JP2019168630A - Display unit and method for controlling display unit - Google Patents

Abstract

To display an image while maintaining good gradation even when a frame period of input image data varies.SOLUTION: A display unit comprises: an image processing unit 130 that outputs, to a projection unit 110, a driving signal for displaying an image based on image data developed in a frame memory 135; and an output pattern storage unit 1315 that stores a plurality of output patterns regulating the driving signal. The image processing unit 130 outputs the driving signal with an output period as a unit, the output period corresponding to the frame period of the image data and including an on period and an off period of the driving signal; the output pattern is a pattern regulating the timing to turn on or off the driving signal in the output period; the output pattern storage unit 1315 stores a plurality of output patterns different in length of the output period; and the image processing unit 130 selects any one of the plurality of output patterns on the basis of the difference between the frame period of the image data and the output period of the driving signal and outputs the driving signal.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a display device and a control method for the display device.

2. Description of the Related Art Conventionally, there is known an apparatus that performs gradation display of an image by dividing one frame into a plurality of sub periods and applying an on or off voltage to a display element in each sub period (see, for example, Patent Document 1). ).
Patent Document 1 discloses an electro-optical device that expresses the gradation of an image by setting a short period length for some of the plurality of subfields constituting one frame.

JP 2008-287063 A

However, the electro-optical device of Patent Document 1 is based on the premise that the frame period of input image data is constant, and when the frame period of the image data varies, the gradation of the display image may deteriorate. there were.
An object of the present invention is to display an image while maintaining good gradation even when the frame period of input image data varies.

In order to solve the above problems, the present invention provides a display unit for displaying an image, a drive signal for expanding an image based on input image data into an image memory for each frame, and displaying the image expanded in the image memory. An image processing unit that outputs the output signal to the display unit, and a storage unit that stores a plurality of output patterns that define the drive signal. The image processing unit transmits the drive signal to a frame period of the input image data. The output signal is output in units of an output period including an ON period and an OFF period of the drive signal, and the output pattern is a pattern that defines the ON and OFF timings of the drive signal in the output period, and A plurality of output patterns having different output periods, and the image processing unit outputs a frame period of the input image data and the output of the drive signal. Based on the difference between the periods, select one of a plurality of said output patterns, and outputs the driving signal according to the output pattern selected.
According to this configuration, one of a plurality of output patterns having different output periods is selected based on the difference between the frame period of the input image data and the output period of the drive signal. For this reason, by outputting a drive signal in accordance with the selected output pattern, an image can be displayed while maintaining good gradation even when the frame period of the input image data varies.

Further, in the present invention, the image processing unit is based on a difference between an input vertical synchronization signal that defines a frame period of the input image data and an output vertical synchronization signal that defines the output period of the drive signal. Select an output pattern.
According to this configuration, since the output pattern is selected based on the difference between the input vertical synchronization signal and the output vertical synchronization signal, even if a variation occurs in the frame period of the input image data, the optimum corresponding to the variation that has occurred Output patterns can be selected.

According to the present invention, the storage unit stores a first output pattern and a second output pattern having an output period longer than the first output pattern, and the image processing unit stores a frame period of the input image data. And when the calculated difference deviates from a preset setting range, the drive signal is output during the output period corresponding to the second output pattern. When the difference is within the set range, the drive signal is output in an output period corresponding to the first output pattern.
According to this configuration, either the first output pattern or the second output pattern is selected according to the difference between the frame period of the input image data and the output period of the drive signal, and the output period corresponding to the selected output pattern Can output a drive signal. Therefore, even if the frame period of the input image data varies, an optimal output pattern can be selected and an image can be displayed while maintaining good gradation.

According to the present invention, the storage unit includes a first output pattern, a second output pattern having a longer output period than the first output pattern, and a third output pattern having a shorter output period than the first output pattern. The image processing unit obtains a difference between a frame period of the input image data and an output period of the drive signal, and if the obtained difference is larger than a preset setting range, the second When the drive signal is output in the output period corresponding to the output pattern and the obtained difference is smaller than the set range, the drive signal is output in the output period corresponding to the third output pattern, and the obtained difference is If it is within the set range, the drive signal is output in an output period corresponding to the first output pattern.
According to this configuration, the first output pattern, the second output pattern, or the third output pattern is selected according to the difference between the frame period of the input image data and the output period of the drive signal, and the selected output pattern A drive signal can be output in an output period corresponding to the above. Therefore, even if the frame period of the input image data varies, an optimal output pattern can be selected and an image can be displayed while maintaining good gradation.

Further, according to the present invention, the storage unit stores an output pattern for each gradation value that can be expressed by the display unit, and each of the output patterns turns on the drive signal according to a corresponding gradation value. The image processing unit acquires an output pattern corresponding to a gradation value of the input image data, and outputs the drive signal according to the acquired output pattern.
According to this configuration, it is possible to output the drive signal according to the output pattern corresponding to the gradation value of the input image data, and display the image corresponding to the gradation value on the display unit.

According to the present invention, the drive signal has a plurality of sub-periods, and the image processing unit sets each of the plurality of sub-periods to an on period or an off period according to the selected output pattern.
According to this configuration, the drive signal can be switched between the on state and the off state for each sub period. For this reason, an image corresponding to the gradation value of the input image data can be displayed on the display unit.

