Patent Grant
9443481
The Present application claims priority from Japanese application JP 2013-145248 filed on Jul. 11, 2013, the content of which is hereby incorporated by reference into this application.
The present invention relates to a liquid crystal display driver integrated circuit (IC), and particularly to a liquid crystal display driver integrated circuit which is connected to a liquid crystal display panel with various resolutions and can be used suitably therefor.
In a liquid crystal display system, a liquid crystal display driver IC receives image data to be displayed from a host processor such as an application processor, and displays an image on the liquid crystal display panel, by controlling gate lines of the liquid crystal display panel and by driving source lines of the liquid crystal display panel. In general, the liquid crystal display driver IC has versatility so as to be suitable for a display panel with various sizes (resolutions), but recently the resolution of the display panel has been increased and it is required to be suitable for a resolution up to 4K×2K, Wide-Quad-XGA (WQXGA: 1600RGB×2560) or the like. Depending upon a tendency of a high resolution of the display panel, an amount of the image data transferred from the host processor is also increased.
For a data transfer from the host processor to the liquid crystal display driver IC, a high speed serial data communication such as a mobile industry processor interface/display serial interface (MIPI/DSI) is used. Here, the MIPI is a communication interface standard for mobile devices which is established by an MIPI alliance formed by a plurality of companies.
In JP-A-2013-054356, a display driver IC which is connected to an application host processor via a communication channel according to the MIPI/DSI is disclosed. The display driver IC, in accordance with a mode switching command, performs switching between a command mode in which image data of a still image is transferred to a display via a frame memory and a video mode in which image data of a moving image is transferred to the display by bypassing the frame memory.
In JP-A-2002-311913, a liquid crystal display device that increases the number of ports of the display data supplied to a liquid crystal display module and a format degree of freedom and that enables test data to be combined, is disclosed. The liquid crystal display device relates to a timing controller circuit which simultaneously operates in parallel by dividing a driver group of the liquid crystal display device into a left half quantity and a right half quantity on a screen. The liquid crystal display device converts the display data of various formats of multiple ports from a display digital data output unit into the display data of the multiple ports divided into the data of the left half quantity and the right half quantity of the screen in a memory, the display data is selectively output by an input selection circuit, and thus it is possible to correspond to various display data.
The present inventor has reviewed JP-A-2013-054356 and JP-A-2002-311913 and found that there were the following new problems.
First, it was found that, in order to adapt to a resolution improvement of a display panel, there is concern about an insufficient band-width of data transfer of the MIPI/DSI described in, for example, JP-A-2013-054356. WQXGA is a resolution of 1600 RGB×2560 lines, and 4K×2K is configured by approximately 4000 pixels×2000 lines, in most cases, by 4096×2160. When image data with 24 bits of three colors of 8 bit×RGB is assigned to each pixel and the image data of the moving image is transferred by 30 fps (30 frames per second: 30 frame/s), a necessary transfer rate becomes 4096×2160×24×30=5.93 Gbps. The MIPI/DSI includes one clock lane and a maximum of four data lanes, and implements a data transfer amount of 1 Gbps/lane, and accordingly, a band-width of the data transfer performed by one port which is configured by one clock lane and four data lanes, is 4 Gbps. For this reason, one port is insufficient. As a countermeasure against this, it is also possible to take an option to increase a transfer speed per lane, but there is a limit in bandwidth expansion because there are problems in which it is difficult to realize a circuit with good high-frequency characteristics and electromagnetic radiation is deteriorated.
Thus, the present inventor has reviewed a liquid crystal display driver IC in which a plurality of ports are mounted. A technology of making parallel communication channels for expanding the band-width of the data transfer is used routinely for a communication between ICs, but in order to employ the technology in the liquid crystal display device, the following problems to be solved are found in the liquid crystal display driver IC.
Since the host processor or the display panel to be connected is not limited to one type in the liquid crystal display driver IC, it is necessary to have versatility. For example, it is preferable that the size of the display panel to be connected be set so as to be able to be freely selected from various sizes to some degree. In addition, in this case, it is preferable that the band-width required for the data transfer between the liquid crystal display driver IC and the host processor can also be changed. For example, it is preferable that the number of communication channels which perform parallel operation be variably set.
The liquid crystal display driver IC has a function of outputting the input image data to the display panel by left-right reversing, but it is preferable that the same function be implemented even in a case of the parallel communication channels.
In the technology described in JP-A-2002-311913, in order to increase the number of ports of the display data and the format degree of freedom, the data input from the multiple ports of the display data is temporarily stored in the memory, and then is read out to an appropriate output port. It is assumed that the memory is used in this technology, but there is no guarantee that the memory is allowed to be embedded in a general liquid crystal display driver IC in view of a chip cost.
Units used for solving such a problem are described as follows, but other problems and new features will be apparent from the description of the present specification and the accompanying drawings.
The present invention is as follows.
