective columns (x1 to xn) of the matrix. The light source device 3 includes a semiconductor laser as a light source, a collimator lens (none of which is shown) arranged on the emission surface side, and the like. The laser light emitted from the semiconductor laser is parallel light (spot parallel light). To the outside. A photodiode (not shown) for monitoring the laser beam is provided on the surface opposite to the emission surface of the semiconductor laser, and this is used to control the optical output of the semiconductor laser to be constant. Be able to. Each light source device 3 emits parallel light along each row of the mirror formation surface 2a in the + Y direction parallel to the mirror formation surface 2a.

  The drive circuit 40 tilts the posture of each mirror 20 according to the input image signal, and selectively reflects the parallel light emitted from the light source device 3 toward the projection lens 4. As a result, an image composed of m × n pixels corresponding to each mirror 20 is projected from the projection lens 4.

2 and 3 are diagrams showing a schematic configuration of the mirror type modulation device 2. FIGS. 2A and 3 are views of the mirror type modulation device 2 as viewed from the −X side, and FIG. These are figures which looked at the mirror type modulation apparatus 2 from the -Y side. In these drawings, only one mirror 20 is shown enlarged.
As shown in FIGS. 2A and 2B, the mirror type modulation device 2 includes an aluminum mirror 20 having a reflection surface 20 a that reflects light, and an actuator unit 30 that drives the mirror 20. These are formed on the semiconductor substrate 10 in which the drive circuit 40 is built. The actuator unit 30 includes an address electrode 31 formed on the semiconductor substrate 10 and a deflection element 32 that rotates on the address electrode 31. The address electrode 31 is an end of the deflection element 32 on the −Y side. It arrange | positions so that a part may be opposed. The mirror 20 and the deflection element 32 are integrally fixed by a column (post) 33.

  The deflection element 32 includes a drive electrode 34 that drives the deflection element 32 in cooperation with the address electrode 31. Further, as shown in FIG. 2B, the deflection element 32 is provided with a pillar 35 (in FIG. 2A) that protrudes from the semiconductor substrate 10 via a torsion spring 36 extending in the ± X direction. The torsion spring 36 is twisted so that the semiconductor substrate 10 can be rotated. The deflection element 32 is fixed to the torsion spring 36 at a position shifted to the −Y side from the center line Cz of the mirror 20 in the Z direction.

  Here, when a predetermined voltage is applied to the address electrode 31 of the actuator unit 30, an electrostatic attractive force acts between the address electrode 31 and the drive electrode 34. Accordingly, as shown in FIG. 3, the deflection element 32 is attracted to the address electrode 31, and together with the mirror 20, with the torsion spring 36 as an axis, the −Y side end is in the −Z direction and the + Y side end. The part rotates so as to move in the + Z direction. The mirror type modulation device 2 is provided with a stopper mechanism (not shown), and the mirror 20 is stable in a posture (hereinafter referred to as an ON state) inclined by 45 ° with respect to the original posture parallel to the XY plane. It is like that. In this state, the parallel light emitted from the light source device 3 in the + Y direction is reflected by the reflecting surface 20a of the mirror 20, and the traveling path is changed by 90 ° toward the projection lens 4 provided in the + Z direction. On the other hand, when the voltage applied to the address electrode 31 becomes 0, the deflecting element 32 and the mirror 20 are stabilized in a state parallel to the XY plane (hereinafter referred to as an off state) by the restoring force of the torsion spring 36. In this state, the parallel light emitted in the + Y direction from the light source device 3 passes on the surface of the mirror 20.

FIG. 4 is a block diagram showing a circuit configuration of the projector 1.
As shown in FIG. 4, the projector 1 includes a control unit 50, an operation unit 51, an image signal processing unit 52, a light source control, in addition to the mirror type modulation device 2, the light source device 3, the projection lens 4, and the drive circuit 40 described above. A portion 53 is provided.

  The control unit 50 includes a CPU (Central Processing Unit), a ROM that stores control programs and various data, a RAM (Random Access Memory) that is used for temporary storage when performing various data processing, and the like, and functions as a computer. It is. The control unit 50 performs overall control of the operation of the projector 1 by operating according to a control program stored in the ROM.

  The operation unit 51 includes a plurality of operation buttons for giving various instructions to the projector 1. When the user operates various operation buttons of the operation unit 51, the operation unit 51 corresponds to the operation content of the user. An operation signal is output to the control unit 50.

  The image signal processing unit 52 generates an image signal composed of gradation information (information indicating brightness) for each pixel (mirror 20) in units of frames (screen) based on image signals of various formats input from the outside. And output to the drive circuit 40.

  The light source control unit 53 controls turning on and off of the light source device 3.

