Patent Publication Number: US-6335720-B1

Title: Data transfer method, display driving circuit using the method, and image display apparatus

Description:
This is a divisional application of application Ser. No. 08/636,496, filed on Apr. 23, 1996 now U.S. Pat. No. 6,078,318. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a data transfer method used in a display apparatus driving circuit for driving a display apparatus such as a flat display and, more particularly, to an improved data transfer method for a driving integrated circuit, which can reduce the average data transfer amount. 
     2. Related Background Art 
     Conventionally, data for one line must be transferred to a driving circuit of a flat display (to be referred to as an FPD hereinafter: Flat Panel Display) since the display operation on the FPD is performed by a line or dot sequential method. More specifically, in a conventional display, all the bits of display data must be transferred in synchronism with the frame frequency. Also, driving data of a driving integrated circuit is updated each time display data is transferred. 
     FIG. 1 is a physical schematic diagram showing the conventional data transfer method. The system shown in FIG. 1 includes a display apparatus (panel)  1 , information line side driving integrated circuits (segment drivers)  2 , segment bus boards  5 , data buses  7 , clock signal lines  8 , serial data input signal lines  9 , and a controller  10 . 
     FIG. 2 is a schematic diagram of the segment drivers  2  in the conventional data transfer method shown in FIG.  1 . The video data buses  7  for supplying video data ID 0  to ID 7  and the clock signal line  8  for supplying clocks (CLK) are connected in parallel with the segment drivers  2  ( 2 - 1 ,  2 - 2 ,  2 - 3 , . . . ), and the serial data input signal (CSDi) line  9  is cascade-connected to these drivers  2 . The first segment driver  2 - 1  receives a serial data input signal CSDi from the controller  10 . A serial data output signal a output from the first segment driver  2 - 1  is connected to the serial data input pin of the second segment driver  2 - 2 , and a serial data output signal b output from the second segment driver  2 - 2  is connected to the serial data input pin of the third segment driver  2 - 3 . 
     FIG. 3 is a timing chart in the conventional data transfer method shown in FIG.  1 . FIG. 4 is a block diagram showing the arrangement of the driver in the conventional data transfer method shown in FIG.  1 . 
     The conventional data transfer method will be explained below with reference to FIGS. 1 to  4 . As shown in FIG. 3, segment image data (video data) for all the drivers are serially transferred in an 8-bit width, and when first data, i.e., D 0  to D 7 , of these image data are supplied, the serial data input signal CSDi simultaneously changes to “1”. Then, the first segment driver  2 - 1  shown in FIG. 2 begins to latch the input image data and simultaneously begins to count the number of clocks. When the segment driver  2 - 1  has counted  20  clocks CLK, it completes the data input operation, and sets the serial data output signal a to be “1”. Similarly, the second and third segment drivers receive image data in the same procedure as described above. With this operation, data D 0  to D 159  are received as image data of the first segment driver, data D 160  to D 319  are received as image data of the second segment driver, and data D 320  to D 479  are received as image data of the third segment driver, thus completing the transfer operation of image data for one horizontal scanning period. 
     However, in the above-mentioned prior art, since each driving integrated circuit has neither a latch memory nor a multiplexer circuit, sequentially transferred data are latched by a required amount (corresponding to the data holding performance of the integrated circuit), or data corresponding to a sub-scanning width are sequentially transferred using n driving integrated circuits via a shift register to form 1-line data. 
     Therefore, in the conventional data transfer method, even when a display apparatus with memory characteristics such as a ferroelectric liquid crystal display (to be referred to as an FLCD hereinafter: Ferroelectric Liquid Crystal Display) is to be driven, data for one line are transferred. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a display apparatus wherein two kinds of informations are transmitted through a common bus in time series. 
     Another object of the present invention is to provide a display apparatus which can recognize an arrangement position even in case of using the same curcuit structure of IC. 
     The present invention has been made in consideration of the conventional problems, and has as its object to reduce the average data transfer amount from a controller to drivers in a display apparatus driving circuit. By reducing the data transfer amount, consumption power and radiation noise are expected to be reduced. 
     In order to achieve the above object, according to the present invention, in a data transfer method for transferring data to information-side drivers for driving a display apparatus, driver circuits each comprising a chip address/video data discrimination circuit and a unit driver are mounted around the display apparatus, each unit driver is set with its own chip address by means of a hardware pattern, and data exchange with the driver circuits is performed, so that chip address information and video data information are time-divisionally transferred to the target unit driver by utilizing a chip address/video data common bus line and a chip address/video data discrimination control signal. 
     According to a preferred embodiment of the present invention, the display apparatus comprises a flat display. Each driver circuit comprises an integrated circuit having the chip address/video data discrimination circuit and one unit driver. The unit driver comprises a chip address terminal consisting of a plurality of pins, which are used for setting its own address. Each unit driver comprises a latch means for holding previous data until it receives new data, and outputting data in accordance with the held data, and transfers data of only the unit driver whose video data has changed. In this case, the output pins of each unit driver are divided into a plurality of blocks, and data of only blocks whose video data have changed are transferred. Alternatively, only data between output pin blocks designated by start and end block signals of the output pins of each unit driver are transferred. 
     According to the present invention, when, for example, a segment-side driving integrated circuit comprises a latch circuit, a multiplexer circuit, and a chip address discrimination circuit to realize a data transfer method with control data, only changed data are transferred to the driving integrated circuit, thus reducing the average data transfer amount. More specifically, the driving integrated circuits for the flat display are mounted around the panel, and data exchange with the integrated circuits is performed so that a controller outputs data with address information and control information (driver output block information/start block information/end block information) to a target driving integrated circuit. In this manner, the integrated circuit can receive target data on the basis of the address information and the control information. Therefore, the controller designates only a position where data has changed and outputs the data thereto, thereby realizing the above-mentioned concept. 
     In the prior art, since chip select signals are required in units of chips, a large-screen, high-resolution display which is expected to be developed in future suffers an increase in the number of scanning lines, and the number of drivers increases accordingly, resulting in an increase in the number of signal lines. 
