JP2004272072A - Display controller and manufacturing apparatus of display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display clear images free from bleeding and fluctuation by solving a phase deviation between a video signal and a synchronizing signal even when a temperature change in a display device is large. <P>SOLUTION: A display controller is provided with a temperature sensor 6 for detecting temperature, a microcomputer 7 for calculating a correction value concerned with the phase of a signal in accordance with the detected temperature, a video input I/F circuit 3 for processing a video signal (a) and a synchronizing signal (b), and a video processing circuit 4 for correcting the phase of the synchronizing signal (d) processed by the video input I/F circuit 4 on the basis of phase correction data computed by the microcomputer 7 and outputting the video signal processed by the video input I/F circuit 3 to a display panel 5 while synchronizing it with the phase-corrected synchronizing signal. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a display control device and a display device manufacturing device.
[0002]
[Prior art]
2. Description of the Related Art As a display device, a vehicle-mounted display device that displays a video signal from a navigation device or a television receiver mounted on a vehicle is widely used.
FIG. 7 is a block diagram showing a system configuration of a display control device applied to a conventional in-vehicle display device. In this figure, a video signal a and its synchronizing signal b are input from a device 11 such as a navigation device or a television receiver to a display device 12 via a transmission path. The display device 12 includes a video input I / F (interface) circuit 13, a video processing circuit 14, and a display panel 15.
[0003]
The video input I / F circuit 13 performs an amplification process, a filter process, or the like on the input video signal a, inputs the video signal a to the video processing circuit 14 as the video signal c, and outputs the input synchronization signal b , And performs processing such as amplification processing and waveform shaping processing, and inputs the same to the video processing circuit 14 as a synchronization signal d.
[0004]
The video processing circuit 14 generates a dot clock based on the synchronization signal d, samples the video signal c using the dot clock, and generates a video signal having a dot (pixel) cycle. FIG. 8 is a timing chart of a signal waveform in the video processing circuit 14. In this figure, (A) shows a video signal, (B) shows a synchronization signal, and (C) shows a dot clock. Since the video signal starts with a phase delayed by the time t from the falling timing of the synchronization signal, a dot clock is generated in accordance with the start of the video signal. The video signal sampled by the dot clock is input to a display panel 15 composed of a liquid crystal display device or the like, and an image of the video signal is displayed. In order to display a clear image without bleeding or fluctuation, sampling timing is important.
[0005]
FIG. 9 is a timing chart showing ideal sampling of a video signal. In the figure, (B) is a synchronizing signal having a period Th (horizontal synchronizing signal having a period of about 63.5 μsec), and (A) is a video signal having a dot period Td starting with a delay of time t from the fall of the synchronizing signal. It is. In FIG. 9A, the vertical dotted arrow indicates the timing of sampling by a dot clock having a period Ts. As shown in this figure, if the central part of each dot of the video signal is sampled, a clear image without blur or fluctuation is displayed on the display panel 15. For this reason, it is necessary to configure the display device so that there is no phase shift between the phase of the synchronizing signal from which the dot clock with accurate timing is generated and the phase of the video signal.
[0006]
To match the phases of these two signals, a PLL (phased lock loop) circuit is generally used. In a conventional liquid crystal display device, in order to display an image of a computer device with high quality, a PLL circuit is configured by a phase comparison circuit, a low-pass filter, a VCO, and a frequency dividing circuit, and a horizontal synchronization signal bar provided from the computer device is provided. Generate a synchronized internal dot clock. The gate circuit extracts the reference dot clock of the computer device superimposed on the portion between the horizontal retrace lines of the video signal, and the phase comparison circuit, the low-pass filter, and the VCO determine the phase of the internal dot clock by the phase of the reference dot clock. Adjust to The liquid crystal panel is driven based on the internal dot clock (for example, see Patent Document 1).
[0007]
[Patent Document 1]
JP-A-9-198013 (page 1)
[0008]
[Problems to be solved by the invention]
However, in a display device of a liquid crystal display device as disclosed in Patent Document 1, the product cost increases due to electronic components and substrates for forming a PLL circuit, a manufacturing process, an inspection process, and the like, and the PLL circuit is mounted. There is a problem that it is difficult to reduce the size of the product due to the space required.
Even if a PLL circuit is used, if the display device is used in an environment where there is a large temperature change, the temperature characteristic of electronic components such as a semiconductor component and a coupling capacitor constituting the PLL circuit may cause a synchronization with a video signal. When the phase shift of the signal is out of the control range of the PLL circuit, there is a problem that the phase shift cannot be eliminated.
