JP2538300Y2 - Lightning display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention relates to an electronic display device that displays information including characters, patterns, and the like on a display panel in which light-emitting diodes (hereinafter abbreviated as LEDs) are arranged in a matrix. .

[Prior Art] Conventionally, a display panel is formed by arranging unit panels in which LEDs are arranged in a matrix in a desired matrix, and information such as characters and figures is displayed on the display panel in a flowing manner.

By the way, since the LEDs used have different luminances with respect to the drive current depending on the production lot, it is expensive to purchase LEDs of the same luminance. Therefore, we purchased LEDs with different brightness for cost reduction and divided the LED into several levels of brightness.
Were arranged in a matrix for each unit panel. As a result, it is necessary to adjust the luminance because luminance variation occurs between the unit panels. In addition, since this type of lightning display is installed outdoors, the brightness of the LED is increased when the surroundings are bright such as during the daytime, and the brightness of the LEDs is decreased when the surroundings are dark such as at night. It was necessary to improve visibility.

To solve these problems, the configuration shown in FIG. 1 has been conventionally used.

In Figure 1, 1 is a unit panel 1 ₁ is disposed an LED in a matrix of vertical and horizontal N × N, 1 _2, ..., a 1-m in the display panel arranged on one line M row unit panels 1 − ₁ , _1-2 ,
.., LEDs having relatively equal light emission luminance are arranged in a matrix every 1-m. _{2-1, 2-2,} ..., 2-m each unit panels 1 _1, 1 _2, ..., the drive circuit provided for every 1-m,
Each drive circuit _{2- 1, 2- 2, ...,} 2-m each unit panels 1 ₁ to, 1- _2, ..., N pieces of the transistor array, each for driving a row of LED arranged in 1-m transistor array groups _3-1 were set, 3 _2, 3-m and the shift of latching the shift register has N number set to provide a drive signal to each transistor array enter the display data to be output from the control circuit 6 to be described later register group 4 _1, 4 _2, ..., consists 4-m, each drive circuit _{2-1, 2-2,} ..., 2-m to the display panel 1 are connected in series are Sutatekku lights. 5 _1, 5 _2,
..., 5-m each unit panel _{1-1, 1-2,} ..., 1-m in luminance adjustment circuit for adjusting the emission luminance of the control circuit 6 from each shift register group 4 _1, 4 _2, ... , 4-m is inserted into an on / off signal line for turning on / off an LED to change the duty ratio of the on / off signal. Reference numeral 6 denotes a control circuit for controlling the static lighting of the display panel 1, a CPU 7 for performing arithmetic processing, a program ROM, a kanji ROM, and data.
A memory 8 composed of a RAM or the like; a video RAM 9 for developing fonts to be displayed on the display panel 1;
It is formed from a data controller 10 that outputs display data, a clock signal, a latch signal, and an on / off signal developed in M9. Reference numeral 11 denotes an illuminance sensor such as a photodiode for detecting illuminance around the display panel 1, and an A / D conversion circuit 1
Via two outputs to CPU 7, each drive circuit 2 ₁ from the data controller 10 on the basis of the illuminance data obtained from the illumination sensor 11, CPU 7, 2 _2, ..., on the output to 2-m
The duty ratio of the off signal is set. FIG. 2 shows the input ON rate of the ON / OFF signal with respect to the illuminance obtained from the illuminance sensor 11 (the ON time To with respect to the cycle T of the ON / OFF signal).
This is an explanatory diagram showing the relationship of the ratio of n = Ton / T. When the surroundings are bright and the illuminance is high, such as during the daytime, the input on-rate (on-time ratio) of the on / off signal is increased, and conversely, at night. When the surroundings are dark and the illuminance is low, the input ON rate of the ON / OFF signal is reduced, and the luminance of the light emission is adjusted according to the surrounding brightness, thereby improving the visibility of the display panel 1.

Figure 3 is the in detailed view of a brightness adjustment circuit _5-1, a delay circuit 13 resistance consisting capacitor C of the variable resistor Rv and discharge variably by adjusting the volume, the delay circuit
The on-off signal input 13 to the output and the brightness adjusting circuit _5-1 of formed from the AND gate IC for receiving a variable resistor
By adjusting the volume of Rv, the brightness adjustment circuit 5
- on-time Ton of the input on-off signal of the OFF time Toff to on-off signal outputted from the luminance adjustment circuit _5-1 adds a fixed delay time Tdr is reduced to _1. The other brightness adjustment circuit _5-2, ..., and subjected to the same circuit configuration for 5-m, the unit panel 1 _2, ..., luminance modulation of 1-m is performed.

