JPH05341728A - Led display module - Google Patents

Abstract

PURPOSE:To enable adjusting brightness if necessary by varying emitting time during one scanning period based on brightness data supplied from the outside while keeping scanning time of a light emitting diode display array constant. CONSTITUTION:A timing circuit 13 supplies a latch signal to a latch circuit 3and lets LED emitting data latch at the point of time that LED emitting data of a light emitting diode of one scanning line is accumulated in a serial/parallel conversion circuit 1. The latch circuit 3 supplies LED emitting data of (n) bits of one scanning period latched to a LED driver 5 of a signal side. The timing circuit 13 renews a scanning line command signal every scanning period, and supplies it to an LED driver 9. Also, the timing circuit 13 supplies an enable signal EN based on an external brightness data supplied from a signal side LED driver 5 and a scanning side LED driver 9 and surrounding illuminance data supplied from a brightness sensor 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED (light emitting diode) display device, and more particularly to a dot matrix type LED display device capable of changing display brightness.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional dot matrix type LED module includes a serial / parallel conversion circuit 1, a latch circuit 3, a signal side LED driver 5, a timing circuit 7, a scanning side LED driver 9, and an LED. It is composed of an array 11. Next, the operation of the LED module shown in FIG. 5 will be described with reference to the timing chart of FIG.

The serial / parallel conversion circuit 1 is composed of, for example, a shift register and supplies from the timing circuit 7 the LED light emission data which is serially supplied in the first half of each scanning period (timing T1 in FIG. 3A). Captured in sync with the signal, converted to parallel data,
It is supplied to the latch circuit 3. At the time when the signal for one scanning line is accumulated in the serial / parallel conversion circuit 1, the timing circuit 7 supplies the latch signal shown in FIG. Latch display data. The latch circuit 3 supplies the light emission data for one scanning period to the signal side LED driver 5. Timing circuit 7
Scan line instruction signal is updated every scanning period to scan side LE.
It is supplied to the D driver 9.

Further, the timing circuit 7 is a scanning side LE.
The drive signal shown in FIG. 6C is supplied to the D driver 5 and the scanning side LED driver 9. In response to this drive signal, the signal side LED driver 5 supplies the light emission data for one scanning period to the signal electrode of the LED array 11, and the scanning side LE.
The D driver 9 decodes the supplied scanning line instruction signal and selects one of the scanning lines of the LED array 11. Among the LEDs on the selected scanning line, the LED designated by the LED light emission data emits light for the period shown in FIG. 6C.

For each scanning line, in the same manner as described above, input of LED light emission data, serial / parallel conversion, data retention,
Light emission and refreshing (clearing data held in registers, latches, etc.) are repeated. Then, the above operation is repeated from the uppermost scanning line to the lowermost scanning line to form a screen for one field.

Further, in the case of displaying k gradations, one frame screen is formed from k fields, and the gradation of the display screen is linearly changed by adjusting the number of fields for emitting LEDs. ..

[0007]

In the above-mentioned dot matrix LED display device, the brightness of the LED is constant, the ambient illuminance cannot be dealt with when the dot matrix LED display device is installed, and it is difficult to save power. It was Further, when the ambient illuminance changes, it is impossible to cope with the change in the ambient illuminance, and it is impossible to save power at night.

Further, when gradation display is performed, a one-frame screen is formed from k fields and the number of fields for emitting LEDs is adjusted to adjust the display gradation.
Only linear gradation display is possible, and it is difficult to perform non-linear gradation display suitable for human vision.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an LED display device capable of adjusting the brightness of an LED as necessary. Another object of the present invention is to provide an LED display device capable of displaying gradation that changes non-linearly.

[0010]

To achieve the above object, an LED display module according to a first aspect of the present invention includes an LED display array and the LED display array corresponding to display data supplied from the outside. While driving, while keeping the scanning time of the LED display array constant, the LE during one scanning period is controlled by the luminance data supplied from the outside.
D means for changing the light emission time.

A dot matrix type LED display module according to a second aspect of the present invention includes an LED display array, a sensor for measuring ambient illuminance and outputting corresponding illuminance data, and an externally supplied display data corresponding to the display data. The L
A means for driving the ED display array, keeping the scanning time of the LED display array constant, and changing the LED emission time in response to the illuminance data from the sensor is provided.

A dot matrix type LED display module according to a third aspect of the present invention is an LED display array and the LED corresponding to display data supplied from the outside.
The display array is driven to gradationally display one frame image in a plurality of fields, and the means for performing nonlinear gradation display by changing the LED light emission time for each field according to the brightness data supplied from the outside.