  The drive circuit 40 corresponds to the mirror drive unit of the present invention, and controls the attitude of the mirror 20 in a time-sharing manner in units of one row (n) based on the image signal input from the image signal processing unit 52. Specifically, for each period (selection period) obtained by dividing the period for forming an image for one screen (frame period) by the number of rows m in the matrix (selection period), the row to be controlled (selected row) is sequentially switched and selected. The posture of each mirror 20 included in the row is controlled based on the gradation information of the corresponding pixel. The control of the mirror 20 by the drive circuit 40 is to turn on the mirror 20 for a time corresponding to the brightness represented by the gradation information, and when the gradation information represents the brightest state, it is selected. While most of the time during the period, the mirror 20 is turned on, while in the case of gradation information representing the darkest state, the off state is maintained throughout the selection period. Further, the mirrors 20 in the rows other than the control target (non-selected rows) are held in the off state until the next selection.

  The light emitted from each light source device 3 is reflected by this mirror 20 and projected from the projection lens 4 onto the screen SC while the mirror 20 of the selected row in the corresponding column is in the on state. As a result, light for one line (line light) is projected for each selection period, and when all the lines (y1 to ym) have been selected, line light for m lines, that is, one screen is projected. When the projector 1 performs this control at a high frame frequency (for example, 60 Hz), each line light is synthesized by the afterimage effect and visually recognized as a two-dimensional image composed of m × n pixels.

  Note that the mirror type modulation device 2, the light source device 3, and the drive circuit 40 in the present embodiment form an image corresponding to an input image signal, and thus correspond to the image forming apparatus of the present invention. In addition to this image forming apparatus, the projector 1 provided with the projection lens 4 as display means for displaying the formed image so as to be visible corresponds to the image display apparatus of the present invention.

As described above, according to the projector 1 of the present embodiment, the following effects can be obtained.
(1) According to the image forming apparatus and the projector 1 of the present embodiment, the parallel light emitted from the light source device 3 is sequentially reflected by the mirror type modulation device 2 in units of rows, thereby forming an image. Compared to the case of irradiating the entire image forming surface with light, means (integrator optical system) for uniforming the distribution of irradiation luminance can be omitted, and the apparatus can be miniaturized.

  In addition, you may change embodiment of this invention as follows.

(Modification 1)
In the embodiment, the light source device 3 emits parallel light along the columns, and the drive circuit 40 controls the posture of the mirror 20 in units of rows. And the drive circuit 40 may control the posture of the mirror 20 in units of rows.

(Modification 2)
In the embodiment, it is also possible to form a multicolor image. For example, if necessary, the row pitch (X direction pitch) of the mirror 20 is narrowed to increase the number of rows, and different color lights such as R (red) light, G (green) light, and B (blue) light are emitted. The light source devices 3 may be arranged periodically (for example, in order of RGBRGB ...) corresponding to each column. In addition, a light source device that can selectively emit different color lights is provided for each column, and the emission color is changed in a time-sharing manner, and mirror control corresponding to the emission color is performed in synchronization with the change of the emission color. May be. Alternatively, a mirror type modulation device 2 may be provided for each color light, and an image formed for each color light may be synthesized by a light synthesis means such as a cross dichroic prism.

(Modification 3)
In the embodiment, the gradation of the image is represented by controlling the time for which the mirror 20 is turned on. However, as illustrated in FIG. 5, the light source control unit 53 receives the image signal from the image signal processing unit 52. If the light source device 3 is controlled to be turned on and off according to the tone information, the tone can be represented by the lighting time of the light source device 3. Alternatively, if the light source control unit 53 is configured to receive the image signal from the image signal processing unit 52 and control the light emission luminance of the light source device 3 according to the gray level information, the light source control unit 53 represents the gray level by the level of the light emission luminance. It is also possible to make it. With the configuration as described above, when the dark color portion of the image is displayed, the light emission state of the light source device 3 is turned off or in a low luminance state, so that the power consumption of the light source device 3 can be suppressed. It becomes.
In this modification, the drive circuit 40 should always keep all the mirrors 20 in the selected row of the mirror type modulation device 2 on during the selection period based on the synchronization signal input from the light source control unit 53. The light source controller 53 may perform gradation control according to gradation information of each pixel included in the selected row in conjunction with the selection of the row.
Further, in this modification, since it is not necessary to change the posture of the mirror 20 for each column, as shown in FIG. y1 to ym) may be arranged in parallel, and a plurality of light source devices 3 may emit parallel light substantially perpendicular to the longitudinal direction (X direction) of each mirror 20 along the mirror forming surface 2a. is there. In this case, the drive circuit 40 may incline the mirrors 20 one by one and control the light emission states of the plurality of light source devices 3 in conjunction with the selection of the mirrors 20 based on the image signal.

