JPH01307796A - Led display device - Google Patents

Abstract

PURPOSE:To make a uniform-brightness display by controlling the illumination time of an LED according to the kind of the LED. CONSTITUTION:An illumination time control circuit 5 sends three kinds of outputs, i.e. a timer counter output as pulse width data for specifying the illumination time, a drive array data for specifying an array to be driven from an array data circuit 3 to a source driver 2a, and LED illumination data to a driving circuit 2 at a constant period to drive an LED matrix display part 1, and thus the specific LED is made to illuminate, thereby making a display. At this time, the set value of a programmable timer counter is varied according to the kind of the LED to be driven and then the illumination time of the LED is varied to balance the brightness of the LED. Consequently, the brightness of a display screen is uniformed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an LED display device in which various types of LEDs are arranged in a matrix to form a display device. This invention relates to an LED display device that makes the brightness of the display surface of the display device uniform regardless of the type.

[Prior art] In conventional LED display devices, the display device has various
The EDs are arranged in a matrix on an element-by-element basis, and each element is dynamically illuminated by a single drive circuit during driving.

[Problem to be solved by the invention] In this conventional LED display device, different types of LEDs
Since D does not need to be driven by a separate circuit, it has the advantage of requiring a minimum hardware configuration.

On the other hand, multiple types of LEDs have different emitted light colors.
When the drive circuit dynamically lights up the LEDs for each element, a problem arises in that the brightness differs. In addition, even if the luminescent color is the same, if the forward voltage characteristics are different, the current that flows will be different, resulting in a difference in brightness, which makes it difficult to balance the brightness when looking at the display as a whole. .

The present invention has been made in view of such problems in the prior art, and its purpose is to provide a display device that drives various types of LEDs with the same drive circuit. The object of the present invention is to provide an LED display device that achieves uniform brightness on the display surface by balancing the luminance of light emitted from a plurality of separately divided LEDs.

[Means for Solving the Problems] In order to achieve the above object, the LED display device of the present invention includes an LRD matrix display section in which a plurality of LEDs are grouped according to type and arranged in a matrix;
L E I) A drive circuit consisting of a column driver that drives columns and a row driver that drives rows of a matrix display section, a column data circuit that specifies and outputs column data to be driven to the column driver, and a drive circuit that drives the row driver. a row data circuit that outputs on/off data of the row to be processed;
A lighting time control circuit that outputs a signal for controlling lighting time for each type of ED to the column data circuit, and a comprehensive control device that comprehensively controls the row data circuit, the column data circuit, and the lighting time control circuit. It is characterized by consisting of the following.

[Example] Examples will be described with reference to the drawings.

FIG. 1 is a block system diagram showing a specific embodiment of the LED display device of the present invention.

In FIG. 1, 1 is, for example, a red 7-segment L
ED (here represented by section A as the 1st to 3rd dots in the row), red bar graph LED (here represented by section B as the 4th to 5th dots in the row).

A plurality of LEDs, such as a green bar graph LED (represented here as section C as the 6th to 7th dots in the row) and a yellow surface-emitting LED for character illumination (here represented as the 8th dot in the row and in sections). For example, 8X
This is an LED matrix display section consisting of 8 dots arranged in a matrix. Reference numeral 2 denotes an LED drive circuit consisting of a column driver (hereinafter referred to as "source driver") 2a that drives the columns of the LED matrix display section 1 and a row driver (hereinafter referred to as "sink driver") 2b that drives the rows. A column data circuit 3 designates and outputs a column to be driven to the source driver 2a, and is composed of, for example, a data latch circuit. 4 drives to sink driver 2b and ED
This is a row data circuit that specifies and outputs on/off data of a row, and is composed of, for example, a data latch circuit. 5 is LEI)
This is a lighting time control circuit that outputs a signal for controlling the lighting time for each type to the column data circuit 3, and is composed of, for example, a pulse width controller (eg, a programmable timer counter, etc.) that controls the pulse width. Reference numeral 6 denotes a comprehensive control device consisting of a CPU circuit that controls the column data circuit 3, the row data circuit 4, and the lighting time control circuit 5 by, for example, outputting data and setting pulse widths according to a predetermined program. .

FIG. 2 is a time chart for explaining the operation of FIG. 1.

In FIG. 2, the display circuit shown in FIG. 1 receives the timer/counter output (which is pulse width data specifying the lighting time) from the lighting time control circuit 5 (1) according to the program.
τ is the LED lighting time), θ1) is the drive column data for specifying the column to be driven from the column data circuit 3 to the source driver 2a, and @ is the LED lighting data (LF at high level (1).

D lights up, LED goes off at low level (0), of the data in rows 1 to 8 in the diagram, the section between the vertical line data transitions means that the LED lighting data is either on or off. The three types of outputs of the LEDs to be driven are outputted to the drive circuit 2 at regular intervals to drive the LBD matrix display section, and a predetermined LED is lit to display a display.At this time, programmable For example, change the timer/counter setting value to set the LED lighting time to τ1. τ
By changing the brightness by 2°τ, the brightness of the LED can be balanced. That is, for brighter LEDs, the pulse width is set shorter. In this way, the L P of the dynamic lighting method
According to the D display device, by controlling the lighting time of the LED depending on the type of LED, it is possible to balance the luminance of the plurality of LEDs classified by type.
Uniform brightness on the display surface can be achieved.

By the way, the present invention is not limited to the above description. For example, in the embodiment shown in FIG. 1, two switches for dimmer control (for up and down) SWa, SWb and By adding the switch input circuit (pass buffer) 7, it is possible to realize an LED display device with uniform brightness and a dimmer function.

[Effects of the Invention] Since the present invention is configured as described above, it produces the following effects.

Even if many types of LEDs with different characteristics are used, a display device with uniform brightness can be realized with minimum hardware cost.

[Brief explanation of the drawing]

FIG. 1 is a block system diagram showing a specific embodiment of the LED display device of the present invention, and FIG. 2 is a time chart for explaining the operation of FIG. 1.

Claims (1)

[Claims] LED that drives and displays multiple LEDs with the same drive circuit
In a display device, an LED matrix display section including the plurality of LEDs arranged in a matrix by type, and an LED drive circuit including a column driver for driving columns and a row driver for driving rows of the LED matrix display section. a column data circuit that specifies and outputs column data to be driven to the column driver; and a row data circuit that outputs on/off data of the row to be driven to the row driver;
a lighting time control circuit that outputs a signal for controlling lighting time for each type of LED to the column data circuit; and a comprehensive control that comprehensively controls the row data circuit, the column data circuit, and the lighting time control circuit. An LED display device comprising: