JP2012068362A - Projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection device capable of automatically adjusting projection light quantity by the projection device alone, according to a state of a screen.SOLUTION: The whole of a projection surface 60 before projecting an image is imaged by an imaging element 50, and converted into an imaging signal to be outputted. The imaging signal is processed by an imaging element control unit and an imaging signal processing unit 55, and photoreception amount (a brightness value) is outputted. The brightness value is obtained by an image signal from the imaging element 50, and if that is, for example, a brightness value B, a control unit 70 calls out illumination light amount b corresponding to the brightness value B, and controls an illumination light source control unit 15 to make an illumination light source 10 emit light so as to be the illumination light amount b in a step S105.

Description

  The present invention relates to a projection apparatus that projects an image.

  The problem with the conventional projection apparatus is that the image quality of the projected image changes depending on the state of the screen on which the image is projected. More specifically, for example, when indoor illumination light is irradiated on the screen, the clarity of the projected image tends to decrease. On the other hand, when projecting an image on a screen in a completely dark room, if the projected image is too bright, it may be difficult to see.

  On the other hand, Patent Document 1 discloses a technique in which the amount of projection light is detected using a sensor provided in the vicinity of a screen, and an operator adjusts the amount of projection light according to the output of the sensor. If such a technique is used, an optimal projection light quantity can be set based on, for example, the brightness on the screen at the operator's discretion.

JP 2000-199929 A

  However, in the technique described in Patent Document 1, since the operator manually adjusts the projection light amount, there is a problem that it takes time for adjustment, and there are individual differences between workers, so that the projected image is always always in the same state. Can't be appreciated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a projection apparatus that can automatically adjust the amount of light projected by a single projection apparatus according to the state of the screen.

The projection apparatus according to claim 1 is provided.
An illumination light source;
An illumination control unit that controls the illuminance of light emitted from the illumination light source;
A reflective liquid crystal element that modulates and reflects light from the illumination light source based on an image signal;
A polarizing beam splitter that reflects light of a predetermined polarization direction;
A projection optical system capable of moving in the optical axis direction and projecting the modulated light reflected by the reflective liquid crystal element onto a projection surface;
An image sensor that images the projection plane;
The imaging device captures a projection surface before an image is projected, and the illumination control unit emits light emitted from the illumination light source so as to obtain a light amount corresponding to an image signal obtained from the imaging device. It is characterized by adjusting.

  According to the aspect of the invention, the image pickup device includes the image pickup device that picks up an image of the projection surface. Therefore, the image pickup device picks up the projection surface before the image is projected, and the illumination control unit is obtained from the image pickup device. The light emitted from the illumination light source can be adjusted so that the amount of light corresponds to the image signal, so that an appropriate projected image can be viewed regardless of the state of the screen.

  According to a second aspect of the present invention, in the invention of the first aspect, a plurality of combinations of the image signal obtained from the image sensor and the corresponding light quantity are stored in advance, One of them is selected, and the light emitted from the illumination light source is adjusted based on the selected combination. Thereby, the brightness of a projection image can be automatically adjusted according to a user preference.

  According to a third aspect of the present invention, there is provided the projection apparatus according to the first or second aspect, wherein the projection plane is divided into a plurality of areas and an image signal is output for each of the divided areas. The light emitted from the illumination light source is adjusted so that the amount of light corresponds to an image signal from a region where the value of the image signal is high. Since the region having the highest image signal value is the brightest region on the projection plane, an easy-to-see projection image can be provided by automatically adjusting the amount of light based on this region.

  According to a fourth aspect of the present invention, in the invention according to the first or second aspect, the imaging device divides the projection surface into a plurality of regions and outputs an image signal for each of the divided regions. The light emitted from the illumination light source is adjusted so that the amount of light corresponds to the average value of image signals from all regions. By automatically adjusting the light amount based on the average value, it is possible to provide a projection image that is easy to see as a whole.