By the way, the display panel 1 unit panel _{1-1, 1-2,}
..., since the variation in emission luminance occurs every 1-m, the unit panels 1 _1, 1 _2, ..., it is necessary to perform the brightness adjustment of 1-m. Therefore, the brightness adjustment of the display panel 1 will be described with reference to FIGS.

Figure 4 is a luminance adjusting circuit _{5- 1, 5- 2, ...,} 5-m inputs to the on-off signal input on the unit does not perform the brightness adjustment to rate panel 1 ₁ and unit panel 1 for brightness control - brightness adjustment circuit 5 _{1 2,} explanatory view showing a relationship between output oN rate of the on-off signal outputted from _5-2, FIG. 5 (a) ~ (c ') is a conventional brightness adjustment in time chart for explaining that, for example, the duty ratio of 8: 2 by input on of 80% of the on-off signal (FIG. 5 (a)) each drive from the data controller 10 of the circuit 2 _1, 2 − ₂ ,…, 2
And outputs to the -m lit all the LED of the display panel 1, if the most luminous lower unit panels 1 ₁ luminance was set to the basic panel visually, a unit panel 1 ₁ The underlying perform brightness adjustment not, then the output on-off signal input to the luminance adjustment circuit _5-1 (FIG. 5 (a)) the same on-off signal (FIG. 5 (b)) to the shift register group _4-1, luminance adjustment is 80% equal to the input on rate for receiving the output oN rate of the on-off signal outputted from the circuit _5-1 to the luminance adjustment circuit _5-1.

On the other hand, other basic panel which performs brightness adjustment 1 ₂ Basic panel 1 ₁ of the luminance and equal way unit panels 1 ₂
Varying the variable resistance Rv of the brightness adjustment circuit 5 _2. When the luminance of the unit panels 1 ₂ to match the unit panels 1 ₁ of the luminance by adjusting the variable resistor Rv, off-time of on-off signal outputted from the luminance adjustment circuit _5-2 Toff 'brightness adjusting circuit 5 - becomes a time obtained by adding the delay time Tdr off time Toff of the on-off signal to be input to _2, the shift output on 60% of the on-off signal (FIG. 5 (c)) from the luminance adjustment circuit _5-2 and outputs to the register group _4-2. Thus, while the input on rate of on-off signal input to the luminance adjustment circuit _5-2 is 80%, the output on rate of on-off signal outputted from the luminance adjustment circuit 5 ₂ 60% , And the ratio of the output ON rate to the input ON rate is 4: 3.

In this way, the characters,
Information composed of symbols and the like is displayed, and the duty ratio of the on / off signal output from the control circuit 6 is varied based on the illuminance obtained from the illuminance sensor 11. In particular, when an on / off signal (FIG. 5 (a)) with an input on-rate of 80% during brightness adjustment is changed to an on / off signal (FIG. 5 (a ')) with an input on-rate of 40%, delay off time Toff of the on-off signal off time of the on-off signal outputted from the luminance adjustment circuit 5 _second unit panel 1 ₂ for brightness adjustment Toff 'is input to a luminance adjusting circuit _5-2 time and becomes plus Tdr, and outputs the luminance adjustment circuit _5-2 to the shift register group 4 ₂ output on 20% of the on-off signal (FIG. 5 (c ')). Therefore, the output on rate of on-off signal outputted from the luminance adjustment circuit _5-2 whereas the input on rate of on-off signal input to the luminance adjustment circuit _5-2 is 40% to 20% That is, the ratio of the output ON ratio to the input ON ratio is 2: 1.

[Devise a problem to be solved point] However, the unit panel 1 ₂ was subjected to brightness adjustment darkened drops luminance than the unit panel 1 of _the basic, during the unit panels 1 ₁ and 1 ₂ Variations in luminance occur. This is because the ratio of the output ON ratio to the input ON ratio at the time of luminance adjustment of the unit panel _1-2 whose luminance has been adjusted is 4: 3.
This is because the ratio of the output ON ratio to the input ON ratio when the duty ratio of the ON / OFF signal is varied changed to 4: 2, and the ratio of the output ON ratio to the input ON ratio fluctuated.

