JP2005031316A - Image display device and image display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the time until a fresh image is displayed after a system of an input image signal changes. <P>SOLUTION: A change in system identification information is monitored. In case of the occurrence of the change in the system identification information, the kind of the system of the input image signal is identified and decided based on the system identification information detected thereafter in the first time by a system identification information detecting section and the display operation of the image represented by the input image signal is tentatively started according to the result of the identification and decision obtained by the above identification and decision. Further, when the same system identification information is detected continuously the prescribed number of times by the system identification information detecting section, the kinds of the system of the input image signal are identified and decided based on the detected system identification information and the display operation of the image represented by the input image signal is started again according to the results of the identification and decision obtained by the above identification and decision. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for automatically identifying the type of an input image signal system and displaying an image represented by the input image signal by performing processing according to the identified type of system.
[0002]
[Prior art]
Direct-view image display devices such as a liquid crystal display (LCD) and a plasma display (PDP), a liquid crystal display (LCD) panel (also simply referred to as “liquid crystal panel”), and a digital micromirror device (referred to as “DMD”) TI. In general, a projection-type image display apparatus (projector) using a trademark of a company, for example, can display images expressed by various image signal systems.
[0003]
For example, image signals output from a personal computer have different horizontal and vertical frequencies depending on the dot configuration (so-called resolution) of one screen. Even with the same resolution, there is a slight difference between these frequencies. There are also various types of television signals such as NTSC, PAL, and SECAM.
[0004]
Therefore, in order to display an image expressed by various image signal methods on one image display device according to the input image signal method, an internal image signal can be displayed according to the input image signal method. It is required to adjust the processing condition settings. For this reason, such an image display apparatus has a function of automatically identifying and determining the method of the input image signal, and identifying the method of the input image signal.
[0005]
As a method for identifying the method of the input image signal, various information (also referred to as “method identification information”) having different values depending on the method, such as the horizontal frequency and the vertical frequency of the input image signal, is detected. A method of identifying and determining a corresponding method based on these detection results is used (see, for example, Patent Document 1 and Patent Document 2).
[0006]
[Patent Document 1]
JP-A-7-87457 [Patent Document 2]
Japanese Patent Laid-Open No. 10-312182 [0007]
[Problems to be solved by the invention]
By the way, the method of the input image signal supplied to the image display apparatus may change midway. For example, in a personal computer, the method of an image signal output to the image display device may be switched by switching the display resolution. In the image display device, an input image signal (hereinafter also referred to as “PC signal”) from a personal computer is switched to a television signal (hereinafter also referred to as “TV signal”) of a video recorder or the like. Conversely, there is a case where the TV signal is switched to the PC signal. As described above, when the method of the input image signal is changed in the middle, the display is temporarily stopped and the identification determination is performed, and then the image display is started according to the new method of the input image signal. Accordingly, until the display of a new image is started, the display is usually stopped. It is preferable that the time during which such display is stopped, that is, the time from when the method of the input image signal is changed to when a new image is displayed is shorter. However, in the conventional image display apparatus, this time is relatively long due to the following problems.
[0008]
The horizontal and vertical frequencies of the image signal immediately after switching are not stable, and accurate identification and determination may not be performed. Therefore, in the conventional identification determination, in order to accurately perform the identification determination, the system identification information of the input image signal is detected by taking a sufficient time from the time of switching. For example, it is possible to measure the system identification information such as the horizontal frequency and the vertical frequency several times over a sufficient time and confirm that the measurement result is not varied, and then use the confirmed measurement result as the system identification information. Done. Therefore, in the conventional identification determination, it takes a relatively long time to identify and determine the method of the input image signal, and correspondingly, the comparison is performed from when the image signal is switched to when a new image is displayed. Time was required. For example, a conventional image display device generally requires about 1 to 2 seconds.
[0009]
Therefore, when the method of the input image signal changes, it is desired to shorten the time from when the method of the input image signal changes to when the display of a new image is started.
[0010]
The present invention has been made to solve the above-described problems in the prior art, and is a technique capable of shortening the time until a new image is displayed after the method of the input image signal is changed. The purpose is to provide.
