JP2008256770A - Scanner and projection type display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for increasing the scanning velocity of a scanner, with a simple configuration. <P>SOLUTION: In the scanner, a reflection/transmission element 30 configured so that a wire grid polarization plate 32 is held between a glass plate 31 and a 1/4 wavelength plate 33, is arranged between a movable mirror 20 and a light source apparatus 10 so that the wire grid polarization plate 32 is located on the side of a light source apparatus 10. The reflection/transmission element 30 transmits linear polarized light from the light source apparatus 10 (transmitted incident light P1), and first mirror reflected light P2 which is reflected on the mirror part 21 of the movable mirror 20 is reflected again to the mirror part 21 (element reflected light P3). The element reflected light P3 is reflected in the second time on the mirror part 21 (second mirror reflected light P4). The reflection/transmission element 30 transmits the second mirror reflected light P4. Laser light is reflected twice on the mirror part 21, and the emission angle becomes four times the angular deflection dθ of the mirror part 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a scanning device used in a projection system optical device such as a projector or a printer.

  Some projection optical systems use a scanning device for scanning light from a light source device such as laser light. As a scanning device, one that performs scanning by controlling the angle of reflection of light from a light source by controlling the angle of a reflecting plate such as a mirror is known (Patent Document 1, etc.).

JP2006-10715 JP 2006-18250 A JP-A-2005-352488 JP-A-2005-338413

  Incidentally, in a scanning device, generally, an improvement in scanning speed is required. In the conventional scanning device, there is a method of increasing the scanning speed by reducing the size of the reflecting plate and increasing the speed at which the angle of the reflecting plate is displaced. However, if the area of the reflection plate is reduced, the projection light may be diffracted at the outer peripheral end of the reflection surface, and the projection light may spread. For this reason, the conventional scanning device has a problem that the scanning speed cannot be increased sufficiently.

  An object of the present invention is to provide a technique capable of increasing the scanning speed of a scanning device with a simple configuration.

  An apparatus according to an aspect of the present invention is disposed between a light source that emits light, a movable reflector that can control an angle of a reflecting surface, and the light source and the movable reflector. A reflection / transmission element that selectively transmits or reflects light, and the reflection / transmission element transmits incident light from the light source toward the movable reflector, and transmits through the reflection / transmission element. The first reflected light reflected by the movable reflector is reflected again toward the movable reflector, and the first reflected light is reflected by the reflector. It is characterized by passing through.

  According to this configuration, the light from the light source is repeatedly reflected on the movable reflector between the reflection / transmission element and the movable reflector, and then emitted from the scanning device to the scanning object. Accordingly, the amount of displacement of the reflected light emission angle can be increased with respect to the amount of angular displacement of the movable reflector, and the scanning speed can be increased.

  The reflection / transmission element transmits a first linearly polarized light and reflects a second linearly polarized light having a polarization direction orthogonal to the first linearly polarized light, and more than the reflective polarizing plate A quarter-wave plate disposed on the side closer to the movable reflector, and the light source may emit the first linearly polarized light.

  According to this configuration, the polarizing plate of the reflection / transmission element transmits incident light from the light source toward the movable reflection plate. Moreover, the linearly polarized light that has been repeatedly transmitted through the quarter-wave plate and reflected by the movable reflector has its polarization component orthogonal to the original polarization component. Accordingly, the polarizing plate of the reflection / transmission element can reflect the first reflected light and transmit the second reflected light.

  The present invention can be realized in various forms, for example, a scanning device, a form of a projection optical system using the scanning device, specifically, a laser projector, a laser printer, an image, and the like. It can be realized in the form of a detection device or the like.

A. First embodiment:
FIG. 1A is a schematic diagram showing a configuration of a laser projector 100 as an embodiment of the present invention. The laser projector 100 includes a scanning device 110 that scans light and a control circuit 120 that controls the scanner device 110. The scanning device 110 includes the light source device 10 and the movable mirror 20. The light source device 10 is a light source capable of emitting laser light. The laser projector 100 may include an optical system lens (not shown) on the laser beam path.