FIG. 10 is a diagram illustrating a timing relationship between a video signal and a dot clock when a phase of a video signal and a phase of a synchronization signal have a phase shift in a conventional display device. In FIG. 10, the video signal of (A) sampled at the rising edge of the dot clock of (B) has a low signal level and is at an unstable position p1, so that the displayed image is blurred or fluctuated. .
[0009]
The present invention has been made in order to solve the above-described problems, and enables inexpensive manufacturing cost and product miniaturization, and even when a temperature change in a display device is large, a video signal and a synchronization signal It is an object of the present invention to obtain a display control device and a display device manufacturing device which can display a clear image without bleeding or fluctuation by eliminating the phase shift.
[0010]
[Means for Solving the Problems]
The display control device according to the present invention includes: a temperature detection unit configured to detect a temperature of a predetermined location in the display device; and a calculation unit configured to calculate a correction value related to a phase of a signal corresponding to the temperature detected by the temperature detection unit. A first signal processing unit for processing an input video signal, a second signal processing unit for processing a synchronization signal input along with the video signal, and a second signal processing unit based on a correction value calculated by the calculation unit. Phase correction means for correcting the phase of the synchronization signal processed by the second signal processing means, and the video signal processed by the first signal processing means being displayed in synchronization with the synchronization signal whose phase has been corrected by the phase correction means. Signal output means for outputting to the means.
[0011]
An apparatus for manufacturing a display device according to the present invention includes a temperature setting unit that changes a temperature of a display device assembled in a predetermined process, a phase of a video signal input from the signal generation unit to the display device, and a synchronization signal. A phase shift measuring unit for measuring a phase shift with respect to a phase in accordance with a temperature change in the display device, and a phase correction table for correcting a phase shift with respect to the temperature change measured by the phase shift measuring device. Storage control means for storing in the storage means.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a configuration of an embodiment of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a system configuration according to the first embodiment. In this figure, a video signal a and its synchronizing signal b are input from a device 1 such as a navigation device or a television receiver to a display device 2 via a transmission path. The display device 2 includes a video input I / F (interface) circuit (first signal processing means, second signal processing means) 3, a video processing circuit (phase correction means, signal output means) 4, a display panel (display means) 5, a temperature sensor (temperature detecting means) 6, a microcomputer (calculating means) 7, a table 8 stored in a flash memory (not shown) in the microcomputer 7, and an operating section (operating means) 9.
[0013]
Next, the operation will be described.
The video input I / F circuit 3 performs a process such as an amplification process or a filter process on the input video signal a, and inputs the video signal a to the video processing circuit 4 as a video signal c (first signal processing unit). ), A circuit such as an amplification process or a waveform shaping process is performed on the synchronization signal b input along with the video signal a, and is input to the video processing circuit 4 as the synchronization signal d (second signal processing). Means) and other circuits.
[0014]
The temperature sensor 6 is a component of a brightness adjustment circuit (not shown) that detects a temperature near a backlight (not shown) of the display panel 5 and automatically adjusts the brightness of the display panel 5. . The microcomputer 7 generates a luminance adjustment control signal based on the temperature information g detected by the temperature sensor 6 and corrects the phase of the synchronization signal d input from the video input I / F circuit 3 to the video processing circuit 4. Then, a phase correction data (correction value) is calculated, and a correction control signal h carrying the calculated phase correction data is input to the video processing circuit 4.
[0015]
The table 8 in the microcomputer 7 is a part of a storage area of a flash memory (storage means) which is a rewritable nonvolatile memory, and is a table of phase correction data for temperature stored at the time of shipment of a product. FIG. 2 is a diagram illustrating a data configuration of the table 8. As shown in this figure, the table of the phase correction data with respect to the temperature is based on the television reception signal which is the type of the video signal and the video signals corresponding to the navigation systems # 1, navigator # 2,. And a plurality of types of tables. Therefore, the microcomputer 7 determines whether the video signal a input from the device 1 to the display device 2 is a video signal of the television reception signal, based on the video identification signal f from the device 1 such as a navigation device or a television receiver. It is determined which manufacturer's navigation video signal it is.
[0016]
The video processing circuit 4 corrects the phase of the synchronization signal d input from the video input I / F circuit 3 with the phase correction data h from the microcomputer 7, and generates a dot clock based on the corrected synchronization signal. Then, the video signal c is sampled by the generated dot clock to generate a video signal e having a dot (pixel) cycle and input to the display panel 5. The display panel 5 displays an image of the video signal of the dot cycle.