A liquid crystal display driver IC according to the present invention is configured to be able to connect to a host processor and a plurality of communication channels, and is configured to be able to drive a plurality of source lines of a display panel, and drive the source lines of the display panel based on the image data supplied from the host processor via the communication channels. The liquid crystal display drive IC includes a plurality of communication interface circuits, a plurality of driving circuits which drive the plurality of source lines, and a selector circuit. The selector circuit can select to which one of the plurality of driving circuits each of a plurality of image data outputs respectively received from a plurality of communication interface circuits is supplied.
An advantage obtained by the present invention can be simply described as follows.
That is, the liquid crystal display driver IC according to the present invention can have versatility with regard to the number of parallel communication channels which are connected to the host processor and the resolution of a drivable display panel, without damaging a function of left-right reversing the display image. Furthermore, it is possible to configure even a liquid crystal display driver IC without an embedded memory for sorting the display data, and to reduce chip cost.
First, summary of representative embodiments of the invention disclosed in the application will be described. Reference numerals in drawings in parentheses referred to in description of the summary of the representative embodiments just denote components included in the concept of the components to which the reference numerals are designated.
[1]<Selector Between DSI Port and Source Line Output>
A liquid crystal display driver IC (10) according to the present invention is configured to be able to connect to a host processor (30) and a plurality of communication channels (31), and is configured to be able to drive a plurality of source lines (22, for example S1 to S2400 when a display panel 20 is WQGXA) of the display panel (20). The liquid crystal display driver IC drives the source lines of the display panel based on image data which is supplied from the host processor via the communication channel.
The liquid crystal display driver IC is connected to a plurality of communication interface circuits (3_1 to 3_m) which can be connected to the plurality of communication channels, a plurality of driving circuits (6_1 to 6_n) which drive each of the plurality of source lines, and each input of the plurality of driving circuits. The liquid crystal display driver IC includes a plurality of latches (5_1 to 5_n) that retain the data which is supplied to each driving circuit, and a first selector circuit (1). The first selector circuit is configured in such a manner that it can be selected to which one of the plurality of latches each of a plurality of image data outputs respectively received from the plurality of communication interface circuits is supplied.
As a result, the liquid crystal display driver IC according to the present invention can have versatility with regard to the number of parallel communication channels which are connected to the host processor and the resolution of a drivable display panel, without damaging a function of left-right reversing a display image. That is, it is possible to freely configure transfer channels of the image data from the required number of communication interface circuits among the plurality of communication interface circuits to the driving circuits for driving source lines at desired positions, and it is possible to freely relate the number of communication interface circuits being used, that is, the number of ports, and the number and position of the source lines being driven.
[2]<Pixel Data Counter>
In section 1, the liquid crystal display driver IC (10) according to one embodiment of the present invention further includes a pixel data counter (7) which counts the number of pieces of pixel data output from at least one communication interface circuit among the plurality of communication interface circuits. The first selector circuit is configured in such a manner that a supply relationship of the image data between the communication interface and the latch can be changed, based on a count value of the pixel data counter.
As a result, even in a case where the number of communication interfaces used for obtaining a required bandwidth is smaller than the number of communication interfaces which are included in the liquid crystal display driver IC, it is possible to select a position which is displayed in accordance with the input sequence, with regard to the image data received from the communication interface circuit connected to the pixel data counter.
For example, there is a case where the resolution of the connected display panel is low. In this case, the number of communication interfaces used for obtaining a required bandwidth is smaller than the number of communication interfaces which are included in the liquid crystal display driver IC. In addition, the number of source lines being driven is smaller than the number of driving circuits which are included in the liquid crystal display driver IC. In this way, in a case where the display panel with a low resolution is connected, it is possible to arbitrarily set the position of the driving circuit which is connected to the source line of the connected display panel.
In addition, for example, since the image data in the communication channel is data-compressed and then transferred, it is the same even in a case where the number of communication interfaces being used is smaller than the number of communication interfaces which are included in the liquid crystal display driver IC. In a case where the display panel with a low resolution is connected, it is possible to arbitrarily set the position of the driving circuit which is connected to the source line of the connected display panel.
[3]<Input Side Selector+Output Side Selector>
In section 1, the liquid crystal display driver IC (10) according to the one embodiment of the present invention further includes a second selector circuit (2), a plurality of video adapters (Slot_1 to Slot_m) (4_1 to 4_m), a command adaptor (9), and a control register (8).
The second selector is configured in such a manner that it can be selected to which video adaptor each of a plurality of image data outputs respectively received from the plurality of communication interface circuits is supplied among the plurality of video adaptors instead of the plurality of latches.
The plurality of video adaptors extracts the image data from the data received from the communication interface, and supplies the extracted image data to the first selector.
The command adaptor is connected to one video adaptor of the plurality of video adaptors, extracts a command from the data received from the communication interface, and sets a value based on the extracted command in the control register.
The first selector is configured to be able to select to which one of the plurality of latches each of the plurality of image data outputs respectively extracted by the plurality of video adaptors is supplied, based on the value set in the control register.
As a result, it is possible to freely switch a relationship between the communication channel through which the host processor transfers the command, and the video adaptor which can extract a command and reflect content thereof to the control register of the liquid crystal display driver IC. Even in a case where a positional relationship between the host processor and embedding of the liquid crystal display driver IC is rotated by 180°, a connection can be made without intersecting the communication channel.