     According to an embodiment of the present invention, there is provided a data transfer method which can reduce the number of signal lines between a controller and drivers in a display apparatus driving circuit and has a predetermined number of signal lines independently of the resolution of a display apparatus. 
     According to another embodiment of the present invention, as scanning-side drivers for driving a display apparatus, unit drivers each comprising a chip address/pin address discrimination circuit are mounted around the display apparatus, each unit driver is set with its own chip address by means of a hardware pattern, and data exchange with the unit drivers is performed so that chip address information and pin address information are time-divisionally transferred to a target integrated circuit by utilizing a chip address/pin address common bus line and a chip address/pin address discrimination control signal. 
     In a preferred embodiment of the present invention, the display apparatus comprises a flat display. Each unit driver comprises a one-chip IC, which has a chip address terminal consisting of a plurality of pins. The chip address information is supplied to each driver by one or two clocks. 
     According to the embodiment of the present invention, integrated circuits each comprising, e.g., a chip address/pin address discrimination circuit are mounted around a flat display panel, each integrated circuit is set with its own chip address by means of a hardware pattern, and data exchange with the integrated circuits is performed so that chip address information and pin address information is time-divisionally transferred to a target driving integrated circuit by utilizing a bus line arranged around the panel. In this manner, the number of signal lines between a controller and drivers can be reduced, and the present invention can be applied to a panel having a higher resolution (a larger number of scanning lines) without increasing the number of signal lines between the controller and drivers. 
     In the prior art, as for the common side (scanning side), data are transferred by a method different from that for the segment side without using a common data line, and the controller must independently output segment data and common data, thus requiring a larger number of signal lines. 
     According to an embodiment of the present invention, the number of signal lines between the controller and drivers in a display apparatus driving circuit can be reduced, the number of signal lines does not depend on the resolution of a display apparatus, and the average data transfer amount from the controller to the drivers can be reduced. 
     For this purpose, according to the present invention, in a data transfer method for transferring data to drivers for driving a display apparatus, scanning-side drivers and information-side drivers are mounted around-the display apparatus, and data transfer to the scanning- and information-side drivers is performed using a common bus line which transfers information to both the scanning- and information-side drivers. 
     According to a preferred embodiment of the present invention, the display apparatus comprises a flat display. Each of the scanning- and information-side drivers comprises one or a plurality of one-chip integrated circuits, and each integrated circuit is set with its own chip address by means of a hardware pattern. For example, each integrated circuit comprises a chip address terminal consisting of a plurality of pins, and its chip address is set by fixing the respective pins to ground (GND) or VCC. Information to each scanning-side driver consists of chip address information and pin address information, and information to each information-side driver consists of chip address information and video data information. Each information-side driver has a data latch means for latching previous data until it receives new data, and outputting data in accordance with the held data. A controller transfers data of only the drivers whose video data have changed. The drivers are arranged at the four corners of the display apparatus, and the common bus is formed into a ring pattern. 
     According to an embodiment of the present invention, for example, each of segment-side driving integrated circuits comprises a latch circuit, a multiplexer circuit, and a chip address discrimination circuit, a common bus is used as segment/common lines, and data to be output from a controller have a common format so as to realize a data transfer method with control data, thereby reducing the number of signal lines between the controller and driving integrated circuits. At the same time, the controller transfers only changed data to the driving integrated circuits (in particular, segment-side ICs), thereby reducing the average data transfer amount. This method is particularly effective for a high-resolution display. More specifically, since driving integrated circuits for a flat display are mounted around the panel and data exchange with the integrated circuits is performed so that the controller outputs data with address information and control information to a target driving integrated circuit by utilizing a bus line arranged around the panel, the integrated circuit can receive target data on the basis of the address information and the control information. Therefore, the controller can designate only a position (arbitrary segment and common pin addresses) where data has changed and can output data thereto, thus realizing the above-mentioned concept. 
     In each conventional scanning-side driver, a pin address signal, a chip select signal, a waveform information signal, a mode set signal, and the like are transferred using independent signal lines. In each information-side driver, a video data signal, a waveform information signal, a test mode signal, and the like are transferred using independent signal lines. For this reason, the number of signal lines increases, resulting in an increase in cost and an increase in unnecessary radiation noise. 
     Since no latch memory for output control information is arranged, and an output control information signal line is connected in parallel with a plurality of drivers, identical waveform information can only be set in all the drivers. 
     Furthermore, since scanning- and information-side signals have independent signal formats, the number of signal lines further increases. 
     An embodiment of the present invention has been made in consideration of the conventional problems, and has as its object to reduce the number of signal lines that connect a controller and scanning- or information-side drivers to attain a cost reduction and a reduction of unnecessary radiation noise, and to transfer waveform information and the like in units of a plurality of drivers. 
     In this embodiment, data to be output from the controller to each scanning-side/information-side driver has a common data format, and chip address information, pin address information, waveform information, and mode set information for the scanning-side drivers, chip address information, video data information, waveform information, and test mode information for the information-side drivers, and control data for discriminating such information are time-divisionally transferred using a common bus. 
     With the above-mentioned data transfer method, the number of signal lines between the controller and drivers can be reduced, and at the same time, waveform information and mode set information can be independently transferred in units of drivers. 
     FIG. 5 shows the arrangement of a conventional matrix type display apparatus to which the above embodiment is to be applied. Referring to FIG. 5, the apparatus comprises a display unit  401  for displaying an image, driving circuits  402  for driving the scanning lines of the display unit  401 , driving circuits  403  for driving the information lines of the display unit  401 , a bus board  404  for supplying a power supply signal and a control signal to the driving circuits  402 , a bus board  405  for supplying a power supply signal and a control signal to the driving circuits  403 , a control means (to be referred to as a controller hereinafter)  406  for generating the power supply signals and control signals to be supplied to the driving circuits  402  and  403 , a cable  407  for supplying the power supply signal and control signal generated by the controller  406  to the bus board  404 , and a cable  408  for supplying the power supply signal and control signal generated by the controller  406  to the bus board  405 . 
