JP6574632B2 - Display driver - Google Patents

Description

  The present invention relates to a display driver that drives a display device in accordance with a video signal.

  For example, a liquid crystal display device as a display device includes a liquid crystal display panel and a display driver that supplies a gradation voltage corresponding to the luminance level of each pixel based on a video signal to the liquid crystal display panel. As one of the tests prior to product shipment for such a display driver, each gradation voltage corresponding to each pixel of one horizontal hysteresis line has an appropriate voltage value corresponding to the gradation for each gradation. A gradation test is performed to test whether or not the image is being processed.

  In the gradation test, the display driver is operated by the test data sent from the tester, and at this time, each gradation voltage output through each output channel of the display driver is measured by the tester (for example, Patent Documents). 1).

JP 2007-65538 A

  By the way, according to such a test method, the number of test data patterns to be prepared on the tester side is the result of the number of luminance gradations × the number of output channels. Therefore, the number of test data patterns prepared on the tester side becomes enormous with the increase in screen size and definition of the liquid crystal display device. In addition, since the number of output channels to be tested and the number of luminance gradations differ depending on the specifications of the display driver to be tested, it is necessary to prepare dedicated test data for each display driver specification.

  Therefore, an object of the present invention is to provide a display driver that can facilitate a test before product shipment.

The display device driver according to the present invention is a display driver that outputs a plurality of drive voltages for driving the display device according to a video signal, and specifies the number of output channels of the drive voltage to be tested. information, and a storage unit to store the number of tones designation information designating the number of luminance gradation to be tested, the input of the test signal, the number of channels specified information stored in the storage unit and the floor based on the tone number specifying information, test data piece indicating the gradation in the luminance gradation number of the tone number specifying information, for each tone, the test generating the number of the output channel number of the number of channels designating information A data selector that selects one of the pixel data pieces each indicating the luminance gradation of each pixel based on the video signal, and the generated test data pieces; Serial converts the gradation voltage to a side selected by the data selector among the pixel data pieces and the test data pieces, having a voltage conversion output portion for outputting the driving voltage having the gradation voltages.

  According to the display driver of the present invention, at the time of testing, the display driver specifications (the number of luminance gradations and the number of output channels) are based on the gradation number designation information and the channel number designation information stored in the display driver. Corresponding test data is automatically generated in the display driver. Therefore, it is not necessary to prepare dedicated test data corresponding to various specifications of the display driver on the tester side, and the test before product shipment can be facilitated.

It is a figure which shows schematic structure of the display apparatus 100 containing the display driver which concerns on this invention. 2 is a block diagram showing an internal configuration of a data driver 13. FIG. It is a time chart which shows the outline | summary of a gradation test. It is a time chart which shows the test operation | movement in each of the 1st and 2nd gradation test process GT1 and GT2. It is a figure which shows the connection form of the tester 200 and the data driver 13 used as a test object. 6 is a block diagram illustrating another example of the internal configuration of the data driver 13. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a display device 100 including a display driver according to the present invention. In FIG. 1, the display device 20 is composed of, for example, a liquid crystal or an organic EL panel. The display device 20 includes m horizontal scanning lines S _{1 to} S _m (m is a natural number of 2 or more) extending in the horizontal direction of the two-dimensional screen, and n (n is a vertical extension of the two-dimensional screen). (Natural numbers of 2 or more) data lines D _{1 to} D _n are formed. Display cells that carry pixels are formed at the intersections of the horizontal scanning lines and the data lines. The horizontal scanning lines S _{1 to} S _m of the display device 20 are connected to the scanning driver 12, and the data lines D _{1 to} D _n are connected to the data driver 13.

  The drive control unit 11 detects a horizontal synchronization signal from the video signal VD and supplies it to the scanning driver 12. Further, the drive control unit 11 generates a series of pixel data PD that represents the luminance level of each pixel in, for example, an 8-bit luminance gradation based on the video signal VD, and supplies the generated data to the data driver 13.

