JP2012068364A - Projection device - Google Patents

Abstract

A projection apparatus capable of automatically adjusting the color of a projected image in consideration of the color of a screen.
A reference image modulated by a reflective liquid crystal element (20) that has been initially adjusted is projected onto a projection plane (60) on which an image is actually projected using the light emitted from an illumination light source (10), and the projection plane is projected. Since the reference image projected on 60 is picked up by the image pickup device 50, the color balance of the illumination light source 10 is adjusted so that the balance of the actual color signal values output from the image pickup device 50 approaches a predetermined value. Regardless of the color, it is possible to automatically adjust the color of the image projected on it and to always appreciate the image of the same hue.
[Selection] Figure 3

Description

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

  A 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, if the screen is yellowed, the color of the image projected on the screen may change, and the person viewing the projected image may feel uncomfortable.

  On the other hand, Patent Document 1 discloses a projector that causes a video optical device to form a corrected image in which a fading with respect to a projected image is reduced based on a usage time.

JP 2008-039957 A

  However, with the technique described in Patent Document 1, it is possible to compensate for yellowing of an image as time-dependent fading that is predicted to occur according to the use time, but it is possible to compensate for coloring of the screen that is unrelated to the use time. There is a problem that you can not. In particular, in the case of a small portable projector, there is a demand for projecting an image regardless of the screen.

  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 color of a projected image in consideration of the color of a 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 that is movable in the optical axis direction and that projects the modulated light reflected by the reflective liquid crystal element;
An image sensor for receiving a color signal value of a projection image projected via the projection optical system;
A memory for storing a value relating to the color balance of the illumination light source,
In an initial state, when a reference image modulated by the reflective liquid crystal element is projected onto a reference screen using light emitted from the illumination light source, and the reference image projected on the reference screen is captured by the imaging element In addition, the color balance of the illumination light source is initially adjusted so that the balance of the initial color signal value output from the image sensor becomes a predetermined value,
A reference image modulated by the reflective liquid crystal element that has been initially adjusted is projected onto the use screen on which an image is actually projected using the light emitted from the illumination light source, and is projected onto the use screen. A reference image is picked up by the image pickup device, and the color balance of the illumination light source is adjusted so that the balance of actual color signal values output from the image pickup device approaches the predetermined value.

  According to the present invention, in the initial state, the reference image modulated by the reflective liquid crystal element is projected onto the reference screen using the light emitted from the illumination light source, and the reference image projected on the reference screen is Use screen on which the color balance of the illumination light source is initially adjusted and an image is actually projected so that the balance of the initial color signal values output from the image sensor becomes a predetermined value when imaged by the image sensor In addition, the reference image modulated by the reflective liquid crystal element that has been initially adjusted is projected using the light emitted from the illumination light source, and the reference image projected on the screen to be used is captured by the imaging element. Since the color balance of the illumination light source is adjusted so that the balance of the actual color signal values output from the image sensor approaches the predetermined value, the color of the screen used Regardless, performed automatically the color adjustment image projected thereto, it is possible to always watch the images of the same hue. “Color balance of illumination light source” means, for example, when the illumination light source has a red light emitting part, a blue light emitting part, and a green light emitting part, by changing the drive current value and the ratio of the duty ratio of each color light emitting part, Is to change. In this case, the “value relating to the color balance of the illumination light source” is a drive current value or a duty ratio. However, the present invention is not limited to this, and it is only necessary to change the light quantity ratio of the three colors.

  According to a second aspect of the present invention, in the invention according to the first aspect, the reference image is a uniform white image. However, it may be a uniform gray image.

  According to a third aspect of the present invention, in the invention according to the first or second aspect, the imaging device includes an RGB filter, and the color signal value includes an R value, a G value, and a B value. It is characterized by. The RGB filter is a filter composed of a red filter, a green filter, and a blue filter arranged on the object side of the pixels arranged in a matrix and arranged one by one for each pixel. For example, Japanese Patent Application Laid-Open No. 2002-176653 It is described in the publication. A signal output from the red filter pixel is an R value, a signal output from the green filter pixel is a G value, and a signal output from the blue filter pixel is a B value.

