JP3543745B2 - Drive circuit and drive unit - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a drive circuit for driving a light-emitting element such as an LED (light-emitting diode), and a drive unit used for an LED display, an LED lighting device, and the like.
[0002]
[Prior art]
Generally, a dynamic driving method is used as a driving method of the LED display. For example, as shown in FIG. 1, in the case of an LED display configured with an M row × N column dot matrix, the anode terminal of the LED 11 a that is a light emitting element located in each row is commonly connected to one common source line 12, The cathode terminals of the LEDs located in each column are commonly connected to the current lines 13 in that column. Each of the current lines 13 is connected to a constant current source 14a. The M rows of common source lines 12 are sequentially turned on at a predetermined cycle, and the LED drive current is supplied to the N columns of current lines 13 according to the image data corresponding to the turned-on lines. As a result, an LED drive current corresponding to the image data is applied to the LED 11a of each pixel, and an image is displayed.
[0003]
In the case of a large LED display to be installed outdoors, it is generally configured by combining a plurality of LED units, and each part of the full screen data is displayed on each LED unit. In the LED unit, LEDs each having one set of RGB are arranged in a dot matrix on a substrate, and each unit performs the same operation as the above-described LED display. In a large-sized large LED display, a large number of LEDs are used. For example, in the case of 300 × 400, a total of 120,000 LEDs are used.
[0004]
FIG. 2 shows a signal flow in a conventional drive circuit for each LED unit. A driving circuit of the image display device shown in FIG. 2 includes a display unit 1 in which a plurality of light emitting elements are arranged in a matrix, and a vertical driving unit 2 which selects each row of the display unit 1 and applies a voltage to sequentially switch the display in a vertical direction. And a plurality of stages of horizontal driving units 3 for supplying a driving current corresponding to the display data to each column of the selected row of the display unit 1.
[0005]
In the case of luminance gradation control in the pulse modulation method, gradation data (DATA) is input to the horizontal drive unit 3 of the image display device. The display unit 1 is sequentially switched for each row by the vertical drive unit 2. The lighting control signal input to the lighting control unit 15 becomes valid in synchronization with the start of image display for each horizontal line corresponding to each row of the display unit 1. A latch (LATCH) signal for holding image data is input in synchronization with the lighting control signal. The gradation data of each color is taken into a shift register provided in a memory unit 17 of an LED driver unit (LED Driver 1 to N) constituting the horizontal driving unit 3 of the image display device, and a shift clock (SCLK) synchronized with the shift register is provided. The data is input to the control unit 18 within the valid period of the data. The LED driver unit is configured as a driver IC in which the horizontal drive unit 3 having a predetermined number of constant current outputs is integrated into an IC, for example.
[0006]
The driving current for each horizontal line supplied to the display unit 1 is supplied by each constant current driving unit 14 provided in the horizontal driving unit 3. The vertical drive unit control address is synchronized with the lighting control signal, and a control signal synchronized from the decoder 16 is input to the vertical drive unit 2, and accordingly, the constant current drive of the horizontal drive unit 3 connected to each column is performed. A drive current is supplied from the unit 14. The display is switched on sequentially by the vertical drive unit 2 for each row of the display unit 1 and turned on.
[0007]
In the conventional LED display, the connection between the LED units, which are the components of the display, is such that the direction of the signal line input to the drive circuit is uniquely fixed. Therefore, the connection from the control circuit to the LED unit is one-way, and as shown in FIG. 3, the connection from the control circuit to each LED unit requires a cable connection for the line from the control circuit.
[0008]
[Problems to be solved by the invention]
However, in the conventional LED unit, since the communication directions in the respective LED driver units (LED Drivers 1 to N) corresponding to the driving circuits for driving the light emitting elements are fixed, these can be flexibly connected. Did not. Further, in the conventional LED display unit, for example, there is a problem that the wiring becomes long due to the routing of the pattern wiring in the same LED display unit, and pulse distortion and pulse width fluctuation due to signal reflection occur. In particular, since the frequency of the grayscale clock needs to be increased as the number of grayscales increases, the influence on the circuit operation increases, and the influence on the data bus due to radiation noise and the like cannot be ignored. Therefore, measures such as mounting a PLL circuit in the driver IC and supplying a low-frequency clock can be considered. However, this method further increases the cost of the driver IC, and further modulates the gamma correction of the image by modulating the gradation reference clock. Cannot be performed.