This invention is made to deal with this problem, the control circuit 6 from the unit panel 11 based on the illuminance data obtained from the illuminance sensor _11, 1 _2, ..., a drive circuit 1-m 2
- _1, 2 _2, ..., unit panels 1 ₁ for the luminance adjusted by varying the duty ratio of the ON-OFF signal given to 2-m,
1 _2, ..., the ratio of the output on rate for input on rate of 1-m held constant, the unit panels 1 _1, 1 _2, ..., intended to eliminate the luminance variation among 1-m is there.

[Means for Solving the Problems] In order to solve such problems, the present invention arranges LEDs having the same light emission luminance in a matrix for each unit panel, and a plurality of LEDs having different light emission luminances as a whole. A display panel in which unit panels are arranged in a desired matrix, a drive circuit for driving each LED for each unit panel, and output of display data and on / off signals for turning on and off the LEDs to each drive circuit And an illuminance sensor that detects illuminance around the display panel, and varies the duty ratio of an on / off signal based on the illuminance obtained from the illuminance sensor to change the brightness of the display panel to the surrounding brightness. In the electro-optical display device that adjusts according to the brightness, the drive circuit includes a brightness adjustment circuit that varies a duty ratio of an on / off signal output from a control circuit, and the brightness adjustment circuit includes the brightness adjustment circuit. The ratio of the ratio of the on-time of the on / off signal input to the luminance control circuit to the ratio of the on-time of the on / off signal output from the luminance control circuit is always kept constant to reduce the light emission luminance between the unit panels. It controls equally.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

Note that the present invention is a luminance adjusting circuit _5-1 in the overall structure of the conventional example shown in FIG. 1, 5 _2, ..., luminance adjustment circuit 14 of the present invention since only 5-m are different Figure 6 This will be described based on FIG.
Also, the same structures as those in the conventional example are denoted by the same reference numerals.

In FIG. 6, IC ₁ is an inverter which outputs a signal obtained by inverting the on / off signal output from the data controller 10 to a discharge circuit 15, a constant current source variable circuit 16 and a smoothing circuit 17 connected to the output side. I have. C ₁ is interposed between the charge and discharge capacitor for the output point V and the ground G of the discharge circuit 15 and a constant current source variable circuit 16. The discharge circuit 15 has a base terminal connected to the output side of the inverter IC ₁ and an emitter grounded N.
A transistor Tr ₁ in the PN type, consists discharge protection resistor Rd that interposed between the output point V and the collector of the transistor Tr _1, the capacitor C to conduct the transistor Tr ₁ by the rise of the inverted ON-OFF signals Discharge protection resistance Rd from ₁
Has a rapid discharge through. The constant current source variable circuit 16
The output terminal of the inverter IC ₁ is connected to the base of the PNP transistor Tr ₂ , the DC power supply Vcc is connected to the emitter via a variable resistor Rv ₁ whose resistance is variable by a volume, and the output point V is connected to the collector via a collector resistor Rc. to connect a constant voltage diode D between the base of the DC power supply Vcc and the transistor Tr ₂ as well as connected to form a constant current source, the amount of current by varying the resistance value of the variable resistor Rv ₁ is increased or decreased,
The fall of the inverted on-off signal to turn on the transistor Tr ₂ is charging the capacitor C ₁ with a constant current. The smoothing circuit 17 is a resistor R ₃ and capacitor C _2,
Connect inverted by the inverter IC ₂ on and off signals of the group split points by resistance-dividing by the resistance R ₁ and R _2, on
The off signal is converted to an average voltage. IC ₃ is a smoothing circuit 17
The impedance conversion is performed by an operational amplifier that receives the output of IC ₄ is a comparator with hysteresis. The output of the operational amplifier IC ₃ is input to the (+) input terminal via the resistor Ri, and the output of the output point V of the capacitor C _{1 is} input to the (−) input terminal. the chattering preventing hysteresis circuits Ri and Rf, the terminal voltage of the capacitor C ₁ is compared whether reaches the output voltage Vref of the operational amplifier IC _3. IC ₅ is NOR gate, the output of the comparator receives the output of the IC ₄ the duty ratio variable has been on-off signal to the shift register group 4 _first inverter IC _1, 4 _2,
…, 4-m. The other drive circuits 2 _1,
2 _2, ..., is provided with a brightness control circuit of the same configuration applies to 2-m.

