WO2001018779A1

WO2001018779A1 - Led display device and control method therefor

Info

Publication number: WO2001018779A1
Application number: PCT/KR2000/000136
Authority: WO
Inventors: Jin Ho Song; Bak Kwang Kang
Original assignee: C. I. Brain Co., Limited
Priority date: 1999-09-06
Filing date: 2000-02-21
Publication date: 2001-03-15
Also published as: AU2697500A; TW518541B; KR20000006665A

Abstract

The display device includes an LED display unit having therein P number of LED arrays, each array containing M x N LED elements and a control unit for providing display data to the LED modules. The display data including P number of data sets, wherein each data set includes data to be displayed by LED elements on a row or a column of an LED array. The data included in each data set is provided to the LED arrays simultaneously.

Description

LED DISPLAY DEVICE AND CONTROL METHOD THEREFOR

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a display device and control method therefor; and more particularly, to a light emitting diode (LED) display device and simplified control method therefor.

BACKGROUNG ART

LED is one of the flat panel displays being widely used for displaying information and messages. Some of the reasons for LED popularity may include reduced operation voltage and current requirements, greater durability, a higher level of brightness and greater optical efficiency as compared to other types of display panels. Since, however, it is difficult to manufacture very large LED display panels, conventional LED display devices are constructed by using an array of LED modules, each including a control circuit and an LED array having a plurality of LED elements.

Referring to Fig. 1, there is illustrated a schematic block diagram of one of the LED modules included in such a conventional dot-matrix LED display device (see, e.g., disclosed in U.S. Pat. No. 5,717,417 issued to Takahashi et al. and entitled "DOT-MATRIX LED DISPLAY DEVICE HAVING BRIGHTNESS CORRECTION CIRCUIT AND METHOD FOR CORRECTING BRIGHTNESS USING THE CORRECTION CIRCUIT") . As shown in Fig. 1, a dot-matrix LED module 10 includes an LED array having M x N LED elements, a data conversion circuit 14, a data output circuit 16 and a column decoder 18. Input data and control signals are inputted to the LED module 10 from a main controller (not shown) . The input data is provided sequentially on a pixel -by-pixel basis. In response to the control signals, the serial pixel data is converted into parallel data for all the pixels to be displayed on one column of the LED array 12. The converted parallel data is provided to the rows of the LED array 12 through the data output circuit 16 and the columns of the LED array 12 are scanned by the column decoder 18 under the control of the control signals.

As disclosed above, each LED display module included in the conventional LED device employs therein a data conversion circuit for converting the serial pixel data into a parallel format, complicating the circuitry in each LED module and increasing the manufacturing cost thereof.

DISCLOSURE OF THE INVENTION

It is, therefore, an object of the present invention to provide an LED (light emitting diode) display device and simplified control method therefor.

In accordance with one aspect of the present invention, there is provided an LED display device comprising: an LED display unit having therein P number of LED modules, each LED module including an LED array having M x N LED elements, P, M and N being positive integers greater than 1; one or more buses coupled to the LED display modules; and a control unit for providing display data on the buses, the display data including P number of segment data sets being sequentially provided one of on the buses, wherein each segment data set includes data to be displayed by LED elements on a display line, the display line being one of the rows and the columns of each LED array, and the data included in each segment data set is provided on the buses simultaneously.

In accordance with another aspect of the invention, there is provided a display device comprising: a display unit having therein a plurality of display modules, each display module including a display array having more than one display element arranged in a pattern having one or more rows and one or more columns; and a control unit for sequentially providing a multiple number of data sets, wherein each data set includes data to be displayed by more than one display element on a display line, the display line being one of the rows and the columns of each display array, and the data included m each data set is provided simultaneously.

In accordance with still another aspect of the present invention, there is provided a method for use m a display device including a plurality of display modules, each display module having a display array containing more than one display elements arranged m a pattern having one or more rows and one or more columns, the method comprising the steps of: sequentially providing a multiplicity of data sets, wherein each data set includes data to be displayed by more than one display element on a display line, the display line being one of the rows and the columns of each display array, and the data included m each data set is provided m parallel; storing a data set m a corresponding display module; and selecting the display line of each display array to thereby display the data sets on the display arrays.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiment given m conjunction with the accompanying drawings, m which:

Fig. 1 represents a schematic block diagram of a conventional dot -matrix LED display module; Fig. 2 exemplifies a schematic block diagram of an LED display device m accordance with the present invention;

Fig. 3 presents a block diagram of one of LED display modules included m the LED display device;

Fig. 4 illustrates a timing diagram explaining the operation of the LED display device; and

Fig. 5 depicts a flow chart explaining the operation of the LED display device in accordance with the present invention .

