JP2006301271A - Led lighting driving circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED lighting driving circuit which requires a display data memory 10 for only one screen by writing and reading display data to and out of the display data memory 10 simultaneously in parallel. <P>SOLUTION: Disclosed is the LED lighting driving circuit of a dynamic lighting system which converts display data sent in series into parallel signals by lines by a shift register 3 and sends the parallel signals to a data input of a dot matrix type LED panel 1. The LED lighting driving circuit has the display data memory 10 equipped with multi-digit line memories 10a (flip-flop circuit) for a plurality of lines, a memory writing decoder 9 which writes the display data converted into the parallel signals by the shift register 3 to one-line memories 10a selected in order in the display data memory 10, and a memory reading decoder 11 which reads display data held in one-line memories 10a selected in order in the display data memory 10 and sends them to the data input of the LED panel 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an LED lighting drive circuit for driving a dot matrix type LED panel by a dynamic lighting method.

  As shown in FIG. 2, the dot matrix type LED panel 1 is a display panel in which LEDs (light emitting diodes) are arranged on each display dot 1 a arranged in a row (row) direction and a column (column) direction. . In each display dot 1a, there may be a case where one LED having a single emission color or one LED having a plurality of types of emission colors is arranged, or an LED having the same emission color and / or an LED having a different emission color. In some cases, a plurality of are arranged. In FIG. 2, display dots 1a of 16 × 16 dots are arranged in the row direction and the digit direction, and one or a plurality of red light emission, green light emission and blue light emission LEDs are arranged in each display dot 1a. Show. The display data to be displayed on the LED panel 1 includes red / display data for lighting a red light emitting LED, green / display data for lighting a green light emitting LED, and a blue light emitting LED. Three types are used: blue and display data. Further, the data corresponding to each display dot 1a of red, display data, green, display data, and blue and display data is set to 1 bit, respectively, and the LED of each light emitting color is displayed in two gradations of ON and OFF. Show.

  The LED panel 1 performs display by the dynamic lighting method by lighting the LEDs of the display dots 1a in the rows sequentially selected by the scan circuit 2. Further, the LED panel 1 has 16 data inputs for red, green and blue (hereinafter referred to as “RGB”), and the data input of each terminal is a display corresponding to 16 rows of corresponding digits. The corresponding light emitting color LEDs in the dots 1a are respectively connected via switching elements. Then, the scanning circuit 2 performs display by the dynamic lighting method by sequentially turning on the switching elements of the 16-digit display dots 1a in any one row. Therefore, for example, when red / display data is input to one terminal of the red data input, the red light emitting LED of the display dot 1a in the row selected by the scan circuit 2 in the digit corresponding to this terminal is turned on / off. Thus, display by the dot matrix method is performed.

  The conventional LED lighting drive circuit for driving the LED panel 1 by the dynamic lighting system converts display data sent serially into parallel signals for each row and sends them to the data input of the LED panel 1. It has become. That is, in the case of FIG. 2, RGB display data is input to the RGB shift register 3 bit by bit in accordance with the dot clock, and each time 16 bits of RGB display data is input for one row, the horizontal synchronization signal is input. It is latched by the latch circuit 4. Then, the display data latched by the latch circuit 4 is sent to the RGB data input of 16 bits in the LED panel 1, and the display dot 1a in any row is turned on / off to perform display. In addition, since the scan circuit 2 performs scanning for sequentially switching the display rows in accordance with the scan signal that is a horizontal synchronization signal, the display data sent serially is sequentially displayed on each row by 16 bits for each RGB, and dynamic Display by lighting system is performed.

  By the way, in the LED lighting drive circuit, when the input of the display data, the horizontal synchronization signal, etc. is stopped, the display of the LED panel 1 is also stopped. Further, the LED panel 1 can only perform display by a dynamic lighting method synchronized with a horizontal synchronizing signal of display data, and a dynamic lighting method according to an internal synchronizing signal or an external synchronizing signal having a speed (frequency) different from this. Cannot be displayed.

  Therefore, conventionally, display data sent serially is held in a memory for each screen (frame) of the LED panel 1, and the display data read from this memory is displayed on the LED panel 1. An LED lighting drive circuit has been developed. That is, as shown in FIG. 3, the LED lighting drive circuit has a screen memory 6 for one screen of display data for one row converted into a parallel signal by the shift register 3 sequentially through the bank switching writing circuit 5. The display data in the screen memory 6 is read out line by line by the bank switching readout circuit 7 and sent to the data input of the LED panel 1 for display. The bank switching writing circuit 5 and the bank switching reading circuit 7 are connected to the screen memory 6 via a 16-bit data bus, a 4-bit address bus (not shown), and an appropriate bit control bus. A write or read signal is sent, a row is specified by the address bus, and in the case of the bank switching write circuit 5, display data for one row is sent to the data bus, so that 16 bits for one row of the screen memory 6 This memory cell (in the case of SRAM, a flip-flop circuit) is accessed.