     The controller  406  determines the operations of the driving circuits  402  and  403  required for drawing an intended image on the basis of image information transferred from a computer or the like, and transfers data to the bus boards  404  and  405 . More specifically, the controller  406  supplies control signals and power supply signals required for displaying the image to the bus boards  404  and  405  via the cables  407  and  408 . The driving circuits  402  and  403  receive the control signals and power supply signals associated with the operations from the bus boards  404  and  405 , and perform predetermined operations. 
     FIG. 6 shows the arrangement of general driving circuits. The same reference numerals denote the same parts as in FIG. 5, and a detailed description thereof will be omitted. Referring to FIG. 6, a data bus  409  transfers image data transferred from the controller  406 . A clock signal line  410  supplies a clock signal for attaining synchronization of the reception timings of image data from the image data bus  409  to the driving circuits  403  and a clock signal for attaining synchronization of the operation timings in the driving circuits, i.e., for attaining synchronization of the operation timings of clock counters and latch circuits (to be described later). A chip select (to be abbreviated as CS hereinafter) signal line  411  supplies a CS signal for designating a driving circuit which is to receive image data. A drive signal line  412  supplies a drive signal used for simultaneously outputting image data to the display unit after image data for one line are received by all the driving circuits  403 . 
     In the above-mentioned arrangement of the driving circuits, the number of CS signal lines for designating driving circuits which are to receive image data increases when the number of driving circuits increases upon realization of a large-screen or high-resolution display, and consequently, the number of control signals to be transferred from the controller increases. The increase in the number of control signals must be avoided as much as possible since it leads to an increase in unnecessary radiation noise. 
     This embodiment has been made to solve the above-mentioned problem, and provides a means for transferring image data to the respective driving circuits without increasing the number of control signals to be output from the controller, which problem arises upon an increase in the number of driving circuits. 
     In order to solve the above-mentioned problem, an image display apparatus of this embodiment comprises a display unit for displaying an image, driving circuits for driving the display unit, a bus board for supplying a power supply signal and a control signal to the driving circuits, a control means for generating the power supply signal and the control signal to be supplied to the driving circuits, and a transmission means for supplying the power supply signal and the control signal generated by the control means to the bus board. Data obtained by adding a signal, which indicates the start of transfer, to the beginning of image data transferred from the control means is transferred to the driving circuits, and each driving circuit comprises a circuit for recognizing its mounting position on the basis of a hardware pattern on the bus board. 
     According to this embodiment, even when the number of driving circuits increases, image data can be sequentially received in units of driving circuits without increasing the number of control signal lines, and the controller need not supply any chip select (CS) signal, thus obtaining an effect of suppressing unnecessary radiation noise, and the like. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a physical schematic diagram showing a conventional data transfer method; 
     FIG. 2 is a schematic diagram showing the conventional data transfer method; 
     FIG. 3 is a timing chart showing the conventional data transfer method; 
     FIG. 4 is a diagram showing the arrangement of a segment driver in the conventional data transfer method; 
     FIG. 5 is a physical schematic diagram showing the arrangement of a general image display apparatus; 
     FIG. 6 is a block diagram showing the arrangement of conventional driving circuits in correspondence with FIG. 7; 
     FIG. 7 is a physical schematic diagram showing a data transfer method according to the first embodiment of the present invention; 
     FIG. 8 is a schematic diagram showing a method of assigning chip addresses in a hardware manner in the first embodiment of the present invention; 
     FIG. 9 is a schematic chart showing the data transfer method according to the first embodiment of the present invention; 
     FIG. 10 is a timing chart showing the data transfer method according to the first embodiment of the present invention; 
     FIG. 11 is a circuit diagram showing the arrangement of a segment driver according to the first embodiment of the present invention; 
     FIG. 12 is a table showing the block division method in the data transfer method according to the first embodiment of the present invention; 
     FIG. 13 is a timing chart showing a data transfer method according to the second embodiment of the present invention; 
     FIG. 14 is a circuit diagram showing the arrangement of a segment driver according to the second embodiment of the present invention; 
     FIG. 15 is a physical schematic diagram showing a data transfer method according to the first embodiment of the present invention; 
     FIG. 16 is a schematic diagram showing the method of assigning chip addresses in a hardware manner in the first embodiment of the present invention; 
     FIG. 17 is a schematic chart showing the data transfer method according to the first embodiment of the present invention; 
     FIG. 18 is a timing chart showing the data transfer method according to the first embodiment of the present invention; 
     FIG. 19 is a timing chart showing a data transfer method according to the second embodiment of the present invention; 
     FIG. 20 is a timing chart showing a data transfer method according to the third embodiment of the present invention; 
     FIG. 21 is a table showing the addressing method in the data transfer method according to the third embodiment of the present invention; 
     FIG. 22 is a physical schematic diagram showing a data transfer method according to the first embodiment of the present invention; 
     FIG. 23 is a schematic diagram showing the method of assigning chip addresses in a hardware manner in the first embodiment of the present invention; 
     FIG. 24 is a schematic chart showing the data transfer method according to the first embodiment of the present invention; 
     FIG. 25 is a timing chart showing the data transfer method for common drivers according to the first embodiment of the present invention; 
     FIG. 26 is a timing chart showing the data transfer method for segment drivers according to the first embodiment of the present invention; 
     FIG. 27 is a circuit diagram showing the arrangement of the segment driver according to the first embodiment of the present invention; 
     FIG. 28 is a physical schematic diagram showing a data transfer method according to the second embodiment of the present invention; 
     FIG. 29 is a physical schematic diagram showing a display apparatus driving circuit that adopts the data transfer method according to the first embodiment of the present invention; 
     FIG. 30 is a schematic diagram showing the method of fixing chip addresses of drivers in a hardware manner in the circuit shown in FIG. 29; 
     FIG. 31 is a schematic chart showing the data transfer method in the circuit shown in FIG. 29; 
     FIG. 32 is a view showing the data format for a scanning-side driver in the circuit shown in FIG. 29; 
     FIG. 33 is a view showing the data format for an information-side driver in the circuit shown in FIG. 29; 
     FIG. 34 is a view showing the format of a data discrimination signal in the circuit shown in FIG. 29; 
     FIG. 35 is a block diagram showing the arrangement of an information-side driver in the circuit shown in FIG. 29; 
     FIG. 36 is a correspondence table showing the relationship between the combination of waveform information signals and the output voltage in a scanning-side driver in a conventional data transfer method; 
     FIG. 37 is a correspondence table showing the relationship between the combination of test mode signals in an information-side driver and the output voltage in the conventional data transfer method; 
     FIG. 38 is a block diagram showing the arrangement of driving circuits according to the first embodiment of the present invention; 
     FIG. 39 is a block diagram showing in more detail the arrangement of the driving circuit shown in FIG. 38; 
     FIGS. 40A to  40 E are timing charts showing the operations of the driving circuits shown in FIG. 38; 
     FIG. 41 is a block diagram showing the arrangement of a driving circuit according to the second embodiment of the present invention in correspondence with FIG. 39; and 
     FIGS. 42 and 43 show display apparatuses using a data transfer method according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One preferred embodiment of the present invention is a display apparatus which adopts a data transfer method for supplying a driving circuit selection signal to driving circuits via a common bus. 