  According to a fifth aspect of the present invention, in the invention according to the first or second aspect, the imaging device divides the projection surface into a plurality of regions and outputs an image signal for each of the divided regions. The light emitted from the illumination light source is adjusted so that the amount of light corresponds to a value obtained by weighting the image signal from each region. By automatically adjusting the light amount based on the weighted value, for example, it is possible to provide an easy-to-see projection image centered on the part of interest.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the imaging device is disposed at a position conjugate with the reflective liquid crystal device, and the projected image is projected. Imaging is performed through an optical system and the polarization beam splitter. Thus, the projection optical system can be shared as an imaging optical system, and the projection apparatus can be reduced in size. In such a configuration, it is preferable to move the projection optical system to the in-focus position for focusing before image projection.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the projection apparatus which can adjust a projection light quantity automatically with a projection apparatus single-piece | unit according to the state of a screen.

It is a schematic diagram which shows an example of arrangement | positioning structure of the main structural member of the projection apparatus which concerns on this Embodiment. It is a block diagram which shows the control relationship of the projection apparatus which concerns on this Embodiment. It is a flowchart which shows the operation | movement outline | summary of the projection apparatus which concerns on this Embodiment. It is a figure which shows the state which divided | segmented the projection surface 60, but the continuous line in a projection surface is a virtual line.

  Hereinafter, the present invention will be described with reference to embodiments, but the present invention is not limited thereto. FIG. 1 is a schematic diagram illustrating an example of an arrangement configuration of main components of the projection device 1 according to the present embodiment. Note that a holding member, a casing, a power source, and the like that hold the optical system and main components are omitted.

  As shown in FIG. 1, the projection apparatus 1 according to this embodiment includes an illumination light source 10, a condensing optical system 11, a polarization conversion element 12, a polarization beam splitter PBS, a reflective liquid crystal element 20, and a λ / 4 wavelength plate 41. , A projection optical system 30, an actuator 31, an optical system position detection unit 32, and an image sensor 50. Reference numeral 60 denotes a projection plane.

  As the illumination light source 10, for example, a three-color LED (for example, a red LED, a blue LED, and a green LED, but the emitted light of the white LED may be decomposed into three colors) is used. In the initial state, the red LED, blue LED, and green LED emit light at a light amount ratio of approximately 1: 1: 1. The condensing optical system 11 converts light emitted from the illumination light source 10 into substantially parallel light.

  The polarization conversion element 12 is an optical element that converts the incident light into specific polarization without reducing the amount of incident light. For example, as shown in the figure, a polarization separating film 12P that transmits P-polarized light, a λ / 2 wavelength plate 12a that converts P-polarized light transmitted through the polarization separating film 12P into S-polarized light, and S-polarized light reflected by the polarization separating film 12P. In this case, the light is reflected again and emitted.

  The polarization beam splitter PBS is obtained by bonding right-angle prisms having a reflection surface R formed on a slope to reflect light linearly polarized in a predetermined direction. Thereby, the light linearly polarized in the predetermined direction that has passed through the polarization conversion element 12 is reflected.

  The reflective liquid crystal element 20 is a micro display also called LCOS (Liquid crystal on silicon), and a liquid crystal is directly placed on the surface of a silicon chip. In the reflective liquid crystal element 20, a voltage corresponding to an image signal is applied to the liquid crystal layer from the drive control unit for each pixel, and modulation is performed by changing the arrangement of liquid crystal molecules, thereby displaying a desired image. The reflective liquid crystal element 20 displays a reverse image, and incident on the reflective liquid crystal element 20 while sequentially switching the emitted light of the red LED, blue LED, and green LED in a short time, thereby corresponding to the reverse image. Each color image is reflected while being shifted on the time axis, thereby forming a color image on the screen. Therefore, the color balance can be arbitrarily changed by individually adjusting the light emission amount or the light emission time by changing the drive current and duty ratio of the red LED, blue LED, and green LED (see Japanese Patent Application Laid-Open No. 2007-79402). .