Figure 7 is the time chart diagram showing a waveform of each part of the brightness adjusting circuit 14, FIG. 7 (a) is a waveform on-off signal input to the output waveform (luminance adjustment circuit 14 of the inverter IC ₁ is inverted ), Figure 7 (b) is the output point of the capacitor C ₁ V
FIG. 7 (c) shows the output waveform of the NOR gate IC ₅ (on / off signal output from the brightness adjustment circuit 14).

Now, when the inverted waveform of the on / off signal output from the inverter IC ₁ rises from low level to high level,
The output voltage of the capacitor C ₁ holds approximately equal reset time Tres low level and off time Toff of the rapid discharge to on-off signal via a discharge protection resistor Rd. Thereafter, when the on-off signal obtained by inverting falls from the high level to the low level, to charge the capacitor C ₁ by a constant current output from the constant current source variable circuit 16, the charging voltage of the capacitor C ₁ in a tapered shape Is increasing.

On the other hand, the smoothing circuit 17 is connected to the (+) terminal of the comparator IC _4.
Reference voltage Vr converted to the average voltage of on / off signal by
ef (dotted Figure 7) is, (-) inputs, respectively the output voltage of the capacitor C ₁ to the terminal, when the output voltage of the capacitor C ₁ exceeds the reference voltage Vref, the output of the NOR gate IC ₅ from the low level The off-time Toff ′ of the on / off signal output from the NOR gate IC ₅ becomes high level and the brightness adjustment circuit
The terminal voltage of the capacitor C ₁ to the on-off time Toff input to 14 becomes time obtained by adding the charging time Taj to reach the output voltage Vref of the operational amplifier IC _4. That is, the variable resistor Rv constant current source to increase the resistance of the _first variable circuit 16 for brightness adjustment
The amount of current output increases from the capacitor C ₁ is rapidly charged by on-off signals of the off-time Toff 'is shortened output from the luminance adjustment circuit 14, reducing the resistance value of the variable resistor Rv in the opposite reduces the amount of current output from the constant current source variable circuit 16, a luminance adjusting circuit slowly charging the capacitor C ₁
The off time Toff 'of the on / off signal output from 14 becomes longer. Also, if the resistance value of the variable resistor Rv ₁ is kept constant and the on-time Ton of the on / off signal to be input to the luminance circuit circuit 14 is increased to increase the input on-rate, the reference voltage Vref increases, Conversely, when the on-time Ton is reduced to lower the input on-rate, the reference voltage Vref decreases.

Next, the brightness adjustment of the display panel 1 according to the present invention will be described with reference to FIGS.

Figure 8 is from the luminance adjustment circuit 14 of the unit panels 1 ₂ for unit panels 1 ₁ and brightness control is not performed brightness control for the input on rate of on-off signal to be inputted to the luminance adjustment circuit 14 of the present invention FIG. 5 is an explanatory diagram showing a relationship between an output on-rate of an output on-off signal and an on-off signal (FIG. 5 (a)) having an input on-rate of 80% from a control circuit 6 as in the conventional case. circuit 2 _1, and outputs _2-2, ... to 2-m. Among the brightness adjustment circuits that input the on / off signal,
Luminance adjustment circuit 14 of the unit panels 1 ₁ underlying not performed brightness adjustment and outputs the input on-off signal the same output on rate of 80% of the on-off signal (FIG. 5 (b)),
Variable resistor Rv as luminance adjustment circuit 14 of the unit panels 1 ₂ for brightness adjustment is equal to the unit panels 1 ₁ brightness
The ON / OFF signal (FIG. 5 (c)) with an output ON rate of 60% is output by the variation of (1). Then, each drive circuit 2
- _1, from 2- _2, ..., _2-m on-off signal to be output to the (FIG. 5 (a ')) If you change the input on rate of 60%, luminance adjustment circuit 14 performs a luminance adjustment The pulse waveform of the output ON / OFF signal is as shown in FIG. 5 (C ″), and the ON rate of the ON / OFF signal input to the brightness adjustment circuit 14 is 40%.
Thus, the output ON ratio of the ON / OFF signal output from the brightness adjustment circuit 14 becomes 30%. Thus, the luminance ratio of the output on rate for input on rate of adjusting the luminance adjustment circuit 14 performs the luminance adjustment at the rate same as 4: 3, and the respective unit panels 1 _1, 1
- _2, ..., variations in light emission luminance between 1-m can be eliminated.