  According to a fourth aspect of the present invention, in the invention according to the third aspect, the predetermined value is such that an R value, a G value, and a B value are approximately 1: 1: 1. The color balance does not have to be strictly 1: 1: 1, and may have a practically acceptable error range, for example, variation within ± 3%. Therefore, it is set to about 1: 1: 1 including such a variation.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth 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.

  According to the present invention, it is possible to provide a projection apparatus that can automatically adjust the color of a projected image in consideration of the color of the 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 at the time of the shipping inspection of the projection apparatus which concerns on this Embodiment. It is a flowchart which shows the operation | movement outline at the time of actual use of the projection apparatus which concerns on this Embodiment.

  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, the blue LED, and the green LED emit light at a light quantity ratio of 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, and includes an RGB filter. 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 operations performed at the time of shipping inspection of the projection apparatus 1 according to the present embodiment. FIG. 4 is a flowchart showing an outline of operations performed when the projection apparatus 1 according to the present embodiment is actually used. Hereinafter, it demonstrates according to a flow.

  First, the operation at the time of shipping inspection will be described with reference to FIG. As preprocessing, the system is initialized in advance by turning on the power switch of the operation key unit 72. The system initialization includes, for example, energization of each unit and confirmation of an operable state (the presence or absence of a failure) and moving the projection optical system 30 to an optimum focus position.

  First, in step S101, a predetermined drive current (or duty ratio) is supplied from the illumination light source control unit 15 to the illumination light source 10, and a predetermined light amount (however, the light amount ratio of red, blue, and green is approximately 1: 1: 1). The three-color LED emits light with a color balance. Then, the illumination light is modulated by the reflective liquid crystal element 20 and the reference image (here, a uniform white image) stored in the memory 73 is projected onto the reference screen (here, the uniform white screen). .

  In step S102, the image sensor 50 captures a reference image projected on the reference screen, converts it into an image signal, and outputs it. The imaging element control unit and the imaging signal processing unit 55 process the imaging signal, and output an R value, a G value, and a B value as color signal values.

  In subsequent step S103, the control unit 70 determines whether or not the intensity of the R value, the G value, and the B value is approximately 1: 1: 1. If it is determined that the intensity of the R value, the G value, and the B value is not approximately 1: 1: 1, the control unit 70 determines in step S104 that the color balance of the initial color signal value approaches 1: 1: 1. Since the light amount balance (drive current ratio or duty ratio) of each color LED is changed, in step S102, the image sensor 50 captures an image projected on the reference screen, and a new R value, G value, and B value are obtained. Is output.

  On the other hand, if it is determined in step S103 that the intensity of the R value, the G value, and the B value is approximately 1: 1: 1, in step S105, the control unit 70 determines the light quantity balance of each color LED that is finally set. (Ratio of drive current ratio and duty ratio) or individual set values are stored in an EEPROM (not shown). The operation at the time of shipping inspection is thus completed.

  Next, with reference to FIG. 4, the operation | movement which projects an image on the projection surface 60 (use screen) actually used is demonstrated. First, in step S201, the system is initialized by turning on the power switch of the operation key unit 72. In addition to the above-described operation, the system initialization reads the light amount balance (ratio of drive current ratio and duty ratio) or individual set values of each color LED stored from the EEPROM, and illuminates the light source so as to achieve such light amount balance. Including setting 10.

  In a succeeding step S202, a predetermined drive current (or duty ratio) is supplied from the illumination light source control unit 15 to the illumination light source 10, and the three-color LEDs are caused to emit light with the light quantity balance. Then, the illumination light is modulated by the reflective liquid crystal element 20, and the reference image stored in the memory 73 is projected onto the projection surface 60.

  Further, in step S203, the image sensor 50 captures a reference image projected on the projection surface 60, converts it into an image signal, and outputs it. The imaging element control unit and the imaging signal processing unit 55 process the imaging signal, and output an R value, a G value, and a B value as color signal values.