[0011]
[Means for solving the problems and their functions and effects]
In order to achieve the above object, an image display device of the present invention includes:
An image display device that automatically identifies a type of a method of an input image signal and displays an image represented by the input image signal according to the identified type of the method,
A scheme identification information detector for detecting scheme identification information used to identify the type of scheme of the input image signal;
A method determination unit for determining the type of the method of the input image signal based on the detected method identification information,
The method determination unit
1) Monitor the change of the method identification information,
2) When a change occurs in the method identification information, the type of the input image signal is identified and determined based on the method identification information detected for the first time by the method identification information detection unit, and the identification According to the identification determination result obtained by the determination, the display operation of the image represented by the input image signal is temporarily started,
3) Furthermore, when the same scheme identification information is detected continuously a predetermined number of times by the scheme identification information detection unit, the type of the scheme of the input image signal is determined based on the detected scheme identification information. The identification determination is performed, and the display operation of the image represented by the input image signal is restarted according to the identification determination result obtained by the identification determination.
[0012]
In the image display device of the present invention, when a change occurs in the method identification information detected by the change of the method of the input image signal, based on the method identification information detected in the subsequent detection of the method identification information. The type of the input image signal can be identified and determined, and an image display operation can be temporarily started according to the obtained identification determination result. As a result, when the method identification information is detected for the first time, the input image signal is more stable in the case where the input image signal is already stable than when the method identification determination is performed a plurality of times as in the prior art. It is possible to shorten the time from the change of the signal system to the start of display of a new image.
[0013]
In the above image display device,
The method determination unit
It is preferable to monitor changes in at least the horizontal frequency and vertical frequency of the input image signal in the method identification information.
[0014]
In this way, it is possible to easily detect that the method of the input image signal has changed.
[0015]
The present invention can be realized in various forms, for example, in various forms such as an image display apparatus and method, an image processing apparatus and method, and the like.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in the following order based on examples.
A. Overall configuration of the device:
B. Image signal type identification:
C. Variation:
[0017]
A. Overall configuration of the device:
FIG. 1 is a block diagram showing a projector as an embodiment of the image display apparatus of the present invention. The projector PJ includes an image signal conversion unit 10, an image processing unit 20, a liquid crystal panel (LCD) driver 30, a liquid crystal panel 40 as a light valve, an illumination device 50, and a projection optical system 60. Yes. The image signal conversion unit 10 includes an AD conversion circuit (ADC) 12, a clock generator 14, and a method identification information detection unit 16. The image processing unit 20 includes an image processing execution unit 22 and an image processing control unit 24.
[0018]
The AD conversion circuit 12 converts the input image signal from an analog signal to a digital signal. The clock generator 14 generates a sampling clock for conversion processing executed by the AD conversion circuit 12 in synchronization with a horizontal synchronization signal included in the input image signal. The clock generator 14 is constituted by a PLL circuit. The frequency of the sampling clock is determined by the frequency division ratio of the PLL circuit set by the image processing control unit 24 of the image processing unit 20.
[0019]
The system identification information detector 16 measures system identification information used for identifying and determining the system of the input image signal. The system identification information includes the horizontal and vertical frequencies of the horizontal synchronization signal and vertical synchronization signal included in the input image signal, the polarity of these synchronization signals, and the like. The horizontal frequency and the vertical frequency can be easily measured, for example, by counting the length of one period with a reference clock for measurement whose period is known, and these measurement circuits are well known. A circuit for detecting the polarity of the synchronization signal is also well known. Therefore, the description of the circuit constituting the system identification information detection unit 16 is omitted.
[0020]
The image signal conversion unit 10 receives various types of image signals such as an image signal (PC signal) output from a personal computer and an image signal (TV signal) output from a video tape recorder. Also, various types of image signals are input as PC signals.
