CN100399394C - Display control method and control circuit of an organic electroluminescence display - Google Patents

Abstract

This invention relates to organic light display control method and control circuit in electron technique field and to plane display control technique, which comprises the following steps: through changing traditional display data form and adding control information on each line of data and adding line information; under this display data form design, it provides one organic light display control method and control circuit and loads the display data onto display by use of displacement as control label.

Description

Display control method and control circuit of an organic electroluminescence display

technical field

The invention discloses a display control method and a control circuit of an organic electroluminescent display, which belong to the field of electronic technology and relate to the display control technology of flat panel displays.

Background technique

Organic electroluminescent technology is one of the most competitive display technologies developed in the past decade. It has quickly become a research hotspot in the field of flat panel display due to its advantages of wide viewing angle, fast response speed, light and thin volume, high brightness, high efficiency, low driving voltage and active light emission.

Organic electroluminescent display (Organic Light Emitting Device-OLED) is a new generation display device with excellent image quality (especially in terms of brightness and contrast), which integrates cathode ray tube (CRT) and liquid crystal display ( LCD) comprehensive features. It is recognized as one of the most potential technologies in the development of the display field in the future. Its structure is a typical sandwich structure, with an organic small molecule film or a polymer film sandwiched between the anode and the cathode. The anode is indium tin oxide (ITO) conductive glass with high work function, and the cathode is metal or alloy with low work function. Under the action of an external electric field, electrons from the cathode and holes from the anode move to the light-emitting layer through their respective transport layers to recombine and emit light.

The OLED control circuit has two functions: first, the control circuit is to provide timing signals and column display data for the OLED display; second, in the computer system, the OLED display control circuit should be used as an interface circuit connected to the computer. According to the structural characteristics of the dot-matrix organic electroluminescent display screen, its driving method usually adopts a dynamic scanning method. The row is connected to one end of the source, and the column determines whether to connect to the other end of the source according to the display data. Each row is strobed row by row to provide display data on the corresponding column. After all the rows have been scanned, the scan of the next cycle starts from the first row. This cycle will form a complete picture on the screen. As long as the scanning frequency is fast enough, people will not feel the flicker phenomenon. Therefore, the signals that need to be provided for the control circuit include: display row scanning frame signal; display data latch signal, which is also a shift pulse signal of frame signal; display data shift pulse signal; display column data signal.

At present, OLED technology is still in the research and development stage, and its dedicated driver chips are still rare, and there is no special international standard for display control circuits, and the LCD display control method is basically used. The display control method of the existing liquid crystal display (including other mature flat panel displays), its display data format (taking the display of 64 rows × 128 columns as an example), as shown in Figure 1, is continuous row by row, and each row displays The data consists of the display data of all columns, and there is no control information at the beginning and end of the line. Its display control method is shown in Figure 2. To display a frame of image, it mainly includes the following steps (taking a display with 64 rows×128 columns as an example):

1. Initialization, generally the entire display control system is initialized by the controller (MCU)

2. Read the display data, and the data to be displayed is stored in the memory RAM through the I/O interface.

3. Serial-to-parallel conversion, the MCU fetches one byte of data from the RAM in parallel, and sends it to the column gate in a serial manner through the parallel-to-serial converter.

4. Column display data is shifted and counted. When the data is sent to the column strobe, the counter counts the input column data. When all the data of a byte is sent to the column strobe, the MCU will fetch it again. next byte of data.

5. Repeat steps 3 and 4 until all the data in the 128 columns is ready.

6. The MCU outputs the column signal, and the MCU outputs the column signal prepared in step 5 through the column data output interface.

7. The MCU gives the line signal/line count, and the MCU gives the strobe signal to strobe the corresponding line; the counter counts the lines at the same time.

