TW559768B - Photo sensor calibration method of automatic brightness control in LCD - Google Patents

Abstract

An photo sensor calibration method of automatic luminance control in LCD is disclosed, the method at least comprises the following steps: firstly, set up a matching correspondence range table between the environmental luminance and the luminance control of LCD panel; then input the input voltage signal to a voltage-controlled oscillator, and generate an output frequency; select a corresponding range, set the maximum, medium and minimum value; finally, compare the matching correspondence range table, input the output frequency into a microprocessor, and output a control signal to control and calibrate the luminance of the backlight plate of LCD.

Description

559768 V. Description of the invention (i) · ---- [Field of the invention] The present invention is a photo sensor correction for automatic brightness control. It is especially suitable for 4 kinds of applications in liquid crystal displays. Controlled photo sensor calibration method. [Background of the Invention] When a photoresistor (CDS) is used as a light sensor to control the backlight brightness of a liquid crystal display (LCD), the hardware cost can be greatly reduced, but due to the resistance of the photoresistor itself The value error is very large, so that when operating in automatic mode, the output value of the light sensor varies considerably with different photoresistor elements. In fact, this difference did not cause the malfunction of the light-sensing circuit, but only the output range was different depending on the different photoresistors. Therefore, it caused troubles in mass production in the factory. The accepted range wastes a lot of time to repeatedly check the circuit, and even affects the quality and progress of the shipment. In the conventional technology, a photoresistor (CDS) 1 00 is used as a light sensor to control a liquid crystal display (Liquici Crystal

Display; LCD) backlight brightness, as shown in Figure i, the conversion of ambient brightness into digital data is completed by an analog / digital converter (ADC) 丨 丨 0, whether ADC Π 0 contains or external microprocessor丨 2 〇 The cost is very high, and if the sensor board (Sensor Board) 130 and the microprocessor 12 are designed separately, the connection of the signal data line requires at least 8 transmission lines 1 4 0. Another cost-saving technology also uses a photoresistor (CDS) 2 0 0 as a light sensor to control the liquid crystal display (Liquid

Page 4 559768 V. Description of the invention (2)

Crystal Display; LCD) backlight brightness, as shown in Figure 2, the voltage-controlled oscillator (Voltage-Control led Oscillator; VCO) 2 1 0 to convert the ambient brightness to a certain frequency, sent to the microprocessor 2 2 〇 Calculate its frequency cycle, you can know the brightness change, and if the photosensitive plate (Sens〇r B 〇ard) 2 3 0 and the microprocessor 2 2 0 when the design of the connection signal, the data line only needs one piece of data 2 40, not only lower cost, but also easier to obtain parts, the price of the voltage-controlled oscillator 210 is about ADc 100%. However, the device using the ADC 1 1 0 or the voltage-controlled oscillator 2 J 〇 as the two-blade motion brightness control device cannot yet set different output range values for different night crystal display properties, but cannot be strong. The characteristics of the device, unless the design of the hardware circuit is changed, but the actual benefits of circuit stability are consumed. This document does not meet the requirements of the present invention. [Summary and purpose of the invention] The present invention is a light sensor calibration method using a software calibration program for automatic brightness control. Its main purpose is for the liquid crystal display to be correct because of different light sensors, which is to solve the problem of distortion of the automatic brightness control of the liquid crystal display. Is the range, and the created = the disclosed method of automatic brightness suppression of the liquid crystal display disclosed by the invention includes at least the following steps: · The first corresponding photo sensor crystal display 2 panel brightness control matching range table 7 The liquid generates a round input voltage signal; then the input voltage ^ _ is controlled by the optical sensor in the oscillator, and the ancient σΚ 咸 is turned into a thunder, and, ... κ Aya generates an output frequency; provides options Prostitute voltage, sub-5, maximum, middle, and minimum values; finally, select a corresponding range table and input the output frequency to a microprocessor according to t, and output the corresponding range in $. The control signal is 559768. V. Invention Explanation (3) Control and correct the brightness of the LCD backlight panel. About the present invention ^ The following: m Tanuchi and technology 'will be described in conjunction with the drawings, such as [detailed description of the invention] The present invention proposes a liquid a view-correction method, mainly in the auxiliary :: photo sensor with automatic brightness control Respond to the output correction of the reactor, and then dream of the automatic brightness control of the light sensor by 1 = the automatic brightness control of the light sensor; the control 'reach the liquid crystal display as Ay day Γ Among them, the third picture is the present invention using VC0 Min + ^ Γ schematic circuit diagram, that is, using photoluminescence.丨 ... dp is a light sensor to control the backlight brightness of the LCD (LiqU1d Crystal Dlsplay; lcd) 34〇 'and then a voltage control vibrator (v〇1 tage_c〇ntr〇i ied Γ / 1.01 · 77) 310 to convert the ambient brightness to a certain frequency, and send it to 2 = Liyi 3 2 0 to calculate its frequency period, and then the microprocessor 3 2 0 outputs pulse I degree modulation (PWM) To control the brightness of the backlight panel of the LCD 34. = The signal of the voltage-controlled oscillator 3 turns into turns. At the receiving end, the design of a one-weight resistor 33 0 makes the photoresistor 300 generate different round-in voltages (Vi) according to different resistance values. The corresponding output frequency (Vo) of the oscillator output is controlled according to the voltage. The fourth figure is the relationship between the input voltage and the output frequency of the automatic brightness control 7 of the liquid crystal display using VC0 according to the present invention. As can be seen from the fourth figure, the input voltage and the output frequency are inversely proportional. According to the characteristics of this relationship, we can establish = A large-scale comparison table to tolerate the error range of the photoresistor (CDS) 3 00 itself, and introduce a software calibration program that will meet