[4]<Input Side Selector+Pixel Data Counter+Output Side Selector>
In section 3, the liquid crystal display driver IC (10) according to the one embodiment of the present invention further includes a pixel data counter (7) which counts the number of pieces of pixel data output from at least one video adaptor of the plurality of video adaptors. The first selector circuit is configured in such a manner that a supply relationship of the image data between the video adaptor and the latch can be changed, based on a count value of the pixel data counter.
As a result, it is possible to provide the liquid crystal display driver IC which obtains all the effects described in sections 2 and 3.
[5]<Designation of Communication Interface Circuit to which Command is Input by a Terminal>
In section 3 or 4, the liquid crystal display driver IC (10) according to the one embodiment of the present invention further includes one or more of a second selector control terminal (PIN_2).
The second selector circuit is configured in such a manner that from which communication interface circuit among the plurality of communication interface circuit the data is received and then supplied to the command adaptor, can be selected, based on the value set in a second selector control terminal.
As a result, it is possible to control the second selector so as to select communication channel through which the data including the command is transferred among the plurality of communication channels connected and to connect to the video adaptor connected to the command adaptor, by a fixed terminal embedded in the display panel, with respect to the liquid crystal display driver IC.
[6]<RAM>
In anyone of sections 1 to 5, the liquid crystal display driver IC (10) according to the one embodiment of the present invention further includes a memory (11) and a memory interface circuit (12). The memory interface circuit is configured in such a manner that it is possible to write the pixel data output from the plurality of communication interface circuits to the memory, to read out the written pixel data from the memory and to supply the read pixel data to the first selector circuit.
As a result, in the same manner as in the liquid crystal display driver IC in which a frame memory is embedded, it is possible to provide the liquid crystal display driver IC which obtains the effects described in sections 1 to 5.
[7]<Designation of the Connected Display Panel Performed by Command>
In any one of sections 1 to 6, the liquid crystal display driver IC (10) according to the one embodiment of the present invention further includes the command adaptor (9) and the control register (8) which includes a first selector control bit (F/B) with one or more bits.
The command adaptor is configured in such a manner that a value set on the basis of the command received from at least one communication interface circuit among the plurality of communication interface circuits can be written to the first selector control bit of the control register.
The first selector circuit selects to which one of the plurality of latches each of the plurality of image data respectively received from the plurality of communication interface circuits is supplied, based on the set value which is stored in the first selector control bit.
As a result, the host processor issues a command with respect to the liquid crystal display driver IC by using at least one of the plurality of communication channels, and thereby it is possible to perform a control suitable for a type such as the size (resolution) of the display panel connected to the liquid crystal display driver IC.
[8]<Designation of the Connected Display Panel Performed by Terminal>
In any one of sections 1 to 6, the liquid crystal display driver IC (10) according to the one embodiment of the present invention further includes one or more of a first selector control terminal (PIN_1).
The first selector circuit is configured to be able to select to which one of the plurality of latches each of the plurality of image data outputs respectively received from the plurality of communication interface circuits is supplied based on the value set in the first selector control terminal.
As a result, it is possible to perform a control suitable for a type such as the size (resolution) of the display panel connected to the liquid crystal display driver IC, by the fixed terminal embedded in the display panel.
[9]<Designation of the Connected Display Panel Performed by Command and Terminal>
In any one of sections 1 to 6, the liquid crystal display driver IC (10) according to the one embodiment of the present invention further includes the command adaptor (9), the control register (8) which includes the first selector control bit of one or more bits, and one or more of the first selector control terminal (PIN_1).
The command adaptor is configured in such a manner that the value set on the basis of the command received from at least one communication interface circuit of the plurality of communication interface circuits is written to the first selector control bit of the control register.
The first selector circuit selects to which one of the plurality of latches each of the plurality of image data outputs respectively received from the plurality of communication interface circuits is supplied, based on the set value which is stored in the first selector control bit and the value set in the first selector control terminal.
As a result, by combining the command issued from the host processor and a state of the first selector control terminal, it is possible to perform a control suitable for a type such as the size (resolution) of the display panel connected to the liquid crystal display driver IC.
[10]<Communication Channel According to MIPI/DSI>
In anyone of sections 1 to 9, the liquid crystal display driver IC (10) according to the one embodiment of the present invention is configured in such a manner that the communication channel includes one clock lane (CLKX_j; j=1 to 4) according to the MIPI/DSI standard and four data lanes (DATAXi_j; i=1 to 4 and j=1 to 4).
As a result, a plurality of ports according to the MIPI/DSI standard is included, and it is possible to provide the liquid crystal display driver IC which can be connected to the host processor.
[11]<Suspending Unused Communication Interface>
In section 1, the liquid crystal display driver IC (10) according to the one embodiment of the present invention can set a communication interface circuit which is not connected to the plurality of communication channels to a low power consumption state among the plurality of communication interface circuits.
As a result, it is possible to suppress unnecessary power consumption due to the unused communication interface circuit.