8. The MCU controls the circuit to repeat steps 2 to 7 to display the next line of data.

9. This process is repeated 64 times, and then one frame of image data is displayed.

The display control circuit realized according to the above display control method, as shown in Figure 3, mainly includes: I/O buffer, row/column output interface, MCU control module, row/column counter, clock generator, memory RAM, serial parallel conversion unit and column completion signal generator, etc.

The most important work in the design of the control circuit is to ensure the strict synchronization of the timing while generating each signal. The traditional liquid crystal display control interface uses a counter for timing. In the process of data transmission, from reading data to transmission, and finally display output requires many different timing signals, so several counters are required to work together, and there are also strict requirements for delay, and the complexity of the circuit will naturally increase.

The existing display control methods and control circuits need to rely on the MCU to control the entire display control (including drive) circuit. The MCU must provide the row and column strobe signals and the corresponding output control signals. The operating speed of the system is relatively low and cannot meet the needs of large High-speed display screen requirements; at the same time, since most of the control is performed by software through the MCU, it is not conducive to integration.

Contents of the invention

The invention provides a display control method and a control circuit of an organic electroluminescence display, which no longer needs the control of an MCU, can run at a relatively high speed, and meets the requirements of a large-screen high-speed display screen.

The present invention draws lessons from the communication data format in the communication technology, proposes a kind of new display data storage format, still take the display of 64 rows * 128 columns as an example, its display data format is shown in Figure 4: a frame of display data consists of Composed of 64 rows, each row of data consists of 18 bytes, of which the 2nd to 16th bytes are column display data, the first byte is 8-bit control information without latch status, and the last byte is 8-bit Line number information.

Based on the above display data storage format, the display control method of a kind of organic electroluminescent display proposed by the present invention (the dot matrix display with M rows and N columns provided with electroluminescent display), as shown in Figure 5, mainly includes the following step:

1. Initialize, initialize the entire control circuit through the host computer;

2. Display information + control information input, the data is input into the buffer RAM through the I/O buffer;

3. Determine whether the buffer is full, if yes, go to the next step, otherwise continue to step 2;

4. Read the data, and input the data in the buffer to the parallel data input interface in parallel;

5. Serial-to-parallel conversion;

6. Column shift;

7. Whether the column control information is read, if yes, go to the next step, otherwise continue to step 6;

8. Shift clock off;

9. Output column data;

10. Give the travel signal;

11. Whether the line signal is read, if yes, the display control of one subframe (one line) data is completed, otherwise, repeat steps 2 to 10;

12. Repeat step 2 to step 11 to complete the display control of the next subframe (next line) data until the display control of one frame of data is completed.

A display control circuit of an organic electroluminescent display (with an electroluminescent display of 64 rows and 128 column dot matrix displays), as shown in Figure 6, includes a data input port interface, an I/O buffer, a display data Buffer, parallel data input interface, row number generator, shift clock generator, row scan output interface and column addressing output interface, as well as row data output interface and column data output interface; display data and control information through the data input terminal The interface is temporarily stored in the display data buffer through the I/O buffer, and the display data and control information in the data buffer are output in parallel to the parallel data input interface and then serially input to the line number generator after parallel-to-serial conversion; display data and control information The first 17 bytes in the information are serially input to the column addressing output interface through the row number generator, and the display data and control information are gradually shifted from low bits to high bits in the column addressing output interface, among which the control of the first byte The information overflows through the column addressing output interface, and the display data of the 2nd to 17th bytes are output to the column driving circuit in parallel through the column addressing output interface; the row number signal of the 18th byte is input in parallel by the row number generator and output by row scanning interface;

It also includes a grayscale clock source, a grayscale value generator, a multiplex counter and a multiplexer. The grayscale value generator generates a series of grayscale values under the control of the clock generated by the grayscale clock source. The multiplexer is responsible for Select the gray scale weight value of the current data, and its output acts on the three-state output control terminal of the line scan output interface, and the control terminal of the multi-channel selection is selected by a special counter through counting;

It is characterized in that it also includes a start-stop controller and a D-type flip-flop, and the shift clock generator generates and provides a unified shift clock to the parallel data input interface, row number generator, column addressing output interface, and start-stop controller signal to ensure the synchronous transmission of data; the start-stop controller receives the control information from the first byte overflowed through the column addressing output interface and generates a control signal to close the shift clock, and triggers the D-type flip-flop to generate a trigger signal; The trigger signal generated by the D-type flip-flop is output to the column addressing output interface to display all column display data of the current row, and is simultaneously output to the row scanning output interface to output row signals.