[0009]
The present invention has been made in view of such a problem, and has as its object to provide a drive circuit and a drive unit that enable flexible connection.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a driving circuit of the present invention is a driving circuit for driving a light emitting element, a first communication unit capable of selectively communicating either reception or transmission of data by a common line, A second communication unit capable of performing communication by selecting differently from the first communication unit by using a common line for either reception or transmission of data, a reception processing unit for performing data reception processing, and When the first communication unit and the second communication unit are in a reception state, and data reception is detected in one of the first communication unit or the second communication unit, based on the data reception, The communication unit in which data reception is detected is referred to as a receiving communication unit, and the reception processing unit performs reception processing on data after reception by the receiving communication unit, and the other communication unit is referred to as a transmitting communication unit. , The sender communication And a communication control unit for fixed control the communication direction until a reset signal is input to transmit data from.
[0011]
In the drive circuit according to the present invention, the communication control unit controls the other communication unit to transmit data based on a synchronous clock at the time of data reception.
[0012]
Further, in the drive circuit of the present invention, the first communication unit and the second communication unit each have a reception buffer and a transmission buffer, and the communication control unit includes one of the reception buffer and the transmission buffer in each communication unit. When data reception is detected, control is performed so as to select either reception or transmission in each communication unit by a select signal that activates the reception buffer of the reception side communication unit and the transmission buffer of the non-reception side. Do.
[0013]
Further, in the drive circuit of the present invention, the first communication unit and the second communication unit are set to the reception state by inputting a reset signal to the drive circuit or receiving reset data in the reception processing unit.
[0014]
Further, the driving unit of the present invention is a driving unit having a plurality of driving circuits for driving a light emitting element, wherein each driving circuit communicates by a common line capable of selecting either data reception or transmission. In addition to having a communication unit, the drive circuits are connected in series by a common line, and at the time of initial setting, each drive circuit controls so that the two communication units receive data. When the data reception is detected by the communication unit, the communication unit in which the data reception is detected based on the detection of the data reception is referred to as a reception communication unit, the other communication unit is referred to as a transmission communication unit, and thereafter, the reception communication unit. The received data is transmitted from the other communication unit on the transmission side, and the other drive circuits receive data in one communication unit in the order in which they are connected by the common line. Based on the detection of the data reception, the communication unit in which the data reception is detected is referred to as a receiving communication unit, the other communication unit is referred to as a transmitting communication unit, and data received by the receiving communication unit thereafter is referred to as the other communication unit. , The communication direction is fixedly set until a reset signal is input.
[0015]
In the drive unit of the present invention, the drive circuit is provided in one of the communication units. De When data reception is detected, data received by the communication unit from which data reception is detected is transmitted from the other communication unit based on the synchronization clock at the time of data reception.
[0016]
Further, the drive unit of the present invention further includes a drive control unit that controls driving of the light emitting element by transmitting data to one communication unit of a drive circuit connected to an end of the drive unit.
[0017]
In the drive unit of the present invention, the initial setting is such that the first communication unit and the second communication unit are set to the reception state by inputting a reset signal from the drive control unit to the drive circuit or receiving reset data in the reception processing unit. Is done.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 4 shows a conceptual diagram of a drive circuit according to the present invention. Receiving or sending data A first communication unit 101 capable of communicating any one of the above through a common line L, Receiving or sending data , A communication control unit 103 for controlling communication in the first and second communication units 101 and 102, and a communication unit 103 for transmitting data received by the drive circuit. It comprises a reception processing unit for performing reception processing and a drive unit 105 for driving the light emitting element based on the received data.
[0019]
The data received by the first communication unit 101 via the line L is transmitted from the second communication unit 102 to the line L, and the data received by the reception unit 104 via the communication control unit 103. Can be entered. Similarly, data received by the second communication unit 102 via the line L is connected to the line L so as to be able to be transmitted from the first communication unit 101 and received by the reception unit 104 via the communication control unit 103. The user can input the received data.
The communication control unit 103 sets the first communication unit and the second communication unit in a reception state at the time of initial setting, and when data is received by the first communication unit or the second communication unit, Based on the reception, control is performed so that the data after the reception by one of the communication units is received by the reception unit, and the data is transmitted from the other communication unit. In this way, the drive circuit of the present invention can be set to perform communication in only one direction based on the received data after the initial setting.
[0020]
Further, the communication control unit 103 detects received data based on a synchronization clock at the time of data reception, and controls communication between the first communication unit 101 and the second communication unit 102, that is, when data is received by one of them, Based on the data reception, it is preferable to control the reception processing unit 104 to perform reception processing on the data after being received by one of the communication units and to transmit the data from the other communication unit. This is because there is no need to transmit data indicating the communication direction, and the communication direction can be quickly set.
[0021]
In addition, by using a drive unit in which two communication units capable of receiving and transmitting data by a common line according to the present invention are connected in series by a common line, flexible connection is possible. For example, a connection configuration in which the drive unit 300 is connected as a star to the drive control unit 400 shown in FIG. 3, and the drive control unit 400 and each drive unit 300 shown in FIG. 6 and a connection mode in which the drive control unit 400 and each drive unit 300 shown in FIG. 6 are connected in series with data communication directions alternately different.