[0021]
These image signals are composed of a horizontal synchronization signal and a vertical synchronization signal, and a signal representing a portion of an image that is actually displayed. The signal representing the image portion includes, for example, a format composed of three luminance signals of R (red), G (green), and B (blue), or Y (luminance signal) and Cr, Cb (color difference signals). ) And the like. In the following, a signal representing the image portion may be referred to as a “color signal” when particularly distinguished.
[0022]
The AD conversion circuit 12 performs an appropriate conversion process according to the above-described format of the input image signal, and outputs a digitized color signal. The format of the output color signal is also output in a format that can be used by an image signal processing unit described later. Here, three luminance signals R, G, and B are output as digital signals.
[0023]
The image processing execution unit 22 performs various image processing on the image represented by the color signal input from the image signal conversion unit 10 and outputs a display image signal for actual display. Note that as the image processing, for example, enlargement / reduction of an image, correction of keystone distortion, and the like are executed.
[0024]
The image processing control unit 24 includes a CPU, a RAM, a ROM, and the like (not shown), and controls the image processing operation in the image processing execution unit 22 and the processing operations of the AD conversion circuit 12 and the clock generator 14 to thereby control the projector PJ. Controls the image display at.
[0025]
Here, in particular, the image processing control unit 24 functions as the method determination unit 24a, and executes identification determination of the method of the input image signal based on the method identification information detected by the method identification information detection unit 16. Then, the image processing control unit 24 sets appropriate operating conditions for each of the AD conversion circuit 12, the clock generator 14, and the image processing execution unit 22 based on the method of the image signal identified by the method determination unit 24a. Each processing operation is controlled. The identification determination of this method will be further described later.
[0026]
The liquid crystal panel driver 30 generates a drive signal for driving the liquid crystal panel 40 in accordance with the display image signal input from the image processing unit 20. The liquid crystal panel 40 functions as a light valve (light modulator) that forms an image by modulating the illumination light emitted from the illumination device 50 in accordance with the drive signal output from the liquid crystal panel driver 30.
[0027]
The illumination light modulated in the liquid crystal panel 40 is emitted toward the screen SC by the projection optical system 60 as light representing an image (image light). Thereby, an image is projected on the screen SC.
[0028]
Although not shown, the liquid crystal panel 40 includes three liquid crystal panels corresponding to the three colors R, G, and B. Therefore, each of the AD conversion circuit 12, the image processing execution unit 22, and the liquid crystal panel driver 30 has a function of processing color signals of three colors of R, G, and B. The illumination device 50 has a color light separation optical system that separates light source light into three colors of light, and the projection optical system 60 combines image light of the three colors to represent a color image. And a projection lens. In addition, about the structure of the optical system of such a projector, since the structure of the optical system of various general projectors can be utilized, description is abbreviate | omitted here.
[0029]
Further, the configuration of the projector shown in FIG. 1 mainly shows a configuration for explaining the present invention, and it is naturally possible to have other various functions provided in a general projector. is there.
[0030]
B. Image signal type identification:
FIG. 2 and FIG. 3 are flowcharts showing the identification determination operation of the input image signal system. When the projector PJ is started and its operation is started, the method determination process shown in FIGS. 2 and 3 is executed in the method determination unit 24a.
[0031]
First, in step S110, the method identification information detection unit 16 is instructed to measure the frequency of the horizontal synchronization signal and the vertical synchronization signal, and the measurement result is acquired. In step S120, a change in the measurement result is monitored. If there is no change in the measurement result, after waiting for a predetermined time, the process returns to step S110 and the frequency measurement of the horizontal synchronizing signal and the vertical synchronizing signal is executed again. On the other hand, if there is a change in the measurement result, the image display is stopped in step S130, and the process proceeds to step S140. As described above, in steps S110 and S120, the frequency change of the horizontal synchronizing signal and the vertical synchronizing signal is monitored.
[0032]
When a change in the frequency of the horizontal synchronization signal or the vertical synchronization signal is detected in step S120, at least the frequency of the horizontal synchronization signal and the vertical synchronization signal is measured in step S140, and the measurement result is acquired as method identification information. In step S150, the system corresponding to the acquired system identification information is identified and determined. Then, various parameters to be set in each unit of the AD conversion circuit 12, the clock generator 14, and the image processing execution unit 22 are calculated according to the identified and determined method. The calculated value is set in the corresponding register of each unit, and an operation corresponding to this can be started. In step S160, image display is started.