Further, according to the present invention, the display unit includes a light modulation unit including a plurality of light modulation elements, and drives the plurality of light modulation elements according to the drive signal. A drive unit that changes the modulation state to control an on state in which the light emitted from the light source is transmitted and an off state in which the light emitted from the light source is not transmitted;
According to this configuration, it is possible to display the image corresponding to the gradation value of the input image data by controlling the modulation state of the light modulation element by the drive signal.

In order to solve the above problems, the present invention develops an image based on input image data in an image memory for each frame, and generates a drive signal for displaying the image developed in the image memory; The generated drive signal corresponds to a frame period of the input image data, and is output to a display unit in units of output periods including an ON period and an OFF period of the drive signal, and the display unit receives the input image data. A step of generating an image based on the output signal, and the step of generating the drive signal includes a plurality of output periods having different lengths based on a difference between a frame period of the input image data and an output period of the drive signal. The output signal is selected according to the selected output pattern, and the output pattern defines the drive signal. A pattern that is a pattern that defines the timing of the drive signal on and off in the output period.
According to this configuration, one of a plurality of output patterns having different output periods is selected based on the difference between the frame period of the input image data and the output period of the drive signal. For this reason, by outputting a drive signal in accordance with the selected output pattern, an image can be displayed while maintaining good gradation even when the frame period of the input image data varies.

The block diagram which shows the structure of a projector. The block diagram which shows the structure of an image process part. The figure which shows the input Vsync, the output Vsync, and a drive signal. The figure which shows the input Vsync, the output Vsync, and a drive signal. The figure which shows the input Vsync, the output Vsync, and a drive signal. The figure which shows the input Vsync, the output Vsync, and a drive signal. The figure which shows the input Vsync, the output Vsync, and a drive signal. The flowchart which shows operation | movement of an image process part.

[1. Projector configuration]
FIG. 1 is a block diagram illustrating a configuration of a projector 100 that operates as a display device. First, the configuration of the projector 100 will be described with reference to FIG.

  The projector 100 includes an image interface unit (hereinafter, the interface is abbreviated as I / F) 105. The image I / F unit 105 includes a connector, an interface circuit, and the like, and is wired to an image source device 200 that transmits image data for display to the projector 100. The image source device 200 is a video playback device such as a DVD (Digital Versatile Disk) player, a personal computer, or the like.

  The image I / F unit 105 receives an image signal from the image source device 200 and acquires image data and a synchronization signal included in the received image signal. The image data is data indicating the gradation of each of a plurality of pixels for each color component, and corresponds to “input image data” of the present invention. The synchronization signal is a signal indicating synchronization timing, and includes a horizontal synchronization signal and a vertical synchronization signal. The image I / F unit 105 outputs the synchronization signal to the control unit 150 and the image processing unit 130, and outputs the image data to the image processing unit 130. Hereinafter, the horizontal synchronization signal and the vertical synchronization signal acquired from the image signal by the image I / F unit 105 are hereinafter referred to as an input synchronization signal. The vertical synchronization signal acquired from the image signal received by the image I / F unit 105 from the image source device 200 is referred to as an input vertical synchronization signal (hereinafter referred to as input Vsync). The control unit 150 determines processing execution timing based on the input synchronization signal, and controls each unit of the projector 100. The image processing unit 130 generates a drive signal for driving the light modulation unit 112 described later based on the input synchronization signal and the image data.

  The projector 100 includes a projection unit 110, and projects an image based on the image data onto the screen SC by the projection unit 110. Image data projected by the projector 100 onto the screen SC may be data stored in a memory 155 described later, or data received by the image I / F unit 105. The image data may be image data transmitted from an external device by wireless communication and received by a wireless communication unit 127 described later.

  The projection unit 110 includes a light source unit 111, a light modulation unit 112, a projection optical system 113, a light source drive unit 116, and a light modulation unit drive unit 117. The projection unit 110 operates as the “display unit” of the present invention.

  The light source unit 111 is configured by a lamp such as a halogen lamp, a xenon lamp, or an ultra-high pressure mercury lamp, or a solid light source such as an LED (Light Emitting Diode) or a laser light source. The light source unit 111 emits light by the electric power supplied from the light source driving unit 116. The light source driving unit 116 supplies a driving current and a pulse to the light source unit 111. The light source driving unit 116 may have a function of adjusting the luminance of the light source unit 111 under the control of the control unit 150.

  The light modulation unit 112 modulates the light emitted from the light source unit 111 by the light modulation element 115 to generate image light. The image term generated by the light modulation unit 112 is incident on the projection optical system 113. In the present embodiment, a case where the light modulation unit 112 includes a transmissive liquid crystal panel as the light modulation element 115 will be described as an example. However, the light modulation element 115 is not limited to the transmissive liquid crystal panel. It may be a reflective liquid crystal panel, DMD (digital mirror device), or the like.

  A synchronization signal and a drive signal are input from the image processing unit 130 to the light modulation unit drive unit 117. The light modulation unit driving unit 117 drives the light modulation unit 112 based on the synchronization signal or the drive signal input from the image processing unit 130, and the light modulation element 115 of the light modulation unit 112 has an image in frame (screen) units. To draw. The light emitted from the light source unit 111 is modulated by an image drawn under the control of the light modulation unit driving unit 117, and the modulated light is synthesized by a synthesis optical system such as a cross dichroic prism and emitted to the projection optical system 113. .

  The projection optical system 113 includes a lens and a mirror that image the light modulated by the light modulation unit 112 on the screen SC. The projection optical system 113 may include various lenses or lens groups such as a zoom lens and a focus lens.