[0022]
Here, an example is shown in which the drive circuit in the drive unit 300 is controlled by receiving data from the drive control unit 400 provided outside, but the drive circuit may have a drive control unit inside the drive unit. Good. In this case, the communication between the drive control units and the communication between the drive circuits can be performed hierarchically by connecting the respective drive control units of the plurality of drive units and performing communication.
[0023]
In particular, the connection configuration of FIG. 6 can prevent the communication line from being lengthened by connecting the respective drive circuits in series and by routing. To realize a large-screen display device, it is necessary to increase the pixel pitch size, which increases the size of one LED unit. In this case, if the number of output ports of the control circuit is reduced, as shown in FIG. Configuration is required. In this configuration, the signal wiring from the upper unit to the lower unit is longer because the longer the unit, the longer the cable length and the greater the influence of the reflection distortion of the signal transmission. It is extremely effective to realize the connection form as shown in FIG. In addition, as shown in FIG. 7, the outdoor drive unit and the like have a louver or the like for blocking external light, and are generally not vertically symmetrical. It is difficult to change the communication direction. The drive unit of the present invention does not need to prepare two types of drive units having different communication directions in order to realize the connection configuration of FIG.
[0024]
Here, the data necessary for the drive circuit includes a drive current value of the light emitting element, gradation control data, and the like. Usually, one driver circuit is highly integrated and a plurality of light emitting elements are driven, and a plurality of driver circuits (Drivers) are connected according to the number of pixels. FIG. 6 shows a configuration in which the drive circuits are connected in series at the communication terminals of the communication unit. Each drive circuit in the present invention has a communication terminal of the first communication unit and a communication terminal of the second communication unit. The connection in FIG. 6 is performed according to the connection sequence of each drive circuit. An example of connection is shown in a case where the input direction from both the input direction from the unit and the input direction from the second communication unit can be supported. The connection to the circuit group can be minimized by cable wiring, and the short wiring length can improve the data transmission quality, so that a more stable data transmission system can be constructed.
[0025]
FIG. 8 is a block diagram schematically showing an example of a communication function part of the drive circuit according to the present invention. The drive circuit of the present invention can be set in any communication direction by hardware autonomy. The left and right communication terminals (communication terminals of the first communication unit and the second communication unit) are a left communication terminal DATA_L and a right communication terminal DATA_R, and the communication units for the left and right terminals have a reception buffer and a transmission buffer having a gate control function. are doing. In the figure, the reception buffer 711 receives data on the left communication terminal DATA_L side, and the transmission buffer 712 transmits data. However, the gate is controlled so that only one of the gates operates effectively. In the gate control signal (select signal) in the initial state, the reception buffer side is set to the valid state on both the left and right terminals. The reception data detection unit 731 and the reception data detection unit 732 output a detection signal (data reception detection flag) when receiving data from one of the left and right terminals, and control the gate of each transmission / reception buffer. For example, when data reception is detected on the left side, the voltage level of the data reception detection flag F1 is inverted from the reception data detection unit 731, the gate of the transmission buffer 722 on the right side is enabled, and the reception buffer 721 on the right side is disabled. . At this time, the reception data selection circuit 740 selects the data received from the left communication terminal DATA_L and sends it to the reception processing unit 750. Similar processing is performed when data is received from the right side. As a precondition, data reception is uniquely determined on either side. That is, the system is such that the data receiving direction does not change.
[0026]
【Example】
FIG. 9 shows a specific embodiment of the communication function part in the drive circuit of the present invention. The signal transmission method shows an example in which a DS code method using a data signal (DATA_L / DATA_R in the figure) and a strobe signal (STROBE_L / STROBE_R) is adopted. The DS code is a data signal DATA and a strobe signal STROBE on the receiving side. By taking the exclusive OR (hereinafter, referred to as EXOR) of the above, a synchronous clock signal can be obtained. Negative logic gate control receiving buffers (805 and 808 in the figure) and positive logic gate control transmission buffers (806 and 807 in the figure) are provided at both left and right terminals (communication terminals of the first communication unit and the second communication unit). For each gate control, a gate control signal (select signal; LBus_CTL / RBus_CTL) is generated by the left data reception detection unit 803 and the right data reception detection unit 804.
[0027]
Here, an operation when data is input to the left communication terminal will be described.
