JP5104627B2 - Communication control device for LED display device - Google Patents

Description

  The present invention can be applied to an LED driving communication control device and the like, and relates to a data transmission / reception control circuit in a communication unit and a reception unit. In particular, it is an object of the present invention to provide a communication control device capable of displaying desired data even when a communication failure occurs.

  In recent years, high-performance red, green and blue LEDs have been developed, and full-color LED display has become possible. Among large display devices, LED display devices that utilize the features of LEDs such as high brightness, long life, and light weight are rapidly spreading. In addition, their uses are diversifying, and there is a demand for a system that can flexibly handle various applications such as large televisions, advertisements, traffic information, stereoscopic displays, and lighting.

  The displays that use these LEDs range from large outdoor displays such as for billboards to medium and small screen sizes for semi-indoors such as platforms, depending on the application and location. Various displays with different pixel pitches have been used. In addition, the conventional vertical / horizontal screen ratio (aspect ratio) tends to change. When high-definition video such as HDTV is displayed on an LED, the amount of video data increases, and the display panel further increases in screen size. We have to deal with it. Also, under the advanced information network, it is required that the display is connected to such a communication infrastructure and can handle display control, maintenance, etc. by remote operation.

  In such a display, for example, LEDs of about 16 dots × 16 dots are arranged in a matrix and modularized as a single LED unit, and the LED unit is arranged according to the screen size, vertical / horizontal aspect ratio, and the like. Concatenated in a matrix. FIG. 5 shows an LED display 801 as a configuration example. A plurality of distributors 804 connected to the controller 803 are arranged for each row of the LED units 802 and supply video data for display and various control signals to the LED units 802.

  The control signal 820 includes, for example, a video data synchronization clock, a horizontal synchronization signal, a vertical synchronization signal, a blank signal, a gradation reference signal, a video data latch signal, and the like. It supplies to each LED unit 802 via 804. The display full-color video data 810 transmitted from the distributor 804 to each LED unit 802 requires at least RGB (red, green, blue) video data, and the bit width of the video data is determined according to the gradation resolution.

  For example, when displaying with 256 gradations per color, an 8-bit video data bus is required for three colors. These video data are supplied to the LED unit 802 by time-dividing the number of LED units × the number of display dots. The video data 810 is bit-shifted by the shift register circuit 805 in each LED unit 802, the data is latched when a predetermined number of data is supplied, and the captured video data is displayed as the display video data 810. it can.

  However, such an LED display device transmits display video data 810 between the controller 803, the distributor 804, and the LED unit 802 via a parallel bus as a signal interface, and supplies synchronized clocks and various control signals 820 synchronized therewith. Yes. Therefore, there has been a problem that the number of signal lines increases as the LED display device becomes higher definition or larger. In particular, at present, when the display screen tends to be larger and the number of LED units increases, the signal lines increase and become longer, and the gray scale reference signal, the deterioration of the pulse width of the video data synchronization clock, and the effects on noise are serious problems. Become.

  In order to support the HDTV specification, the aspect ratio of the screen changes, and it becomes necessary to further increase the number of connected LED units, and the transfer rate of video data must be increased accordingly. As the number of LED units connected increases, the pulse deterioration of each signal increases, and there is also a problem that the input / output timing between the video data and the synchronous clock becomes particularly difficult.

  Further, the level of image quality required for image display of LED display devices has been increasing year by year, and along with the miniaturization of LEDs, the technical development of LED displays capable of fine display has become an urgent task. In order to realize fine display of video, it is necessary to increase the gradation resolution. Specifically, it is necessary to change the bus specification such as changing the conventional display video data bus width from 8 bits to 10 bits. In order to realize fine display, it is necessary to reduce the size of the LED and reduce the dot pitch width. When the dot pitch is reduced, the LED unit size is reduced proportionally. Therefore, there is a problem that the ratio of the mounting area of components such as connectors increases due to the increase in the video data bus width.

  Further, the conventional LED display device cannot communicate with a plurality of LED display devices having different display gradations or different numbers of pixels per one LED display device by a common communication method.