The scan driver 12 sequentially applies a horizontal scan pulse to each of the horizontal scan lines S _{1 to} S _m of the display device 20 at a timing synchronized with the horizontal synchronization signal supplied from the drive control unit 11.

The data driver 13 is formed on a semiconductor IC (integrated circuit) chip. When the test signal TES supplied from the outside of the semiconductor IC chip indicates the normal mode, the data driver 13 outputs the pixel data PD supplied from the drive control unit 11 for one horizontal scanning line, that is, every n. The pixel drive voltages G _{1 to} G _n having gradation voltages corresponding to the luminance gradations indicated by the pixel data PD are converted. Then, the data driver 13 applies the pixel drive voltages G _{1 to} G _n to the data lines D _{1 to} D _n of the display device 20. That is, the data driver 13 supplies the pixel drive voltages G _{1 to} G _n to the data lines D _{1 to} D _n of the display device 20 through n output channels, respectively.

On the other hand, when the test signal TES indicates the test mode, the data driver 13 executes a self-fault diagnosis test (described later). In the self-fault diagnosis test, the data driver 13 changes the polarity of the gradation voltage from the positive electrode to the negative electrode or from the negative electrode to the positive electrode based on the polarity switching signal POL supplied from the outside. In this self-failure diagnosis test, the data driver 13 outputs pixel drive voltages G _{1 to} G _n generated based on test data (described later) in accordance with a data load signal LN supplied from the outside. .

  FIG. 2 is a block diagram showing the internal configuration of the data driver 13. In FIG. 2, the register 130 stores in advance channel number designation information CN for designating the number of output channels to be tested and tone number designation information GN for designating the number of luminance gradations to be tested. .

For example, when all n output channels corresponding to the pixel driving voltages G _{1 to} G _n are to be tested, channel number designation information CN indicating “n” is stored in the register 130 in advance. On the other hand, when the first to Kth gradations represented by the gradation number K (K is an integer of 2 or more) as the number of luminance gradations are to be tested, the gradation number designation information indicating “K”. GN is stored in the register 130 in advance. For example, when the pixel data piece represents 256 levels of luminance with 8 bits, "256", and when the pixel data piece represents 6 levels with 64 levels of luminance, the number of gradations indicating "64" The designation information GN is stored in the register 130 in advance.

  The register 130 supplies the channel number designation information CN and the gradation number designation information GN stored as described above to the test data generation unit 131.

  For example, when the test signal TES is in a logic level 1 state indicating the test mode, the test data generation unit 131 determines the luminance for each pixel as test data based on the channel number designation information CN and the gradation number designation information GN. A series of test data TD representing gradation is generated, and the series of test data TD is sent to the data selector 132.

  That is, the test data generation unit 131 corresponds to the first to Kth gradations shown in FIG. 3 based on the gradation number designation information GN that designates the gradation number K, respectively. Test processes GT1 to GT (K) are sequentially executed. For example, when the number of gradations K indicates “256”, the test data generation unit 131 sequentially executes the first to 256th gradation test steps GT1 to GT256. For example, when the number of gradations K indicates “64”, the test data generation unit 131 sequentially executes the first to 64th gradation test steps GT1 to GT64.

  The test data generation unit 131 outputs the test data TD representing the value of the gradation in each of the first to Kth gradation test steps GT1 to GT (K) designated by the channel number designation information CN. The number of channels is repeatedly generated, and the generated series of test data TD is sent to the data selector 132.

  In other words, the test data generation unit 131 assigns the test data piece (TD) representing each gradation based on the number of gradations specified by the gradation number designation information (GN) to the above-described channel number designation for each gradation. Only the number of output channels specified in the information (CN) is generated.

  Furthermore, in each of the first to Kth gradation test steps GT1 to GT (K), the test data generation unit 131 has not completed the transmission of the test data over the period during which the test data TD is transmitted. A ready signal RDY having a logic level 0 indicating that is output to the outside. In each of the first to K-th gradation test steps GT1 to GT (K), the test data generation unit 131 is ready to become a logic level 1 for a predetermined period each time the test data TD is completely transmitted. The signal RDY is output to the outside.