[12]<Suspending Unused Driving Circuit>
In section 1, the liquid crystal display driver IC (10) according to the one embodiment of the present invention can set a driving circuit which is not connected to the plurality of source lines among the plurality of driving circuits to the low power consumption state.
As a result, it is possible to suppress unnecessary power consumption due to the unused driving circuit.
An embodiment will be described in further detail.
The liquid crystal display driver IC 10 according to the present invention, although not particularly limited, is formed on a single semiconductor substrate of silicon or the like, using a technology of manufacturing, for example, a well-known Complementary Metal-Oxide-Semiconductor (CMOS) field effect transistor semiconductor integrated circuit. The liquid crystal display driver IC 10 can be connected in parallel with the host processor 30 by one or a plurality of communication channels, and based on the image data which is supplied from the host processor 30 via the communication channel, the plurality of source lines which are connected to the display panel 20 can be driven.
Since the liquid crystal display driver IC 10 can be connected in parallel using the plurality of communication channels, the plurality of ports Port_1 to Port_m are included. In each port, the plurality of communication interface circuits (DSI_1 to DSI_m) 3_1 to 3_m are provided, and each port is connected to the slots (Slot_1 to Slot_m) 4_1 to 4_m in which the data adaptors are embedded. Each signal which configures the ports is connected to the host processor 30 via the pads 13. In order to drive the plurality of source lines (for example S1 to S2400) of the connected display panel, the liquid crystal display driver IC 10 includes driving circuits 6_1 to 6_n and latches 5_1 to 5_n which retain input data thereof. Outputs of the driving circuits 6_1 to 6_n are connected to the display panel 20 via pads 14.
The liquid crystal display driver IC 10 according to the present invention includes a selector 1 which can control a selection of connection relation of the outputs of the slots (Slot_1 to Slot_m) 4_1 to 4_m and the latches 5_1 to 5_n which are connected to the driving circuits 6_1 to 6_n. The selector 1 performs a control of selecting to which one of the plurality of latches 5_1 to 5_n each of the plurality of image data outputs respectively received from the communication interface circuits (DSI_1 to DSI_m) 3_1 to 3_m which are provided in the plurality of ports Port_1 to Port_m is supplied. The selector 1 can be configured by, for example, m pieces of 1:n selection circuits (for example, crossbar switches). In addition, the n pieces of latches are divided into several groups, and the selector 1 can be configured to be able to select to which group the slot can supply the image data. According to the former, it is possible to improve a degree of freedom, and according to the latter, it is possible to suppress a circuit size of the selector 1 to a small size.
The number of source lines to be connected and driven is determined by the size or the resolution of the display panel 20 to be connected. Based on this, the driving circuits 6_1 to 6_n and the latches 5_1 to 5_n to be used are determined. In addition, by the size or the resolution of the display panel 20 to be connected, a band-width required for the data transfer at the time of the supply of the image data from the host processor 30 can be calculated, and thereby it is possible to calculate the number of communication channels to be used in parallel, that is, the number of ports from a data transfer quantity per communication channel of one system.
The communication channel of one system is configured to include one clock lane and four data lanes according to, for example, the MIPI/SDI standard. As a result, it is possible to configure the communication channel in such a manner that the liquid crystal display driver IC 10 can be connected to the host processor including the plurality of ports according to the MIPI/DSI standard.
By setting the unused communication interface circuit 3, the slot 4, the latch 5, and the driving circuit 6 to the low power consumption state, it is possible to decrease the power consumption of the liquid crystal display driver IC 10. The low power consumption state can be realized by a method such as decreasing a bias current which is supplied to the unused circuit, or stopping a power supply to the unused circuit.
The configuration example of the liquid crystal display device 100 which includes the liquid crystal display driver IC 10 according to the present invention will be described.
The liquid crystal display driver IC 10 is an example of a case where m=4 and n=2400 which are illustrated in
An operation of the liquid crystal display device 100 illustrated in
The image data displayed by the pixels of a total of 4800 pixels, which are the product of 1600 pieces and three colors of RGB, per line of the display panel 20, is referred to as R1 to R1600, G1 to G1600, and B1 to B1600. The image data of the total of 4800 pieces per line is divided into four groups, for example, ports 1 to 4 and is transferred in parallel. That is, the image data R1 to R400, G1 to G400, and B1 to B400 are transferred via the port Port_1, the image data R401 to R800, G401 to G800, and B401 to B800 are transferred via the port Port_2, the image data R801 to R1200, G801 to G1200, and B801 to B1200 are transferred via the port 3, and the image data R1201 to R1600, G1201 to G1600, and B1201 to B1600 are transferred via the port 4. The image data R1 to R400, G1 to G400, and B1 to B400 which are transferred via the port Port_1 are transferred to the slot 4_1 via the communication interface (DSI_1) 3_1, and are extracted as the image data from a communication packet by the data adaptor of the slot 4_1. The extracted image data R1 to R400, G1 to G400, and B1 to B400 are sequentially written in the latches 5_1 to 5_400 via the selector 1. The image data R1 to R400, G1 to G400, and B1 to B400 written to the latches 5_1 to 5_400 are converted into corresponding voltage levels by the driving circuits 6_1 to 6_400, and the sources lines S1 to S600 are driven by drive signals with the converted voltage levels.