In order to deal with the above problems, a new control circuit using bidirectional packet communication was developed. As a result, the following problems were newly found.
First, if the received data is in the correct format (regular format data), the end of the data can be recognized correctly. For example, if a portion for specifying the number of data is added to the received data format and compared with the number of actually received data, the end of the data can be recognized. However, if illegal data such as noise (unregular format data) is received, the number of data actually received will be indeterminate if the number of data is not specified, so the end of the data will be recognized correctly. I can't. The fact that the end of the data cannot be recognized means that the data reception state continues despite the end of data reception, and the next received data is recognized as part of the previously received data. It may cause malfunction.
Secondly, contrary to the first problem, there are cases where reception temporarily stops despite data reception due to power fluctuations or poor communication line contact, etc. If it is not recognized as a part of the data before the reception is stopped, it causes a malfunction. In view of the above problems, these have been recognized as new issues.
Accordingly, the object of the present invention is to firstly reliably recognize the end of data, and after receiving the data, is placed in a reception waiting state so that the next data can be received. Secondly, with respect to the temporary stop of the received data, the receiving circuit can be summarized into two points that keep the receiving state. In addition, an object is to provide a circuit that can ensure stable and reliable communication.

  The communication control device for an LED display device according to the present invention is a communication control device for an LED display device that communicates data between a controller that supplies a control signal of a unit and the unit or between the units. Receiving circuit, a protection circuit that outputs a control signal to the receiving circuit after an arbitrary time (Tr) after the reception of the data is temporarily stopped or terminated, and the receiving circuit is controlled by the control signal of the protection circuit, It is a communication control device for an LED display device, which recognizes a temporary stop or end of the data and enters a reception waiting state.

  The arbitrary time (Tr) satisfies the relationship of (data transfer time for one data) ≦ Tr ≦ (Tp / 2) with the set time (Tp) until the data is next received. Is preferred.

  Further, the receiving circuit has a reception data counter circuit that performs a counting operation while receiving the data and stops a counter operation when the data is temporarily stopped or ended, and the protection circuit is receiving the data The counter value of the reception data counter circuit is reset to a predetermined value, and the counter operation continues after the counter operation of the reception data counter circuit is stopped to detect the arbitrary time (Tr). The count operation is performed only when the main counter circuit is reset, and when the count operation of the main counter circuit is stopped in the reset state, the counter operation is continued and the arbitrary time (Tr At least a spare counter circuit for detecting.

  In addition, in the circuit that operates the reception data counter at the time of receiving all the data (including the regular format and the irregular format) input to the communication unit in the unit or controller-unit communication, the reception data counter operation stops counting. And an LED drive communication control circuit characterized by having a function of detecting the end of data, and preferably, the protection circuit includes a main counter circuit (counter circuit 1) and a spare circuit. It has at least two circuits of a counter circuit (counter circuit 2), has a function of resetting a receiving circuit after recognizing the end of data, and additionally, a time from the end of data to resetting of the receiving circuit Is preferably adjustable.

  The next data received from the end of the data until the receiving circuit is reset is recognized as a part of the previous data, and the data received after the receiving circuit is reset is the same as the previous data. By providing a function for recognizing as different data, it is possible to cope with interruption of data reception.

  By using this invention, the receiving circuit can recognize the end of the received data regardless of the contents of various illegal data such as noise and the length of the data, regardless of the data received, and the receiving circuit is always normal. Therefore, the data can be received correctly, and the communication reliability can be improved.

First of all, a reception data counter circuit is prepared in the reception circuit, and the data is counted at a certain period during data reception. Further, another counter circuit 1 is prepared, and this counter also performs a counting operation during data reception, but is reset when the value of the reception data counter circuit reaches a certain value. When the data reception is completed, the counter circuit 1 is not reset, so that the count is advanced and the value is further increased. When this value becomes an arbitrary value, a reset signal is sent to the receiving circuit through the reset circuit. When the receiving circuit is reset by the reset signal, the receiving circuit is initialized so that the receiving state is changed to the reception waiting state. Further, by installing the counter circuit 2 as a spare circuit, the counter circuit 1 is used as an auxiliary counter when the counter circuit 1 is fixed (also referred to as freeze), for example, reset.