MODES OF CARRING OUT THE INVENTION

The preferred embodiment of the present invention will now be described with reference to Figs. 2 to 5B .

Referring to Fig. 2, there is provided a schematic block diagram of an LED display device 20 in accordance with the present invention. As shown in Fig. 2, the LED display device 20 comprises an external manipulation unit (EMU) 210, a control unit 220 and an LED display unit 230, wherein the LED display unit 230 includes a plurality of LED display modules, e.g., 232-1 to 232-n, n being a positive integer greater than 1. Each LED module includes an LED array having a multiplicity of, e.g., 16 x 16, LED elements. The control unit 220 includes therein a memory 222, a controller 224, a buffer 226 and a display control block 228 and is coupled to the LED display unit 230 through buses 240, 250 and 260.

The EMU 210 can be, e.g., a computer, a key matrix, a keyboard, a touch screen, or a combination thereof; and serves to revise data pre-stored in the memory 222, input new data into the memory 222, and/or generate an operation start signal via the controller 224 in response to inputs by an operator.

The controller 224 serves to control the memory 222, the buffer 226 and the display control block 228. The display control block 228 controls the overall operation of the LED display unit 230.

The memory 222 is made of, e.g., a non-volatile memory device such as an EEPROM and a flash memory, whereas the buffer 226 is made of, e.g., a volatile memory device such as an SRAM or a DRAM. The memory 222 stores various alphanumeric and/or graphic data sets provided by the EMU

210 through the controller 224. Upon receiving an operation start signal, which includes a designation signal indicating a data set to be displayed, from the EMU 210, the controller 224 retrieves a portion of the data set from the memory 222 and temporarily stores same m the buffer 226 prior to providing same to the display control block 228.

The portion of the data set corresponds to pixel data of one line (a column or a row) of an LED array included m each LED module. After storing the pixel data for each LED module, the controller 224 provides a data write signal (/DATA_WR) shown m Fig. 4 and the pixel data to the display control block 228. In response thereto, the display control block 228 provides display data (DIS_DATA) on the bus 240, a data hold signal (DATA_HOLD) and a latch enable signal

(/LATCH_EN) on the bus 260, and a line selection signal (LINE_SEL) , a power driver enable signal (/PD_EN) and a data scan clock signal (SC_CLK) on the bus 250. The data and signals provided on the buses 240 to 260 will be described m detail with reference to Figs. 3 to 5.

Referring to Fig. 3, there is illustrated a block diagram of one of the LED display modules, e.g., 232-1 of the LED display unit 230, in accordance with the present invention. The structures of the LED display modules 232-1 to 232 -n are identical each other. As shown m Fig. 3, each of the LED display modules 232-1 to 232 -n includes an LED array 310, a latch 320, a gradation control circuit 325 and a power driver 330, wherem the LED array 310 includes, e.g., 16 x 16 LED elements, each corresponding to one pixel. As well known m the art, one pixel may include R, G, B elements and m that case one LED element include three diodes. For the sake of simplicity, the present invention will be described assuming that one pixel is composed of one LED. It is to be understood to those skilled m the art, however, that the subject invention is not limited to such a case but can be readily extended to the pixels having RGB elements.

The display data DIS_DATA is comprised of sets of pixel data sequentially provided on the bus 240 by the display control block 228, wherein each set of pixel data corresponds to pixel data of one pixel line of an LED array and pixel data m one set is provided m parallel on the bus 240. For instance, if one pixel is expressed by m bits, m being a positive integer, and one line of a LED array to be displayed at the same time has 16 pixels, 16 x m bits are simultaneously provided m one set of pixel data for an LED array and the respective sets of pixel data for the LED arrays are sequentially provided on the bus 240.

The latch 320 is connected to data lines numbered [1] to [16] of the LED array 310, wherein the data lines [1] to

[16] are connected to respective rows (or columns) of the

LED array 310 through the gradation control circuit 325. The gradation control circuit 325 serves to convert the m bit data on each data line into one of 2^m gradation levels to be displayed on the LED array 310. If m=l, i.e., each LED element is merely controlled on and off, a gradation level control may not be necessary and thus the output from the latch 320 can be directly coupled to the LED array 310 without having to employ the gradation control circuit 325. The power driver 330 is connected to the LED array 310 through power lines numbered [1] to [16] , each of which is connected to corresponding columns (or rows) of the LED array 310.