[Effect of the Invention] The present invention is configured as described above, and LEDs having the same light emission luminance are arranged in a matrix for each unit panel, and a plurality of unit panels having different light emission luminances are arranged in a desired matrix as a whole. A display panel, a drive circuit that drives an LED for each unit panel, a control circuit that outputs display data and an on / off signal for turning on and off the LED to each of the drive circuits, and a control circuit around the display panel. An illuminance sensor that detects illuminance, and an electronic display device that varies the duty ratio of an on / off signal based on the illuminance obtained from the illuminance sensor to adjust the luminance of the display panel according to the surrounding brightness. A brightness adjustment circuit that varies a duty ratio of an on / off signal output from a control circuit in the drive circuit, wherein the brightness adjustment circuit inputs an ON / OFF signal to the brightness adjustment circuit. By always keeping the ratio of the ratio of the ON time of the OFF signal to the ratio of the ON time of the ON / OFF signal output from the luminance adjustment circuit constant to control the light emission luminance between the unit panels equally, Even if the duty ratio of the on / off signal varies depending on the brightness, the brightness between the unit panels can be kept equal by the brightness adjustment circuit, and good display can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of the entire structure of a conventional electro-optical display device, FIG. 2 is an explanatory diagram showing the relationship between illuminance and the on-rate of an on / off signal, and FIG. 3 is a luminance adjustment circuit 5 in FIG. ₁ detailed view, FIG. 4 is a unit panel performing unit panels 1 ₁ and brightness control is not performed brightness control for the input on rate of on-off signal to be inputted to the conventional brightness adjustment circuits _5-1 and _5-2 explanatory view showing the relationship between the output on rate of 1 _second luminance adjusting circuit _5-1 and _5-2 from the outputted on-off signal, FIG. 5 is for explaining the luminance adjustment of the conventional and the present invention FIG. 6 is a detailed diagram of the brightness adjusting circuit 14 of the electro-optical display device according to the embodiment of the present invention, and FIG. 7 is a time chart diagram showing voltage waveforms at various parts of the brightness adjusting circuit 14 according to the embodiment of the present invention. FIG. 8 shows the ON / OFF signal input to the brightness control circuit 14 of the present invention. Explanatory view showing the relationship between the output ON rate of the output on-off signals from the luminance adjustment circuit 14 of the unit panels 1 ₂ for unit panels 1 ₁ and brightness control is not performed brightness control to a force on factor. 1 display _{panel, 1- 1, 1- 2, ...} , 1-m is a unit panel,
_{2- 1, 2- 2, ...,} 2-m drive circuit, the sixth control circuit,
11 is an illuminance sensor and 14 is a brightness adjustment circuit.

Claims (1)

(57) [Scope of request for utility model registration] 1. A display panel in which LEDs having the same light emission luminance are arranged in a matrix for each unit panel, and a plurality of unit panels having different light emission luminances are arranged in a desired matrix as a whole. A drive circuit that drives each LED, a control circuit that outputs display data and an on / off signal for turning on and off the LED to each drive circuit,
An illuminance sensor for detecting the illuminance around the display panel, and varying the duty ratio of the on / off signal based on the illuminance obtained from the illuminance sensor to adjust the luminance of the display panel according to the ambient brightness In the electro-optical display device,
The drive circuit includes a brightness adjustment circuit that varies a duty ratio of an on / off signal output from a control circuit,
The brightness adjustment circuit always keeps the ratio of the ratio of the ON time of the ON / OFF signal input to the brightness adjustment circuit to the ratio of the ON time of the ON / OFF signal output from the brightness adjustment circuit to be constant. An electro-optical display device wherein the light emission luminance between panels is controlled equally.