  Note that the test data generation unit 131 enters an operation stop state when the test signal TES indicates the normal mode.

  The data selector 132 selects the one corresponding to the test signal TES from among the series based on the test data TD sent from the test data generation unit 131 and the series of pixel data PD supplied from the drive control unit 11, This is supplied to the data fetch unit 133. That is, when the test signal TES indicates the normal mode, the data selector 132 selects the series of pixel data PD supplied from the drive control unit 11 and supplies the selected series of pixel data PD to the data capturing unit 133. To do. On the other hand, when the test signal TES indicates the test mode, the data selector 132 selects a series of test data TD and supplies the selected series of test data TD to the data capturing unit 133.

The data capturing unit 133 sequentially captures a series of pixel data PD or a series of test data TD supplied from the data selector 132. The data capturing unit 133 captures n pieces of data (PD or TD) each time the capturing of n pieces of pixel data PD or test data TD for one horizontal scanning line, that is, all output channels is completed. The pixel data R _{1 to} R _n are supplied to the data latch unit 134.

When the test signal TES indicates the normal mode, the data latch unit 134 takes in the pixel data R _{1 to} R _n at different timings, and performs gradation voltage conversion as the pixel data Q _{1 to} Q _n at the timings of taking in the pixel data R _{1 to} R _n , respectively. To the unit 133. When the test signal TES indicates the test mode, the data latch unit 134 takes in the pixel data R _{1 to} R _n at different timings according to the externally supplied data load signal LN, and takes in each of them. gradation voltage converter 133 supplies the gradation voltage conversion unit 133 as pixel data Q ₁ to Q _n at the timing the pixel data Q ₁ to Q _n supplied from the data latch unit 134, indicated by the pixel data Q Are converted to positive gradation voltages P _{1 to} P _n having a positive voltage value corresponding to the luminance gradation. Further, the gradation voltage converter 133 converts each of the pixel data Q _{1 to} Q _n into a negative gradation voltage N ₁ having a negative voltage value corresponding to the luminance gradation indicated by the pixel data Q. to convert to ~N _n.

The gradation voltage conversion unit 133 supplies positive gradation voltages P _{1 to} P _n and negative gradation voltages N _{1 to} N _n to the polarity switching unit 136.

When the test signal TES indicates the normal mode, the polarity switching unit 136 alternately switches the positive gradation voltages P _{1 to} P _n and the negative gradation voltages N _{1 to} N _n at a predetermined cycle. selected, to the output unit 137 a better choice as the gradation voltages a ₁ to a _n. On the other hand, when the test signal TES indicates the test mode, the polarity switching unit 136 determines the positive gradation voltages P _{1 to} P _n and the negative gradation voltage according to the polarity switching signal POL supplied from the outside. n ₁ while selecting the one of the to n _n, and supplies the output unit 137 a better choice as the gradation voltages a ₁ to a _n.

The output unit 137 sends the pixel driving voltage G ₁ ~G _n obtained gray scale voltages A ₁ to A _n, respectively and separately amplified.

  Hereinafter, a gradation test performed on the data driver 13 after manufacture and before product shipment will be described. In performing the gradation test, as shown in FIG. 5, the tester 200 is connected to the data driver 13 to be tested.

  First, as shown in FIG. 3, the tester 200 supplies a test signal TES having a logic level 1 indicating a test mode to the data driver 13. In response to the test signal TES, the test data generation unit 131 generates a series of test data TD based on the channel number designation information CN and the gradation number designation information GN stored in the register 130. That is, the test data generation unit 131 corresponds to each of the first to Kth gradation test steps GT1 to GT (K) shown in FIG. 3 corresponding to the gradation number K designated by the gradation number designation information GN. Thus, the test data TD representing the gradation value is repeatedly generated for the number of output channels designated by the channel number designation information CN stored in the register 130.