     Together with the driving circuit selection signal (chip address) supplied via the common bus, a scanning line selection signal (pin address) and display data (video data) can be time-serially supplied via the same bus. Furthermore, additional information such as intra-chip block selection information, scanning mode information, waveform data information, test mode information, and the like can be supplied via the same bus. 
     Another preferred embodiment of the present invention adopts a data transfer method for transferring the pin address and video data to driving circuits via a common bus. 
     Of course, the chip address and additional information can be sent via the same bus. 
     On the other hand, a control signal for identifying various kinds of information is supplied to the driving circuits via a line different from the above-mentioned bus. 
     FIG. 42 is a block diagram of a display apparatus according to the above-mentioned embodiment. 
     Each driving circuit DR time-serially receives various kinds of information output from a controller via a common bus. When a control signal synchronous with the information to be transferred is supplied via a control line (not shown), the kind of information to be transferred via the common bus can be discriminated. 
     In another embodiment of the present invention, as shown in FIG. 43, each driving circuit comprises a means CAD for specifying the position information of the driving circuit. 
     The means CAD is preferably constituted by an outer circuit of IC chips of the driving circuits DR, so that the driving circuits DR can use IC chips having the same circuit arrangement. Such outer circuit can be easily manufactured by, e.g., a wiring pattern formed on a common bus board. 
     The driving circuit preferably uses a tape-carrier-packaged IC, and a common wiring board that presents the bus preferably uses a multi-layered printed wiring board. 
     As a display unit used in the present invention, an active matrix type liquid crystal element, a plasma display, an electron emission element, a ferroelectric liquid crystal element, and a digital micro-mirror device may be used. 
     The preferred embodiments of a display apparatus which adopts the data transfer method of the present invention will be described in detail hereinafter. 
     FIG. 7 is a physical schematic diagram showing the data transfer method for a display apparatus driving circuit according to a first embodiment of the present invention (the common-side data transfer is not shown). FIG. 8 is a schematic diagram showing the method of fixing chip addresses of segment drivers  2  in FIG. 7 in a hardware manner. Referring to FIGS. 7 and 8, the driving circuit comprises a display apparatus (FPD)  1 , information line-side driving integrated circuits (segment drivers)  2 , a common bus  3 , chip select terminals  4 , a segment bus board  5 , a control signal (CS) line  6 , a clock signal (CLK) line  8 , and a controller  10 . FIG. 9 is a schematic chart showing the data transfer method in the circuit shown in FIG.  7 . FIG. 10 is a timing chart for explaining in detail information to be received by the segment drivers  2  ( 2 - 1 ,  2 - 2 ,  2 - 3 , . . . ) in the circuit shown in FIGS. 7 and 8, i.e., showing the data format on a 16-bit bus and the timing of a control signal. FIG. 11 is a block diagram showing the arrangement of the segment driver in the circuit shown in FIG.  7 . 
     In this embodiment, as shown in FIG. 7, the plurality of drivers  2  for driving the display apparatus  1  are connected via the common bus  3 , and a unique chip address is assigned to each driver by fixing a plurality of pins of the chip address terminal  4  to ground (GND, e.g., “0”) or VCC (the upper reference potential, e.g., “1”) as shown in FIG.  8 . The controller  10  time-divisionally outputs chip addresses CA 0  to CA 7 , block select signals BS 0  to BS 3  and AS, and video data in the data format shown in FIGS. 9 and 10 onto the common bus  3 . When a control signal is “1”, each driver  2  compares the input chip address signal with its own chip address, which is designated in advance in a hardware manner. When the two addresses match, the driver recognizes that the data following the control signal is information addressed thereto. For example, the first driver  2 - 1  shown in FIG. 8 is assigned a fixed chip address “0, 0, 0, 0, 0, 0, 1, 0”. When the control signal (CS) is “1”, and the chip addresses CA 0  to CA 7  of the information on the bus are “0, 0, 0, 0, 0, 0, 1, 0”, the first driver  2 - 1  recognizes that the information following the control signal is video data to be received by itself. When the block select signal AS of the information on the bus is “0”, data according to the combination of the signals BS 0  to BS 3  are transferred from the controller  10 . For example, when the signals BS 0  to BS 3  are “0, 1, 0, 0”, video data for the 64th to 95th output pins corresponding to the second one of blocks obtained by dividing 256 outputs into eight blocks are transferred. On the other hand, when the signal AS is “0”, data for all the output pins are transferred independently of the value BS. FIG. 12 is a table showing such block division method. 