  The projector 100 includes an image processing unit 130, an input / output I / F unit 125, a wireless communication unit 127, and a control unit 150. These units are connected to each other via a bus 107 so that they can communicate with each other. As will be described later, a remote control light receiving unit 121 and an operation panel 123 are connected to the input / output I / F unit 125, and a frame memory 135 is connected to the image processing unit 130. The frame memory 135 corresponds to the “image memory” of the present invention.

  The image processing unit 130 develops the image data input from the image I / F unit 105 in the frame memory 135. The image processing unit 130 performs various types of image processing on the image data expanded in the frame memory 135. The image processing unit 130 generates a drive signal for driving the light modulation unit driving unit 117 based on the processed image data, and outputs the generated drive signal to the light modulation unit driving unit 117.

  The image processing unit 130 and the frame memory 135 are configured by an integrated circuit (IC) or other digital circuits. An analog circuit may be included in part of the configuration of the image processing unit 130 and the frame memory 135. The integrated circuit includes an LSI, an application specific integrated circuit (ASIC), and a PLD. The PLD includes, for example, an FPGA. Each of the above sections may be a combination of a processor and an integrated circuit. The combination is called, for example, a microcontroller (MCU), an SoC (System-on-a-chip), a system LSI, a chip set, or the like.

  The control unit 150 includes a processor 153 including a CPU (Central Processing Unit) and a microcomputer, and a memory 155. The memory 155 is a storage device that stores a program and data executed by the processor 153 in a nonvolatile manner, and includes a magnetic storage device, a semiconductor storage element such as a flash ROM, or other types of nonvolatile storage devices. The memory 155 may include a RAM that constitutes a work area of the processor 153. The memory 155 stores data processed by the control unit 150 and a control program executed by the processor 153.

  Further, the processor 153 may be configured by a single processor, or may be configured such that a plurality of processors function as the processor 153. The processor 153 executes a control program and controls each unit of the projector 100. For example, the processor 153 controls the wireless communication unit 127 to perform wireless communication with an external device, and causes the function unit corresponding to the projector 100 to execute processing corresponding to the operation received by the remote controller 5 or the operation panel 123. Further, when the image is projected onto the screen SC by the projection unit 110, the processor 153 controls the light source driving unit 116 to turn on or off the light source unit 111 and controls the light modulation unit driving unit 117 to perform image processing. The light modulator 112 is driven based on the drive signal input from the unit 130.

  The input / output I / F unit 125 receives an operation by a user. The projector 100 includes a remote control light receiving unit 121 and an operation panel 123 as input means operated by a user. The remote control light receiving unit 121 receives an infrared signal transmitted from a remote control (not shown) and decodes the received signal. The operation panel 123 includes various switches for operating the projector 100, an indicator lamp that indicates the operating state of the projector 100, and the like. The input / output I / F unit 125 is connected to the remote control light receiving unit 121 and the operation panel 123, detects an operation on the operation panel 123, and outputs operation data corresponding to the accepted operation to the control unit 150. Further, the input / output I / F unit 125 outputs data input from the remote control light receiving unit 121 to the control unit 150.

  The wireless communication unit 127 includes an antenna (not shown), an RF (Radio Frequency) circuit, and the like, and communicates with an external device based on a wireless communication standard under the control of the control unit 150. The projector 100 and the external device are connected so that various data can be transmitted and received by a wireless communication method. The communication method implemented by the wireless communication unit 127 is not particularly limited, such as a wireless LAN (including Wi-Fi (registered trademark)), Bluetooth (registered trademark), UWB, and a wireless communication method using a mobile phone line.

[2. Configuration of Image Processing Unit 130]
FIG. 2 is a block diagram illustrating a configuration of the image processing unit 130.
The image processing unit 130 includes a counter 1311, a process execution unit 1312, and an output signal generation unit 1313.

  The counter 1311 receives an input synchronization signal from the image I / F unit 105. Further, the output signal generation unit 1313 notifies the counter 1311 of the output timing of the vertical synchronization signal (hereinafter referred to as output Vsync) output from the output signal generation unit 1313 to the optical modulation unit drive unit 117. The output Vsync is a signal indicating the display period of image data for one screen, and corresponds to the output vertical synchronization signal of the present invention. The light modulation unit driving unit 117 switches an image to be drawn on the light modulation element 115 of the light modulation unit 112 based on the output Vsync. When the counter 1311 receives a notification of the output timing of the output Vsync from the output signal generation unit 1313, the counter 1311 starts counting. The counter 1311 stops counting when the input Vsync included in the input synchronization signal is input from the image I / F unit 105, and outputs the counted value to the output signal generation unit 1313.

  The process execution unit 1312 executes various image processes on the image data expanded in the frame memory 135. For example, the process execution unit 1312 executes a resolution conversion process for converting the resolution of the image data in accordance with the display resolution of the light modulation unit 112. Further, the process execution unit 1312 executes a shape correction process for correcting the shape of the image data, a color tone correction process for correcting the color tone of the image data, and the like. The image data after image processing is developed in the frame memory 135.

  The output signal generation unit 1313 reads image data for which image processing by the processing execution unit 1312 has been completed from the frame memory 135, and generates a drive signal for driving the light modulation unit 112 based on the read image data. The output signal generation unit 1313 outputs the generated drive signal to the light modulation unit drive unit 117. The output signal generation unit 1313 performs a process of generating a drive signal at the final stage of the image processing unit 130, and outputs the generated drive signal to the projection unit 110.