In the example illustrated in
As described above, the selector 1 sequentially transfers the image data extracted from the slot 4_1 to the latches 5_1 to 5_400, and thereby the drive signals based on the image data R1 to R400, G1 to G400, and B1 to B400 which are received via the port Port_1 are output to the source lines S1 to S600. Also in the other ports, in the same manner as above, the selector 1 sequentially transfers the image data extracted from the slot 4_2 to the latches 5_401 to 5_800, and thereby the drive signals based on the image data R401 to R800, G401 to G800, and B401 to B800 which are received via the port Port_2 are output to the source lines S601 to S1200. The selector 1 sequentially transfers the image data extracted from the slot 4_3 to the latches 5_801 to 5_1200, and thereby the drive signals based on the image data R801 to R1200, G801 to G1200, and B801 to B1200 which are received via the port 3 are output to the source lines S1201 to S1800. Furthermore, the selector 1 sequentially transfers the image data extracted from the slot 4_4 to the latches 5_1201 to 5_1600, and thereby the drive signals based on the image data R1201 to R1600, G1201 to R1600, and B1201 to B1600 which are received via the port 4 are output to the source lines S1801 to S2400.
The image data R1 to R1600, G1 to G1600, and B1 to B1600 are image data which are arranged from left to right of one line. In the operation described above, the image data transferred from the host processor 30 are displayed as is without left-right reverse. In contrast, it is possible to display the image data by left-right reversing in the liquid crystal display driver IC 10. In order to left-right reverse, the selector 1 sequentially transfers the image data extracted from the slot 4_1 to the latches 5_1600 to 5_1201, and thereby the drive signals based on the image data R1 to R400, G1 to G400, and B1 to B400 which are received via the port Port_1 are output to the source lines S2400 to S1601. The image data R1, G1, and B1, which are displayed on a left end in a case of the above description in which the left-right reverse are not designated, is displayed on a right end of the display panel 20 when the left-right reverse is designated. The selector 1 sequentially transfers the image data extracted from the slot 4_4 to the latches 5_400 to 5_1, and thereby the drive signals based on the image data R1201 to R1600 G1201 to G1600, and B1201 to B1600 which are received via the port 4 are output to the source lines S400 to S1. The image data R1600, G1600, and B1600, which are displayed on the right end in a case of the above description in which the left-right reverse is not designated, are displayed on the left end of the display panel 20 when the left-right reverse is designated. Also in the two ports of the center portion, in the same manner as above, the selector 1 is controlled in such a manner that the image data is supplied to the latch 5 by being left-right reversed. The selector 1 sequentially transfers the image data extracted from the slot 4_2 to the latches 5_1800 to 5_1201, and thereby the drive signals based on the image data R401 to R800, G401 to G800, and B401 to B800 which are received via the port Port_2 are output to the source lines S1800 to S1201. The selector 1 sequentially transfers the image data extracted from the slot 4_3 to the latches 5_1200 to 5_601, and thereby the drive signals based on the image data R801 to R1200, G801 to G1200, and B801 to B1200 which are received via the port 3 are output to the source lines S600 to S1201.
As a result, by controlling the selector 1, it is possible to display the image data by reversing the left and right of the image, by maintaining as is the output ports or the output sequence of the image data output from the host processor 30.
An operation of the liquid crystal display device 100 illustrated in
The image data of a total of 4800 pieces per line are transferred by being divided into four groups in the example of
As described above, the selector 1 sequentially transfers the image data extracted from the slot 4_1 to the latches 5_1 to 5_1200, and thereby the drive signals based on the image data R1 to R800, G1 to G800, and B1 to B800 which are received via the port Port_1 are output to the source lines S1 to S1200. Also in the port Port_2, in the same manner as above, the selector 1 sequentially transfers the image data extracted from the slot 4_2 to the latches 5_1201 to 5_2400, and thereby the drive signals based on the image data R801 to R1600, G801 to G1600, and B801 to B1600 which are received via the port Port_2 are output to the source lines S1201 to S2400.
In contrast, in order to left-right reverse the displayed image, the selector 1 sequentially transfers the image data extracted from the slot 4_1 to the latches 5_2400 to 5_1201, and thereby the drive signals based on the image data R1 to R800, G1 to G800, and B1 to B800 which are received via the port Port_1 are output to the source lines S2400 to S1201. The selector 1 sequentially transfers the image data extracted from the slot 4_2 to the latches 5_1200 to 5_1, and thereby the drive signals based on the image data R801 to R1600, G801 to G1600, and B801 to B1600 which are received via the port Port_2 are output to the source lines S1200 to S1.