  In the laser projector 100, the control circuit 120 controls the scanning device 110 in accordance with the image signal, so that the scanning device 110 scans the laser beam as indicated by a broken line arrow on the projection screen 200 and projects an image. Specifically, the laser light emitted from the light source device 10 is reflected by the movable mirror 20 and projected onto the projection screen 200. The laser beam scans on the projection screen 200 as the angle of the reflecting surface of the movable mirror 20 is displaced. The control circuit 120 emits laser light as image light representing an image at the scanning position by intensity-modulating the light source device 10 according to the image signal. The control circuit 120 also realizes two-dimensional scanning by controlling the operation of the scanning device 110 according to the periodic signal of the image signal.

  FIG. 1B is a schematic diagram for explaining the configuration of the movable mirror 20. The movable mirror 20 can be constituted by a biaxial MEMS scanner. Here, “MEMS” is an abbreviation for Micro Electro Mechanical Systems, and is a micro component in which mechanical component parts, sensors, actuators, electronic circuits, etc. are integrated on a single silicon substrate. Refers to the device.

  The movable mirror 20 includes a mirror portion 21 that reflects light from a light source, and an outer peripheral frame plate 22 provided on the outer periphery of the mirror portion 21. The mirror unit 21 preferably has an area sufficiently larger than the beam diameter of the laser light emitted from the light source device 10. This is because, when the beam diameter is larger than or substantially the same as the area of the mirror part 21, the laser light is diffracted at the outer periphery of the mirror part 21, and the projection light may spread. It is.

  The mirror portion 21 and the outer peripheral frame plate 22 are connected by a first rotating shaft 23 that can be driven to rotate about the Y axis in the drawing. That is, the mirror portion 21 rotates about the Y axis with respect to the outer peripheral frame plate 22 by the rotational drive of the first rotation shaft 23, and the angle of the reflection surface thereof is also displaced accordingly. On the other hand, the outer peripheral frame plate 22 is fixed in the scanning device 110 by a second rotating shaft 24 so as to be rotatable around the X axis in the drawing. By the rotation of the second rotation shaft 24, the entire movable mirror 20 rotates about the X axis, and the angle of the reflection surface of the mirror portion 21 is also displaced accordingly. In addition, the mirror part 21 and the outer periphery frame board 22 are good also as what obtains rotational driving force by electrostatic attraction.

  FIG. 2 is an explanatory diagram showing the configuration of the scanning device 110 and the path of the laser beam. The scanning device 110 includes a reflection / transmission element 30 between the light source device 10 and the movable mirror 20. The reflection / transmission element 30 is a plate-like element that selectively transmits the first linearly polarized light out of the incident light and selectively reflects the second linearly polarized light orthogonal thereto. It is an element. A specific configuration of the reflection / transmission element 30 will be described later.

  The laser beam P0 emitted from the light source device 10 passes through the reflection / transmission element 30 and reaches the movable mirror 20, as indicated by a broken line in the drawing. Hereinafter, the laser light transmitted through the reflection / transmission element 30 is referred to as “transmission incident light P1”. The laser light is incident on the outer surface of the reflection / transmission element 30 perpendicularly, but may be incident obliquely.

  The transmitted incident light P <b> 1 is reflected by the mirror unit 21 of the movable mirror 20. Hereinafter, this reflected light is referred to as “first mirror reflected light P2”. Here, it is assumed that the movable mirror 20 is in a state where the angle is displaced with respect to the reflection / transmission element 30 so as to have an inclination of an angle dθ around the second rotation shaft 24. Hereinafter, this angular displacement dθ is referred to as “mirror angular displacement dθ”. At this time, the angle formed by the transmitted incident light P1 and the first mirror reflected light P2 is twice the angle dθ.

  The first mirror reflected light P <b> 2 that reaches the reflection / transmission element 30 is reflected by the reflection / transmission element 30. Hereinafter, the light reflected by the reflective / transmissive element 30 is referred to as “element reflected light P3”. The element reflected light P3 is reflected again by the mirror unit 21. This reflected light is referred to as “second mirror reflected light P4”. At this time, the angle formed by the element reflected light P3 and the second mirror reflected light P4 is four times the mirror surface angular displacement dθ. As will be described later, since the second mirror reflected light is linearly polarized light that passes through the reflection / transmission element 30, it passes through the reflection / transmission element 30 and reaches the projection screen 200 (FIG. 1). .