[0017]
The operation unit 9 inputs data i relating to the phase correction input by a user operation to the microcomputer 7. The data i relating to the phase correction includes a change of the phase correction data at each temperature, a change of a predetermined time which is a time interval of the phase correction, and a change of a predetermined value which is a unit temperature difference of the phase correction. The microcomputer 7 changes the contents of the table stored in the flash memory at the time of product shipment according to the data i from the operation unit 9.
[0018]
FIG. 3 is a flowchart showing the operation of the microcomputer 7 in the phase correction process. After a predetermined initialization process such as clearing of various registers or resetting of a timer, a video signal discrimination process is performed by a video identification signal f from the device 1 such as a navigation device or a television receiver (step ST1). Further, temperature information input from the temperature sensor 6 is obtained (step ST2). Next, a correction amount for correcting the phase of the synchronization signal is calculated based on the temperature information (step ST3). That is, the table 8 is referred to. Then, a correction execution availability determination process is performed (step ST4).
[0019]
FIG. 4 is a flowchart of a subroutine of correction execution availability determination processing. In this flow, it is determined whether or not the value of the timer that is incremented for each timer interrupt has exceeded a set predetermined time (step ST11). When the value of the timer exceeds the predetermined time, the value of the timer is reset (step ST12), and the previously obtained temperature is compared with the currently obtained temperature to determine whether the temperature change is larger than the predetermined value. Is determined (step ST13). If the temperature change is larger than the predetermined value, it is determined that correction is to be performed (step ST14). If the timer value does not exceed the predetermined time in step ST11, or if the temperature change is equal to or less than the predetermined value in step ST13, the execution of the correction is not determined.
[0020]
As a result of the correction availability determination processing in the flow of FIG. 4, it is determined in FIG. 3 whether or not correction is to be performed (step ST5). If the correction has been performed, the correction value is updated (step ST6). That is, the phase correction data of the table 8 corresponding to the temperature from the temperature sensor 6 is read out, and the phase correction data or necessary arithmetic processing (for example, encoding processing) is performed on the phase correction data to obtain the phase correction data. Is input to the video processing circuit 4. Thereafter, the process proceeds to step ST1 to perform the video signal determination process again.
[0021]
The video processing circuit 4 corrects the phase of the synchronization signal d input from the video input I / F circuit 3 based on the phase correction data input from the microcomputer 7. As a phase correction method, a conventionally well-known technique is used. For example, the phase of the synchronization signal d is delayed using a delay circuit or a memory circuit. Then, a dot clock is generated based on the synchronization signal whose phase has been corrected.
[0022]
FIG. 5 is a diagram comparing a timing relationship between a video signal and a dot clock between a dot clock that has not been phase-corrected and a corrected dot clock that has been phase-corrected. In this figure, (A) is a video signal, (B) is a dot clock without phase correction (that is, the dot clock shown in FIG. 10), and (C) is a phase correction of the dot clock of (B) by Δt. This is the corrected dot clock. As shown in this figure, the position of the video signal sampled by the correction dot clock is a position p2 where the level is high and stable. Therefore, a clear image without blur and fluctuation is displayed by the video signal e sampled and input to the display panel 5.
[0023]
As described above, according to the first embodiment, the temperature sensor 6 that detects the temperature near the backlight in the display device 2 and the phase of the signal corresponding to the temperature detected by the temperature sensor 6 , A video input I / F circuit 3 for processing an input video signal a and a synchronization signal b input along with the video signal a, and phase correction data calculated by the microcomputer 7 , The phase of the synchronization signal d processed by the video input I / F circuit 3 is corrected, and the video signal processed by the video input I / F circuit 3 is synchronized with the synchronization signal whose phase has been corrected. 5 and the image processing circuit 4 for outputting the image data to the display device 5. To eliminate the phase shift between the signal and the synchronization signal, there is an effect that a clear image without bleeding or vibration can be displayed on the display panel 5.
[0024]
Further, according to the first embodiment, the phase correction table 8 corresponding to the temperature at a predetermined location in the display device 2 is stored in the flash memory of the microcomputer 7, and the microcomputer refers to the table 8 Since the phase correction data corresponding to the temperature detected by the sensor 6 is calculated, the load on the microcomputer 7 required for the phase correction calculation process is extremely light, and there is an effect that other processes are not affected.