559768- V. Description of the invention (4) " " --- The brightness requirement of the backlight panel of the LCD. Fig. 5 is a flowchart of the photo sensor f of the automatic brightness control of the liquid crystal display of the present invention. First, 'establish—the ambient brightness matches the corresponding range table of the LCD display panel control (step 500). This brightness can be set to a plurality of setting values (complex order). Taking the present invention as an example,' it is set to 0 during the order. A total of 32 setting values of ~ 31 'are used to define 800ux real production corresponding to 31, and 350 LUX brightness automatically corresponds to 0; in the second two, this shell degree is set to 32 to 32 setting values. It is used to define the automatic correspondence of 75 degrees as 31, and the automatic correspondence of 3 0 0 LUX brightness is 0. After waiting for the definition of the corresponding range of the ambient brightness matching (step 50), '' Factory calibration process 4 and By the light sensor, the device generates an input voltage signal (/ step 510), and then inputs the input voltage signal to the ―voltage control ~ benefit, sub-generates an output frequency (step 52), and enters the light sensor of the liquid crystal dynamic brightness control. Device calibration process; mention a pair of self-setting, and set the maximum, middle, and minimum (step 53), after setting the top ten crimes = matching corresponding range *, input the output frequency to a small place Empty H Tiger to control and correct the LCD black bezel back The luminance plate (shame step 540). In the present invention, a voltage controlled oscillator (VC0) 31 is used as an example of a device for converting the ambient brightness. The control signal output by the microprocessor is a pulse width modulation (PWM). And applying a conventional device that uses analog / digital conversion (ADC) as a device to convert ambient brightness, not only can correct the error range of the corrected photoresistor (CDS) itself, but also can achieve the accurate 4-parent positive effect. The method provided by the present invention further includes a normal value setting for indicating

559768 V. Description of the invention (5) The maximum value> the middle value> the minimum value. And when a light sensor output frequency range is too small, a warning or error message is displayed. Although the present invention is disclosed in the foregoing preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and retouching without departing from the spirit and scope of the present invention. The scope of protection of the invention shall be determined by the scope of the attached patent application.

Page 8 55976 & Simple illustration [Simplified illustration] Figure 1 is not intended to be a circuit using the ADC for automatic brightness control of a liquid crystal display, and Figure 2 is a conventional circuit to use a VCO for automatic brightness control of a LCD It is not intended that FIG. 3 is a schematic circuit diagram of the present invention using a VCO as the automatic brightness control of the liquid crystal display; FIG. 4 is a relationship diagram of the input voltage and the output frequency using the VCO as the automatic brightness control of the liquid crystal display; and

Fig. 5 is a flow chart of a light sensor calibration method for automatic brightness control of a liquid crystal display of the present invention. [Symbol description] 100, 2 0 0, 3 0 0 Photoresistor (CDS) 110 Analog / Digital Converter (ADC) 1 2 0, 2 2 0, 3 2 0 Microprocessor 130, 230 Sensor Board 1 4 0, 2 4 0 Transmission line 2 1 0, 3 1 0 Voltage controlled oscillator

3 3 0 Voltage-dividing resistor 340 LCD panel Step 5 0 0 Establish a table of the corresponding range of ambient brightness and LCD panel brightness control Step 5 1 0 Generate an input voltage signal by the light sensor Step 5 2 0 Input voltage signal Input to a voltage controlled oscillator,

55976 & diagram on page 9 briefly explains and generates an output frequency. Step 5 3 0 Select a corresponding range and set the maximum, middle and minimum steps. Step 5 4 0 Input the output frequency into a microprocessor according to the matching range table. And output a control signal to control and correct the brightness of the LCD backlight panel

Page 10

Claims (1)

559768 VI. Application for patent scope 1. A light sensor calibration method for automatic brightness control of a liquid crystal display, the method includes at least the following steps: establishing a matching range table of ambient brightness and brightness control of the liquid crystal display panel; The sensor generates an input voltage signal; inputs the input voltage signal to a voltage controlled oscillator, and generates an output frequency; Select a corresponding range and set the maximum, middle, and minimum values; and refer to the matching corresponding range table, input the output frequency to a microprocessor, and output a control signal to control and correct the brightness of the LCD backlight panel. 2. The method for calibrating a light sensor for automatic brightness control of a liquid crystal display according to item 1 of the scope of patent application, wherein the light sensor is a photoresistor. 3. The light sensor calibration method for automatic brightness control of a liquid crystal display according to item 1 of the scope of the patent application, wherein the matching correspondence range table is a correspondence range defined according to the ambient brightness. 4. The light sensor calibration method for automatic brightness control of a liquid crystal display according to item 1 of the scope of patent application, wherein the corresponding range can be set to a plurality of setting values. 5. The light sensor calibration method for automatic brightness control of a liquid crystal display as described in item 1 of the scope of the patent application, which further includes a normal value setting to represent the maximum value> the middle value> the minimum value. 6. Automatic brightness control of liquid crystal display as described in item 1 of the scope of patent application Page 11 559768. VI. The patented photo sensor calibration method further includes a warning or error message when the photo sensor output frequency range is too small. 7. The light sensor calibration method for automatic brightness control of a liquid crystal display according to item 1 of the scope of patent application, wherein the voltage-controlled oscillator can be replaced by an analog / digital converter. Page 12