  The LED lighting drive circuit shown in FIG. 3 holds display data for one screen in the screen memory 6, so even if the input of display data sent serially is stopped, it is sent immediately before. By repeatedly reading the displayed data from the screen memory 6, the display on the LED panel 1 can be maintained. The LED lighting drive circuit includes an operation mode selection circuit 8 and sends the horizontal synchronization signal of display data to the bank switching readout circuit 7 as it is, and sends it to the scan circuit 2 (not shown in FIG. 3) as a scan signal. In addition, the internal synchronization signal generated internally can be used in place of the horizontal synchronization signal. Therefore, when this internal synchronization signal is used, even if the input of the horizontal synchronization signal is stopped, the bank switching read The circuit 7 and the scan circuit 2 can continue to operate, and the display of the LED panel 1 can be maintained.

  The screen memory 6 can hold display data for one screen by having a capacity of 16 × 16 bits for each RGB. However, such a screen memory 6 not only shares the data bus for writing and reading display data, but also shares the decoder for decoding the address specified by the address bus for writing and reading, so that it can display simultaneously. Data cannot be written or read. Therefore, at least two banks are required for each RGB, and the screen memory 6 accesses the screen memories 6 in different banks while alternately switching the banks by the bank switching writing circuit 5 and the bank switching reading circuit 7. Must do so. Moreover, when the operation mode selection circuit 8 selects an internal synchronization signal whose speed is different from the horizontal synchronization signal of the display data, the bank switching writing circuit 5 writes the display data for one screen in the screen memory 6. And the time required for the bank switching readout circuit 7 to read the display data for one screen from the screen memory 6 are different from each other in the screen memory 6 for at least 3 banks as shown in FIG. It is necessary one by one. Further, the LED lighting drive circuit sends an external synchronization signal sent separately from the display data from the outside to the bank switching readout circuit 7 and the scan circuit 2 so that the LED panel 1 can be driven at an arbitrary speed desired by the user. Therefore, even if the operation mode selection circuit 8 selects this external synchronization signal, three banks of screen memory 6 are required.

  The screen memory 6 can be configured by mounting a general-purpose memory device separately from the integrated circuit of the LED lighting drive circuit, for example. Further, when the LED lighting drive circuit is constituted by a gate array, a memory area prepared in advance for a part of the gate array can be used.

  However, the LED lighting drive circuit shown in FIG. 3 requires three banks of screen memory 6 for one screen of 16 × 16 bits for each RGB, so that a large memory capacity is required and the circuit device is expensive. there were. Further, when the screen memory 6 is used in this manner, the circuit device becomes expensive. Therefore, in applications where no memory is required, the LED lighting drive circuit as shown in FIG. 2 is used. Not only is it necessary to provide two different types of LED lighting drive circuits, but there is also the problem that the user has the inconvenience of having to replace the circuit device when memory is required after the start of use. .

  Further, in the LED lighting drive circuit of FIG. 3, the display data is read from the screen memory 6 by the bank switching readout circuit 7 using the horizontal synchronization signal of the display data, and the LED panel 1 is scanned by the scan circuit 2. In this case, when the input of the horizontal synchronizing signal is stopped, there is a problem that the display of the LED panel 1 cannot be maintained. Even when the display data is read and the LED panel 1 is scanned using the external synchronizing signal, When the input of the external synchronization signal is stopped, there is a problem that the display of the LED panel 1 cannot be maintained.

  According to the present invention, a display data memory comprising a flip-flop circuit is connected to an independent memory selective write circuit and a memory selective read circuit so that display data can be written and read simultaneously in parallel. The present invention is intended to provide an LED lighting drive circuit in which display data memory is sufficient for one screen.

  According to a first aspect of the present invention, there is provided a dynamic lighting type LED lighting driving circuit which converts display data sent serially into a parallel signal for each row by a shift register and sends it to a data input of a dot matrix type LED panel. The display data memory provided with a plurality of rows of flip-flop circuits for a plurality of rows and the display data converted into parallel signals by the shift register are written into the flip-flop circuits for one row sequentially selected in the display data memory. A memory selection writing circuit; and a memory selection reading circuit that reads display data held in flip-flop circuits for one row sequentially selected in the display data memory and sends the data to a data input of the LED panel. To do.

  According to a second aspect of the present invention, there is provided a display data synchronization mode in which the memory selection read circuit performs a display data read operation in accordance with a display data synchronization signal sent serially, a synchronization signal generated internally, and / or separately. One or more operation modes in which display data is read out in accordance with a synchronization signal sent from the outside are provided, and these modes are switched by a control signal.

  According to a third aspect of the present invention, in addition to the display data synchronization mode, the memory selection read circuit includes an internal synchronization mode for performing a display data read operation in accordance with at least an internally generated internal synchronization signal. During the operation, when the synchronization signal of the display data sent serially is not input, the mode is automatically switched to the internal synchronization mode.

  According to a fourth aspect of the present invention, there is provided an internal synchronization mode in which the memory selective read circuit performs a display data read operation in accordance with an internally generated internal synchronization signal, and a display data read operation in accordance with an external synchronization signal sent from the outside. An external synchronization mode is provided, and when the external synchronization signal is not input from the outside during the operation in the external synchronization mode, the mode is automatically switched to the internal synchronization mode.

  According to the first aspect of the present invention, the display data sent serially is converted into a parallel signal by the shift register, and then the memory selection writing circuit sequentially selects one row in the display data memory. It is written in the flip-flop circuit. Further, the display data written in the display data memory in this way is read out from the flip-flop circuits for one row sequentially selected by the memory selection / read circuit. Moreover, the flip-flop circuit can perform input / output separately and asynchronously, and the memory selection writing circuit and the memory selection reading circuit are also provided independently, so that display data can be written to and read from the display data memory. Can be done in parallel at the same time. Therefore, the LED lighting drive circuit of the present invention can maintain the display of the LED panel even if the input of the display data or the like is stopped by providing a display data memory for one screen. The same can be done when the writing speed and the reading speed are different.

  According to the second aspect of the present invention, since the memory selection / readout circuit can select the synchronization signal for reading the display data from the display data memory by the control signal, the display data sent serially can be selected. In addition to the display data synchronization mode using the synchronization signal, the LED panel can be displayed in an operation mode using an internal or external synchronization signal that may have a different frequency or phase. Moreover, in the display data synchronization mode, it is not always necessary to use the display data memory. However, since this display data memory has a capacity for one screen, there is almost no wasteful cost. Therefore, it is no longer necessary for manufacturers to provide two types of LED lighting drive circuits depending on the presence or absence of the display data memory, and when the user needs display data memory after the start of use, the LED lighting drive circuit is replaced. The inconvenience of having to do is eliminated.

  According to the third aspect of the present invention, even if the input of the display data synchronization signal is stopped due to circumstances such as the input of the display data being stopped during the operation in the display data synchronization mode, the internal synchronization mode is automatically set. The display of the LED panel can be maintained by switching to

  According to the invention of claim 4, during the operation in the external synchronization mode, the display of the LED panel is automatically switched to the internal synchronization mode even if the input of display data or the input of only the external synchronization signal is stopped. Will be able to maintain. At this time, if the display data and the synchronization signal associated therewith continue to be input, the display content of the LED panel will not stop.

  Hereinafter, the best embodiment of the present invention will be described with reference to FIG. In FIG. 1 as well, the same reference numerals are given to constituent members having the same functions as those of the conventional example shown in FIGS.

  In the present embodiment, an LED lighting drive circuit for driving a dot matrix type LED panel 1 similar to the conventional example shown in FIGS. 2 and 3 by a dynamic lighting method will be described. In this LED lighting drive circuit, each RGB display data sent serially is converted into a parallel signal of 16 bits for one row by the shift register 3 as in the conventional example. The 16-bit display data converted into the parallel signals is written into the display data memory 10 for each of RGB via the memory write decoder 9.

  Each of the RGB display data memories 10 is a memory having 16 row memories 10a each consisting of 16-bit flip-flop circuits for one row, and 1-bit input of each flip-flop circuit is a memory write. Is connected to the decoder 9 for each. The flip-flop circuit has an input terminal and an output terminal. For example, in the case of a D flip-flop circuit, 1-bit data input to the input terminal (D terminal) is stored (latched) at a timing such as a rising edge of a clock signal. The stored data is always output from the output terminal (Q, Q bar terminal).