When the EXOR 803a receives 2 bits of data, the left data reception detection unit 803 can generate a one-pulse clock, and latches the flip-flop 803b to a High output at the falling edge of the clock. The flip-flop 803b outputs a low level “0” at the time of reset. That is, when 2 bits of data are input, RBus_CTL changes from LOW “0” to HIGH “1”, and the right communication buffer gate turns on the right transmission buffer 807 and turns off the right reception buffer R808. At this time, since there is no data reception from the right side, the gate control signal LBus_CTL in the left communication buffer control bus Lb1 remains LOW, and the left communication buffer has a gate state in which the left reception buffer 805 is ON and the left transmission buffer 806 is OFF. State. Immediately after the reset, the reception buffer of the left and right communication buffers is in an ON state, that is, an input enabled state, and the transmission buffer is in an OFF state until data is received. Thereafter, when either the left or right data reception is detected, the reception side turns on the reception buffer, the non-reception side turns on the transmission buffer, and the communication directions of the left and right buffers are reset to the left and right data reception detection units 803 and 804. It is fixed until a signal (Xreset) is input. Further, after determining the communication direction, the data selection circuit 802 selects the data on the receiving side by selecting and controlling both the gate control signal LBus_CTL in the left communication buffer control bus Lb1 and the gate control signal RBus_CTL in the right communication buffer control bus Lb2. Are input to the reception processing unit 801. As described above, after the left and right directions are reset, the input-enabled state is set, and after data reception, the non-receiving side is set from the input to the output state.
[0028]
Here, an example in which the reset signal (Xreset) is input from the outside of the drive circuit (for example, the drive circuit control unit) has been described. However, reset data indicating the initial setting is transmitted from the drive control unit or the like to each drive circuit. The reception processing unit may be configured to perform initial setting when receiving reset data. Further, it is possible to configure so that the reception processing unit that receives the reset data generates a reset signal and inputs the reset signal to the left and right data reception detection units 803 and 804.
[0029]
10a and 10b show an example of an LED unit (drive unit) 300 in which drive circuits (drv1 to drv8 in the figure) having a direction control function of the present invention are connected in series and mounted. FIG. 10C is an operation time chart of the gate control signal for determining the transmission / reception direction of the drive circuit in one LED unit at the time of data reception. FIG. 10A shows an example in which data is input from the left connector CON_L, and FIG. 10B shows an example in which data is input from the right connector CON_R.
[0030]
As shown in FIG. 10C, when there are eight driving circuits in one LED unit, by inputting 16-bit data, it is possible to generate eight synchronous clock pulses RCLK, and this synchronous clock pulse RCLK By sequentially turning on the gate control signal RBus_CTL in the right communication buffer control bus Lb2 or the gate control signal LBus_CTL in the left communication buffer control bus Lb1 of each drive circuit (drv1 to drv8) at the falling edge of The data communication direction of the drive circuit can be determined. FIG. 10C shows an operation time chart at the time of inputting the left data of FIG. 10A.
[0031]
FIG. 11 is a block diagram schematically illustrating an example of an image display device according to the drive unit of the present invention. The image display device shown in this figure has the following configuration.
(A) The display unit 1 in which a plurality of light emitting elements 11 are arranged in a matrix of M rows × N columns.
(B) A vertical drive unit (drive circuit) 2 for applying a current to each row of the display unit 1 while selecting each row.
(C) A horizontal drive unit 3 that supplies a drive current to each column of the display unit 1 according to the image data corresponding to the selected row.
(D) A drive control unit (drive control unit) 4 including a unit communication unit 5, a driver communication unit 6, and a first reference clock generation unit 7.
(E) A correction data storage unit 9 storing correction data for correction.
[0032]
The operation of each component is controlled by the drive control unit 4. This image display device receives only data for controlling the image display device from an external controller that supplies image data, and performs autonomous generation of a signal required for driving inside the image display device inside the image display device to perform lighting display. . The drive circuit of this embodiment shows a method of driving the light emitting element 11 by current control.
[0033]
The display unit 1 has a plurality of light emitting elements 11 arranged in a matrix of M rows × N columns on a substrate on which a conductive pattern is formed. As the light emitting element 11, an LED or the like is used. In this embodiment, three light emitting diodes capable of emitting red, green, and blue (RGB) light are respectively arranged adjacent to each other in units of three to constitute one pixel. An LED with RGB adjacent to each pixel can realize full-color display. However, the present invention is not limited to this configuration, and two colors can be arranged close to each other, or two or more LEDs can be arranged for one color.
[0034]
As the light emitting diode, a semiconductor light emitting element that can emit various lights can be used. Examples of the semiconductor element include an element using a semiconductor such as GaP, GaAs, GaN, InN, AlN, GaAsP, GaAlAs, InGaN, AlGaN, AlGaInP, and InGaAlN as a light emitting layer. Further, the semiconductor structure may be a homostructure having a MIS junction, a PIN junction or a PN junction, a heterostructure, or a double heterostructure.
[0035]
The emission wavelength of the semiconductor light emitting device can be variously selected from ultraviolet light to infrared light depending on the material of the semiconductor layer and the degree of mixed crystal thereof. Furthermore, in order to have a quantum effect, a single quantum well structure or a multiple quantum well structure in which the light emitting layer is a thin film can be used.