  An arrow Pc indicated by a dotted line in FIG. 2 indicates a laser light emission direction when the reflection / transmission element 30 is omitted. In this case, the mirror part 21 reflects the laser beam only once. The emission angle of the laser beam at this time is twice the mirror surface angle displacement amount dθ of the mirror portion 21 (dθ × 2). Here, “laser beam emission angle” refers to an angle formed by the emission direction of the laser beam emitted from the light source device and the emission direction of the laser beam emitted from the scanning device.

  On the other hand, when the reflection / transmission element 30 is used, the laser beam is reflected twice by the mirror unit 21. Therefore, when the reflection / transmission element 30 is used, the emission angle of the laser light emitted from the scanning device 110 is doubled (dθ × 4) compared to the case where the reflection / transmission element 30 is not provided. That is, by using the reflection / transmission element 30, the amount of displacement of the laser beam emission angle associated with the angular displacement of the mirror portion 21 can be doubled.

  FIG. 3 is a schematic diagram showing the configuration of the reflection / transmission element 30. The reflection / transmission element 30 includes a glass plate 31, a wire grid polarization plate 32, and a quarter wavelength plate 33, and the wire grid polarization plate 32 is sandwiched between the glass plate 31 and the quarter wavelength plate 33. It is a configuration.

  The wire grid polarizing plate 32 has metal wires 32w arranged in parallel at equal intervals, and has a function of reflecting linearly polarized light parallel to the metal wires 32w and transmitting linearly polarized light perpendicular to the metal wires 32w. . The quarter-wave plate 33 can convert incident linearly polarized light into circularly polarized light, and conversely, can convert incident circularly polarized light into linearly polarized light.

  The outer surfaces of the glass plate 31 and the quarter wavelength plate 33 are respectively covered with an antireflection film 34. The antireflection film 34 can suppress a decrease in the transmittance of laser light due to reflection. The outer peripheral edge of the bonding surface of the glass plate 31, the wire grid polarizer 32 and the quarter wavelength plate 33 is covered with a sealing agent 35.

  FIG. 4 is an explanatory diagram for specifically explaining the process of laser light transmission and reflection in the reflection / transmission element 30. FIG. 4 shows an enlarged laser beam path in the scanning apparatus 110 similar to that in FIG. For convenience of explanation, the antireflection film 34 of the reflection / transmission element 30 is not shown, and a space is provided between the wire grid polarizer 32 and the quarter wavelength plate 33.

  The laser beam P0 from the light source device 10 is linearly polarized light having a polarization component that is transmitted through the wire grid polarizer 32. Therefore, the laser beam P 0 passes through the glass plate 31 and the wire grid polarizer 32 and reaches the quarter wavelength plate 33. The laser light transmitted through the quarter wavelength plate 33 is converted into circularly polarized light. That is, the transmitted incident light P1 described in FIG. 2 is circularly polarized light.

  In general, when circularly polarized light is reflected by a mirror, the rotation direction is reversed. Accordingly, the first mirror reflected light P2, which is the light reflected by the mirror portion 21 of the transmitted incident light P1, is circularly polarized light that rotates in reverse to the transmitted incident light P1. When the first mirror reflected light P2 passes through the quarter wavelength plate 33, it is converted again into linearly polarized light. At this time, the polarization component of the linearly polarized light P2a is the laser light P0 projected from the light source device 10. Are orthogonal polarization components. Therefore, the linearly polarized light P2a is reflected by the wire grid polarizing plate 32, and then converted again to circularly polarized light by the quarter wavelength plate 33, and becomes element reflected light P3. The rotation direction of the circularly polarized light of the element reflected light P3 is the same as that of the first mirror reflected light P2. The element reflected light P3 that has become circularly polarized light is reflected by the mirror unit 21, and its rotation direction is reversed. That is, the second mirror reflected light P4 is circularly polarized light in the same rotational direction as the transmitted incident light P1.

  The second mirror reflected light P4 is converted into linearly polarized light by the quarter wavelength plate 33. Since the polarization component at this time is the same as the laser light P0 emitted from the light source device 10, it passes through the wire grid polarizing plate 32 and is emitted outside the scanning device 110.

  Thus, according to the configuration of the present embodiment, the amount of displacement of the laser beam emission angle accompanying the angular displacement of the mirror portion 21 can be increased with a simple configuration. Therefore, the scanning speed of the laser beam of the scanning device can be improved.