  The memory write decoder 9 is a circuit for connecting the 16-bit parallel output of the shift register 3 to the 16-bit input of any one of the row memories 10a of the display data memory 10, and according to the horizontal synchronization signal and the vertical synchronization signal. The connection of the row memory 10a is sequentially switched. That is, the memory write decoder 9 performs an operation of repeatedly switching the connection from the first row memory 10a to the sixteenth row memory 10a every time the horizontal synchronization signal rises, When the vertical synchronizing signal rises, this connection is forcibly reset to the first row memory 10a.

  The 1-bit outputs of the flip-flop circuits in the 16 row memories 10a of the RGB display data memories 10 are connected to the memory read decoder 11, respectively. The memory read decoder 11 performs a connection switching operation opposite to that of the memory write decoder 9, and the 16-bit output of one of the row memories 10a of the display data memory 10 is not shown in FIG. This is a circuit connected to the data input of the corresponding terminal 16 for the corresponding color of the LED panel 1, and the connection of the row memory 10a is sequentially switched in accordance with the synchronizing signal from the operation mode selection circuit 8. That is, the memory read decoder 11 sequentially repeats the connection from the first row memory 10a to the sixteenth row memory 10a every time the synchronization signal from the operation mode selection circuit 8 rises. Perform switching operation.

  The operation mode selection circuit 8 of this embodiment is a circuit that switches the display data synchronization mode, the internal synchronization mode, and the external synchronization mode, which are the operation modes of the LED lighting drive circuit, as in the conventional example shown in FIG. In addition to the horizontal synchronization signal, internal synchronization signal, and external synchronization signal of the display data, a memory use control signal is also input. The memory use control signal is a 1-bit control signal that indicates whether to effectively use the display data memory 10.

  When the memory use control signal is inactive, the operation mode selection circuit 8 sends the horizontal synchronization signal of the display data as it is to the memory read decoder 11 and also scans the scan circuit 2 not shown in FIG. By sending the signal as a signal, the operation of the display data synchronization mode for synchronizing the display data reading operation from the display data memory 10 by the memory reading decoder 11 with the display data sent serially is performed.

  The operation mode selection circuit 8 sends the internal synchronization signal to the memory read decoder 11 and the scan circuit 2 when the memory use control signal is active and no external synchronization signal is input. Then, an operation in the internal synchronization mode is performed in which the display data read operation by the memory read decoder 11 is synchronized with an internal synchronization signal generated in the LED lighting drive circuit. Further, the operation mode selection circuit 8 sends the external synchronization signal to the memory read decoder 11 and the scan circuit 2 when the memory use control signal is active and the external synchronization signal is input. Thus, an operation in the external synchronization mode is performed in which the display data read operation by the memory read decoder 11 is synchronized with an external synchronization signal sent from the outside of the LED lighting drive circuit.

  In addition, when the operation in the display data synchronization mode is being performed, the operation mode selection circuit 8 detects the stop of the input of the horizontal synchronization signal and detects the internal synchronization signal as the memory read decoder 11 or the scan circuit. By switching to send to 2, the operation in the internal synchronization mode is automatically performed. Accordingly, in this case, the immediately preceding screen is repeatedly displayed on the LED panel 1.

  Further, when the operation in the external synchronization mode is being performed, the operation mode selection circuit 8 detects when the input of the external synchronization signal is stopped, and detects the internal synchronization signal so as to send the internal synchronization signal to the memory read decoder 11 or the scan circuit 2. By switching to send to, the operation in the internal synchronization mode is automatically performed. Therefore, although the scan speed may change by switching from the external synchronization signal to the internal synchronization signal, the display on the LED panel 1 is continued as it is. Then, if the input of the display data and the horizontal synchronizing signal is also stopped, the previous screen is repeatedly displayed on the LED panel 1.

  With the above configuration, the LED lighting drive circuit according to the present embodiment is configured to write display data to the display data memory 10 by the memory write decoder 9 and read display data from the display data memory 10 by the memory read decoder 11. Can be performed simultaneously in parallel, it is not necessary to prepare two or more banks of the display data memory 10 when the speeds of the write operation and the read operation are the same, and the speeds of the write operation and the read operation are different. In this case, it is not necessary to prepare three or more banks for the display data memory 10. Therefore, this LED lighting drive circuit has one screen of the display data memory 10 for maintaining the display of the LED panel 1 when input of display data or the like is stopped, or for arbitrarily changing the scan speed of the LED panel 1. Since it is only necessary to prepare a portion, the cost of the circuit device can be reduced.