  For example, when the channel number designation information CN indicating “n”, which is the number of all output channels of the data driver 13, is supplied, the test data generation unit 131, for example, in the first gradation test process GT1, FIG. As shown, a series of n test data TDs representing the first gradation represented by 8-bit data [00] h is generated and sent to the data selector 132. Further, for example, in the second gradation test step GT2, as shown in FIG. 4, the test data generation unit 131 continuously includes n pieces of test data TD in which the second gradation is represented by 8-bit data [01] h. A series to be generated is generated and sent to the data selector 132.

During this time, the data selector 132 sequentially supplies a series of test data TD to the data fetch 133 according to the test signal TES of the logic level 1 indicating the test mode. Therefore, in each of the gradation test step GT1~GT of the first to K (K), data acquisition 133 captures a sequence of n test data TD, the data latch section as the pixel data R ₁ to R _n 134.

  Further, the test data generation unit 131, in each of the gradation test processes GT1 to GT (K), for example, as shown in FIG. When the transmission is completed, a ready signal RDY that becomes a logic level 1 only for a predetermined period TP is supplied to the tester 200.

  As shown in FIG. 4, the tester 200 changes from the logic level 0 state to the logic level 1 when the ready signal RDY transitions from the logic level 0 to the logic level 1 as shown in FIG. 4 in each of the gradation test steps GT1 to GT (K). The transition data load signal LN is supplied to the data driver 13. Further, the tester 200 has the logic level 0 in the period TSP1 when the period TP in which the ready signal RDY is in the logic level 1 is divided into the first period TSP1 and the subsequent second period TSP2. In the period TSP2, the polarity switching signal POL having the logic level 1 is supplied to the data driver 13.

Therefore, for example, in the first gradation test step GT1, as shown in FIG. 4, the data driver 13 responds to the data load signal LN and the first gradation ([00] h) indicated by the test data TD. N pixel drive voltages G _{1 to} G _n having grayscale voltage values corresponding to are output. At this time, the data driver 13 outputs pixel drive voltages G _{1 to} G _n having a positive gradation voltage in the period TSP1 shown in FIG. 4 and a negative gradation in the period TSP2 based on the polarity switching signal POL. Pixel drive voltages G _{1 to} G _n having voltages are output.

Therefore, the tester 200 takes in the positive pixel drive voltages G _{1 to} G _n corresponding to the first to n-th output channels in the period TSP1 of the first gradation test process GT1, and outputs the output for each output channel. Then, it is determined whether or not the voltage value of the pixel driving voltage G has an appropriate positive polarity gradation voltage value corresponding to the first gradation ([00] h). Subsequently, the tester 200 takes in the negative pixel drive voltages G _{1 to} G _n corresponding to the first to n-th output channels in the period TSP2, and the voltage value of the pixel drive voltage G for each output channel. Is determined to have an appropriate negative gradation voltage value corresponding to the first gradation ([00] h).

  The tester 200 and the data driver 13 repeatedly perform the same operation as that in the first gradation test process GT1 in each of the gradation test processes GT2 to GT (K).

  Therefore, in the first to Kth gradation test steps GT1 to GT (K) described above, appropriate positive electrodes corresponding to the first to Kth gradations individually for each output channel of the data driver 13. A gradation test is performed to determine whether or not a pixel driving voltage G having negative and negative gradation voltage values is obtained.

  As described above, in the data driver 13, the test data generation unit 131 formed in the data driver 13 automatically generates test data representing each gradation in accordance with the test signal TES supplied from the outside. A gradation test is executed based on the test data. This eliminates the need for preparing test data on the tester 200 side, thereby facilitating the test.