[0025]
Further, according to the first embodiment, the flash memory of the microcomputer 7 stores a plurality of types of tables corresponding to the types of video signals, and the microcomputer 7 refers to the tables corresponding to the types of the input video signals. Since the phase correction data is calculated in this way, it is possible to sufficiently cope with video signals from a television receiver and video signals from navigation devices of various manufacturers.
[0026]
Further, according to the first embodiment, since the operation unit 9 for changing the phase correction table stored in the flash memory of the microcomputer 7 according to the operation is provided, the contents of the table at the time of product shipment are used. Even when the table is not adapted to the environment, there is an effect that the contents of the table can be easily changed by a user operation.
[0027]
Further, according to the first embodiment, the temperature sensor 6 for detecting the temperature of the backlight of the display panel 5 in the display device 2, the microcomputer 7 for controlling the display device 2, and the control program thereof are stored. Since the table 8 of the flash memory is also used, there is an effect that resources of the existing hardware can be effectively used by newly developing software for phase correction.
[0028]
Embodiment 2 FIG.
In the second embodiment, in a display device including a PLL circuit for correcting a phase shift between a video signal and a synchronization signal, the influence of a temperature change is eliminated. FIG. 6 is a block diagram showing a system configuration according to the second embodiment. In this figure, components that are basically the same as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and descriptions of those components are omitted. 6, the PLL circuit 10 compares the phase of the video signal c processed by the video input I / F circuit 3 with the phase of the synchronization signal d, and inputs a phase shift correction signal j to the video processing circuit 4. Thus, the phase shift is eliminated.
[0029]
Next, the operation will be described.
The microcomputer 7 refers to the phase correction data in the table 8 according to the temperature information g from the temperature sensor 6 and the video identification signal f from the device 1 such as a navigation or a television receiver, and converts the phase correction data into a PLL. Input to the circuit 10. Table 8 shows the phase correction data when the temperature inside the display device 2 rises significantly due to the heat of the outside air, the heat of the engine and the air conditioner, the heat of the backlight, and the like, and the case where the outside air temperature drops significantly in a cold region. Are stored. That is, phase correction data for a temperature at which the PLL circuit 10 may malfunction may be stored.
[0030]
As described above, according to the second embodiment, the microcomputer 7 performs synchronization outside the control range of the PLL circuit that corrects the phase shift between the video signal c processed by the video input I / F3 and the synchronization signal d. Since the correction value for correcting the phase of the signal is calculated, the phase shift between the video signal c and the synchronization signal d is caused by the temperature characteristic of the electronic components such as the semiconductor component and the coupling capacitor constituting the PLL circuit 10. There is an effect that even if it is out of the control range, the phase shift can be eliminated by the phase correction data from the microcomputer 7.
[0031]
In each of the embodiments, the temperature versus phase correction data in the table 8 of the flash memory in the microcomputer 7 is written at the time of shipment of the product. For this reason, a manufacturing apparatus for writing the phase correction data corresponding to the temperature into the table 8 is required in a factory where the display device 2 is manufactured. The manufacturing apparatus according to the present invention measures, for each display device, a phase shift between a video signal and a synchronization signal with respect to a temperature change, and based on the measurement result, stores phase correction data with respect to temperature in a flash memory of the display device. Write.
[0032]
That is, the display device manufacturing apparatus according to the present invention includes a temperature setting unit that changes the temperature of the display device assembled in a predetermined process, a phase of a video signal input from the signal generation unit to the display device, and a synchronization signal. A phase shift measuring means for measuring a phase shift with respect to the phase of the display device in accordance with a temperature change in the display device, and a phase correction table for correcting the phase shift with respect to the temperature change measured by the phase shift measuring device. Storage control means for storing the data in the storage means. Therefore, according to the manufacturing apparatus of the present invention, a high-quality display device free from bleeding and fluctuation is corrected by correcting the tolerance of temperature characteristics of semiconductors and other electronic components in individual products (variation within a design allowable range). There is an effect that it can be manufactured with a high yield and provided to the market.
[0033]
Further, in each of the above embodiments, the display control device applied to the in-vehicle display device that displays the video signal from the navigation device or the television receiver mounted on the vehicle has been described. Is not limited to a display device mounted on a vehicle. Applicable to all displays, both private and public. In particular, a remarkable effect can be expected in a display device used in an environment where the temperature changes drastically.