     Each driver  2  holds previous data until it receives new data, and drives the display apparatus  1  in accordance with the held data. Therefore, according to the data transfer method of this embodiment, the controller detects a change in video data, and transfers data corresponding to only the changed portion (in units of drivers) so as to reduce the average data transfer amount, thus contributing to reductions of consumption power and radiation noise. In addition, a driving voltage can be applied to the display apparatus  1  in correspondence with only blocks whose data are updated. The data transfer method of this embodiment is particularly effective for a partial rewrite driving method performed in a device with memory characteristics such as a ferroelectric liquid crystal device, i.e., a method of updating display data in correspondence with only the change point of video data. 
     FIG. 13 is a timing chart showing the data transfer method according to a second embodiment of the present invention. FIG. 14 is a block diagram showing the arrangement of the segment driver to which the data transfer method of the second embodiment is applied. In this embodiment, the respective segment drivers are set with chip addresses, as shown in FIG.  8 . Furthermore, the output pins of each segment driver are set with output pin addresses. The controller  10  designates the output pin address that transfers data using start block information signals SB 0  to SB 3  and end block information signals EB 0  to EB 3  in addition to the above-mentioned chip address. For example, when the control signal is “1” and the chip addresses CA 0  to CA 7  of the information on the bus are “0, 0, 0, 0, 0, 0, 1, 0”, the first driver  2 - 1  (see FIG. 8) recognizes that the information following the control signal is information to be received by itself. At this time, when the signals SB 0  to SB 3  are “0, 0, 0, 0”, and the signals EB 0  to EB 3  are “1, 1, 1, 0”, video data from the 0th block, i.e., the 0th output pin to the 14th block, i.e., the 239th output pin are transferred from the controller. Therefore, according to the data transfer method of the second embodiment, data can be transferred by selecting a plurality of continuous blocks in the driver. 
     As described above, according to the present invention, since each segment-side driving integrated circuit  2  comprises a latch circuit, a multiplexer circuit, and a chip address discrimination circuit to realize a data transfer method with control data, only changed data can be transferred to each driving integrated circuit, thereby reducing the average data transfer amount. 
     Furthermore, since each driver is divided into a plurality of blocks, the output pin blocks are set with addresses, and data are transferred to only pins designated by start block information and end block information, the average data transfer amount can be further reduced. 
     Since the average data transfer amount can be reduced, as described above, reductions of consumption power and radiation noise can be attained, and a driving voltage can be applied to the display apparatus  1  in correspondence with only blocks whose data are updated. This method is particularly effective for a partial rewrite driving method performed in a device with memory characteristics such as a ferroelectric liquid crystal device, i.e., a method of updating display data in correspondence with only the change point of video data. 
     FIG. 15 is a physical schematic diagram showing the data transfer method for a display apparatus driving circuit according to a third embodiment of the present invention (the segment-side data transfer is not shown). FIG. 16 is a schematic diagram showing the method of setting the chip addresses of the respective unit drivers in the circuit shown in FIG. 15 in a hardware manner. Referring to FIGS. 15 and 16, the circuit comprises a bus  101 , scanning-side driving integrated circuits (common drivers)  102 , fixed chip address input pins  103 , a common bus board  104 , a controller  105 , a control signal line  106 , a clock signal (CLK) line  107 , a display apparatus (panel)  110 , information-side driving integrated circuits (segment drivers)  111 , and a segment bus board  112 . FIG. 17 is a schematic chart showing the data transfer method in the circuit shown in FIG.  15 . 
     In this embodiment, as shown in FIG. 15, the controller  108  and the drivers  102  (unit drivers  12 - 1 ,  12 - 2 ,  12 - 3 , . . . ) for driving the display apparatus  110  are connected via the common bus  101 . As shown in FIG. 16, each driver  102  is assigned a unique chip address by fixing the plurality of chip address input pins (terminals)  103  to ground (GND: corresponding to, e.g., “0”) or VCC (the upper reference potential: corresponding to, e.g., “1”) on the printed board  104 . The controller time-divisionally transfers the chip and pin addresses in the data format shown in FIG.  17 . 
     FIG. 18 is a timing chart for explaining in detail information to be received by the common drivers  102  in the circuit shown in FIGS. 15 and 16, and showing the data format on the 4-bit data bus  101  and the timings of the control signal. 
     The operation of each driver  102  will be explained below with reference to FIGS. 15 to  18 . When the control signal is “1”, each driver  102  compares data on the bus  1  with its own address, which is designated in advance in a hardware manner. When the two addresses match, the driver  102  recognizes that the data following the control signal is addressed to itself. For example, the driver  12 - 1  shown in FIG. 16 is assigned a fixed chip address “0, 0, 1, 0”. When the control signal is “H” and information (CA 0  to CA 3 ) on the bus indicates “0, 0, 1, 0”, the driver  12 - 1  recognizes that the information after this information indicates its own pin address, and begins to read the pin address (PA 0  to PA 7 ). As described above, according to this embodiment, using the 4-bit bus and a single control signal line, information for a maximum of 4,096 (=16×256) scanning lines can be transferred. With the data transfer method of this embodiment, even when the number of scanning lines increases, data can be transferred without increasing the number of signal lines, and this method is particularly effective for a large-screen, high-resolution display in future. 
     Since the address on the common driver side need only be designated within one horizontal scanning period, even when, e.g., 2,048 scanning lines are scanned at a speed of 60 Hz, the speed of the clock signal CLK at that time can be as low as about several hundreds of Hz, and data can be transferred at a relatively low transfer speed despite the small number of signal lines. 
     FIG. 19 is a timing chart showing the data transfer method according to a fourth embodiment of the present invention. In this embodiment, the chip address is serially transferred for two clocks using a 4-bit bus. With this arrangement, the number of drivers can be increased more easily. For example, in this embodiment, the number of drivers can be increased up to 256 without increasing the number of signal lines. More specifically, this embodiment can cope with a large-screen, high-resolution display having a maximum of 65,536 (=256×256) scanning lines. 
     FIG. 20 is a timing chart showing the data transfer method according to a fifth embodiment of the present invention. FIG. 21 is a table showing the method of addressing output pins in accordance with a mode signal in the fifth embodiment. This method is used when data is displayed on a display having, e.g., 2,048 physical scanning lines in a graphic mode with a resolution (e.g., 480 lines) lower than that of the display. When the mode set signal is “0”, the driver  102  shown in FIG. 15 selects output pins one by one in accordance with the table shown in FIG.  21 . When the mode set signal is “1”, the controller  105  transmits a chip address while ignoring the least significant bit PA 7  of the pin address signal, and the driver simultaneously selects output pins in units of two pins in accordance with the table shown in FIG.  21 . Of course, this method can be applied to 4- or 8-pin simultaneous selection. 
     As described above, since the format of data output from the controller is realized by the data transfer method with control data, the number of signal lines between the controller and the driving integrated circuits can be reduced. 
     The present invention can easily cope with a case wherein the number of scanning lines is large, i.e., the number of driving integrated circuits (especially, common-side ICs) is large, and is particularly effective for a high-resolution display. 
     FIG. 22 is a physical schematic diagram showing the data transfer method for a display apparatus driving circuit according to a sixth embodiment of the present invention. FIG. 23 is a schematic diagram showing the method of fixing the chip addresses of segment and common drivers in the circuit shown in FIG. 22 in a hardware manner. Referring to FIGS. 22 and 23, the circuit comprises a display apparatus (FPD)  201 , segment drivers  202 , common drivers  203 , a common bus  204 , chip address terminals  205 , bus boards  206 , a control signal line  207 , a controller  208 , and a clock signal (CLK) line  210 . FIG. 24 is a schematic chart showing the data transfer method of transferring data to the segment drivers  202  in the circuit shown in FIG.  22 . 
     In this embodiment, as shown in FIG. 22, the controller  208  and the drivers  202  and  203  for driving the display apparatus  201  are connected via the common bus  204 , and a chip address signal, a pin address signal, video data, and a data discrimination signal are time-divisionally transferred in the data format shown in FIG.  24 . Designation of the output pins of the common drivers  203  and transfer of video information corresponding to all the segment drivers  202  (or the drivers corresponding to a change point) are completed within one horizontal scanning period, thus driving the-display apparatus  201 . 
     FIG. 25 is a timing chart for explaining in detail the information to be received by the common drivers  203  ( 203 - 1 ,  203 - 2 ,  203 - 3 , . . . ) in the circuit shown in FIGS. 22 and 23, i.e., showing the data format on the 16-bit bus  204  and the timings of the control signal. 
     The operation of each common driver  203  will be described below with reference to FIGS. 22 to  25 . Note that the output pin address of each common driver  203  to be described below must be designated for the purpose of various kinds of interlaced scanning operations. When the control signal is “1”, each common driver  203  recognizes that the data on the bus  204  is chip address information. Each common driver  203  is assigned a unique chip address by fixing a plurality of pins of its chip address terminal  205  to ground (GND: corresponding to, e.g., “0”) or VCC (the upper reference potential: corresponding to, e.g., “1”) on the printed board  206 , as shown in FIG.  23 . When the chip address data on the bus  204  agrees with its own chip address, the common driver  203  recognizes that the following data is its own pin address information, and fetches the information. According to the data transfer method of this embodiment, which transfers each pin address information, as described above, even when the number of scanning lines increases, data can be transferred without increasing the number of signal lines, and this method is particularly effective for a large-screen, high-resolution display in future. 
     FIG. 26 is a timing chart for explaining in detail the information to be received by the segment drivers  202  ( 22 - 1 ,  22 - 2 ,  22 - 3 , . . . ) in the circuit shown in FIGS. 22 and 23, i.e., showing the data format on the 16-bit data bus  204  and the timings of the control signal. FIG. 27 is a block diagram showing the arrangement of the segment driver in the circuit shown in FIG.  22 . 
     The operation of each segment driver  202  will be described below with reference to FIGS. 22 to  24  and FIGS. 26 and 27. When the control signal is “1”, each segment driver  202  recognizes that the data on the bus  204  is chip address information. Each segment driver  202  is assigned a unique chip address by fixing a plurality of pins of its chip address terminal  205  to ground (GND: corresponding to, e.g., “0”) or VCC (the upper reference potential: corresponding to, e.g., “1”) on the printed board  206 , as shown in FIG.  23 . When the chip address data on the bus  204  is equal to its own chip address, the segment driver  202  recognizes that the following data is video data information addressed thereto. When data for 10 clocks are transferred on the 16-bit bus, transfer of video data for 160 bits is completed. Each segment driver  202  holds previous data until it receives new data, and drives the display apparatus in accordance with the held data. Therefore, according to the data transfer method of this embodiment, the controller detects a change in video data, and transfers data of only the changed portion (in units of drivers) to reduce the average data transfer amount, thus contributing to reductions of consumption power and radiation noise. 
     FIG. 28 is a physical schematic diagram showing the data transfer method according to a seventh embodiment of the present invention. That is, in the driving circuit of the seventh embodiment, the common drivers  203  are arranged on the right and left sides of the display apparatus  201 , the segment drivers  202  are arranged on the upper and lower sides of the display apparatus  201 , and these drivers are connected via the common bus line  204  to surround the four sides of the display apparatus  201 . According to the second embodiment, even when the number of scanning lines is as large as the bus boards (printed boards)  206  required on the four sides of the display apparatus  201 , a space-saving wiring layout can be realized without increasing the number of signal lines from the controller  208 . Since the bus boards  206  are arranged on the four sides of the display apparatus  201  in a ring pattern, and the drivers  202  and  203  and the controller  208  are connected via the common bus line  204 , connection points to the controller  208  can be set at arbitrary positions on the bus line  4 , thus allowing easy connection with an external device. 
     As described above, according to the present invention, since the common bus includes both segment and common signal lines and data output from the controller have a common data format to realize a data transfer method with control data, the number of signal lines between the controller and driving integrated circuits can be reduced. 
     By transferring only changed data to the driving integrated circuits (especially, segment-side ICs), the average data transfer amount can be reduced. 
     Furthermore, the present invention can easily cope with a case wherein the number of driving integrated circuits (especially, common-side ICs) is large, and is particularly effective for a high-resolution display. 
