JPH1039820A - Control circuit for light emitting diode display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a display screen in which the nonuniformity of intensity of light emission caused by the difference of structure can be compensated and which has uniform luminance and is easy to watch by constituting plural light emitting devices with a single memory and a signal system and simplifying circuit constitution. SOLUTION: A memory (VRAM) is made only 1 and 2 for both planes of R and G, read-out of this VRAM is performed in time division manner for each display element, and the number of channels of a circuit is reduced. Also, the difference of light emission is compensated by writing doubly the same information in a memory so that emitting is performed repeatedly in the prescribed time for elements of a low luminance side and effective brightness is improved by increasing light emission frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for a display device using a character display panel using light emitting diodes and a numeric display panel having a seven-segment structure.

[0002]

2. Description of the Related Art Conventionally, a display panel used in a display device is a combination of a light emitting diode array in which light emitting diodes shown in FIG. 2 are arranged in a matrix and a numeric display panel having a seven-segment configuration shown in FIG. Things have been used. Here, as the diode matrix, for example, a method of arranging a large number of 16 × 16 elements (dots) as a unit and scrolling characters in a bulletin board style or displaying statically is used. In particular, recently, as a light emitting diode used for 16 × 16 dot display, a light emitting diode capable of emitting two colors of green (G) and red (R) has been used.

FIG. 4 shows a configuration of a driving circuit of the above-mentioned display device which has been conventionally used. In FIG. 4, the signal generator 12
A part of the character / symbol information supplied from the image memory (VRAM) for red display is used as a signal for the light emitting diode array 6.
-R) 1 and green display image memory (VRAM-G)
2 and the remaining information is temporarily stored in a character display memory (VRAM-C) 7 for 7-segment numeric display boards (hereinafter, numeric display boards) 11 and 11 '.
Here, VRAM-R1 is an R plane for temporarily storing red information, and VRAM-G2 is a G plane for temporarily storing green information. These red and green data are read out according to the control signal from the light emitting diode array signal control circuit 18 corresponding to each color, and are each a red display signal type serial-parallel conversion circuit (hereinafter, SP conversion circuit R) 3. After the signal arrangement is converted into parallel data by a green-display signal system serial-parallel conversion circuit (hereinafter referred to as an SP conversion circuit G) 4, the signals are transmitted to the light-emitting diode arrays 6 and 6 ′ via a light-emitting diode array signal buffer circuit 5. Supplied. In addition, a character display memory (VRAM
-C) 7 is for temporarily storing a character code for driving a character generator 8 for generating a character to be displayed on the numeral display boards 11, 11 '. That is, the character code serving as the character information supplied from the signal generator 12 is temporarily stored in the VRAM-C7,
It is read out at a predetermined timing by the control circuit 19, and the character generator 8 reads the seven-segment numeral display board 1.
It is output as character data for driving 1, 11 '. This character data is arranged in the form of a parallel output signal as a signal for driving the numeric display panel by an SP conversion circuit C9, and supplied to the numeric display panels 11 and 11 'via a character data signal buffer circuit 10. .

As described above, in the conventional method, when the light emitting diode panel and the numeric display panel are simultaneously driven and displayed, each signal system is provided with a separate circuit having the same configuration.

[0005]

As described above, in the conventional configuration, it is necessary to install a similar circuit configuration in parallel for a predetermined number of channels (the number of signal sequences) according to the type of display means. And the circuit scale has increased with the number of channels. As a solution to this, there is a method of processing the information of each channel in a time-division manner with a single signal transmission system. In this case, if the time-division is equally divided, the effective light emission intensity due to the difference in the light emission method is considered. , There is a problem that the brightness of the displayed characters becomes non-uniform. in this way,
When a plurality of display panels having different display methods are used in parallel, the circuit scale becomes large, and non-uniformity of the emission intensity is inevitable.

In both the light emitting diode arrays 6 and 6 'and the seven-segment numeral display boards 11 and 11', the former forms one character with 16 × 16 dots, and the latter has seven elements (segments). Therefore, the light emitting area per one light emitting element is large on the numeric display panel, and the effective luminance is lower than that of the light emitting diode panel. For this reason, the problem that the brightness of the display is not uniform due to the structure of the display panel has also been a problem to be solved.

[0007]

In order to achieve the above object, according to the present invention, there is provided a light emitting diode array capable of multicolor display and a different light emitting structure of a numeric display panel composed of seven segments. In an information display device having two types of display devices, a memory for temporarily storing data to be displayed on both display devices is commonly used, and the contents of these memories are read out in a time division manner and can be displayed on the display device. After converting to a signal form, a signal is supplied to the display device.