[0034]
【The invention's effect】
As described above, according to the present invention, the display control device is provided with a temperature detecting means for detecting a temperature at a predetermined location in the display device, and a correction relating to a phase of a signal corresponding to the temperature detected by the temperature detecting means. A calculating means for calculating a value, a first signal processing means for processing an input video signal, a second signal processing means for processing a synchronizing signal input along with the video signal, A phase correction unit for correcting the phase of the synchronization signal processed by the second signal processing unit based on the corrected value, and a video signal processed by the first signal processing unit, the phase of which is corrected by the phase correction unit. A signal output means for outputting to the display means in synchronization with the synchronizing signal is provided, so that inexpensive manufacturing costs and miniaturization of the product can be achieved, and the temperature change in the display device is large. Even if to eliminate the phase shift between the video signal and the sync signal, there is an effect that can display a clear image free from bleeding or vibration.
[0035]
According to the present invention, the display device manufacturing apparatus is provided with a temperature setting unit for giving a temperature change to the display device assembled in a predetermined process, and a phase synchronization of a video signal input to the display device from the signal generation unit. A non-volatile memory in the display device includes a phase shift measuring unit that measures a phase shift with respect to the phase of the signal according to a temperature change in the display device, and a phase correction table that corrects a phase shift with respect to the temperature change measured by the phase shift measuring unit. And storage control means for storing the data in the storage means, so that the tolerance of temperature characteristics of semiconductors and other electronic components in individual products (variation within a design allowable range) is corrected, and bleeding and fluctuation are corrected. There is an effect that a high-quality display device without any defect can be manufactured with a high yield and provided to the market.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a system configuration of a display control device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a data configuration of a table in a microcomputer in FIG. 1;
FIG. 3 is a flowchart showing an operation of a phase correction process of the microcomputer in FIG. 1;
FIG. 4 is a flowchart of a subroutine of a correction execution availability determination process in FIG. 3;
FIG. 5 is a diagram showing a timing relationship between a video signal and a dot clock in the first embodiment.
FIG. 6 is a block diagram showing a system configuration of a display control device according to a second embodiment of the present invention.
FIG. 7 is a block diagram showing a system to which a conventional display device for a vehicle is applied.
8 is a timing chart of signal waveforms in the video processing circuit of FIG. 7;
FIG. 9 is a timing chart showing ideal sampling of a video signal.
FIG. 10 is a diagram showing a timing relationship between a video signal and a dot clock in a conventional display device.
[Explanation of symbols]
1 equipment such as navigation or television receiver, 2 display device (display device), 3 video input I / F circuit (first signal processing means, 2nd signal processing means), 4 video processing circuit (phase correction means, Signal output means), 5 display panel (display means), 6 temperature sensor (temperature detection means), 7 microcomputer (calculation means), 8 table, 9 operation section (operation means), 10 PLL circuit.

Claims (7)

Temperature detection means for detecting the temperature of a predetermined location in the display device,
Calculating means for calculating a correction value for the phase of the signal corresponding to the temperature detected by the temperature detecting means;
First signal processing means for processing an input video signal;
Second signal processing means for processing a synchronization signal input along with the video signal;
Phase correction means for correcting the phase of the synchronization signal processed by the second signal processing means based on the correction value calculated by the calculation means;
And a signal output means for outputting the video signal processed by the first signal processing means to a display means in synchronization with the synchronizing signal whose phase has been corrected by the phase correction means. Storage means for storing a phase correction table corresponding to a temperature at a predetermined location in the display device, wherein the arithmetic means refers to the table in the storage means and corresponds to the temperature detected by the temperature detection means; The display control device according to claim 1, wherein a correction value to be calculated is calculated. The storage means stores a plurality of types of tables corresponding to types of video signals, and the calculation means calculates a correction value by referring to a table corresponding to the types of input video signals. 3. The display control device according to 2. 3. The display control device according to claim 2, further comprising an operation unit that changes a phase correction table stored in the storage unit according to an operation. The display control device according to claim 1, wherein the temperature detecting means detects a temperature of a backlight of the display means in the display device. The calculating means corrects the phase of the synchronizing signal out of the control range of the PLL circuit for correcting a phase shift between the video signal processed by the first signal processing means and the synchronizing signal processed by the second signal processing means. The display control device according to claim 1, wherein a correction value to be calculated is calculated. Temperature setting means for giving a temperature change to the display device assembled in a predetermined process;
Phase shift measuring means for measuring the phase shift between the phase of the video signal and the phase of the synchronization signal input from the signal generating means to the display device in accordance with a temperature change in the display device,
An apparatus for manufacturing a display device, comprising: a storage control unit that stores a phase correction table for correcting a phase shift with respect to a temperature change measured by the phase shift measuring unit in a nonvolatile storage unit of the display device.

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