[0033]
The identification determination based on the scheme identification information can be easily executed by various general methods. For example, it can be executed by referring to a correspondence table prepared in advance or by searching a database or the like. The set parameters include, for example, the horizontal frequency and the vertical frequency, the number of horizontal pixels and the number of vertical pixels (resolution), the length of the front porch and the back porch, the frequency division ratio of the PLL in the clock generator 14 and the sampling clock. Phase adjustment values, enlargement / reduction values in the image processing execution unit 22, and the like.
[0034]
As described above, in steps S140 to S160, after detecting changes in the frequency of the horizontal synchronizing signal and the vertical synchronizing signal corresponding to the change in the method of the input image signal, at least the horizontal synchronizing signal and the vertical synchronizing signal are used as the method identification information. The image signal system is identified and determined based on the measurement result, and image display is temporarily started according to the determined system.
[0035]
Next, in step S170, the two count values N and K are reset. In step S180, at least the frequency of the horizontal synchronizing signal and the vertical synchronizing signal is measured as method identification information, and the measurement result is obtained. Then, in step S190, it is determined whether or not the acquired measurement result matches the previously measured value. If they do not match, the process proceeds to step S200, and if they match, the process proceeds to step S230.
[0036]
If it is determined in step S190 that the acquired measurement result does not match the previously measured value, the count value N is incremented by 1 in step S200, and the count value N is set to the number-of-measurements limit value (this example) in step S210. Then, it is determined whether or not 6). When the count value N is smaller than the measurement number limit value (N <6), the process returns to step S180 and the measurement is performed again. On the other hand, when the count value N is the measurement count limit value (N = 6), it is determined that there is no displayable image signal method and display is impossible. In step S220, display of an image ([Not Support]) indicating that the image signal method is not supported is started.
[0037]
If it is determined in step S190 that the acquired measurement result matches the previously measured value, 1 is added to each of the count values K and N in step S230, and the count value K is continuously matched in step S240. It is checked whether the number of times is set (3 in this example). When the count value K is smaller than the set value (K <3), the process proceeds to step S210, and when the count value N is also smaller than the measurement number limit value (N <6), the process returns to step S180 to perform repeated measurement. To do. On the other hand, if the count value K is the set value (K = 3), it is determined that the horizontal frequency and vertical frequency of the input image signal are stable, and the process proceeds to step S250.
[0038]
In step S250, as in step S150, a method corresponding to the acquired method identification information is identified and determined, and various parameters to be set are calculated. The calculated value is set in the corresponding register of each unit, and an operation corresponding to this can be started. In step S260, image display is started again.
[0039]
And if the image display in step S220, S260 is disclosed, this system determination process will be complete | finished. This method determination process is repeatedly executed at all times until the operation of the projector PJ is completed.
[0040]
In the above description, the count value N count limit value is set to 6. However, the count value N is not limited to this, and can be various values. However, the time until the display in step S220 is executed becomes longer as the measurement number limit value increases. In addition, when the measurement number limit value is small, there is a high possibility that the image signal method that should be displayed can be determined as non-displayable. Accordingly, the count value N count limit value is set to the minimum value that can prevent the determination of the method that takes the longest time for identification determination from among the image signal methods that should be displayable. Is preferred. Further, although the set value of the number of consecutive matches of the count value K is set to 3, it is similarly not limited to this and can be various values.
[0041]
As described above, in this embodiment, when a change in the frequency of the horizontal synchronization signal or the vertical synchronization signal is detected and it is determined that the method of the image signal has changed, then, as the method identification information, at least, The frequency of the horizontal synchronizing signal and the vertical synchronizing signal is measured once, and the corresponding image signal system is identified and determined based on the measurement result. Based on the identification determination result that has been executed, various parameters are set and image display is temporarily started. In addition, after the display of the image is temporarily started, the frequency of the horizontal synchronizing signal and the vertical synchronizing signal is measured again, and if the measured values match continuously a predetermined number of times, the measurement result is Based on this, the corresponding image signal system is identified and determined. Then, various parameters are set based on the identification determination result, and image display is started again. That is, in this embodiment, image signal type identification and image display are executed in two stages. Note that the conventional identification determination corresponds to only the second-stage identification determination in the above embodiment.