  Further, the data driver 13 has, as a test target when performing a gradation test, gradation number designation information GN that designates the number of luminance gradations, and channel number designation information CN that designates the number of output channels of the pixel drive voltage. Is stored. The test data generation unit 131 first reads the gradation number designation information GN and the channel number designation information CN from the register 130 in response to the test signal TES indicating the test mode. Then, the test data generation unit 131 converts a test data piece (TD) indicating each gradation based on the number of luminance gradations designated by the gradation number designation information GN into the channel number designation information CN for each gradation. The number of output channels specified is automatically generated.

  For example, when the luminance gradation number designated by the gradation number designation information GN is “256” and the output channel number designated by the channel number designation information CN is “1440”, the test data generation unit 131 In each of the first to 256th gradation test steps GT1 to GT256, a series of test data pieces in which 1440 test data TDs representing the gradation are continuous is generated. For example, when the luminance gradation number designated by the gradation number designation information GN is “64” and the output channel number designated by the channel number designation information CN is “960”, the test data generation unit 131 In each of the first to 64th gradation test steps GT1 to GT64, a series of test data pieces in which 960 pieces of test data TD representing the gradation are continuous is generated.

  Therefore, according to the above-described configuration, if the information (CN, GN) specifying the number of output channels to be tested and the number of luminance gradations is stored in the register 130, the specification of the data driver 13 in the test mode. Test data corresponding to (the number of luminance gradations and the number of output channels) is automatically generated in the data driver 13. Therefore, it is not necessary to prepare dedicated test data corresponding to the specifications of the data driver (the number of luminance gradations and the number of output channels), so that it is possible to facilitate the test before product shipment.

  In the above-described embodiment, a series of test data TD for one horizontal scanning line, that is, the number of output channels is supplied to the data fetch unit 133 in a serial form via the data selector 132. However, the test data TD corresponding to the number of output channels may be supplied to the data latch unit 134 in parallel without using the data fetch unit 133.

  FIG. 6 is a block diagram showing another example of the internal configuration of the data driver 13 made in view of this point.

  6 employs a test data generation unit 141 instead of the test data generation unit 131 shown in FIG. 2, and employs a data selector 142 instead of the data selector 132 shown in FIG. At this time, the operations of the register 130, the data latch unit 134, the gradation voltage conversion unit 135, the polarity switching unit 136, and the output unit 137 shown in FIG. 6 are the same as those shown in FIG.

In FIG. 6, the data capturing unit 133 sequentially captures the series of pixel data PD supplied from the drive control unit 11. The data fetching unit 133 sets the fetched n pieces of data (PD) as pixel data R _{1 to} R _n to the data selector 142 every time when fetching n pieces of pixel data PD for one horizontal scanning line is completed. Supply.

When the test signal TES indicates the test mode, the test data generation unit 141 represents the luminance gradation as the test data based on the channel number designation information CN and the gradation number designation information GN stored in the register 130. Generate test data. The test data generation operation based on the channel number designation information CN and the gradation number designation information GN is the same as the operation in the test data generation unit 131 described above. The test data generation unit 141 supplies the generated test data to the data selector 142 as test data TD _{1 to} TD _n for every n output channels specified by the channel number specification information CN, for example, n. At this time, the test data generation unit 141 sends the test data TD _{1 to} TD _{n to} the data selector 142 at different timings.

As a result, the timing of the operating current that flows into the data selector 142 with the supply of the test data TD _{1 to} TD _n is temporally dispersed, so that it is possible to suppress noise that is generated when the operating current flows simultaneously. It becomes.

Here, the test data generating unit 141, the number of output channels (e.g., n) of each logic level 0 during a period in which sends the test data TD ₁ ~TD _n number output channels, the test data TD ₁ ~ When transmission of TD _n is completed, a ready signal RDY having a logic level 1 is output to the outside.

  Note that the test data generation unit 131 enters an operation stop state when the test signal TES indicates the normal mode.