In addition, the output signal generation unit 1313 includes an output pattern storage unit 1315. The output pattern storage unit 1315 corresponds to the “storage unit” of the present invention.
The output pattern storage unit 1315 stores a plurality of output patterns that define the drive signal. The output pattern includes a first output pattern whose frame period is a standard period and a second output pattern whose frame period is longer than the first output pattern. The frame period is a display period of image data for one screen (that is, one frame), and is a period during which an image of one frame is projected on the screen SC by the projection unit 110. For example, if the vertical scanning frequency defined by the vertical synchronizing signal is 60 Hz, the reciprocal is 16.7 milliseconds. Within this frame period, an image of one frame is drawn on the light modulation element 115. In the present embodiment, the case where the frame period of the first output pattern is 16.7 milliseconds and the frame period of the second output pattern is longer than 16.7 milliseconds will be described as an example.

  The first output pattern and the second output pattern are prepared for each gradation value specified by the image data, and stored in advance in the output pattern storage unit 1315. For example, if the gradation value of pixel data constituting the image data (hereinafter referred to as pixel data) is 256 gradations from 0 gradation to 255 gradations, the output pattern storage unit 1315 corresponds to each gradation value. Then, 256 first output patterns and second output patterns are stored. In each of the plurality of first output patterns and second output patterns, the timing of turning on and off the drive signal is defined according to the corresponding gradation value.

  Further, the projector 100 according to the present embodiment drives the light modulation element 115 by subfield driving. The subfield driving is a method of expressing the gradation of image data by dividing a frame period into a plurality of subfield periods and turning on or off the light modulation element 115 in each of the divided subfield periods. . The subfield period corresponds to the “subperiod” of the present invention. In each divided subfield period, white display (transmittance) is applied in each subfield period by applying an on potential (high potential) or an off potential (low potential) between the electrodes constituting the pixel of the light modulation element 115. 100%) or black display (transmittance 0%). When an on-potential is supplied between the electrodes constituting the pixel of the light modulation element 115, the pixel of the light modulation element 115 is in an on state that transmits light emitted from the light source unit 111. In addition, when an off potential is supplied between the electrodes constituting the pixel of the light modulation element 115, the pixel of the light modulation element 115 enters an off state where the light emitted from the light source unit 111 is blocked (not transmitted). Thereby, a desired gradation is expressed by one frame or a plurality of frames. The first output pattern and the second output pattern are data that sets whether to apply an on voltage or an off voltage to the light modulation element 115 in each of a plurality of subfield periods.

  The output signal generation unit 1313 receives the count value of the counter 1311. The output signal generation unit 1313 compares the count value with preset first threshold value and second threshold value, and outputs the drive signal according to the first output pattern or according to the second output pattern. Select whether or not.

  The projector 100 has a frame lock function. The frame lock function is a function for matching the frame frequency of the image data projected on the projection unit 110 with the frame frequency of the image signal supplied from the image source device 200. For example, when the frame frequency of the image signal supplied from the image source device 200 is 60 Hz, the projection unit 110 projects an image on the screen SC at a frame frequency of 60 Hz.

  However, the input Vsync of the image signal supplied from the image source device 200 may fluctuate. For example, when the compressed image data is decompressed and transmitted to the projector 100 in the image source device 200, the input Vsync of the image signal fluctuates if the software operating on the image source device 200 becomes busy. was there.

  For this reason, in this embodiment, the output signal generation unit 1313 selects one of a plurality of output patterns based on the difference between the input Vsync and the output Vsync. The input Vsync corresponds to a frame period of image data included in the image signal supplied from the image source device 200. The output Vsync corresponds to the output period of the drive signal. In the projector 100 having the frame lock function, if the input Vsync before the input Vsync fluctuates is 60 Hz, the output Vsync is also 60 Hz, and the output period of the drive signal is 16.7 milliseconds. However, when a change occurs in the input Vsync, the image processing unit 130 changes the output period of the drive signal in response to this change.

  Specifically, the output signal generation unit 1313 compares the count value of the counter 1311 with a first threshold value and a second threshold value set in advance, and a setting range in which the fluctuation range of the input Vsync is set in advance. It is determined whether or not it is inside. The first threshold value is a threshold value that defines the lower limit value of the setting range, and the second threshold value is a threshold value that defines the upper limit value of the setting range.

  When the variation range of the input Vsync is within the set range, that is, when the first threshold value ≦ the count value ≦ the second threshold value, the output signal generation unit 1313 outputs the first output pattern whose frame period is the standard period. select. The output signal generation unit 1313 generates a drive signal based on the selected first output pattern and the pixel data of each pixel constituting the image data read from the frame memory 135. For example, it is assumed that the gradation value indicated by the pixel data of a certain pixel constituting the image data is “40”. In this case, the output signal generation unit 1313 acquires the first output pattern corresponding to the gradation value “40” from the output pattern storage unit 1315. The output signal generation unit 1313 generates a drive signal by setting each subfield period to ON or OFF according to the ON and OFF timings defined in the acquired first output pattern.