As a result, by controlling the selector 1, it is possible to display the image data by reversing the left and right of the image, by maintaining as is the output ports or the output sequence of the image data output from the host processor 30. In addition, the MIPI/DSI includes one clock lane and a maximum of four data lanes, and realizes a data transfer quantity of one Gbps/lane, and thus a band-width of the data transfer performed by one port which is configured by one clock lane and four data lanes is four Gbps. In contrast, when the WQXGA assigns the image data of 24 bits which are the product of eight bits and three colors of RGB for each pixel, in the resolution of 1600 RGB×2560 lines, and the image data of a moving image is transferred by 60 fps (60 frames per second: 60 frame/s), a necessary transfer rate becomes 1600×2560×24×60=5.49 Gbps. In this case, a connection of the host processor 30 with the liquid crystal display driver IC 10 is sufficient by using two ports. In the liquid crystal display driver IC 10 which includes three or more of the communication interfaces (DSI_1 to DSI_4) 3_1 to 3_4 and slots 4_1 to 4_4, in a case where only two ports are used as illustrated in
In the example illustrated in
An operation of the liquid crystal display device 100 illustrated in
The image data of a total of 4800 pieces per line are transferred in parallel by being divided into four groups in the example of
As described above, the selector 1 sequentially transfers the image data extracted from the slot 4_1 to the latches 5_1 to 5_600 and the latches 5_1801 to 5_2400, and thereby the drive signals based on the image data R1 to R800, G1 to G800, and B1 to B800 which are received via the port Port_1 are output to the source lines S1 to S1200 via the pads 14_1 and 14_4.
In contrast, in order to left-right reverse the displayed image, the selector 1 sequentially transfers the image data extracted from the slot 4_1 to the latches 5_2400 to 5_1201 and the latches 5_600 to 5_1 in reverse order to the above, and thereby the drive signals based on the image data R1 to R800, G1 to G800, and B1 to B800 which are received via the port Port_1 are output to the source lines S2400 to S1801 and S600 to S1.
As a result, by controlling the selector 1, it is possible to display the image data by reversing the left and right of the image, by maintaining as is the output ports or the output sequence of the image data output from the host processor 30.
As described above, the liquid crystal display driver IC 10 according to the present invention can have versatility with regard to the number of parallel communication channels which are connected to the host processor 30 and the resolution of the drivable display panel 20, without damaging a function of left-right reversing the display image. That is, it is possible to freely configure the transfer channels of the image data from the required number of communication interface circuits (DSI_1 to DSI_m) 3_1 to 3_m among the plurality of communication interface circuits to the driving circuits 6_1 to 6_n for driving source lines at desired positions, and it is possible to freely relate the number of communication interface circuits being used, that is, the number of ports, and the number and position of the source lines being driven.
A new problem which occurs in a case where the host processor 30 and the liquid crystal display driver IC 10 are connected in parallel by using the plurality of communication channels and which is found by the inventor of the present application will be described.
The host processor 30 generally transfers a control command to the liquid crystal display driver IC 10, controls an operation of the liquid crystal display driver IC 10 by setting an appropriate parameter in a control register provided therein, and in addition, monitors an operation state of the liquid crystal display driver IC 10 by reading out data from an internal status register. Such communication is implemented using the same communication channel, prior to the transfer of the image data, or by being time-shared with the transfer of the image data. In a case where the plurality of communication channels are provided in parallel between the host processor 30 and the liquid crystal display driver IC 10, the communication for the control described above may be implemented using only any one communication channel. At this time, the port through which the host processor 30 performs the communication for control is called a master port, and the other ports are called slave ports. In the liquid crystal display driver IC 10, it is necessary for the communication interface 3 connected to the master port to connect to the slot 4 which is configured to include not only the data adaptor which extracts the image data but also the command adaptor which can extract the control command described above. Such a port of the liquid crystal display driver IC 10 is set as port Port_1, and it is set so that the command adaptor is not connected to the other ports. It is generally considered that in the liquid crystal display driver IC 10, a series of pads 13 which are connected to the communication ports are arranged collectively in sequential order for each port at a side opposite to the side on which the pads 14 connected to the source lines are arranged. Hereinafter, an example of a case where the liquid crystal display driver IC 10 includes two communication ports will be described.
In contrast, it is considered that even in a combination of the liquid crystal display driver IC 10, the host processor 30, and the display panel 20 which are the same as above, the liquid crystal display driver IC 10 is mounted on the top side, which is a side opposite to the host processor 30, of the display panel 20.
If the slots 4 configured to include the command adaptors are connected only to the port Port_1 of the liquid crystal display driver IC 10, there is a problem that in a case of
A function of left-right reversing an arrangement of a plurality of arranged pads within a range of ports of one system is stipulated in MIPI/DSI, but a case where the plurality of ports is connected in parallel is not particularly considered.