     Moreover, since the bus line has a ring-shaped layout, connection points to the controller can be set at arbitrary positions on the bus line, thus allowing easy connection with an external device. 
     FIG. 29 is a physical schematic diagram showing a display apparatus driving circuit according to an eighth embodiment of the present invention, and FIG. 30 is a schematic diagram showing the method of fixing the chip addresses of information- and scanning-side drivers  302  and  303  in the circuit shown in FIG. 29 in a hardware manner. Referring to FIGS. 29 and 30, the circuit comprises a display apparatus (panel)  301 , information-side (segment) drivers  302 , scanning-side (common) drivers  303 , a common bus  304 , chip select terminals  305 , bus boards (printed boards)  306 , a clock signal line  307 , a controller  308 , and a control signal line  309 . 
     FIG. 31 is a schematic chart showing the data transfer method in the circuit shown in FIG.  29 . FIG. 32 shows the data format of the scanning-side drivers  303  in the circuit shown in FIG.  29 . FIG. 33 shows the data format of the information-side drivers  302  in the circuit shown in FIG.  29 . FIG. 34 shows the format of a data discrimination signal in the circuit shown in FIG.  29 . FIG. 35 is a block diagram showing the arrangement of the information-side driver  302  in the circuit shown in FIG.  29 . 
     As shown in FIG. 29, the drivers  302  and  303  for driving the display apparatus  301  are connected via the common bus  304 , and chip address information, pin address information, video data information, a data discrimination signal, waveform information, mode set information, and test mode information are time-divisionally transferred on the bus  304  in the data format shown in FIGS. 31 and 32. 
     When the control signal is “1”, each scanning-side driver  303  recognizes that the data on the bus  304  are chip address information and a data discrimination signal. Each scanning-side driver  303  is assigned a unique chip address by fixing a plurality of pins of its chip address terminal  305  to ground (GND) or VCC (upper reference potential) on the printed circuit board  306 , as shown in FIG.  30 . When the chip address data on the bus  304  agrees with its own chip address, the scanning-side driver  303  recognizes that the following information is that addressed to itself. The driver  303  discriminates in accordance with the combination of data discrimination signals sent simultaneously with the chip address data, i.e., the table shown in FIG. 34, if the following information is pin address information, scanning mode information, or waveform information, and fetches the discriminated information. At this time, if the received data is pin address information, the scanning-side driver  303  applies, from output pins designated by the pin address information, a voltage according to scanning mode information and waveform information, i.e., the correspondence tables shown in FIG. 37, to the display apparatus  301 . In this case, the driver  303  holds previous scanning mode information and waveform information until it receives new information, and outputs data in accordance with the held information. 
     When the control signal is “1”, each information-side driver  302  recognizes that the data on the bus are chip address information and a data discrimination signal. Each information-side driver  302  is assigned a unique chip address by fixing a plurality of pins of its chip address terminal  305  to ground (GND) or VCC (upper reference potential) on the printed circuit board  306 , as shown in FIG.  30 . When the chip address data on the bus  304  is equal to its own chip address, the information-side driver  302  recognizes that the following information is that addressed to itself. Also, the driver  302  discriminates in accordance with the combination of data discrimination signals sent simultaneously with the chip address data, i.e., the table shown in FIG. 34, if the following information is video data information, waveform information, or test mode information. If the received data is video data information, the information-side driver  302  receives video data corresponding to its own output pins, and thereafter, applies a voltage according to waveform information and test mode information, i.e., a voltage according to the correspondence table shown in FIG. 38, to the display apparatus  301  in synchronism with an output waveform control clock signal. At this time, the driver  302  holds previous waveform information until it receives new information, and outputs data in accordance with the held information. 
     By performing the above-mentioned data transfer for all the information- and scanning-side drivers  302  and  303  within one-horizontal scanning period, data transfer within one horizontal scanning period is completed. On the other hand, a mode set signal and a waveform information signal are transferred using a rest period in which no scanning is performed. For example, in a display apparatus having 1,024 scanning lines, even when the mode set signal and the waveform information signal are updated once during the refresh period of one frame, only an interrupt period 1/1024 the horizontal scanning period is required, and has no influence on display quality. 
     As described above, according to the data transfer method of the present invention, data to be output from the controller to the scanning-side/information-side drivers have a common data format, and chip address information, pin address information, waveform information, and mode set information for the scanning-side drivers, chip address information, video data information, waveform information, and test mode information for the information-side drivers, and control data for discriminating such information are time-divisionally transferred onto the common bus. Thus, the number of signal lines between the controller and drivers can be reduced, and the occupation ratio of cables and printed boards in a housing can be reduced, thus attaining a size reduction of the housing and a cost reduction. The decrease in the number of signal lines can contribute to a reduction of radiation noise. Furthermore, since waveform information and mode set information can be independently transferred in units of drivers, each driver can output an arbitrary waveform. 
     FIG. 38 shows the arrangement of a driving circuit according to a nineth embodiment of the present invention. The same reference numerals in FIG. 38 denote the same or corresponding parts as in the prior art shown in FIGS. 5 and 6, and a detailed description thereof will be omitted. Referring to FIG. 39, CS signals  413  ( 413   a,    413   b,    413   c ) are defined by hardware patterns on a bus board  405  and are used for recognizing the mounting positions of driving circuits  403  ( 403   a,    403   b,    403   c ) by themselves. 
     FIG. 39 shows the detailed arrangement of the driving circuit  403 . Referring to FIG. 39, the driving circuit comprises a clock count number setting circuit  414  for calculating the clock count number until the beginning of fetching of image data of the driving circuit  403   a,    403   b,  or  403   c  on the basis of the start bit (SB) signal transferred from a controller and the mounting position information obtained from the bus board, and setting the calculated clock count number in a counter, a clock counter  415  for counting the count number set by the clock count number setting circuit  414 , and enabling a first latch circuit  417  (to be described later) so as to fetch data into the driving circuit upon completion of the count operation, an AND gate  416  for ANDing clocks and an enable signal output from the clock counter  415 , and outputting the AND to the first latch circuit (to be described below), the first latch circuit  417  for sequentially fetching image data from the data bus in synchronism with the signal supplied from the AND gate  416  and supplying the fetched image data to the next latch circuit  418  upon completion of fetching, and a second latch circuit  418  for fetching data for one line into the driving circuit upon reception of image data from the first latch circuit  417 , and thereafter, simultaneously outputting the image data. 