[0036]
In addition to the three primary colors of RGB, a light emitting diode using a combination of light from an LED chip and a fluorescent substance excited and emitted by the LED chip can be used. In this case, by using a fluorescent substance that is excited by light from the light emitting diode and converts it into a long wavelength, a light emitting diode that can emit white light with high linearity using one type of light emitting element can be obtained.
[0037]
Further, light-emitting diodes having various shapes can be used. Specifically, a light emitting element that electrically connects an LED chip, which is a light emitting element, to a lead terminal, and uses a light emitting element itself such as a shell type, a chip type LED, or the like, which is covered with a mold resin or the like.
[0038]
The drive control unit 4 includes a unit communication unit 5, a driver communication unit 6, and a first reference clock generation unit 7. The unit communication unit 5 transmits and receives various data to and from the external controller and the unit communication unit 5 of another image display device connected to the next stage, and further gives an instruction to the driver communication unit 6. The driver communication unit 6 corrects the image data (IMDATA) input from the outside according to the variation in the light emitting element characteristics of each pixel, and outputs the corrected data to the horizontal drive unit 3. On the other hand, the horizontal drive unit 3 includes a driver communication unit 6 and a horizontal drive side communication unit 8 for performing data reception processing.
[0039]
In FIG. 11, the driver communication unit 6 is a DMA control unit 6A. The DMA control unit 6A, which is the driver communication unit 6, includes a memory (RAM) for temporarily storing image data. In order to exchange a large amount of data at a high speed, the DMA control unit 6A directly reads out the contents of the RAM by hardware at a high speed, and performs data transfer to the horizontal drive unit 3.
[0040]
The first reference clock generator 7 switches the current source of each row of the vertical driver 2. In addition, it functions as a timing generation unit 7A that generates a gradation reference clock as a first reference clock for controlling the lighting gradation. The grayscale reference clock is sent from the timing generation section 7A to each horizontal drive section 3. However, in the present embodiment, the first reference clock generator 7 is provided in the drive control unit 4 to transmit the gray scale reference clock, but the first reference clock generator 7 is provided on the horizontal drive unit 3 side. Thus, a configuration in which the timing is autonomously generated can be adopted.
[0041]
The drive control unit 4 further includes an image data correction unit and an image data storage unit. Image data input from the outside is corrected by the image data correction unit according to the variation in the characteristics of the light emitting elements 11 for each pixel, and is output from the DMA control unit 6A to each horizontal drive unit 3. Correction data for this correction is stored in the correction data storage unit 9. The image data correction unit reads information data for correction from the correction data storage unit 9 and performs data correction. The correction data storage unit 9 includes a memory element such as a ROM, ^Two It is composed of a PROM.
[0042]
The correction data for correcting the variation for each light emitting element 11 is stored in the correction data storage unit 9. The correction data storage unit 9 is configured by a ROM that stores correction data calculated in advance. In the drive circuit shown in FIG. 11, the image data correction unit is provided separately from the drive control unit 4, but may be incorporated in the drive control unit 4. The correction data includes, for example, luminance correction data for correcting luminance for each light emitting element.
[0043]
The connection part, which is a physical interface of the signal, is a means for serially transmitting data from the controller to the LED unit, and can be electrically connected using wiring, or transmitted directly using optical fibers and electromagnetic waves. You can also.
[0044]
The vertical drive unit 2 is a common driver that applies a current in a row direction of the display unit 1, and is configured by a semiconductor switching element or the like. In FIG. 11, one vertical drive unit 2 switches a common line of each row in a predetermined order to apply a current. The row selected by the vertical drive unit 2 in one operation may be one row of the display unit 1 or a plurality of rows.
[0045]
The horizontal drive unit 3 has a plurality of stages connected as shown in FIG. An LED driver constituting each horizontal control unit 3 is connected to each column of the light emitting elements 11, and LED drivers 1 to N for N columns are connected in series. Adjacent LED drivers are electrically connected by each horizontal drive side communication unit 8.
[0046]
The horizontal drive unit 3 includes a horizontal drive side communication unit 8, a memory unit 17, a lighting control unit 15, and a constant current drive unit 14. The memory unit 17 includes a shift register and the like. The horizontal drive unit 3 is connected to the LEDs arranged in each column direction, sequentially supplies current to the LEDs in the vertical direction in synchronization with switching of the vertical drive unit 2, and performs dynamic lighting. The horizontal drive unit 3 is configured by a semiconductor switching element and a driver IC.