A more detailed description of the operation of the LED display device 20 will be described with reference to Figs. 2 to 5. Fig. 4 and Fig 5 respectively represent a timing diagram and a flow chart explaining the operation of the LED display device 20 m accordance with the present invention.

At step S502, the controller 224 checks whether or not an operation start signal is inputted from the EMU 210, wherein the operation start signal includes a designation signal indicating a data set to be displayed among one or more data sets stored m the memory 222. The data set represents data to be displayed on the whole LED display unit 230. The data set may correspond to a still image and/or a text, a motion picture, or a text scrolling across the LED display unit 230. The data set is displayed on the LED display unit 230 on, e.g., a frame-by- frame basis, one frame including n x 16 x 16 pixels m this example. If the data set is of a still image and/or a text, the frames thereof would be identical each other. If the data set is of a motion picture or a scrolling text, the frames thereof would be different from each other.

If the result at step S502 is positive, the procedure proceeds to step S504; and, if otherwise, the controller 224 returns to a stand-by mode until an operation start signal is inputted. At step S504, the controller 224 retrieves from the memory 222 a first data segment of the first frame of the data set indicated by the designation signal and stores same m the buffer 226. The first data segment includes n sets of pixel data, each set of pixel data including data for the 16 pixels of the first column of the LED array included m one of the LED modules 232-1 to 232-n. Similarly, an ι^h data segment includes n sets of pixel data, wherein each set of pixel data includes data for the 16 pixels of an ι^th column of the LED array included m each of the LED modules 232-1 to 232-n, I being 1 to 16. At step S506, the controller 224 stores the first data segment m the buffer 226. Address data may be appended to each set of pixel data. The address data designates an LED array on which each set of pixel data is to be displayed.

At step S508, the controller 224 issues at T_x the first data write signal /DATA_WR as shown m Fig. 4 and simultaneously provide the display control block 228 with the sets of pixel data included m the data segment stored m the buffer 226.

In response to /DATA_WR from the controller 224 at step S510, the display control block 228 generates display data (DIS DATA) on bus 240, a latch enable signal (/LATCH_EN) and a data hold signal (DATA_HOLD) on bus 260, and a line selection signal (LINE_SEL) , a power-driver enable signal (/PD_EN) and a data scan clock signal (SC_CLK) on bus 250 as shown in Fig. 4. In Fig. 4, it is assumed that the LED display unit 230 includes 6 LED modules, i.e., n=6. As shown in Fig. 4, DIS_DATA includes the sets of pixel data D.'s (j= 1 to 6) sequentially provided on bus 240, starting from O₁ . On the other hand, pixel data in each D_D are simultaneously provided on bus 240, as described hereinabove. DH_: in DATA_HOLD activates a latch in an j^th LED module if /LATCH_EN is in the logic low state. Therefore, a set of pixel data D_: is simultaneously latched into a latch of an j^th LED module under the control of DATA_HOLD and /LATCH_EN. As shown in Fig. 4, it may be preferable that the logic low state of /LATCH_EN is asserted ahead of D_x by the interval T_x to T₂ and also DH is issued prior to O by the interval T_x to T₂ in order to ensure the latching of D_] into the latch of the i^th LED module. Also, all the sets of pixel data in DIS_DATA should be latched during the interval T₁ to T₃ during which /LATCH_EN is in the low state (step S512) .

At step S514, the power driver 330 is activated when /PD_EN is in the logic low state and SC_CLK is in the logic high state; and the output from the power driver 330 is provided to an i^th column of every LED array in response to LINE_SEL LS_X (i being 1 to 16) to thereby turn on the i^th columns of the LED arrays to display DIS_DATA on the i^h columns of the LED arrays. LS.. designates the i^th column of each LED array to be activated. The ''XX'' marked portions of DIS_DATA, DATA_HOLD and LINE_SEL represents "Don't Care Data¹' or ''Don't Care Signal''.

At step S516, it is checked by the controller 224 whether the display operation is to be terminated. Termination of display may be determined in response to a display termination signal provided from the EMU 210 by the operator or can be done automatically after a preset time period from the onset of the operation start signal . If none of such cases applies, the process returns to step S504 and the display operation described above will be repeated for next data segments of the current frame and its subsequent frames until one of such case applies.

Although the preferred embodiment of the present invention has been described with respect to the LED device, it should be appreciated to those skilled m the art that the invention can be equally applied to other flat panel displays, e.g., fluorescent displays, liquid crystal displays, plasma display panels or the like.