  The projection optical system 30 has a function of forming an image illuminated by the illumination light source 10 and reflected from the reflective liquid crystal element 20 on the projection surface 60 and an image projected on the projection surface 60 on the image sensor. . The actuator 31 is, for example, a piezoelectric element, an electrostatic actuator, or the like, and moves the projection optical system 30 in the optical axis direction for focusing. The optical system position detection unit 32 detects the position of the projection optical system 30 moved by the actuator 31, and when the drive of the actuator 31 and the movement amount of the projection optical system 30 correspond to one to one. It may be omitted.

  The image sensor 50 is a solid-state image sensor such as a CCD (Charge Coupled Device) type image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) type image sensor. The image pickup surface of the image pickup element 50 is optically conjugate with the image display surface of the reflective liquid crystal element 20.

  Hereinafter, the operation of the projection apparatus 1 shown in FIG. 1 will be briefly described. In the following description, an example in which the polarization conversion element 12 is configured to emit S-polarized light as described above and the reflection surface R of the polarization beam splitter PBS is configured to reflect S-polarized light will be described.

  The light beam emitted from the illumination light source 10 is transmitted with S-polarized light by the polarization conversion element 12, enters the polarization beam splitter PBS, and is reflected by the reflection surface R in the direction of the reflective liquid crystal element 20. The element 20 is illuminated.

  The light incident on the reflective liquid crystal element 20 is reflected by the reflective liquid crystal element 20 and is incident again on the polarization beam splitter PBS. A liquid crystal layer (not shown) constituting the reflective liquid crystal element 20 functions as a phase plate when a voltage is applied. Therefore, of the light emitted from the reflective liquid crystal element 20, the light transmitted through the pixel area to which the voltage is applied is converted from S-polarized light to P-polarized light. On the other hand, among the light emitted from the reflective liquid crystal element 20, the light transmitted through the pixel region to which no voltage is applied remains as S-polarized light.

  Of the light reflected by the reflective liquid crystal element 20, P-polarized light is incident on the polarization beam splitter PBS again, passes through the reflection surface R, and is projected onto the projection surface 60 by the projection optical system 30. A λ / 4 wavelength plate 41 is disposed in front of the projection optical system 30, and P-polarized light is converted into circularly-polarized light and projected. The λ / 4 wavelength plate 41 may be disposed between the polarization beam splitter PBS and the projection optical system 30.

  Further, the reflected light of the image projected on the projection surface 60 is converted to S-polarized light by the λ / 4 wavelength plate 41 and passes through the projection optical system 30 in the reverse direction, and then enters the polarization beam splitter PBS. An image is formed on the image sensor 50 by being reflected by R.

  When the amount of light from the illumination light source 10 is sufficient, the polarization conversion element 12 may be omitted, and a polarization filter that transmits only S-polarized light may be disposed between the polarization beam splitter PBS and the imaging element 50. In view of improvement of light utilization efficiency and power saving, the configuration shown in FIG. 1 is preferable. In addition, for the illumination light source 10 and the polarization conversion element 12, a λ / 4 wavelength plate and a reflection surface are disposed on the illumination light source side, the polarization conversion element is used as a reflection type polarization film, and P-polarized light that does not pass through the reflection type polarization film is used. It may be configured to be recycled to be converted to S-polarized light and to pass through.

  FIG. 2 is a block diagram showing a control relationship of the projection apparatus 1 according to the present embodiment. As shown in FIG. 2, the projection apparatus 1 includes a control unit (CPU) 70 that comprehensively controls each unit. The control unit 70 reads out the operation program from a memory (ROM) 73 that stores a predetermined operation program, develops it in a work area in the control unit 70, and controls each unit.

  The control unit 70 controls the amount of light of the illumination light source 10 via the illumination light source control unit 15. The control unit 70 and the illumination light source control unit 15 constitute an illumination control unit. Further, the control unit 70 applies a voltage corresponding to the image signal to the reflective liquid crystal element 20 via the reflective liquid crystal element drive control unit 25 for each pixel to display an image, and from the optical system position detection unit 32. While adding information, the actuator 31 is driven and controlled via the actuator drive control unit 35 to move the projection optical system 30 in the optical axis direction.