[0047]
The horizontal drive unit 3 includes a horizontal drive communication unit 8. The horizontal drive side communication unit 8 communicates with the drive control unit 4 and the horizontal drive side communication unit 8 provided in the horizontal control unit 3 at the next stage. The horizontal drive side communication unit 8 can obtain a synchronous clock signal by taking an exclusive OR (hereinafter, referred to as EXOR) of the data signal DATA and the strobe signal STROBE. The left and right terminals (the communication terminals of the first communication unit and the second communication unit) are provided with a reception buffer with negative logic gate control and a transmission buffer with positive logic gate control. Left data reception detection section 803 and right data reception detection section 804 Thus, a gate control signal (select signal) is generated. Thus, when data reception is detected at one of the left and right communication terminals, the receiving side turns on the receiving buffer, the non-receiving side turns on the transmitting buffer, and the communication directions of the left and right buffers are fixed until a reset is input. .
[0048]
Further, the horizontal drive side communication unit 8 writes data sent from the DMA control unit 6A of the drive control unit 4 to the memory unit 17 provided in the horizontal drive unit 3. In the example of FIG. 11, the DMA control unit 6A sends the image data to the memory unit 17, and the memory unit 17 holds the image data with a shift register. Each of the horizontal drive units 3 is configured to be assigned individual identification information 23, and image data or the like to which the identification information 23 of the destination horizontal drive unit 3 is added is transmitted from the drive control unit 4 of the image display device. You. After recognizing that the data is addressed to itself, the horizontal drive unit 3 performs reception processing.
[0049]
On the other hand, the drive control unit 4 includes a unit communication unit 5. The unit communication unit 5 receives control data from an external controller that transmits data for image display, and performs writing and reading operations of a memory, a register, and the like to the DMA control unit 6A of the drive control unit 4. For example, if the unit communication unit 5 receives image data from an external controller and rewrites the image data in the image data storage RAM provided in the DMA control unit 6A, the image display is updated. The control data of the image display device includes control of the drive circuit, temperature information inside the image display device, monitor information of the power supply voltage, detection of disconnection between the display device and the drive circuit, and failure due to abnormal temperature rise of the horizontal drive unit 3. And a process of checking a signal pattern wiring failure inside the image display device, a data communication state between the control unit and the horizontal drive unit 3, and writing luminance correction data. The unit communication section 5 exchanges these data between the external controller and the image display device according to a predetermined communication method.
[0050]
The DMA controller 6A performs high-speed autonomous hardware data transfer to the horizontal drive side communication unit 8 in a predetermined format using image data, luminance correction data, and the like. In particular, in the case of an image display device using LEDs, an image refresh rate that is approximately 4 to 16 times the image refresh rate at a normal video rate is required. For this reason, at the time of dynamic driving, it is necessary to read out the image data and the luminance correction data directly from the memory by hardware processing and perform high-speed data transfer.
[0051]
FIG. 12 shows a time chart in a frame cycle operation at the 1/4 duty. In the present embodiment, a method is shown in which identification information 23 is provided to the horizontal drive unit 3 and writing to a memory in the horizontal drive unit 3 and synchronization control are performed in the form of a packet from an external controller for communication. The identification ID 23 a as the identification information 23 to be given is, for example, an identification number unique to an IC constituting each horizontal drive unit 3. In FIG. 12, among the signals sent from the external controller to the image display device, a packet for vertical synchronization detection is csp (Cycle Start Packet), and a control data packet to each of the horizontal driving units 3 from 1 to N is ud1. To udN. On the other hand, a response packet transmitted from the horizontal drive unit 3 to the external controller is defined as res. In this embodiment, full-duplex two-way communication is used, but a similar method is also possible in half-duplex two-way communication.
[0052]
In the image display device, the control data for the horizontal drive unit 3 sent from the DMA control unit 6A is data_0 to data_3. Further, in FIG. 12, vsync is generated in the image display device according to the vertical synchronization detection data csp. This data determines the cycle of a packet for transmitting each frame data, and is used as a frame synchronization of each horizontal drive unit 3 and as a data latch trigger.
[0053]
The drive control unit 4 receives the vertical synchronization detection data csp sent from the external controller, recognizes the head of the image frame data, and performs vertical synchronization. By this synchronization detection, a lighting control signal (BLANK) in the image display device and a vertical drive unit control address are generated based on a predetermined display double speed. FIG. 12 shows an example in which quadruple-speed lighting is performed with respect to a vertical synchronization cycle of 60 Hz, and one vertical drive cycle for performing one screen display of one image display device is 240 Hz. In this case, the drive duty ratio is 1/4 for one frame packet section (about 16 ms) of the vertical synchronization cycle of 60 Hz, and four common lines are controlled. In this embodiment, the function of changing the refresh rate is realized by making the lighting double speed variable. In addition, various data such as image data and luminance adjustment data are transferred by N (ud1 to udN), which is the number of the horizontal drive units 3 to be controlled, during one cycle of the vertical synchronization detection data csp. After receiving the data in each horizontal drive unit 3, the data is reflected in the next vertical cycle. Therefore, during the reception of various data, writing to the memory in each horizontal drive unit 3 is performed, and the image data currently displayed is the data transferred in the previous vertical cycle.