Described data input end interface comprises clock source (CLK_S), writes data effective (WR), busy signal (BUSY), 8 data input ports (D7～D0); Described line data output interface is parallel 64 output interfaces ( ROW0~ROW63), the column data output interface is a 128-bit parallel output interface (COL0~COL127).

The design idea of the control circuit can be interpreted as: first, initialize the serial transmission channel of the display data, that is, assign an initial value to the serial-parallel shifter (such as setting "1"), and then pass the display data with control information through the parallel input interface It is converted into a serial data stream, and is serially shifted and transmitted under the action of the shift clock. We set the highest bit of the serial channel to a non-latching state, and load the control information to the front of the display data, and its value is the inverse value of the initialization value of the serial transmission channel (such as setting "0"). In this way, in the process of data shifting, once the front end of the display data moves to the non-latching position of the register, it will overflow immediately, and the overflow flag will trigger the control signal to turn off the shift clock, so that the display data will be positioned at the special location. The overflow flag signal is processed and transformed to control subsequent operations. The first operation to be performed after the display data stops moving is to send the column display data to the column addressing output port, and select the relevant scanning line at the same time. Therefore, the present invention also loads the row number into the display data (such as being placed at the end of the column display data), and the column data and the row number are sent to the corresponding output terminals through the latch control signal triggered by the overflow flag bit, and the row number is then displayed. The current row is selected through the row scanning circuit to realize the display of the row.

The working process of the whole control circuit is:

(1) System initialization

(2) Detect the BUSY signal. Once BUSY is invalid, WR is valid, and the display data is transferred from the memory to the display data buffer. When the buffer data is full, the BUSY signal is valid and stops sending data.

(3) When the data is full, the FULL signal is valid. Since the FULL signal is connected to the back-end hardware system to always open the signal, the entire hardware starts to work.

(4) After the back-end hardware system is turned on, first make the read buffer signal RD effective, then start to read the display data, and send the data to the parallel data input interface sub-module at the same time.

(5) A shift signal is generated, and the data starts to shift sequentially. Every time 8 bits are moved, the RD signal is valid once, and then eight parallel data are taken and sent to the interface. Repeat this action.

(6) After all the column data are fetched and transmitted to the corresponding column, the shift clock off signal is automatically generated, the column latch sends out the signal, and the row number is sent to the input terminal of the row scan output interface module at the same time. Under the control of its clock, the multiplexer outputs the gray value signal of the current column data to control the gating time of the current row of the row scanning output interface module.

(7) Since the display of one sub-frame data of this row is completed, the process from (2) to (6) is repeated to complete the full-screen display under this sub-field.

(8) Repeat the process of (7) to display the entire screen of the next subframe.

(9) Repeat the process of (8) to complete the full-screen display of all sub-frames, and the process of displaying an image with gray scale ends.

The beneficial effects of the present invention are: the present invention loads the control information into the display data, avoids the use of cumbersome precise timing circuits, simplifies the circuit structure, and is beneficial to the miniaturization and integration of the entire control circuit. Moreover, the new data storage format has strong regularity and can be easily converted from traditional display data by hardware or software, making the application of the circuit more universal. There are few external interfaces, and the I/O ports of the microprocessor can be saved during application, and the circuit requires less work of external microprocessor intervention, and the application is convenient. Control information, row and column signals are all stored in the data memory. If it is made into an integrated circuit, after the system is powered on and reset, the display control circuit will no longer need the control of the MCU, and can run at a higher speed to meet the needs of large-screen high-speed display. screen requirements.