  Further, when the variation range of the input Vsync is not within the setting range (departs from the setting range), the output signal generation unit 1313 selects the second output pattern whose frame period is longer than the first output pattern. The case where it is not within the set range is specifically the case where the first threshold value> the count value or the count value> the second threshold value. In this case, the output signal generation unit 1313 generates a drive signal based on the second output pattern and the pixel data of each pixel constituting the image data read from the frame memory 135. The output signal generation unit 1313 acquires a second output pattern corresponding to the gradation value of the pixel data from the output pattern storage unit 1315. The output signal generation unit 1313 generates a drive signal by setting each subfield period to ON or OFF according to the ON and OFF timings defined in the acquired second output pattern.

The output signal generation unit 1313 outputs the generated drive signal and the output synchronization signal to the light modulation unit drive unit 117. The output synchronization signal includes an output vertical synchronization signal and an output horizontal synchronization signal (denoted as output Hsync).
The output signal generation unit 1313 outputs the generated drive signal in units of output periods. The output period corresponds to the frame period of the selected first output pattern or second output pattern.

  Further, an input synchronization signal is input from the image I / F unit 105 to the output signal generation unit 1313. When the second output pattern is selected as the output pattern, the output signal generation unit 1313 changes the frame period of the output Vsync based on the input Vsync included in the input synchronization signal. The frame period of the second output pattern is longer than the frame period of the first output pattern. For this reason, when the second output pattern is selected, it is necessary to change the output timing of the output Vsync. The output signal generation unit 1313 sets the output timing of the output Vsync based on the input Vsync and the frame period of the second output pattern, and outputs the output Vsync to the light modulation unit driving unit 117 at the set timing. In addition, the output signal generation unit 1313 notifies the counter 1311 of the output timing of the output Vsync.

  The operation of the image processing unit 130 will be described more specifically with reference to FIGS. 3 to 7 are diagrams illustrating the input Vsync, the output Vsync, and the drive signal. In particular, FIG. 3 shows that the length of the four frame periods (A, B, C and D) of the input Vsync is “1.0”, that is, 16.7 milliseconds, and there is a variation in each frame period. Indicates no case. In this case, the count value of the counter 1311 input to the output signal generation unit 1313 is a value within a set range that is greater than or equal to the first threshold value and less than or equal to the second threshold value. When the count value of the counter 1311 is a value within the setting range, the output signal generation unit 1313 selects the first output pattern as the output pattern. For this reason, the output signal generation unit 1313 outputs the output Vsync and the drive signal whose frame period length is “1.0” to the optical modulation unit drive unit 117.

In FIG. 4, the length of the frame period “B” of the input Vsync is “0.8”, which is longer than the length “1.0” of the other frame periods “A, C, and D”. The case where is short is shown. “0.8” is a ratio when 16.7 milliseconds is set to “1.0” and is 13.36 milliseconds.
When the length of the frame period “B” changes to “0.8”, the count value output from the counter 1311 is smaller than the first threshold value. In the frame period “A” before the input Vsync whose frame period length is “0.8” is input, the interval between the output Vsync and the input Vsync is “a” shown in FIG. Further, in the frame period “B” in which the input Vsync having the frame period “0.8” is input, the interval between the output Vsync and the input Vsync is “b” shown in FIG. As shown in FIG. 4, the length of “b” is shorter than the length of “a”. In addition, since the input Vsync of “0.8” is input in the frame period “B”, the interval between the output Vsync and the input Vsync remains “b” in the subsequent frame periods “C” and “D”. It becomes.

  In FIG. 5, since a change in the frame period is detected in the frame period “B” of the input Vsync, the output signal generation unit 1313 selects the second output pattern in the subsequent frame periods “C”, “D”, and “E”. In this case, the drive signal is output. FIG. 5 shows a case where the length of the frame period of the second output pattern is 1.2 times the length of the frame period of the first output pattern. Since the frame period of the drive signal output from the output signal generation unit 1313 is changed to 1.2 times longer, as shown in FIG. 5, the output Vsync and the input are input during the frame period “D” of the input Vsync. The interval with Vsync is changed from “b” to “b−α”. “Α” is an arbitrary positive number. The output signal generation unit 1313 selects the second output pattern as the output pattern until the count value of the counter 1311 reaches a value within the setting range (interval “a” shown in FIG. 4), and the output signal generation unit 1313 A drive signal for the frame period is output. As a result, even if a change occurs in the frame period of the input Vsync, the frame period of the output Vsync can be made to correspond to the changed frame period.

In FIG. 6, the length of the frame period “B” is “1.3”, and the length of the frame period is longer than the length “1.0” of the other frame periods “A, C, and D”. Show the case. Note that “1.3” is a ratio when 16.7 milliseconds is set to “1.0”, which is 21.71 milliseconds.
When the length of the frame period “B” changes to “1.3”, the count value of the counter 1311 is larger than the second threshold value. In the frame period “A” before the input Vsync whose frame period length is “1.3” is input, the interval between the output Vsync and the input Vsync is “a” shown in FIG. Further, in the frame period “B” in which the input Vsync having the frame period “1.3” is input, the interval between the output Vsync and the input Vsync is “c” illustrated in FIG. As shown in FIG. 6, the length of “c” is longer than the length of “a”. In addition, since the input Vsync of “1.3” is input in the frame period “B”, the interval between the output Vsync and the input Vsync remains “c” in the subsequent frame periods “C” and “D”. It becomes.