In addition to the configuration of the liquid crystal display driver IC 10 illustrated in
Since the liquid crystal display driver IC 10 can be connected in parallel by using the plurality of communication channels, the liquid crystal display driver IC 10 includes the plurality of ports Port_1 to Port_m, and the communication interface circuits (DSI_1 to DSI_m) 3_1 to 3_m are provided in each port. The data adaptors are embedded in the slots (Slot_1 to Slot_m) 4_1 to 4_m, respectively, and the command adaptor 9 is further connected to the slot (Slot_1) 4_1 among the slots (Slot_1 to Slot_m) 4_1 to 4_m. The control register 8 is connected to the command adaptor 9, and differently from in the first embodiment, the liquid crystal display driver IC 10 includes an input side selector (SEL_2) 2 between the communication interface circuits (DSI_1 to DSI_m) 3_1 to 3_m and the slots (Slot_1 to Slot_m) 4_1 to 4_m. The input side selector 2 is configured to be able to select to which slot each of a plurality of image data outputs respectively received from the communication interface circuits (DSI_1 to DSI_m) 3_1 to 3_m is supplied, among the slots (Slot_1 to Slot_m) 4_1 to 4_m. Video adaptors embedded in the slots (Slot_1 to Slot_m) 4_1 to 4_m extract the image data from the received data and supply to the output side selector 1. The command adaptor 9 is connected to at least one, which is the slot (Slot_1) 4_1 in
The output side selector 1 is configured to be able to select to which one of the plurality of latches 5_1 to 5_n each of the plurality of image data outputs respectively extracted by the video adaptor embedded in the slots (Slot_1 to Slot_m) 4_1 to 4_m is supplied, based on the value (for example, F/B) set in the control register 8. In addition to the value (for example, F/B) set in the control register 8, a control signal which performs a selection control of the output side selector 1 may be supplied from a terminal PIN_1 of the liquid crystal display driver. IC 10.
By providing the input side selector 2, it is possible to freely switch a relationship between the communication channel through which the host processor 30 transfers the command, and the video adaptor 9 which can extract the command and reflect the content of the command in the control register 8 of the liquid crystal display driver IC 10. Even in a case where a positional relationship for embedding between the host processor 30 and the liquid crystal display driver IC 10 is rotated by 180°, it is possible to connect without intersection of the communication channels using, for example, the flexible printed circuit board.
The input side selector 2 is configured to be able to select to which slot the data received from one of the communication interface circuits (DSI_1 to DSI_m) 3_1 to 3_m is supplied among the slots (Slot_1 to Slot_m) 4_1 to 4_m, based on the value set in the terminal PIN_2. As a result, by fixing the terminal when embedded in the display panel 20, a communication channel through which the data including the commands from the plurality of communication channels connected to the liquid crystal display driver IC 10 is transmitted is selected, and thereby the input side selector 2 can be controlled so as to be connected to the slot which is connected to the command adaptor.
The liquid crystal display driver IC 10 includes two ports Port_1 and Port_2, and the communication interface circuits (DSI_1 and DSI_2) 3_1 and 3_2 are provided to each port. The slots 4_1 and 4_2 embed data adaptors, respectively, and the command adaptor 9 is further connected to the slot 4_1 of the slots 4_1 and 4_2, and the control register 8 is connected to the command adaptor 9. The input side selector 2 is provided between the communication interface circuits (DSI_1 and DSI_2) 3_1 and 3_2 and the slots 4_1 and 4_2, and by the terminal PIN_2, it is controlled so as to select which one of the communication interface circuits (DSI_1 and DSI_2) 3_1 and 3_2 is connected to the slot 4_1 to which the command adaptor 9 is connected. Since it is clear at a design step that which one of the two ports Port_1 and Port_2 is a port which enables the master port of the host processor 30 to be connected to the flexible printed circuit board without intersecting with each other or the like, a value of logic fixing of the terminal PIN_2 is designated at the step.
In the same manner as exemplified so far, the liquid crystal display driver IC 10 includes 2400 pieces of output pads 14, 2400 pieces of driving circuits 6, and 2400 pieces of latches 5, in such a manner that, for example, 2400 pieces of source lines can be driven. In
As a result, even in a case where the number of communication interfaces used for obtaining a necessary band-width is smaller than the number of communication interfaces included in the liquid crystal display driver IC 10, it is possible to select a position to be displayed according to the sequence being input with regard to the image data received from the communication interface circuit (slot (Slot_1) 4_1 in
For example, there is a case where the resolution of the connected display panel is low. In this case, the number of communication interfaces used for obtaining the necessary band-width is smaller than the number of communication interfaces included in the liquid crystal display driver IC 10. In addition, the number of source lines to be driven is smaller than the number of the driving circuits included in the liquid crystal display driver IC 10. In this way, in a case where the display panel with a low resolution is connected, it is possible to arbitrarily set the position of the driving circuit connected to the source line of the connected display panel.
For example, in the same manner as that of the liquid crystal display device 100 exemplified in
A different effect according to the provided pixel data counter 7 will be described. It is similar even in a case where in order to compress to transmit the image data over the communication channel, the number of the used communication interface circuits is smaller than the number of the communication interfaces included in the liquid crystal display driver IC. In a case where the resolution of the connected display panel 20 is low, the degree of freedom of selection of the used output pads can be improved.
In the same manner as described in the second embodiment, by fixing the terminal PIN_2 when embedded in the display panel 20, a communication channel through which the data including the commands from the communication channels of two systems connected to the liquid crystal display driver IC 10 is transmitted is selected, and thereby the input side selector 2 can be controlled so as to be connected to the slot (Slot_1) 4_1 which is connected to the command adaptor. As a result, even in a case where a positional relationship for embedding between the host processor 30 and the liquid crystal display driver IC 10 is rotated by 180°, it is possible to connect without intersection of the communication channels using, for example, the flexible printed circuit board.