  In subsequent step S204, the control unit 70 obtains average values of all the pixels of the R value, the G value, and the B value. For example, here, an 8-bit signal has an average value of R as a color signal = 220, an average value of G as a color signal = 220, and an average value of B as a color signal = 202. Then, the total average value AVE becomes 214. This is an example of an actual color signal value obtained when the projection surface 60 is yellowed.

  In step S205, the control unit 70 obtains the maximum value / minimum value of the R value, G value, and B value. In this example, the maximum value MAX is an average value of R and G values = 220, and the minimum value MIN is an average value of B values = 202. Further, in step S206, the control unit 70 determines whether (MAX-AVE) and (AVE-MIN) are within the range of (AVE ± 3%). In this example, since (MAX−AVE) = 6, + 2.8% with respect to AVE = 214, which is within + 3%. On the other hand, since (AVE-MIN) = 12, it is -5.6% with respect to AVE = 214, exceeding -3%.

  If it is determined that (MAX-AVE) and (AVE-MIN) do not fall within the range of (AVE ± 3%), in step S207, the control unit 70 determines (MAX-AVE) and (AVE-MIN). ) Are adjusted within the range of (AVE ± 3%), the light quantity balance (that is, color balance) of each color of the illumination light source 10 is adjusted. In the above example, red light and green light that are within + 3% from the average are not adjusted, but blue light that exceeds −3% from the average is adjusted. More specifically, the light amount or duty ratio (light emission time) of blue light is adjusted to 214/202 × 100 = 106%, but the light amount and duty ratio (light emission time) of red light and green light remain at 100%. By doing so, the balance of the actual color signal values approaches the predetermined value. In addition, you may adjust so that it may approach AVE about all the color lights.

  Thereafter, in step S203, the image sensor 50 captures a reference image projected on the reference projection plane, and outputs new R, G, and B values. In step S204, the control unit 70 outputs a color signal. Average values of R, G, and B are respectively obtained, and in step S205, the maximum value / minimum value of the R, G, and B values are obtained as color signals, and (MAX-AVE) is obtained in step S206. And (AVE-MIN) are determined to be within the range of (AVE ± 3%).

  On the other hand, when it is determined that (MAX-AVE) and (AVE-MIN) fall within the range of (AVE ± 3%), in step S208, the reflective liquid crystal element 20 erases the light amount adjustment image display. Then, the display is switched to the display of the projection image selected and read from the flash memory 78. Thereby, the projection image adjusted according to the color of the projection surface 60 is obtained on the projection surface 60 from the first projection.

  After that, if the power switch of the operation key unit 72 is OFF in step S209, the control unit 70 ends the projection. If not, the process returns to step S208 and continues to project the image.

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 (5)

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 that is movable in the optical axis direction and that projects the modulated light reflected by the reflective liquid crystal element;
An image sensor for receiving a color signal value of a projection image projected via the projection optical system;
A memory for storing a value relating to the color balance of the illumination light source,
In an initial state, when a reference image modulated by the reflective liquid crystal element is projected onto a reference screen using light emitted from the illumination light source, and the reference image projected on the reference screen is captured by the imaging element In addition, the color balance of the illumination light source is initially adjusted so that the balance of the initial color signal value output from the image sensor becomes a predetermined value,
A reference image modulated by the reflective liquid crystal element that has been initially adjusted is projected onto the use screen on which an image is actually projected using the light emitted from the illumination light source, and is projected onto the use screen. A projection apparatus, wherein a reference image is picked up by the image pickup device, and the color balance of the illumination light source is adjusted so that the balance of actual color signal values output from the image pickup device approaches the predetermined value.   The projection apparatus according to claim 1, wherein the reference image is a uniform white image.   3. The projection apparatus according to claim 1, wherein the imaging element includes an RGB filter, and the color signal value includes an R value, a G value, and a B value.   The projection apparatus according to claim 3, wherein the predetermined value is an R value, a G value, and a B value of approximately 1: 1: 1.   5. The image pickup device according to claim 1, wherein the image pickup device is disposed at a conjugate position 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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