[0054]
FIG. 13 shows a data format configuration in a case where communication is performed in packet data format when communication is performed when each horizontal drive unit 3 is controlled by the DMA control unit 6A as the driver communication unit 6. The data packet 20 of this format includes a control field 21 and an information field 22, and the control field 21 is further divided into identification information 23 (ID section) and control identification information 24 (CMD section).
[0055]
The control field 21 is a part for storing various kinds of identification information added to the actual data. The identification information 23 indicates information for identifying each horizontal drive unit 3. Since each horizontal drive unit 3 is individually provided with the identification ID 23a as the identification information 23, it can be said that this information indicates the destination of the data to be transmitted.
[0056]
The control identification information 24 is information indicating a control type of what kind of control is performed on the horizontal drive unit 3. Data types include, for example, horizontal synchronization signal (HSYNC) data, image data, gradation data, brightness adjustment data, rewriting of brightness correction data, reading of fault data, and the like.
[0057]
The information field 22 indicates the content of control data that is actual data corresponding to the control identification information 24 of the CMD section. This enables individual control of each horizontal drive unit 3.
[0058]
The data packet includes data to be transmitted to all the horizontal driving units, in addition to data such as image data to be transmitted to the individual horizontal driving units. Data packets transmitted to all the horizontal drive units include, for example, HSYNC and an automatic ID assignment command. In these data packets, a common ID 23B is set as the identification information 23.
[0059]
FIG. 14 is a block diagram showing a state in which the drive control unit 4 transmits a data packet 20 in the format of FIG. 13 and each horizontal drive unit 3 receives it. In this embodiment, a plurality of horizontal drive units 3 are connected in series to a drive control unit 4. The horizontal drive unit 3 has one input and one output, and is connected between the driver communication unit 6 of the drive control unit 4 and the horizontal communication unit of the horizontal drive unit 3 and via the horizontal communication unit. The spaces are connected. The packet data output from the drive control unit 4 can be transparently transferred to all the horizontal drive units 3.
[0060]
In this embodiment, the flow of data communication is performed only in one direction. In FIG. 14, the horizontal drive side communication unit 8 of the horizontal drive unit 3 can output data only in one direction. The plurality of horizontal driving units 3 connected in series are connected in a ring via a driving control unit 4. Therefore, the data packet 20 output from the driver communication unit 6 of the drive control unit 4 transparently loops through each horizontal drive unit 3 and is connected to the last stage in the transmission direction of the data packet 20. The data packet 20 output from the horizontal drive side communication unit 8 is input to the driver communication unit 6 of the drive control unit 4. That is, the configuration is such that the data packet 20 transmitted from the drive control unit 4 loops through each horizontal drive unit 3 and returns to the drive control unit 4. However, the drive circuit of the present invention can be configured by bidirectional communication.
[0061]
When the identification information 23 is set in each horizontal drive unit 3, each horizontal drive unit 3 monitors the ID that is the identification information 23 of the data packet 20, and when the ID value matches its own identification ID 23a, The packet data to be stored is stored in the memory unit 17 inside the driving device. In FIG. 14, the drive control unit 4 sequentially sends out data packets 201, 202, and 203 to the horizontal drive unit 3. The horizontal drive unit 3 (LED driver 1) with ID = 1 performs reception processing when the data packet 201 passes and accumulates DATA1 in the memory unit 17, and the horizontal drive unit 3 (LED driver 2) with ID = 2. Stores DATA2 in the memory unit 17 when the data packet 202 passes.
[0062]
Here, the example of the LED display unit has been described, but the drive circuit and the drive unit of the present invention can be applied to a lighting device including a light emitting element such as an LED.
[0063]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a drive circuit and a drive unit that enable flexible connection. Furthermore, even when data is input from either of the two communication units, communication is possible through a common line, and the connection between the drive circuit and the drive unit can be minimized, thereby improving data transmission quality. And a more stable data transmission system can be constructed.
[Brief description of the drawings]
FIG. 1 is a circuit diagram schematically illustrating a driving method of an image display device.
FIG. 2 is a block diagram showing a driving circuit of a conventional image display device.
FIG. 3 is a diagram showing a connection example of a driving circuit in a conventional image display device.
FIG. 4 is a conceptual diagram of a drive circuit according to the present invention.
FIG. 5 is a diagram showing a connection configuration in which drive circuits are connected in series with the same data communication direction;
FIG. 6 is a diagram showing a connection configuration in which drive circuits are connected in series with data communication directions being alternately different directions;
FIG. 7 is a schematic view of a drive unit having a louver.
FIG. 8 is a block diagram schematically showing an example of a communication function part of a drive circuit according to the present invention.