B. Second embodiment:
FIG. 5 is a schematic view showing the configuration of a reflection / transmission element 30A used in the scanning apparatus according to the second embodiment of the present invention. FIG. 5 is almost the same as FIG. 3 except that a space 36 is provided between the wire grid polarizer 32 and the quarter-wave plate 33. The reflection / transmission element 30A is arranged and used in the scanning apparatus in the same manner as the reflection / transmission element 30 (FIG. 2) described in the first embodiment.

  Here, since the wire grid polarizing plate 32 is configured by arranging metal wires in parallel as described in the first embodiment, the surface thereof is generally in a state of low smoothness. Accordingly, as in the case of the reflective / transmissive element 30 (FIG. 3) of the first embodiment, it is difficult to configure the element with the wire grid polarizer 32 and the quarter-wave plate 33 in contact with each other. There is. However, since the space 36 is provided between the wire grid polarizer 32 and the quarter wavelength plate 33 in the reflection / transmission element 30A of the second embodiment, the smoothness of the wire grid polarizer 32 is improved. Even if it is low, it is easy to configure the element. In addition, it is preferable that the antireflection film 34 is also provided on the surface on the wire grid polarizing plate 32 side on the quarter wavelength plate 33 side. Even with such a configuration, substantially the same effect as in the first embodiment can be obtained.

C. Third embodiment:
FIG. 6 is a schematic diagram showing the configuration of a laser printer 300 as a third embodiment of the present invention. The laser printer 300 includes a scanning device 310 and a photosensitive drum 50. The scanning device 310 includes the light source device 10, the reflection / transmission element 30, and the polygon mirror 40.

  The scanning device 310 is obtained by replacing the movable mirror 20 with the polygon mirror 40 in the scanning device 110 (FIG. 2) described in the first embodiment. However, in this scanning device 310, unlike the scanning device 110 of the first embodiment, the light source device 10 is arranged so that the laser light is incident at an angle θ with respect to the normal of the incident surface of the reflection / transmission element 30. Has been.

  The polygon mirror 40 is a regular polygonal columnar polyhedron, and all of its side surfaces 41 constitute a mirror surface capable of reflecting laser light. Further, the polygon mirror 40 is disposed in a state where it can be rotationally driven around a central axis 42 penetrating the bottom surface thereof. The emission angle of the laser light from the light source device 10 is displaced by the rotational drive of the polygon mirror 40. That is, the scanning device 310 can scan the laser beam in a certain linear direction.

  The photosensitive drum 50 has a substantially cylindrical shape, and is arranged so as to be rotationally driven around a central axis 51 that penetrates the bottom surface thereof. The scanning device 310 scans the side surface of the rotating photosensitive drum 50 with laser light in a direction along the central axis 51. The photosensitive surface of the photosensitive drum 50 is in a state of static electricity on the entire surface before the laser beam is scanned, and the portion irradiated with the laser beam loses static electricity. The toner does not adhere to the part that has lost static electricity, and the toner adheres to the part that remains charged. The toner adhering to the photosensitive drum 50 is transferred and fixed on the printing paper to form a printed image.

  A laser beam path between the light source device 10 and the polygon mirror 40 may be provided with a lens such as a collimator lens or a cylindrical lens. Further, the laser beam path between the reflection / transmission element 30 and the photosensitive drum 50 may be provided with an fθ lens composed of a spherical lens and a toroidal lens.

  Also in the scanning device 310 of the third embodiment, similarly to the first embodiment, the laser light emitted from the light source device 10 is reflected twice on the reflecting surface 41 of the polygon mirror 40 by the reflecting / transmitting element 30. Is performed and ejected to the photosensitive drum 50. Therefore, the displacement amount of the laser beam emission angle accompanying the angular displacement amount dθ of the polygon mirror 40 is twice that, and the laser beam emission angle is 2θ + dθ × 4. That is, also in the configuration of the present embodiment, the scanning speed of the photosensitive drum 50 by the laser beam can be increased. In the configuration of this embodiment, the scanning distance of the laser beam can be increased. Therefore, the photosensitive drum 50 can be increased in size, and the corresponding printing paper size can be increased.