  Second, there is a time (Tr) that takes into account the pause time of data from the end of actual reception until the receiving circuit recognizes that reception has ended, and the data received within that time is part of the previous data To be recognized as. Further, the time (Tr) can be arbitrarily adjusted. In addition, the communication said to this invention does not ask a wire and radio | wireless.

  A functional block diagram of the circuit of the present invention is shown in FIG. 1, and timing charts are shown in FIGS. While reception data is being input, a reception flag from the reception recognition circuit is raised to indicate a reception state. During this time, the reception data counter circuit always repeats the counting operation (Fig. 2.1 reception data counter. In this case, it is a 3-bit counter operation). When data is being received, that is, when the reception flag is raised, the counter circuit 1 in the protection circuit performs a counting operation, and the reception data counter repeats the counting operation at a certain period, so that an arbitrary value, for example, FIG. In .1, when "4" is reached, the counter circuit 1 is reset in a certain cycle, and the operation of starting counting again from the beginning is repeated.

  However, when the reception is temporarily stopped or ended, the count operation of the reception data counter is stopped, so that the counter circuit 1 is not reset. For example, the count value is changed as in the counter circuit 1 of FIG. More than “6” or “D”, the count up is advanced beyond the range of steady operation.

  When the value of the counter circuit 1 reaches a certain value (N in the figure), a reset signal for the receiving circuit is generated. This reset signal is connected to the reset input of the receiving circuit, the receiving circuit is reset (initialized), and the reception state is changed to the reception waiting state, so that the next received data to be sent can be recognized normally. However, as shown in FIG. 2.2, when the reception data counter is “4”, reception may be temporarily stopped or terminated. At this time, the counter circuit 1 is fixed in a reset state. (Reset fixed state).

  Therefore, as shown in FIG. 1, the counter circuit 2 is prepared inside the protection circuit, and the counter circuit 2 is operated when the counter circuit 1 is in the reset fixed state (here, “0”). When the counter circuit 2 reaches an arbitrary value (Z in the figure), a reset signal is generated to reset the receiving circuit. Further, the reset output 2 from the count circuit 2 is also used as a reset input of the counter circuit 1, and the counter circuit 1 can be restored from the reset fixed state to the normal state. The reset outputs of the counter circuit 1 and the counter circuit 2 are ORed (logical sum), and when one of them outputs a reset signal, the receiving circuit is reset. That is, the protection circuit is provided so as to output a signal for resetting the reception state of the reception circuit after an arbitrary time (Tr) after detecting the temporary stop or end of the reception data.

  Further, since the value of N described above can be set arbitrarily, as shown in FIG. 3, the time Tr from when the reception is temporarily stopped or ended until the reception circuit reset signal is issued can be freely adjusted. ing. For example, as shown in the normal state of FIG. 3, when the next data 2 is input after resetting the receiving circuit (when the interval between the data in FIG. 2 is longer than Tr), the receiving circuit enters a reception waiting state. Therefore, data 1 and data 2 can be received as different data. When the next data 2 is input before resetting the receiving circuit (FIG. 2 “when data is shorter than Tr”), the receiving circuit operates again and takes in data 2 as part of data 1 It has become. In other words, the reception circuit continues to be in a reception state for a temporary stop of reception smaller than Tr.

  For example, when packet data is received due to a communication failure or the like even though it is transmitted as one packet data on the transmission side, even if the data reception is performed as if the data is divided. It can be read as one data as shown in 3 (b).

  The control signal output from the protection circuit according to the present invention is not only various reset signals, but also according to the circuit function of the control signal connection destination such as a circuit sleep signal, a standby signal, a power-on / power-off signal, Various functions can be set.

  (Embodiment 1) FIG. 4 shows an embodiment which is actually designed and operated. It consists of LED unit controller and LED unit connected in multiple stages (LED unit block), and performs full-duplex or half-duplex bidirectional packet communication between LED unit controller and LED unit or between LED units.