It should be noted that the examples only provide a specific implementation circuit. All the information other than the column display data is loaded into the display data, and the realization idea of the control circuit using the shift overflow as the control flag should be included in the scope of the present invention, and the present invention can also be used for the control interface of other displays circuit.

The present invention is not limited to the above examples, and the present invention should be understood that, without departing from the spirit and scope of the present invention defined by the appended claims, those skilled in the art can make various modifications, which should be included in within the scope of the present invention.

Description of drawings

Figure 1 is a schematic diagram of a traditional display data format.

Fig. 2 is a schematic flow chart of a traditional display control method.

Figure 3 is a traditional block diagram of a display control circuit.

Fig. 4 is a schematic diagram of the display data format proposed by the present invention.

FIG. 5 is a schematic flowchart of a display control method proposed by the present invention.

Fig. 6 is a functional block diagram of a display control circuit proposed by the present invention.

Claims (3)

1. the display control method of a display of organic electroluminescence is characterized in that mainly may further comprise the steps:

1), initialization;

2), display message+control information input;

3), judge whether impact damper is filled with, and is then to enter next step, otherwise continue step 2;

4), reading of data;

5), also string conversion;

6), row displacement;

7), whether read the row control information, be then to enter next step, otherwise continue step 6;

8), shift clock is closed;

9), output column data;

10), give the trip signal;

11), whether read capable signal, be the demonstration control of then finishing a sub-frame data, otherwise repeating step 2) to step 10);

12), repeating step 2 to step 11 finishes the demonstration control of next sub-frame data, until the demonstration control of finishing frame data.

2. the display control circuit of the dot matrix display of organic electroluminescence of a row, 128 row, comprise data input pin interface, I/O impact damper, video data impact damper, parallel data input interface, row generator, shift clock generator, line scanning output interface and row addressing output interface, and line data output interface and column data output interface; Video data and control information are temporarily stored in the video data impact damper through the I/O impact damper by the data input pin interface, video data in the data buffer and control information be parallel output to the parallel data input interface through and string change after serial be input to the row generator; Preceding 17 bytes in video data and the control information are input to row addressing output interface through the serial of row generator, video data and control information progressively are shifted to a high position by low level in row addressing output interface, wherein the control information of the 1st byte is overflowed through row addressing output interface, and the video data of the 2nd to the 17th byte is through the parallel column drive circuit of exporting to of row addressing output interface; The row signal of the 18th byte is by the parallel line of input scanning of row generator output interface;

Also comprise grayscale clock source, gray-scale value generator, multichannel gated counter and MUX, produce serial gray-scale value under the clock control that the gray-scale value generator is produced in the grayscale clock source, MUX is responsible for selecting the gray scale weights of current data, its output action is in the ternary output control terminal of line scanning output interface, and the control end that multichannel is selected is selected by counting by a special counter;

It is characterized in that, also comprise on off controller and D flip-flop, the shift clock generator produces and provides unified shift clock signal to parallel data input interface, row generator, row addressing output interface, on off controller, to guarantee the data synchronization transmission; On off controller receives the control information of the 1st byte that the row addressing output interface of hanging oneself overflows and produces control signal closing shift clock, and triggers D flip-flop and produce trigger pip; The trigger pip that D flip-flop produces is defeated by row addressing output interface getting all row video datas of current line, and is defeated by the line scanning output interface simultaneously to export capable signal.

3. the display control circuit of a kind of display of organic electroluminescence according to claim 2 is characterized in that, described data input pin interface comprises clock source (CLK_S), and write data is (WR) effectively, busy signal (BUSY), 8 bit data input ports (D7 ~ D0); (ROW0 ~ ROW63), described column data output interface are 128 bit parallel output interfaces (COL0 ~ COL127) to described line data output interface for parallel 64 output interfaces.

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