D. Fourth embodiment:
FIG. 7 is a schematic diagram showing the configuration of a scanning apparatus 400 as a fourth embodiment of the present invention. The scanning device 400 includes a reflection / transmission element 30, a movable mirror group 60, and a light source group 70. The reflection / transmission element 30 is the same as that described in the first embodiment.

  The movable mirror group 60 includes a plurality of movable mirrors 20 described in the first embodiment arranged in parallel or in a matrix. The movable mirrors 20 may be individually angularly displaced, or all the movable mirrors 20 may be simultaneously displaced by the same angle. The light source group 70 is configured by arranging the light source device 10 described in the first embodiment so that laser light can be emitted to each movable mirror 20 of the movable mirror group 60. According to the configuration of the fourth embodiment, a plurality of laser beams can be scanned simultaneously.

E. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

E1. Modification 1:
In the above embodiment, the scanning is performed by reflecting the laser beam by the movable mirror 20 or the polygon mirror 40 of the scanning device. However, the scanning may be performed using another movable reflective element. For example, it is possible to use a plane mirror that is angularly displaced only in the horizontal direction.

E2. Modification 2:
In the above-described embodiment, a laser light source is used as the light source device 10, but other light sources such as a light emitting diode may be used.

E3. Modification 3:
In the above embodiment, the reflection / transmission element 30 has the configuration including the wire grid polarizer 32 and the quarter wavelength plate 33, but may be configured by other members. That is, the reflection / transmission element transmits incident light directed from the light source to the movable reflection plate, and the transmission light that has passed through the reflection / transmission element is reflected again by the movable reflection plate. It suffices that the first reflection light is reflected toward the movable reflection plate and the second reflection light reflected by the reflection plate is transmitted.

Schematic which shows the structure of a laser projector. Explanatory drawing which shows the structure of a scanning apparatus, and the path | route of a laser beam. Schematic which shows the structure of the reflection / transmission element used for a scanning apparatus. Explanatory drawing which shows reflection and permeation | transmission of the laser beam by a reflection / transmission element. Schematic which shows the structure of the reflection / transmission element used for the scanning apparatus of 2nd Example. Schematic which shows the structure of the laser printer of 3rd Example. Schematic which shows the structure of the scanning apparatus of 4th Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Light source device 20 ... Movable mirror 21 ... Mirror part 22 ... Outer frame plate 23 ... 1st rotating shaft 24 ... 2nd rotating shaft 30, 30A ... Reflecting / transmitting element 31 ... Glass plate 32 ... Wire grid polarizing plate 32w ... Metal wire 34 ... Antireflection film 33 ... 1/4 wavelength plate 35 ... Sealing agent 36 ... Space 40 ... Polygon mirror 41 ... Reflecting surface (side surface)
42 ... central axis 50 ... photosensitive drum 51 ... central axis 60 ... movable mirror group 70 ... light source group 100 ... laser projector 110, 310, 400 ... scanning device 120 ... control circuit 200 ... projection screen 300 ... laser printer P, Pc ... Laser light emission direction P0 ... Laser light P1 ... Transmission incident light P2 ... First mirror reflected light P3 ... Element reflected light P4 ... Second mirror reflected light d [theta] ... Amount of angular displacement (mirror surface angular displacement)
θ ... Laser beam incident angle

Claims (3)

A scanning device for scanning light,
A light source that emits light;
A movable reflector that can control the angle of the reflecting surface;
A reflection / transmission element that is disposed between the light source and the movable reflector and selectively transmits or reflects incident light;
With
The reflective / transmissive element is
Transmits incident light from the light source toward the movable reflector,
The reflected light transmitted through the reflection / transmission element is reflected again by the movable reflection plate toward the movable reflection plate.
The scanning device according to claim 1, wherein the first reflected light transmits the second reflected light reflected by the reflecting plate. The scanning device according to claim 1,
The reflective / transmissive element is
A reflective polarizing plate that transmits the first linearly polarized light and reflects the second linearly polarized light having a polarization direction orthogonal to the first linearly polarized light;
A quarter-wave plate disposed closer to the movable reflector than the reflective polarizer;
Have
The scanning device in which the light source emits the first linearly polarized light. A projection display device that displays an image by projection light,
A scanning device according to claim 1 or 2,
A control circuit that projects and displays an image using image light scanned by the scanning device by controlling the light source and the movable reflector according to an image signal;
A projection display device comprising:

Images