FIG. 9 is a circuit diagram showing a specific example of a communication function part in the drive circuit of the present invention.
FIG. 10 is a schematic diagram showing an example of setting a communication direction in a drive unit according to the present invention.
FIG. 11 is a block diagram showing a driving circuit of the image display device according to one embodiment of the present invention.
12 is a timing chart showing a frame cycle operation of the drive circuit of FIG.
FIG. 13 is a conceptual diagram showing a format of transmission data.
FIG. 14 is a block diagram showing the flow of data reception in packet format.
[Explanation of symbols]
101: first communication unit
102: second communication unit
103 ・ ・ ・ Communication control unit
104 reception processing unit
105 ・ ・ ・ Drive unit
300 drive unit
400 ・ ・ ・ Drive control unit
711, 721 ... reception buffer
721, 722... Transmission buffer
731, 732... Received data detector
740... Received data selection circuit
750, 801 ... reception processing unit
802: data selection circuit
805: Left receiving buffer
806: Left transmission buffer
807 ... right transmission buffer
808: Right side reception buffer
1. Display unit
2: Vertical drive unit
3. Horizontal drive
4: Drive control unit
5 Unit communication unit
6: Driver communication unit
6A: DMA control unit
7: first reference clock generator 7A: timing generator
8 Horizontal communication unit
9: correction data storage unit 11a: LED
12 ... Common source line
13. Current line
14 Constant current drive section
14a: constant current source
15 Lighting control unit
16 ... Decoder
17 ... Memory section
18 ... Control unit
20 ... data packet
201, 202, 203 ... data packets
21 ... Control field
22 Information field
23 ... Identification information
23a ... ID
23A… Individual ID
23B ... Common ID
24 ... Control identification information

Claims (8)

In a driving circuit for driving a light emitting element,
A first communication unit capable of selectively communicating either reception or transmission of data by a common line;
A second communication unit capable of performing communication different from the first communication unit by selecting a different one of data reception or transmission by a common line;
A reception processing unit that performs data reception processing;
At the time of initial setting, the first communication unit and the second communication unit are set to a reception state, and when data reception is detected by one of the first communication unit and the second communication unit, the first communication unit and the second communication unit are set based on the data reception. The communication unit in which the data reception is detected is defined as a reception communication unit, and the reception processing unit causes the reception processing unit to perform reception processing on the data after the reception, and sets the other communication unit to the transmission side. A drive circuit, comprising: a communication unit; and a communication control unit for fixedly controlling the communication direction until a reset signal is input so as to transmit data from the transmission side communication unit . The drive circuit according to claim 1, wherein the communication control unit controls to transmit data from the other communication unit based on a synchronization clock at the time of data reception. The first communication unit and the second communication unit each have a reception buffer and a transmission buffer,
The communication control unit, when data reception is detected in any of the reception buffer or the transmission buffer in each communication unit, puts the reception buffer of the reception communication unit and the transmission buffer of the non-reception side into a valid state. The drive circuit according to claim 1, wherein control is performed such that each of the communication units selects reception or transmission according to the select signal to be performed. 4. The initialization according to claim 1, wherein the first communication unit and the second communication unit are set to a reception state by inputting a reset signal to a drive circuit or receiving reset data in a reception processing unit. 5. Drive circuit. In a driving unit having a plurality of driving circuits for driving the light-emitting element,
Each drive circuit has two communication units that can communicate with a common line that can select either data reception or data transmission, and the drive circuits are connected in series by the common line,
At the time of initial setting, each drive circuit controls so that the two communication units receive data.
When data reception is detected in one of the communication units, the communication unit in which data reception is detected based on the detection of the data reception is referred to as a reception communication unit, the other communication unit is referred to as a transmission communication unit, and reception is performed thereafter. The data received by the transmitting side communication unit is transmitted from the other transmitting side communication unit,
The other drive circuits, in the order in which they are connected by the common line, when data is received by one of the communication units, based on the detection of the data reception , the communication unit in which the data reception is detected as a receiving communication unit, A drive that sets the communication direction fixed until a reset signal is input by transmitting the data received by the other communication unit from the other communication unit after the other communication unit is used as the transmission communication unit. unit. Wherein the driving circuit, when the data reception is detected in one communication unit, the transmission data received by the communication unit the data received after, based on the synchronous clock at the reception of data is detected from the other communication section The drive unit according to claim 5, wherein the operation is performed. The drive unit according to claim 5, further comprising a drive control unit configured to control driving of the light emitting element by transmitting data to one communication unit of a drive circuit connected to an end of the drive unit. The initial setting is such that the first communication unit and the second communication unit are set to a reception state by inputting a reset signal from the drive control unit to a drive circuit or receiving reset data in a reception processing unit. 8. The drive unit according to 7.

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