  The LED unit uses bi-directional communication, so the direction of the signal is not fixed, so there is no distinction between the input and output of the connector (input / output is possible from either the left or right), and the communication line between each unit is the shortest distance It is possible to connect with. As a result, signal waveform attenuation, radiation noise, and the like caused by the length of the communication distance can be minimized. In addition, since the number of signal lines is reduced, it is possible to use a differential transmission method (balanced transmission method), and it is possible to suppress and reduce radiation noise, increase the communication distance, increase the communication speed, etc. It is possible. In this embodiment, balanced transmission method, non-balanced transmission method, or a mixture of them, for example, transmission from the controller by the unbalanced transmission method, and conversion to the unbalanced transmission method in front of the LED unit are also performed and normal operation is performed. I have confirmed.

  In addition, the LED display has conventionally required a wiring of 1 m or more per unit, resulting in transmission speed delay, noise radiation, signal waveform disturbance, and the like. The reliability of communication was improved along with the solution of the above problems.

  The LED unit controller can send packet data individually to all LED units, and the display data packet is normally sent to all LED units at a period of 60 Hz. The received display data is sent to the storage device by the communication unit inside the LED drive circuit mounted one by one in the LED unit. When the driver IC control circuit reads the data, display data is sent to the LED driver IC, and the LED lighting operation is started. In addition, it is possible to write and read control data to the storage device inside each LED unit other than display data, and various setting data (current value, lighting time, etc.) can be transferred to the LED driver IC. Yes.

  The circuit of the present invention is composed of a receiving circuit inside a communication unit and a protection circuit in an LED driving circuit inside the LED unit. The circuit of the present invention according to this embodiment uses a set time Tp between packets (interval between the previous packet and the next packet) as a time Tr from when reception is temporarily stopped or ended until a reception circuit reset signal is issued. It is set to less than half. As a result, Tr is sufficiently smaller than Tp, so that the next packet sent can be normally recognized as another packet. Tr is set longer than the data transfer time for one data. This is a value with a sufficient margin for recognizing that the reception has been completed with certainty. By using this set value Tr, packet communication can be performed under optimum conditions.

  That is, in this embodiment, the most preferable operation setting can be obtained by setting the Tr setting time as (data transfer time for one data) ≦ Tr ≦ (Tp / 2). The setting times Tr and Tp can be appropriately selected so as to be adapted to various characteristics of a circuit to be used and a desired operation state, and are not limited to the settings of the embodiment.

FIG. 1 is a schematic block diagram of a receiving circuit and a protection circuit in a communication unit of the present invention. FIG. 2 is a timing chart for explaining the driving operation of the present invention. FIG. 3A shows a time chart for explaining reception in a normal state in the present invention, and FIG. 3B is a time chart for explaining reception in a communication failure state in the present invention. FIG. 4 is a schematic diagram showing a configuration of an LED display using the communication control device of the present invention. FIG. 5 is a schematic diagram showing the configuration of an LED display shown for comparison with the present invention.

Claims (3)

In a communication control device for an LED display device that bidirectionally communicates data between a controller that supplies a unit control signal and the unit or between the units,
The unit includes a receiving circuit that receives the data, and a protection circuit that outputs a control signal to the receiving circuit after an arbitrary time (Tr) after the reception of the data is temporarily stopped or ended .
The reception circuit includes a reception data counter circuit that performs a count operation during reception of the data and stops a counter operation when the data is temporarily stopped or ended.
The protective circuit is:
While the data is being received, the count value of the reception data counter circuit is reset to a predetermined value, and the counter operation is continued even after the counter operation of the reception data counter circuit is stopped, and the arbitrary time (Tr) is increased. A main counter circuit to detect;
The count operation is performed only when the main counter circuit is in a reset state, and when the count operation of the main counter circuit is stopped in the reset state, the counter operation is continued and the arbitrary time (Tr) is increased. And at least a counter counter circuit for recovering the counter operation of the main counter circuit from a stopped state in a reset state,
The communication control device for an LED display device, wherein the reception circuit enters a reception waiting state by recognizing a temporary stop or end of the data by a control signal of the protection circuit. 2. The communication control for an LED display device according to claim 1, wherein the arbitrary time (Tr) has the following relationship with a set time (Tp) until the data is next received. apparatus.
(Data transfer time for one data) ≦ Tr ≦ (Tp / 2) 3. The LED display device according to claim 1, wherein the unit includes a driver IC control circuit and an LED driver IC, and sends the data to the LED driver IC by the driver IC control circuit. Communication control device.

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