     FIG. 40 is a timing chart of the driving circuit shown in FIG.  39 . FIG. 40A shows image data supplied onto a data bus  409 , FIG. 40B shows enable signals output from the clock counters  415   a  to  415   c  in the driving circuits  403   a  to  403   c,  FIG. 40C shows synchronizing signals which are output from the AND gates  416  and are used for fetching image data into the first latch circuits  417   a  to  417   c,  and FIGS. 40D and 40E show the image data fetching operations of the first and second latch circuits  417   a  to  417   c  and  418   a  to  418   c.    
     The operation principle upon application of the driving circuit shown in FIGS. 38 and 39 to the image display apparatus shown in FIG. 5 will be explained below. Assume that the bus width of the image data bus  409  is 8 bits, and one driving circuit fetches image data for 160 clocks. 
     The start bit (SB) signal transferred from the controller  406  is input to the clock count number setting circuit  414  of each driving circuit. On the other hand, a load position (chip address) information  413  of each driving circuit, which is defined by the hardware pattern on the bus board  405 , is input to the clock count number setting circuit  414 . The clock count number setting circuit  414  calculates the timing, at which each driving circuit begins to fetch data, on the basis of the two different input signals. For example, the cases of the driving circuits  403   a  to  403   c  shown in FIG. 39 will be examined below. Upon reception of the start bit signal, the clock count number setting circuit  414  of the driving circuit  403   a  recognizes based on the mounting position information  413   a  on the bus board that image data after the start bit signal is that to be fetched by its own driving circuit, and the clock counter  415   a  immediately outputs an enable signal. Upon reception of the enable signal, the AND gate  416   a  generates a data fetching signal for the first latch circuit  417   a  in synchronism with a clock signal  410 . Upon reception of the signal output from the AND gate  416   a,  the first latch circuit  417   a  sequentially fetches data from the data bus  409 . This operation is completed when the clock counter  415   a  has counted  160  clocks and then resets the enable signal. Upon completion of storage of image data for  160  counts, the first latch circuit  417   a  transfers data toward the second latch circuit  418   a,  and the image data are held until the driving circuit receives a drive signal from the controller. When the start bit (SB) signal is input to the clock count number setting circuit  414   b,  the driving circuit  403   b  recognizes its own mounting position information  413   b,  and determines that the data starting from the 161st count after the start bit (SB) signal is input are image data to be fetched by itself. Then, the setting circuit  414   b  sets a count clock number “160” until the beginning of the fetching operation in the clock counter  415   b.  The clock counter  415   b  counts the set clock count number, and upon completion of the count operation, image data are sequentially fetched from the data bus  409  in the same procedure as in the driving circuit  403   a.  Thereafter, similar operations are performed in units of driving circuits. After image data are fetched by all the driving circuits, the controller inputs a drive signal to all the second latch circuits  418   a  to  418   c,  thereby simultaneously outputting data toward the display apparatus  401 . 
     As described above, a start bit is assigned to the beginning of image data to be transferred from a controller  406 , the hardware pattern used for recognizing the mounting position of each driving circuit by itself is arranged on the bus board  405 , and the driving circuit itself determines the image data fetching timing based on this information, thereby obviating the need for CS signals from the controller. Thus, even when the number of driving circuits increases, the respective driving circuits can fetch image data without increasing the number of control signals such as CS signals. 
     FIG. 41 shows the arrangement of a driving circuit according to a tenth embodiment of the present invention. The tenth embodiment is characterized in that, in addition to the embodiment shown in FIG. 41, a signal for designating a driving circuit that is to start the fetching operation of image data is set in the start bit signal, and an image data fetching start discrimination circuit  419  for discriminating which driving circuit starts the fetching operation or determining a clock count at which its own driving circuit starts the image data fetching operation is arranged before the clock count number setting circuit  414  in each driving circuit. 
     Upon reception of the start bit (SB) signal, the fetching start discrimination circuits  419  of all the driving circuits  403  discriminate which driving circuit is to start the fetching operation of transferred image data, and set the discriminated information in the next clock count number setting circuits  414 . Each clock count number setting circuit  414  sets a clock number until the beginning of the fetching operation of image data from the data bus  409  in the clock counter  415  on the basis of the driving circuit information indicating the driving circuit which is to start the image data fetching operation and its own mounting position information  413  defined by the hardware pattern on the bus board  405 . The following operations are the same as those in the first embodiment. 
     As described above, in addition to the effect described in the nineth embodiment, since the image data transfer operation from the controller is started from a portion that must be rewritten, image data transfer efficiency onto the data bus can be improved. 
     As described above, according to the present invention, a start bit is assigned to the beginning of image data to be transferred from the controller  406 , the hardware pattern used for recognizing the mounting position of each driving circuit by itself is arranged on the bus board  405 , and a circuit for determining the image data fetching timing of its own driving circuit on the basis of this information is arranged. Accordingly, it would be unnecessary to transmit CS signal from a controller. Thus, even when the number of driving circuits increases, a system for fetching image data into the respective driving circuits can be formed without increasing the number of control signals such as CS signals. In addition, since an increase in the number of control signal lines is suppressed, the present invention is also effective in terms of suppression of radiation noise and the like. 
     Furthermore, a signal for designating a driving circuit that is to start the fetching operation of image data is set in the start bit signal, and each driving circuit comprises, before the clock count number setting circuit, a circuit for discriminating the driving circuit that is to start the fetching operation of image data. Thus, since the controller starts the image data transfer operation from a portion that must be rewritten, image transfer efficiency onto the data bus can be improved.