According to a second aspect of the present invention, the duty ratio of the element having a large area in accordance with the area of the light emitting portion of each of the above structures is controlled so that the light emitting time within a predetermined character display time becomes longer. To reduce the non-uniformity of the brightness due to the difference in the structure of the light emitting element.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit configuration of a display device according to the present invention. In FIG. 1, the VRAM for temporarily storing character / symbol information from the signal generator 12 is an R plane (VRAM-R) 1 and a G plane (VRAM-R) shown in FIG.
G) 2 only, and the VRAM 7 for temporarily storing the character code in FIG. 4 is omitted. Where VR
The memory addresses of the AM-R1 and the VRAM-G2 are both divided into two for the light emitting diode array 6 and two for the numeric display boards 11, 11 '. The addresses for the light emitting diode panels 6, 6 ', that is, the VRAM-R in FIG.
1 and the data stored in the upper part of the VRAM-G2 at predetermined timings supplied from the control signal generation circuit 17 in the same manner as in the above-described conventional technique.
Read from the MG2 and the SP conversion circuits R3 and S3
For example, 16-bit parallel data is converted into 16-bit parallel data by the -P conversion circuit G4, the light-emitting diode panel is turned on via the light-emitting diode array buffer circuit 13, and information is displayed.

On the other hand, in the display signal system of the numeric display panels 11 and 11 'using 7-segment light emitting diodes, the characters to be displayed by the signal generator 12 are directly generated as character data instead of codes, so that the VRAM-
R1, a memory address on the numeric display board side on VRAM-G2,
That is, the lower part of the VRAM in FIG. 1 is already stored as character data. Therefore, when reading this character data, there is no need to convert the character code into character data as in the related art. Therefore, the character signal generator 8 of the conventional example shown in FIG. In this way VRAM
-R, data on the VRAM-G are stored in the control signal generation circuit 17.
Is read out at a predetermined timing supplied from the LCD panel, and is converted into parallel data by the SP conversion circuit R3 and the SP conversion circuit G4 which are common to the signal system of the light emitting diode panels 6, 6 '. After 17, data is displayed on the numeric display boards 11 and 11 ′.

As described above, according to the present invention, VR
In a section from the AM-R1 and the VRAM-G2 to the buffer circuit 13 for the light emitting diode array and the buffer circuit 14 for the numeric display panel, signals are transmitted in a time-division manner. For this reason, the dedicated signal system to each display element described in FIG. 4 becomes unnecessary, and is constituted by a single signal system and a single control system. Only one control circuit 18 or 19 in FIG. , Only the VRAMs 1 and 2 are sufficient.

Regarding the point where the light emission intensity becomes non-uniform as described in the section of the subject, the light emission time per one light emitting element with respect to the light emission time of one character is 1/16 duty in the case of a light emitting diode panel. , And 1/8 in the case of a numeric display
Duty is assigned. For this reason, in FIG. 1, the addresses for the numeric display board data of VRAM-R1 and VRAM-G2, that is, the VRAM in FIG.
The same data is recorded twice in the lower part of (1) and (2) of -R1 and VRAM-G2, and the address for the light emitting diode, that is, VRAM-R1 in FIG.
And reading is performed at the same clock cycle as the reading of the upper part of the VRAM-G2.

The above-described embodiment has been described with respect to the light emitting diode display device having two types of structures.
It goes without saying that these methods can be extended to more light emitting structures or display elements having different light emitting principles.

[0014]

As described above, according to the present invention, a plurality of light emitting devices can be configured with a single memory and signal system, and the circuit configuration can be simplified. At the same time, non-uniformity of the light emission intensity due to the difference in the structure can be corrected, and a display screen with uniform brightness and easy to see can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a display device according to the present invention.

FIG. 2 is a view showing the configuration of a display surface of a light-emitting diode array using 16 × 16 elements (dots).

FIG. 3 is a configuration diagram of a number display plate having seven segments.

FIG. 4 is a circuit configuration diagram of a conventional display device.

[Explanation of symbols]

1: Red display image memory (VRAM-R) 2: Green display image memory (VRAM-G) 3: Red display signal serial-parallel conversion circuit (S-
P conversion circuit R 4... Green display signal system serial-parallel conversion circuit (S-
P conversion circuit G) 5 ... Light emitting diode array signal buffer circuit 6, 6 '... 16 × 16 light emitting diode array 7 ... Character display memory (VRAM-C) 8 ... Character generator 9 ... Character data serial-parallel conversion circuit (SP conversion circuit C) 10 ... Character data signal system buffer circuit 11, 11 '... 7-segment light-emitting diode number display board 12 ... Signal generator 13 ... Light-emitting diode array buffer circuit 14 ... Number display board buffer circuit 15 ... Inverter 16 ... Control circuit for light emitting diode array signal system 17 ... Control circuit for 7 segment light emitting diode number display board signal system 18 ... Control circuit for light emitting diode array display signal 19 ... Control circuit for number display board display signal

Claims (2)

[Claims] In an information display device having two display elements, a light emitting diode panel capable of multicolor display and a numeric display panel formed of display elements composed of seven segments, data to be displayed on both display devices is temporarily stored. A light-emitting diode display, wherein a memory to be stored is commonly used, and the contents of these memories are read out in a time-division manner, converted into a signal form that can be displayed on the display device, and then supplied to the display device. Device control circuit. 2. An information display device comprising a display element having a different structure according to claim 1, wherein a duty ratio of a light emission time is controlled to a predetermined ratio according to an area of a light emitting portion of each structure. A light emitting diode display device control circuit, which emits light.