[0013]

In the dot matrix type LED display module according to the first and second aspects of the present invention, the LED light emission time during one scanning period changes depending on the luminance data supplied from the outside or the illuminance data supplied from the sensor. To do. Therefore, the display brightness of the LED display array changes according to the brightness data supplied from the outside or the illuminance data supplied from the sensor, and the brightness can be set to an arbitrary brightness from the outside or displayed according to the ambient illuminance. The brightness can be changed appropriately to display the data.

In the dot matrix type LED display module according to the third aspect of the present invention, when the one frame image is displayed in gradation in a plurality of fields, the LED emission time is changed for each field by the luminance data supplied from the outside. Therefore, the gradation can be changed non-linearly, and gradation display suitable for human eyes can be performed.

[0015]

Embodiments of the present invention will be described in detail below with reference to the drawings. The configuration of the LED display device according to this embodiment will be described with reference to FIG. In addition, in FIG.
The same parts as those in FIG.

As shown in FIG. 1, the dot-matrix type LED module of this embodiment includes a serial / parallel conversion circuit 1, a latch circuit 3, a signal side (horizontal side) LED driver 5, and a scanning side (vertical side) LED. Driver 9, LED
It is composed of an array 11, a timing circuit 13, and an illuminance sensor 15. Next, the operation of the LED module shown in FIG. 1 will be described with reference to the timing chart of FIG.

The serial / parallel conversion circuit 1 fetches the LED light emission data serially supplied in the first half of a certain scanning period (timing T1 in FIG. 2A) in synchronization with the clock signal supplied from the timing circuit. , Convert to parallel data. Timing circuit 13 is serial /
When the LED light emission data for one scanning line is accumulated in the parallel conversion circuit 1, the latch signal shown in FIG. 2B is supplied to the latch circuit 3 to latch the LED light emission data. The latch circuit 3 supplies the latched n-bit LED light emission data for one scanning period to the signal side LED driver 5. The timing circuit 13 updates the scanning line instruction signal every scanning period and supplies it to the scanning LED driver 9.

Further, the timing circuit 13 has a signal side L.
Based on the external brightness data externally supplied to the ED driver 5 and the scanning side LED driver 9 and the ambient illuminance data supplied from the brightness sensor 15, the enable signal EN is supplied.
To supply.

The period in which the enable signal EN is at the active level is longer, for example, as the external brightness data indicates higher brightness, and is longer as the ambient illuminance data indicates higher ambient illuminance. FIG. 2C shows an enable signal EN.
Example of the case where the active level period of is the longest, FIG. 2 (d)
Shows an example in which the active level period of the enable signal EN is the shortest.

In response to the enable signal EN, the signal side L
The ED driver 5 supplies the n-bit emission data for one scanning period to the signal electrodes of the LED array 11 to scan the LEDs on the scanning side.
The driver 9 decodes the supplied scanning line instruction signal and selects one of the scanning lines of the LED array 11. LED on selected scan line (connected to selected scan electrode)
Of these, the LED designated by the LED light emission data emits light while the enable signal EN is at the active level. The data held in the serial / parallel conversion circuit 1 and the latch circuit 3 is refreshed (cleared) as appropriate.

In each scanning period, similarly to the above, the input of the LED light emission data, the serial / parallel conversion, the retention of the data, the update of the selected scanning line (electrode), the light emission, and the refresh are repeated. Then, the above operation is repeated from the uppermost scanning line to the lowermost scanning line to form a screen for one field.

In the above structure, since the light emission duty of the LED changes according to the external brightness data, the external brightness data can be controlled to directly display the gradation. In addition, as in the conventional method, one frame screen is formed from k fields and LED
Even when the number of fields for emitting light is adjusted to change the gradation of the display screen, non-linear gradation display can be performed by changing the light emission duty of the LED for each field.

As described above, according to this embodiment, the LEDs in the LED array 11 according to the luminance data supplied from the outside and the ambient illuminance data supplied from the illuminance sensor 15.
By adjusting the on-time within one scanning period, the image can be displayed with the brightness corresponding to the ambient illuminance, and the non-linear gradation display can be performed.

In the above description, the signal side LED driver 5 and the scanning side LED driver 9 are set to the enable / disable state by the enable signal EN to adjust the brightness of the LED. The present invention is not limited to this, and one of the signal-side LED driver 5 and the scanning-side LED driver 9 is set to the enable / disable state by the enable signal EN and the LED is turned on.
The brightness of the LED or by the enable signal EN
Set the enable / disable of array 11 to LE
Other configurations such as adjusting the brightness of D may be adopted. Next, an example of the configuration of the timing circuit 13 will be described with reference to FIGS. 3 is a block diagram of the timing circuit,
FIG. 4 is a circuit diagram of the main part of the counter / timer unit 25 of the timing circuit shown in FIG.