  In FIG. 7, since a change in the frame period is detected in the frame period “B” of the input Vsync, the output signal generation unit 1313 selects the second output pattern in the subsequent frame periods “C”, “D”, and “E”. In this case, the drive signal is output. FIG. 7 shows a case where the length of the frame period of the second output pattern is 1.2 times the length of the frame period of the first output pattern. Since the frame period of the drive signal output from the output signal generation unit 1313 has been changed to 1.2 times longer, the output Vsync and the input are input during the frame period “D” of the input Vsync as shown in FIG. The interval with Vsync is changed from “c” to “c-β”. “Β” is an arbitrary positive number. The output signal generation unit 1313 selects the second output pattern as the output pattern until the count value of the counter 1311 reaches a value within the setting range (interval “a” shown in FIG. 4), and the output signal generation unit 1313 A drive signal for the frame period is output. As a result, even if a change occurs in the frame period of the input Vsync, the frame period of the output Vsync can be made to correspond to the changed frame period.

[3. Operation of image processing unit]
FIG. 8 is a flowchart showing the operation of the image processing unit 130.
The operation of the image processing unit 130 will be described with reference to the flowchart shown in FIG.
First, the image processing unit 130 determines whether image data is input from the image I / F unit 105 (step S1). When no image data is input from the image I / F unit 105 (step S1 / NO), the image processing unit 130 waits for the start of processing until image data is input.

  Further, the image processing unit 130 receives the image data from the image I / F unit 105 (step S1 / YES), and when the input image data is expanded in the frame memory 135, the processing execution unit 1312 performs image processing. Execute (Step S2). The output signal generation unit 1313 selects the first output pattern when the image data is the first frame of image data. The output signal generation unit 1313 reads out image data from the frame memory 135 according to the selected first output pattern, generates a drive signal, and outputs the generated drive signal to the light modulation unit drive unit 117 together with the output synchronization signal. Further, the output signal generation unit 1313 outputs a notification to the counter 1311 in accordance with the output timing of the output Vsync.

  When there is no notification of output timing from the output signal generator 1313 (step S3 / NO), the counter 1311 waits for the count to start. Upon receiving the output timing notification (step S3 / YES), the counter 1311 starts counting (step S4).

  Next, the counter 1311 determines whether or not the input Vsync included in the input synchronization signal is input from the image I / F unit 105 (step S5). The counter 1311 continues counting when there is no input of the input Vsync (step S5 / NO). Further, when the input Vsync is input (step S5 / YES), the counter 1311 ends the count (step S6) and outputs the count value to the output signal generation unit 1313 (step S7).

When the count value is input from the counter 1311, the output signal generation unit 1313 compares the input count value with the first threshold value (step S8).
When the count value is smaller than the first threshold value (step S8 / NO), the output signal generation unit 1313 determines that the frame period has changed. In this case, the output signal generation unit 1313 selects the second output pattern as the output pattern (step S14). The output signal generation unit 1313 acquires the gradation value of the pixel data of each pixel constituting the image data, and selects the second output pattern corresponding to the acquired gradation value. The output signal generation unit 1313 generates a drive signal by setting each subfield period to ON or OFF according to the selected second output pattern (step S15). The output signal generation unit 1313 outputs the generated drive signal together with the output synchronization signal to the light modulation unit drive unit 117 (step S16).

  Next, the output signal generation unit 1313 determines whether or not the processing for one frame of image data has been completed (step S17). If the processing for one frame of image data has not been completed (step S17 / NO), the output signal generation unit 1313 returns to step S15 and continues generating the drive signal. Further, when the processing for the image data of one frame is finished (step S17 / YES), the output signal generation unit 1313 proceeds to step S3.

  In step S8, when the count value is equal to or greater than the first threshold value (step S8 / YES), the output signal generation unit 1313 compares the count value with the second threshold value (step S9). When the output signal generation unit 1313 determines that the count value is greater than the second threshold value (NO in step S9), the output signal generation unit 1313 determines that the frame period has changed and selects the second output pattern as the output pattern. (Step S14). Thereafter, the output signal generation unit 1313 repeats the processes of steps S15 to S17 for one frame of image data.

  Further, when the count value is smaller than the second threshold value (step S9 / YES), the output signal generation unit 1313 determines that there is no variation in the frame period, and selects the first output pattern as the output pattern. (Step S10). Thereafter, the output signal generation unit 1313 acquires the gradation value of the pixel data of each pixel constituting the image data, and selects the first output pattern corresponding to the acquired gradation value. The output signal generation unit 1313 generates a drive signal by setting each subfield period to ON or OFF according to the selected first output pattern (step S11). The output signal generation unit 1313 outputs the generated drive signal together with the output synchronization signal to the light modulation unit drive unit 117 (step S12).

  Next, the output signal generation unit 1313 determines whether or not the processing for one frame of image data has been completed (step S13). When the processing for one frame of image data has not been completed (step S13 / NO), the output signal generation unit 1313 returns to step S11 and continues generating the drive signal. Further, when the processing for the image data of one frame is completed (step S13 / YES), the output signal generation unit 1313 proceeds to step S3.

  In the above-described embodiment, the case where the drive signal is generated by the two output patterns of the first output pattern whose frame period is the standard period and the second output pattern whose frame period is longer than the standard period has been described as the output pattern. As a configuration other than this, the drive signal may be generated by three output patterns of the first output pattern and the second output pattern and a third output pattern whose frame period is shorter than the standard period.

The output signal generation unit 1313 selects the third output pattern when the count value of the counter 1311 is smaller than the first threshold value. The output signal generation unit 1313 selects a third output pattern corresponding to the gradation value indicated by the pixel data of each pixel, and generates a drive signal according to the selected third output pattern.
The output signal generation unit 1313 selects the second output pattern when the count value of the counter 1311 is larger than the second threshold value. The output signal generation unit 1313 selects a second output pattern corresponding to the gradation value indicated by the pixel data of each pixel, and generates a drive signal according to the selected second output pattern.
Further, the output signal generation unit 1313 selects the first output pattern when the count value of the counter 1311 is not less than the first threshold value and not more than the second threshold value. The output signal generation unit 1313 selects a first output pattern corresponding to the gradation value indicated by the pixel data of each pixel, and generates a drive signal according to the selected first output pattern.

  As described above, the projector 100 of this embodiment includes the projection unit 110, the image processing unit 130, and the output pattern storage unit 1315.

  The image processing unit 130 develops an image based on the input image data in the frame memory 135 for each frame, and outputs a drive signal for displaying the image developed in the frame memory 135 to the projection unit 110. The output pattern storage unit 1315 stores a plurality of output patterns that define the drive signal. The plurality of output patterns stored in the output pattern storage unit 1315 have different output periods, and are patterns that define the on / off timing of the drive signal in the output period.

  The image processing unit 130 outputs the drive signal in units of output periods corresponding to the frame period of the input image data and including the on period and the off period of the drive signal. Further, the image processing unit 130 selects one of a plurality of output patterns based on the difference between the frame period of the input image data and the output period of the drive signal, and outputs a drive signal according to the selected output pattern.

  Accordingly, one of a plurality of output patterns having different output periods is selected based on the difference between the frame period of the input image data and the output period of the drive signal. Therefore, by outputting the drive signal according to the selected output pattern, an image can be displayed while maintaining good gradation even if the frame period of the input image data varies.

The image processing unit 130 selects an output pattern based on the difference between the input Vsync that defines the frame period of the input image data and the output Vsync that defines the output period of the drive signal.
Therefore, even if a change occurs in the frame period of the input image data, an optimum output pattern corresponding to the change that has occurred can be selected.

The output pattern storage unit 1315 stores the first output pattern and the second output pattern having an output period longer than the first output pattern.
The image processing unit 130 obtains a difference between the frame period of the input image data and the output period of the drive signal, and when the obtained difference deviates from a preset setting range, the output period corresponding to the second output pattern To output a drive signal. Further, when the obtained difference is within the set range, the image processing unit 130 outputs a drive signal in an output period corresponding to the first output pattern.

  Therefore, either the first output pattern or the second output pattern is selected according to the difference between the frame period of the input image data and the output period of the drive signal, and the drive signal is output in the output period corresponding to the selected output pattern. Can be output. Therefore, even if the frame period of the input image data varies, an optimal output pattern can be selected and an image can be displayed while maintaining good gradation.

The output pattern storage unit 1315 stores a first output pattern, a second output pattern having an output period longer than the first output pattern, and a third output pattern having an output period shorter than the first output pattern.
The image processing unit 130 obtains a difference between the frame period of the input image data and the output period of the drive signal, and when the obtained difference is larger than a preset setting range, the output period for the second output pattern To output a drive signal. Further, when the obtained difference is smaller than the set range, the image processing unit 130 outputs a drive signal in an output period corresponding to the third output pattern. Further, when the obtained difference is within the set range, the image processing unit 130 outputs a drive signal in an output period corresponding to the first output pattern.

  Therefore, one of the first output pattern, the second output pattern, and the third output pattern is selected according to the difference between the frame period of the input image data and the output period of the drive signal, and the output corresponding to the selected output pattern. A drive signal can be output in a period. Therefore, even if the frame period of the input image data varies, an optimal output pattern can be selected and an image can be displayed while maintaining good gradation.

The output pattern storage unit 1315 stores an output pattern for each gradation value that can be expressed by the projection unit 110. In each output pattern, the ON / OFF timing of the drive signal is defined according to the corresponding gradation value.
The image processing unit 130 acquires an output pattern corresponding to the gradation value of the input image data, and outputs a drive signal according to the acquired output pattern.
Therefore, it is possible to output a drive signal according to an output pattern corresponding to the gradation value of the input image data, and to project an image corresponding to the gradation value on the projection unit 110.

The drive signal has a plurality of sub-periods.
The image processing unit 130 sets each of the plurality of sub periods to an on period or an off period according to the selected output pattern.
Therefore, since the drive signal can be switched between the on state and the off state for each sub period, an image corresponding to the gradation value of the input image data can be displayed on the projection unit 110.

The projection unit 110 includes a light modulation unit 112 including a plurality of light modulation elements 115. Further, the projection unit 110 includes a light modulation unit driving unit 117 that drives the plurality of light modulation elements 115 according to the drive signal. The light modulation unit driving unit 117 changes the modulation state of the plurality of light modulation elements 115 for each sub-period, and turns on the light emitted from the light source unit 111 and emits the light from the light source unit 111. Control to an off state in which light is not transmitted.
Therefore, the modulation state of the light modulation element 115 can be controlled by the drive signal, and an image corresponding to the gradation value of the input image data can be projected onto the projection unit 110.

The above-described embodiment is a preferred embodiment of the present invention. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.
For example, in the above-described embodiment, the projector 100 is shown as an example of a display device. However, the display device of the present invention may be a liquid crystal monitor that displays an image on a liquid crystal display panel, a liquid crystal television, or the like.