The data selector 142 responds to the test signal TES from the test data TD _{1 to} TD _n sent from the test data generation unit 141 and the pixel data R _{1 to} R _n supplied from the data fetch unit 133. The selected one is supplied to the data latch unit 134. That is, the data selector 142 selects and supplies the pixel data R _{1 to} R _n to the data latch unit 134 when the test signal TES indicates the normal mode. On the other hand, when the test signal TES indicates the test mode, the data selector 142 selects the test data TD _{1 to} TD _n and supplies it to the data latch unit 134.

  As described above, in the configuration shown in FIG. 6, the test data generation unit 141 generates a plurality of test data TD for the number of output channels specified by the channel number specification information CN in parallel form.

  Therefore, when the configuration shown in FIG. 6 is adopted, the test data transfer period in the serial form to the data fetch unit 133 and the data fetch unit required when the configuration shown in FIG. 2 is adopted. The data acquisition period at 133 is not necessary. Therefore, when the configuration shown in FIG. 6 is adopted, the test period spent for the gradation test can be shortened compared to the case where the configuration shown in FIG. 2 is adopted.

  In the above-described embodiment, the channel number designation information CN and the gradation number designation information GN are stored in the register 130 serving as a storage unit. The channel number designation information CN and the gradation number designation information GN are stored in the fuse type. You may make it memorize | store in non-volatile memory | storage parts, such as PROM (Programmable Read Only Memory).

In short, as a display driver (13) that outputs a plurality of drive voltages (G _{1 to} G _n ) for driving the display device (20) according to the video signal (VD), the following storage unit (130), test data generation As long as it has a unit (131, 141), a data selector (132, 142), and a voltage conversion output unit (135, 137), it suffices.

  That is, the storage unit stores channel number designation information (CN) for designating the number of output channels to be tested, and tone number designation information (GN) for designating the number of luminance gradations to be tested. . The test data generation unit generates a test data piece (TD) indicating each gradation based on the number of luminance gradations specified by the gradation number designation information stored in the storage unit in accordance with the test signal (TES). For each gradation, the number of output channels specified by the channel number specification information is generated. The data selector selects one of the pixel data piece (PD) indicating the luminance gradation of each pixel based on the video signal and the above-described test data piece. The voltage conversion output unit converts the one selected by the data selector into a gradation voltage, and outputs a drive voltage having the gradation voltage.

  Therefore, according to such a configuration, in the test mode, the specification of the display driver (the number of luminance gradations, the number of luminance gradations, and the number of channel designation information stored in the storage unit provided in the display driver). Test data corresponding to the number of output channels) is automatically generated in the display driver. Therefore, it is not necessary to prepare dedicated test data corresponding to various specifications of the display driver, and it is possible to facilitate the test before product shipment.

13 Data Driver 20 Display Device 100 Display Device 130 Register
131, 141 Test data generator
132, 142 Data selector

Claims (4)

A display driver that outputs a plurality of drive voltages for driving a display device according to a video signal,
A storage unit to store the number of tones designation information designating the number of luminance gradation of the channel number specifying information that specifies the number of output channels of said drive voltage to be tested, and a test target,
The input of the test signal, on the basis of the said number of channels specified information stored in the storage unit and the number of gradations designated information, test data piece indicating the gradation in the luminance gradation number of the tone number specifying information For each gradation, a test data generation unit that generates the number of output channels of the channel number designation information;
A data selector that selects one of pixel data pieces each indicating a luminance gradation of each pixel based on the video signal and the generated test data pieces;
A voltage conversion output unit for converting the pixel data piece and the test data piece selected by the data selector into a gradation voltage and outputting the driving voltage having the gradation voltage; A display driver characterized by   The display driver according to claim 1, wherein the test data generation unit sends each of the generated test data pieces to the data selector for each number of output channels indicated by the channel number designation information.   3. The display driver according to claim 2, wherein the test data generation unit sends the test data pieces of the number of output channels to the data selector at different timings for each number of the output channels.   4. The display driver according to claim 2, wherein the test data generation unit outputs a ready signal to the outside every time the test data piece is sent to the data selector for each number of output channels.