It is also to be appreciated that each set of pixel data included m DIS_DATA may not necessarily contain data for all the pixels on one row or column. Each set of pixel data may contain a fraction of pixels (but more than one pixel) on one row or column. Also, the number of pixel data sets m DIS_DATA need not be identical to the number of LED modules .

The circuitry included m each of the LED modules of the invention is relatively simple compared to those of the conventional LED modules since the pixel data of one column is supplied simultaneously and all the control signals are provided from the control unit. As a result, the circuitry m each LED module can be placed on one board or m one package together with the control unit, or each LED module can be constructed so that an LED element or an LED array m trouble can be readily replaced with a new one.

It is to be noted that the data write signal /DATA_WR, the latch enable signal /LATCH_EN and the power driver enable signal /PD_EN can have logic high-activated states.

It is also to be appreciated by one skilled m the art that DIS_DATA and the output of the power driver 330 can be applied to columns and rows of the LED arrays, respectively, m lieu of rows and columns as m the preferred embodiment of the invention.

It is also to be understood that if the display device 20 is employed as a sign board or panel mounted in a vehicle, the display device 20 can be constructed to automatically initiate the display operation, e.g., when a driver brakes the car.

While the present invention has been described with respect to certain preferred embodiments only, other modifications and variations may be made without departing from the spirit and scope of the present invention as set forth in the following claims.

Claims

What is claimed is:

1. An LED (light emitting diode) display device, comprising : an LED display unit having therein P number of LED modules, each LED module including an LED array having M x N LED elements, P, M and N being positive integers greater than 1 ; one or more buses coupled to the LED display modules; and a control unit for providing display data on one of the buses, the display data including P sets of pixel data being sequentially provided, wherein each set of pixel data includes data to be displayed by LED elements on a display line, the display line being one of the rows and the columns of each LED array, and the pixel data included m each set is provided on one of the buses simultaneously.

2. The LED device according to claim 1, wherein each LED module further includes a latch for latching a set of pixel data to be displayed on the LED array therein.

3. The LED device according to claim 2, wherein the control unit further provides a latch enable signal and a data hold signal on one of the buses and a set of pixel data is latched m a corresponding LED module m response to the latch enable signal and the data hold signal .

4. The LED device according to claim 3, further comprising means for selecting the display line of each LED array.

5. The LED device according to claim 4, wherein the control unit further provides a line selection signal on one of the buses and the display line is selected m response to the line selection signal.

6. A display device, comprising: a display unit having therein a plurality of display modules, each display module including a display array having more than one display element arranged m a pattern having one or more rows and one or more columns ; and a control unit for sequentially providing a multiple number of data sets, wherein each data set includes data to be displayed by more than one display element on a display line, the display line being one of the rows and the columns of each display array, and the data included m each data set is provided simultaneously.

7. The display device according to claim 6, wherein each display module further includes a latch for latching a data set to be displayed on the display array therein.

8. The display device according to claim 7, wherein the control unit further provides a latch enable signal and a data hold signal and each data set is latched m a corresponding display module m response to the latch enable signal and the data hold signal .

9. The display device according to claim 8, further comprising means for selecting the display line of each display array.

10. The display device according to claim 9, wherein the control unit further provides a line selection signal and the display line is selected m response to the line selection signal.

11. The display device according to claim 10, wherein each data set includes data for all display elements on the display line.

12. The display device according to claim 11, wherein the number of the display modules is identical to the number of the data sets.

13. The display device according to claim 12, wherein each display element is comprised of one or more LEDs .

14. A method for use m a display device including a plurality of display modules, each display module having a display array containing more than one display element arranged m a pattern having one or more rows and one or more columns, the method comprising the steps of: sequentially providing a multiplicity of data sets, wherein each data set includes data to be displayed by more than one display element on a display line, the display line being one of the rows and the columns of each display array, and the data included m each data set is provided m parallel; storing each data set m a corresponding display module; and selecting the display line of each display array to thereby display the data sets on the display arrays.

15. The method according to claim 14, wherein each data set includes data corresponding to all display elements on the display line.

16. The method according to claim 15, wherein each display element is composed of one or more LEDs.

17. The method according to claim 16, further comprising the step of generating a data selection signal, wherein said step of storing each data set is carried out m response to the data selection signal.

18. The method according to claim 17, further comprising the step of providing a line selection signal, wherein the step of selecting the display line is carried out m response to the line selection signal .