  Moreover, each function part shown in FIG.1 and FIG.2 shows a functional structure, and a specific mounting form is not restrict | limited in particular. That is, it is not always necessary to mount hardware corresponding to each function unit individually, and it is of course possible to adopt a configuration in which the functions of a plurality of function units are realized by one processor executing a program. In addition, in the above embodiment, a part of the function realized by software may be realized by hardware, or a part of the function realized by hardware may be realized by software. In addition, the specific detailed configuration of each other part of the projector 100 can be arbitrarily changed without departing from the gist of the present invention.

  The display device control method of the present invention can be realized by causing a computer included in the display device to execute a program corresponding to the display device control method. In addition, this program can be recorded on a recording medium recorded so as to be readable by a computer. As the recording medium, a magnetic or optical recording medium or a semiconductor memory device can be used. Specifically, flexible disk, HDD (Hard Disk Drive), CD-ROM (Compact Disk Read Only Memory), DVD (Digital Versatile Disk), Blu-ray (registered trademark) Disc, magneto-optical disk, flash memory, card A portable recording medium such as a mold recording medium or a fixed recording medium can be used. The recording medium may be a non-volatile storage device such as a random access memory (RAM), a read only memory (ROM), or an HDD, which is an internal storage device included in the image display device. It is also possible to realize a display device control method by storing a program corresponding to a display device control method in a server device or the like and downloading the program from the server device to the display device.

DESCRIPTION OF SYMBOLS 100 ... Projector, 105 ... Image I / F part, 107 ... Bus, 110 ... Projection part, 111 ... Light source part, 112 ... Light modulation part, 113 ... Projection optical system, 115 ... Light modulation element, 116 ... Light source drive part, DESCRIPTION OF SYMBOLS 117 ... Light modulation part drive part, 121 ... Remote control light-receiving part, 123 ... Operation panel, 125 ... Input / output I / F part, 127 ... Wireless communication part, 130 ... Image processing part, 135 ... Frame memory, 150 ... Control part, 153 ... Processor, 155 ... Memory, 200 ... Image source device, 1311 ... Counter, 1312 ... Processing execution unit, 1313 ... Output signal generation unit, 1315 ... Output pattern storage unit.

Claims (8)

A display for displaying an image;
An image processing unit that develops an image based on input image data in an image memory for each frame, and outputs a drive signal for displaying the image developed in the image memory to the display unit;
A storage unit that stores a plurality of output patterns that define the drive signal;
The image processing unit outputs the drive signal in units of an output period corresponding to a frame period of the input image data and including an on period and an off period of the drive signal,
The output pattern is a pattern that defines on and off timings of the drive signal in the output period,
The storage unit stores a plurality of output patterns having different output periods.
The image processing unit selects one of the plurality of output patterns based on a difference between a frame period of the input image data and an output period of the drive signal, and outputs the drive signal according to the selected output pattern Display device.   The image processing unit selects the output pattern based on a difference between an input vertical synchronization signal defining a frame period of the input image data and an output vertical synchronization signal defining the output period of the drive signal; The display device according to claim 1. The storage unit stores a first output pattern and a second output pattern having an output period longer than the first output pattern,
The image processing unit obtains a difference between a frame period of the input image data and an output period of the drive signal, and corresponds to the second output pattern when the obtained difference deviates from a preset setting range. 3. The display device according to claim 1, wherein the drive signal is output in an output period, and the drive signal is output in an output period corresponding to the first output pattern when the obtained difference is within the set range. . The storage unit stores a first output pattern, a second output pattern having a longer output period than the first output pattern, and a third output pattern having a shorter output period than the first output pattern,
The image processing unit obtains a difference between a frame period of the input image data and an output period of the drive signal. When the obtained difference is larger than a preset setting range, the image processing unit applies the second output pattern. The drive signal is output during the output period, and when the obtained difference is smaller than the set range, the drive signal is output during the output period corresponding to the third output pattern, and the obtained difference is within the set range. The display device according to claim 1, wherein the drive signal is output in an output period corresponding to the first output pattern. The storage unit stores an output pattern for each gradation value that can be expressed by the display unit,
Each of the output patterns defines on and off timings of the drive signal according to a corresponding gradation value,
The display according to claim 1, wherein the image processing unit acquires an output pattern corresponding to a gradation value of the input image data, and outputs the drive signal according to the acquired output pattern. apparatus. The drive signal has a plurality of sub-periods;
The display device according to claim 1, wherein the image processing unit sets each of the plurality of sub-periods to an on period or an off period according to the selected output pattern. The display unit
A light modulation section comprising a plurality of light modulation elements;
A plurality of the light modulation elements are driven according to the drive signal, the modulation state of the plurality of light modulation elements is changed for each sub period, and the light emitted from the light source is transmitted, and the light source The display device according to claim 6, further comprising: a drive unit that controls to an off state in which the emitted light is not transmitted. Developing an image based on input image data into an image memory for each frame;
Generating a drive signal for displaying the image developed in the image memory;
The generated drive signal corresponds to a frame period of the input image data, and is output to a display unit in units of output periods including an ON period and an OFF period of the drive signal, and the display unit receives the input image data. Displaying an image based on, and
The step of generating the drive signal selects and selects one of a plurality of output patterns having different output periods based on a difference between a frame period of the input image data and an output period of the drive signal. Generating the drive signal according to the output pattern;
The method for controlling a display device, wherein the output pattern is a pattern that defines the drive signal, and is a pattern that defines on and off timings of the drive signal in the output period.

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