The sensor 15 detects the ambient illuminance and outputs a corresponding analog signal. This analog signal is converted into digital data by the analog-digital converter 21,
It is supplied to the calculation unit 23. The calculation unit 23 calculates the external brightness data and the ambient illuminance data in response to the trigger signal from the counter / timer unit 25, and outputs the calculation result. For example, the calculation unit 23 outputs the quotient (luminance data) obtained by dividing the absolute value of the difference between the external luminance data and the ambient illuminance data by an appropriate natural number. The counter / timer unit 25 counts the clock signal according to the calculation result of the calculation unit 23, and FIG.
The enable signal EN as shown in (d) is output. As in the conventional case, the counter / timer unit 25 counts the clock signals and the serial / parallel conversion circuit 1 fetches the LED light emission data and the timing signals shown in FIG.
The operation of generating the latch signal shown in (b) is also performed.

Next, in the case of adjusting the circuit configuration of the portion of the counter / timer unit 25 which generates the enable signal EN in four steps (4 gradations) of the light emission time of the LED (the output of the arithmetic unit 23 is 2 bits) The case will be described as an example with reference to FIG.

In FIG. 4, the D flip-flops D1 to D4 connected in series operate as a counter and are simultaneously reset by the inversion signal of the latch signal shown in FIG. 2B. The AND circuits AND1 to AND3 take the AND of the inverted Q output of the corresponding D flip-flop and its inverted signal.

The selector S, in accordance with the 2-bit data from the calculator 25, outputs Y1 of the AND circuit AND1, Y2 of the AND circuit AND2, and Y of the AND circuit AND3.
3. Select one of the inverted Q outputs Y4 of the D flip-flop D4. For example, the selector S selects the signal Y4 when the 2-bit data output from the arithmetic unit 23 is “11 (maximum luminance)”, and selects the signal Y3 when “10”.
In the case of "01", the signal Y2 is selected, in the case of "00 (minimum brightness)", the signal Y1 is selected, and the enable signal EN is selected.
Output as. With such a configuration, the LED display can be performed by changing the brightness according to the external brightness data and the ambient illuminance data. The configuration of the timer circuit 13 is not limited to the configurations shown in FIGS. 3 and 4, and other configurations can be adopted as long as the intended purpose can be achieved.

[0029]

In the conventional dot matrix type LED display module, the brightness of the LED is fixed. According to the present invention, it is possible to change the brightness with external input data, and it is possible to significantly reduce the power consumption by finely adjusting the brightness with respect to the ambient illuminance. The change in the brightness of the LED corresponding to the change in the ambient illuminance due to the sensor signal has a remarkable effect on the power saving and the long life of the display device for the display during the day and night. In the case of gradation display, by performing non-linear gradation, it is possible to efficiently perform color display that matches the human eye with a small amount of data, and it is also effective in downsizing the system.

[Brief description of drawings]

FIG. 1 is a block diagram of an LED display module according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the LED display module shown in FIG.

FIG. 3 is a circuit block diagram of the timing circuit shown in FIG.

FIG. 4 is a circuit diagram of a part of the counter / timer unit shown in FIG.

FIG. 5 is a block diagram of a conventional LED display module.

6 is a timing chart showing the operation of the LED display module shown in FIG.

[Explanation of symbols]

1 ... Serial / parallel conversion circuit, 3 ... Latch circuit, 5
... Signal side LED driver, 7, 13 ... Timing circuit,
9 ... Scanning side LED driver, 11 ... LED array, 15
... Illuminance sensor, 21 ... Analog-to-digital conversion circuit, 23
... operation part, 25 ... counter / timer part.

Claims (3)

[Claims] 1. An LED display array comprising light emitting diodes, and a LED display array connected to the LED display array, which drives the LED display array in accordance with display data supplied from the outside and scans the LED display array. An LED display module, comprising means for changing the LED light emission time during one scanning period according to luminance data supplied from the outside while keeping it constant. 2. An LED display array comprising light emitting diodes, a sensor for measuring ambient illuminance and outputting corresponding illuminance data, and being connected to the LED display array and the sensor for externally supplied display data. And driving the LED display array, and changing the LED emission time in response to the illuminance data from the sensor while keeping the scanning time of the LED display array constant. LED display module. 3. An LED display array composed of light emitting diodes, and driving the LED display array corresponding to display data supplied from the outside to display one frame image in gradation in a plurality of fields and to display an LED for each field. An LED comprising means for changing the light emission time according to luminance data supplied from the outside and performing non-linear gradation display.
Display module.