  Based on the signal from the control unit 70, the imaging element control unit and the imaging signal processing unit 55 perform driving calculation of the imaging element 50 and detection calculation of the focus state of the projected image from data regarding the image obtained by the imaging element 50.

  Furthermore, an operation key unit 72 for user operation is connected to the control unit 70, and an operation switching operation (including a light amount adjustment operation described later) is performed by an input from the operation key unit 72. The external interface 74 is used for input / output of image data with an external device.

  The remote control control unit and communication unit 75 communicates with the remote control 76 and transmits input from the remote control 76 to the control unit 70. It is considered that a small projection apparatus such as the present application is often mounted on a small mobile device. In a small mobile device, there is a high possibility that the device itself vibrates when input with the operation key, and the projection image greatly shakes when vibrated. Therefore, the projection device 1 includes the remote control unit and the communication unit 75 and the remote control 76. It is preferable to be configured so that it can be operated without touching the main body.

  The image data to be projected is stored in the flash memory 78, and the selected image data is transmitted based on the signal from the control unit 70.

  The acceleration sensor 77 detects the movement of the projection device 1 and sends acceleration data to the control unit 70. Reference numeral 80 denotes a battery, and power is supplied to each unit via the power supply circuit 81.

  FIG. 3 is a flowchart showing an outline of the operation of the projection apparatus 1 according to the present embodiment. Hereinafter, it demonstrates according to a flow. It is assumed that the control unit 70 stores in advance in the memory 73 a table indicating the relationship between the screen brightness and the amount of illumination light (a plurality of combinations). Such a table is stored at the time of shipment from the factory, and the drive current amount or duty ratio of the reference light source (three color LEDs in this case) is set with respect to the reference screen (for example, a white screen) placed in the adjustment chamber. A white screen in which the brightness on the white screen is changed from “dark” to “bright” in five stages A to E (with the balance of each color light amount being maintained at approximately 1: 1: 1) for irradiation. The brightness of the white screen (image signal obtained from the image sensor) obtained by imaging with the solid element 50 and the reference image (for example, white one color) projected on the white screen changed in five stages A to E, respectively. Are stored in association with the illumination light amounts a to e of the LED light source 10 when the image becomes the most visible. In order to match the user's preference, the illumination light amounts a to e are set as the reference illumination light amount, and the illumination light amounts (a-1) to (e-1) that are one step darker than the illumination light amounts a to e are conversely bright one step. It is preferable that the light amounts (a + 1) to (e + 1) are associated with the brightness of the screens of the five stages A to E described above and stored together in a table.

  First, when the power switch of the operation key unit 72 is turned on, the system is initialized in step S101. System initialization includes, for example, energization of each part and confirmation of an operable state (presence or absence of failure), for example, driving a reflective liquid crystal element 20 to project a predetermined test chart, imaging this, and AF operation The projection optical system 30 is moved to the optimum focus position, but it is not necessary to move to the focus position.

  Next, in step S102, the imaging device 50 captures the entire projection surface 60 before projecting an image, converts it into an imaging signal, and outputs it. Therefore, the control unit 70 outputs the imaging signal to the imaging device control unit. And the imaging signal processing part 55 processes, and outputs light reception amount (here the brightness | luminance of a screen).

  In step S103, the control unit 70 confirms the user setting. Specifically, when the user designates the reference illumination light amount by the input from the operation key unit 72, the control unit 70 selects one of the illumination light amounts a to e corresponding to the screen luminances A to E. select. However, if the user has specified an illumination light amount that is darker than the reference, the user selects the illumination light amounts (a-1) to (e-1) corresponding to the screen luminances A to E, or from the reference. When a bright illumination light quantity is designated, the illumination light quantities (a + 1) to (e + 1) are selected corresponding to the screen luminances A to E. Hereinafter, it is assumed that the user designates the reference illumination light amount.

  If the actual screen brightness obtained in step S102 is B, for example, in step S104, the control unit 70 calls the illumination light amount b corresponding to the screen brightness B from the stored table, and in step S105, The illumination light source control unit 15 is controlled so as to be equivalent to the illumination light amount b, and the drive current amount or the duty ratio is changed (however, the balance of each color light amount is maintained at approximately 1: 1: 1), and the illumination light source 10 is changed. Make it emit light.

  Thereafter, in step S106, the reflective liquid crystal element 20 displays the projection image selected and read from the flash memory 78. As a result, a projection image with appropriate brightness can be obtained on the projection surface 60 from the initial projection.

  In subsequent step S107, if the power switch of the operation key unit 72 is OFF, the control unit 70 ends the projection. If not, the process returns to step S106 to continue projecting the image.

  Note that the image sensor 50 does not necessarily have to image the entire projection surface 60 in order to obtain an actual luminance value. For example, when the projection plane 60 is divided into five as shown in FIG. 4, it corresponds to the luminance value of the image signal from the region with the highest luminance value of the image signal (for example, the regions 60 b and 60 c that are easily affected by the indoor illumination light). Thus, the amount of projection light may be determined, or the image signal of each region is weighted (for example, the luminance value of the central region 60a is weighted to twice the luminance value of the surrounding region). The amount of projection light may be determined from the luminance value. An average value of luminance values of image signals in each region may be obtained, and the projection light quantity may be determined from the average value. Further, the user may specify the area. The number of divisions and the shape of the projection surface 60 are arbitrary. Furthermore, the number of steps of the luminance value in the table to be stored and the number of steps of lightening / darkening are arbitrary.

DESCRIPTION OF SYMBOLS 1 Projection apparatus 10 Illumination light source 11 Condensing optical system 12 Polarization conversion element 15 Illumination light source control part 20 Reflection type liquid crystal element 41 (lambda) / 4 wavelength plate 25 Reflection type liquid crystal element drive control part 30 Projection optical system 31 Actuator 32 Optical system position detection Unit 35 Actuator drive control unit 60 Projection surface 70 Control unit (CPU)
72 Operation Key Unit 73 Memory 74 External Interface 75 Remote Control Unit and Communication Unit 76 Remote Control 77 Acceleration Sensor 78 Flash Memory 80 Battery 81 Power Supply Circuit PBS Polarizing Beam Splitter R Reflecting Surface

Claims (6)

An illumination light source;
An illumination control unit that controls the illuminance of light emitted from the illumination light source;
A reflective liquid crystal element that modulates and reflects light from the illumination light source based on an image signal;
A polarizing beam splitter that reflects light of a predetermined polarization direction;
A projection optical system capable of moving in the optical axis direction and projecting the modulated light reflected by the reflective liquid crystal element onto a projection surface;
An image sensor that images the projection plane;
The imaging device captures a projection surface before an image is projected, and the illumination control unit emits light emitted from the illumination light source so as to obtain a light amount corresponding to an image signal obtained from the imaging device. A projection device characterized by adjusting.   A plurality of combinations are stored in advance for the image signal obtained from the image sensor and the light amount corresponding to the image signal, and one of the combinations is selected and irradiated from the illumination light source based on the selected combination. The projection apparatus according to claim 1, wherein the projection light is adjusted.   The imaging device divides the projection plane into a plurality of regions, and outputs an image signal for each of the divided regions. The image sensor has a light amount corresponding to an image signal from a region with the highest image signal value. The projection apparatus according to claim 1, wherein the light irradiated from the illumination light source is adjusted so as to be.   The imaging element is configured to divide the projection plane into a plurality of regions and output an image signal for each of the divided regions, so that the amount of light corresponds to the average value of the image signals from all regions. The projection apparatus according to claim 1, wherein the light irradiated from the illumination light source is adjusted.   The imaging device divides the projection plane into a plurality of regions and outputs an image signal for each of the divided regions, so that the amount of light corresponds to a weighted value of the image signal from each region. The projection apparatus according to claim 1, wherein the light emitted from the illumination light source is adjusted.   6. The image pickup device according to claim 1, wherein the image pickup device is disposed at a position conjugate with the reflective liquid crystal device, and picks up the projected image through the projection optical system and the polarization beam splitter. A projection apparatus according to claim 1.

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