  Moreover, since the display data memory 10 is sufficient for one screen and the cost can be reduced, an excessive burden is imposed on the user who wants to use only the display data synchronization mode in which the display data memory 10 is originally unnecessary. This eliminates the need to provide a plurality of types of LED lighting drive circuits. In addition, even for a user who uses only the display data synchronization mode, the function of maintaining the display of the LED panel 1 when the input of display data or the like is stopped can be used, and further used in other operation modes later. Therefore, it is not necessary to replace the LED lighting drive circuit.

  Also, even if the input of the horizontal sync signal or external sync signal for display data is stopped during operation in a mode other than the internal sync mode, the display on the LED panel can be maintained automatically by switching to this internal sync mode. become able to.

  As long as the LED lighting drive circuit of the above embodiment is mounted with wired logic, the mounting means is arbitrary. For example, a full custom integrated circuit may be manufactured, or a gate array may be used. it can. The display data memory 10 may be incorporated in these integrated circuits or may be externally attached as another integrated circuit.

  In the above embodiment, the LED lighting drive circuit for lighting and driving the 16 × 16 dot LED panel 1 similar to the conventional example has been described, but the dot configuration of the LED panel is arbitrary, for example, 24 × 24 dots or 32 Even an LED panel of × 16 dots can be similarly implemented. In the above-described embodiment, the case where display is performed with two gradations in which the LEDs of each emission color of each display dot 1a are only turned on and off is shown. However, data of each display dot 1a of each display data of RGB is 2 The present invention can be similarly applied to a case where four or more gradations are displayed as bits or more. For example, full-color display of 8 bits (256 gradations) can also be performed. Furthermore, although the case where three types of display data are used for the LED panel 1 to perform RGB three-color display has been described in the above embodiment, the number of display colors is also arbitrary. For example, two types of display data are displayed. As a result, two colors or the luminescent colors that are lighted simultaneously can be combined to display three colors, and the display data can be a single color display with only one type.

  Moreover, although the case where the internal synchronizing signal and the external synchronizing signal are used in addition to the synchronizing signal (horizontal synchronizing signal) of the display data has been shown in the above embodiment, the same applies to the LED lighting driving circuit that does not use the external synchronizing signal. It can be implemented. However, in this case, the external synchronization mode cannot be used. Furthermore, the internal synchronization signal is not always necessary. However, in this case, the internal synchronization mode cannot be used, and if the input of the horizontal synchronization signal is stopped, the display on the LED panel 1 is also stopped.

1 is a block diagram illustrating a configuration of an LED lighting drive circuit according to an embodiment of the present invention. It is a block diagram which shows a prior art example and shows the structure of the LED lighting drive circuit which does not use a memory. It is a block diagram which shows a prior art example and shows the structure of the LED lighting drive circuit using a memory.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 LED panel 3 Shift register 8 Operation mode selection circuit 9 Decoder for memory writing 10 Display data memory 10a Row memory 11 Decoder for memory reading

Claims (4)

In a dynamic lighting type LED lighting drive circuit that converts display data sent serially into parallel signals for each row by a shift register and sends them to the data input of a dot matrix type LED panel,
A display data memory with multiple rows of flip-flop circuits for multiple digits, and
A memory selection writing circuit for writing display data converted into a parallel signal by the shift register into flip-flop circuits for one row that are sequentially selected in the display data memory;
An LED lighting drive circuit comprising: a memory selection read circuit which reads display data held in flip-flop circuits for one row sequentially selected in a display data memory and sends the data to a data input of an LED panel.   A display data synchronization mode in which the memory selection read circuit performs a display data read operation in accordance with a display data synchronization signal sent serially, a synchronization signal generated internally and / or a synchronization sent separately from the outside 2. The LED lighting drive circuit according to claim 1, further comprising at least one operation mode for performing a display data reading operation in accordance with a signal, wherein the modes are switched by a control signal.   In addition to the display data synchronization mode, the memory selection read circuit has an internal synchronization mode for reading display data in accordance with at least an internally generated internal synchronization signal, and is serially transmitted during operation in the display data synchronization mode. 3. The LED lighting drive circuit according to claim 2, wherein when the synchronization signal of the display data thus received is no longer input, the LED lighting drive circuit is automatically switched to the internal synchronization mode.   The memory selection readout circuit has an internal synchronization mode for reading display data in accordance with an internally generated internal synchronization signal and an external synchronization mode for performing display data reading in accordance with an external synchronization signal sent from the outside. 4. When operating in the external synchronization mode, when no external synchronization signal is input from outside, the mode automatically switches to the internal synchronization mode. LED lighting drive circuit according to.

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