(Modification 4)
In the above-described embodiment, the configuration in which the light source device 3 is provided for each column is shown. However, as shown in FIG. 7, the light emitted from at least one light source 3a is reflected by the collimator lens 3b and the mirror forming surface 2a. May be converted into strip-shaped parallel light (slit light) covering each row of the light, and emitted in the + Y direction along the mirror forming surface 2a. According to this configuration, it is not necessary to provide as many light source devices 3 as the number of columns, so that the configuration can be simplified and the cost can be reduced.

(Modification 5)
In the embodiment described above, the parallel light traveling along the mirror forming surface 2a is reflected in the + Z direction perpendicular to the mirror forming surface 2a by the mirror 20 tilted by 45 °, but is not limited to this configuration. For example, as shown in FIG. 8, it is possible to bend the optical path of the parallel light at an obtuse angle. According to this configuration, since the inclination angle of the mirror 20 can be smaller than 45 °, the mirror type modulation device 2 can be easily manufactured.

(Modification 6)
In the embodiment, the front projector 1 that projects an image from the projection lens 4 onto an external screen SC or the like is described as an example of the image display device. However, the rear projector 1 is integrally provided with a transmissive screen. The present invention can also be applied to a rear projector that projects an image on the side. Further, as shown in FIG. 9, if a configuration including a diffusing plate 5 functioning as a transmission screen instead of the projection lens 4, a direct-view display such as a liquid crystal display device or an organic EL (Electro Luminescence) display device is provided. Like a device, it is possible to realize a small image display device 100.

(Modification 7)
In the above embodiment, the light source device 3 including the semiconductor laser is used as the light source. However, the light source device 3 is not limited to the semiconductor laser as long as the light source device 3 can emit parallel light, and other light sources can be used. is there.

It is a figure which shows schematic structure of the projector which concerns on embodiment, (a) is a side view of a projector, (b) is the front view. It is a figure which shows schematic structure of a mirror type modulation apparatus, (a) is the figure seen from the -X side, (b) is the figure seen from the -Y side. It is a figure which shows the mirror type modulation apparatus of the state which the mirror inclined, and the figure seen from -X side. 1 is a block diagram showing a circuit configuration of a projector according to an embodiment. FIG. 10 is a block diagram showing a circuit configuration of a projector according to Modification 3. It is a figure which shows schematic structure of the projector which concerns on the modification 3, (a) is a side view of a projector, (b) is the front view. The front view of the projector which concerns on the modification 4. FIG. The side view of the projector which concerns on the modification 5. FIG. The side view of the image display apparatus which concerns on the modification 6. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Projector, 2 ... Mirror type | mold modulation apparatus, 2a ... Mirror formation surface, 3 ... Light source device, 4 ... Projection lens, 10 ... Semiconductor substrate, 20 ... Mirror, 20a ... Reflective surface, 30 ... Actuator part, 31 ... Address electrode 32 ... Deflection element 33 ... Post (post) 34 ... Drive electrode 35 ... Column 36 ... Torsion spring 40 ... Drive circuit 50 ... Control unit 51 ... Operation unit 52 ... Image signal processing unit 53 ... light source control unit.

Claims (6)

A mirror-type modulation device in which a plurality of movable mirrors are arranged in a posture such that their reflecting surfaces are substantially in the same plane;
A light source device that emits parallel light along the array of mirrors;
A mirror driving unit that sequentially selects the plurality of mirrors, tilts the selected mirrors based on an input image signal, and reflects the parallel light in a direction of a predetermined angle by the tilted mirrors; ,
An image forming apparatus comprising: The image forming apparatus according to claim 1,
The mirrors are arranged in a matrix composed of a plurality of rows and a plurality of columns, the light source device emits the parallel light along one of the rows and the columns, and the mirror driver An image forming apparatus, wherein the mirror is selected in the other unit of a row and a column. The image forming apparatus according to claim 2,
The image forming apparatus, wherein the light source device emits strip-shaped parallel light that covers the plurality of mirrors arranged in a matrix. The image forming apparatus according to claim 1,
The mirror type modulation device in which a plurality of the mirrors formed in a strip shape are arranged in parallel with each other;
A plurality of the light source devices provided so that the plurality of parallel lights are emitted in parallel to each other substantially perpendicular to the longitudinal direction of the mirror;
A light source controller that controls the light emission state of the plurality of light source devices in conjunction with the selection of the mirror, based on an input image signal;
An image forming apparatus comprising: The image forming apparatus according to any one of claims 1 to 4, wherein
The image forming apparatus, wherein the mirror tilted by the mirror driving unit bends the optical path of the parallel light at an obtuse angle.   An image display apparatus comprising the image forming apparatus according to claim 1.

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