[0042]
When identification determination and image display are executed in two stages as described above, if the frequency of the image signal is stable in the first stage identification determination, the result of the second stage identification determination is also the first stage. As a result, the image display method is changed after the image signal method has changed compared to the case where the image display is started after the identification determination is performed only by the identification determination at the second stage as in the prior art. The time until the start can be effectively shortened.
[0043]
In addition, when the frequency of the image signal is not stable in the first identification determination, the time until the image display is started based on the accurate identification determination is the same as in the conventional case. However, there is an effect that an image can be displayed for the time being based on the first-stage identification determination.
[0044]
In actual cases, when the image signal system changes, a correct identification determination result is often obtained by the first-stage identification determination, and until the image display is newly started after the image signal system changes. Can be shortened on average.
[0045]
C. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0046]
C1. Modification 1:
In the above embodiment, the light modulation device using a liquid crystal panel called a light valve is described as an example. However, the present invention is not limited to this. For example, a projector using a digital micromirror device (DMD) is used. Is also applicable.
[0047]
C2. Modification 2:
In the above embodiment, the projector is described as an example. However, the present invention can be applied to various direct-view image display devices such as a liquid crystal display (LCD) and a plasma display (PDP).
[Brief description of the drawings]
FIG. 1 is a block diagram showing a projector as an embodiment of an image display device of the present invention.
FIG. 2 is a flowchart showing an identification determination operation of an input image signal system.
FIG. 3 is a flowchart showing an identification determination operation of an input image signal system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Image signal conversion part 14 ... Clock generator 16 ... Method identification information detection part 20 ... Image processing part 22 ... Image processing execution part 24 ... Image processing control part 24a ... Method determination part 30 ... Liquid crystal panel driver 40 ... Liquid crystal panel 50 ... Illumination device 60 ... projection optical system PJ ... projector SC ... screen

Claims (3)

An image display device that automatically identifies a type of a method of an input image signal and displays an image represented by the input image signal according to the identified type of the method,
A scheme identification information detector for detecting scheme identification information used to identify the type of scheme of the input image signal;
A method determination unit for determining the type of the method of the input image signal based on the detected method identification information,
The method determination unit
1) Monitor the change of the method identification information,
2) When a change occurs in the method identification information, the type of the input image signal is identified and determined based on the method identification information detected for the first time by the method identification information detection unit, and the identification According to the identification determination result obtained by the determination, the display operation of the image represented by the input image signal is temporarily started,
3) Further, when the same method identification information is detected continuously a predetermined number of times by the method identification information detection unit, the type of the input image signal is determined based on the detected method identification information. Recognizing and determining the display operation of the image represented by the input image signal according to the identification determination result obtained by the identification determination;
An image display device characterized by that. The image display device according to claim 1,
The method determination unit
An image display device that monitors changes in at least a horizontal frequency and a vertical frequency of the input image signal in the method identification information. An image display method for automatically identifying a type of an input image signal and displaying an image represented by the input image signal according to the identified type of the method,
1) Monitor a change in system identification information used to identify the type of system of the input image signal;
2) When a change occurs in the scheme identification information, the scheme identification information is detected once thereafter, and the scheme type of the input image signal is identified and determined based on the detected scheme identification information. According to the identification determination result obtained by the identification determination, the display operation of the image represented by the input image signal is temporarily started,
3) Further, when the method identification information is detected a plurality of times and the same method identification information is detected continuously a predetermined number of times, the input image signal is detected based on the detected method identification information. Recognizing and determining the type of method, and in response to the identification determination result obtained by the identification determination, the display operation of the image represented by the input image signal is restarted.
An image display method characterized by the above.

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