When F/B=0 at PIN_2=0 and PIN_1=0, the image data input from the communication interface circuit (DSI_1) 3_1 is written to the latch 5_1 via the slot (Slot_1) 4_1, and the image data input from the communication interface circuit (DSI_2) 3_2 is written to the latch 5_2 via the slot (Slot_2) 4_2. When the F/B bit which performs the left-right reversing equals “1” (F/B=1), the output side selector 2 is switched, and thereby the image data input from the communication interface circuit (DSI_1) 3_1 is written to the latch 5_2 via the slot (Slot_1) 4_1, and the image data input from the communication interface circuit (DSI_2) 3_2 is written to the latch 5_1 via the slot (Slot_2) 4_2. In contrast, when F/B=0 at PIN_2=1 and PIN_1=0, the image data input from the communication interface circuit (DSI_2) 3_2 is written to the latch 5_1 via the slot (Slot_1) 4_1, and the image data input from the communication interface circuit (DSI_1) 3_1 is written to the latch 5_2 via the slot (Slot_2) 4_2. When the F/B bit which performs the left-right reversing equals “1” (F/B=1), the output side selector 2 is switched, and thereby the image data input from the communication interface circuit (DSI_2) 3_2 is written to the latch 5_2 via the slot (Slot_1) 4_1, and the image data input from the communication interface circuit (DSI_1) 3_1 is written to the latch 5_1 via the slot (Slot_2) 4_2.
In a case where PIN_1 is set to “1” and only one port is used, and when F/B=0 at PIN_2=0, the image data input from the communication interface circuit (DSI_1) 3_1 is written to the latch 5_1 via the slot (Slot_1) 4_1, while the count value of the pixel data counter 7 is smaller than RGB1201, and the image data is written to the latch 5_2 while the count value of the pixel data counter 7 is equal to or larger than RGB1201. In contrast, when the F/B bit which performs the left-right reversing equals “1” (F/B=1) at PIN_2=0, the image data input from the communication interface circuit (DSI_1) 3_1 is written to the latch 5_2 via the slot (Slot_1) 4_1, while the count value of the pixel data counter 7 is smaller than RGB1201, and the image data is written to the latch 5_1 while the count value of the pixel data counter 7 is equal to or larger than RGB1201. In addition, when F/B=0 at PIN_2=1, the image data input from the communication interface circuit (DSI_2) 3_2 is written to the latch 5_1 via the slot (Slot_1) 4_1, while the count value of the pixel data counter 7 is smaller than RGB1201, and the image data is written to the latch 5_2 if the count value of the pixel data counter 7 is equal to or larger than RGB1201. In contrast, when the F/B bit which performs the left-right reversing equals “1” (F/B=1) at PIN_2=0, the image data is written to the latch 5_1, while the count value of the pixel data counter 7 is smaller than RGB1201.
As described above, the setting of “1” or “0” set in the truth table is just an example, and it may be a different setting, or may be positive logic or negative logic.
As a result, it is possible to provide a liquid crystal display driver having the same effect as the liquid crystal display driver IC described in the above-described second embodiment, even with regard to the liquid crystal display driver IC 10 in which the RAM 11 is embedded as a frame memory.
As a result, it is possible to provide a liquid crystal display driver having the same effect as the liquid crystal display driver IC described in the above-described third embodiment, even with regard to the liquid crystal display driver IC 10 in which the RAM 11 is embedded as the frame memory.
When PIN_2=0, PIN_1=0, and F/B=0, the image data input from the communication interface circuit (DSI_1) 3_1 is written to the writing latch W_Latch_1 via the slot (Slot_1) 4_1, and the data is read out to the reading latch R_Latch_1, and then transferred to the latch 5_1. The image data input from the communication interface circuit (DSI_2) 3_2 is written to the writing latch W_Latch_2 via the slot (Slot_2) 4_2, and the data is read out to the reading latch R_Latch_2, and then transferred to the latch 5_2. Including the other case, while the image data input from the communication interface circuits (DSI_1 and DSI_2) 3_1 and 3_2 is transferred to the latches 5_1 and 5_2 via the slots (Slot_1 and Slot_2) 4_1 and 4_2, the only different point is that operations in which the image data is written to the writing latches W_Latch_1 and W_Latch_2 and is read out to the reading latches R_Latch_1 and R_Latch_2 and is temporarily stored in the RAM, are added.
As described above, the setting of “1” or “0” set in the truth table is just an example, and it may be a different setting, or may be positive logic or negative logic.
As described above, the invention performed by the present inventor is specifically described based on the embodiments, but the present invention is not limited thereto, and various modifications can be made within a range without departing from the gist.
For example, a touch panel may be stacked on the liquid crystal display panel 20, and a touch controller may be embedded in the liquid crystal display driver IC. In addition, instead of the terminals PIN_1 and the PIN_2, fuses or non-volatile memory devices can also be mounted.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-145248 | Jul 2013 | JP | national |
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| Number | Date | Country | |
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| 20150015551 A1 | Jan 2015 | US |
