(19) Korean Intellectual Property Office (KR)
`(12) Patent Gazette (B1)
`
`TEUK 1995-0008788 
`
`August 8, 1995
`TEUK 1995-0008788
`TEUK 1994-0017813
`July 27, 1994
`
`Exhibit Kap No. [handwritten:] 12
`
`
`(51) Int. Cl.6
`(45) Publication Date
`(11) Publication Number
`G09G 3/36
`(65) Laid-Open Number
`TEUK 1992-0027453
`(21) Application Number
`(43) Laid-Open Date
`December 31, 1992
`(22) Filing Date
`Ja Hong Koo, LG Electronics Inc.
`(71) Applicant
`20 Yoido-dong, Youngdeungpo-gu, Seoul
`
`
`
`Kwang Jin Choi
`(72) Inventor
`(12/4) 28-21 Jeon-dong, Joong-gu, Incheon-si, Kyunggi-do
`
`Young Cheol Kim
`(74) Agent
`Examiner: Seong Un Kim (Gazette Publication No. 4077)
`(54) LCD Brightness Controller Based on Digital-Analog Converter
`
`Abstract
`Not available.
`
`Representative Diagram
`
`Figure 1
`
`Specification
`[Title of the Invention]
`LCD brightness controller based on digital-analog converter
`
`[Brief Description of the Drawings]
`Figure 1 is a block diagram of the existing LCD brightness controller.
`Figure 2 is a status table of I/O operations of the LCD brightness adjustment part in Figure 1.
`Figure 3 is a block diagram of the LCD brightness controller based on a D/A converter according to the present invention.
`Figure 4 is a status table of I/O of the LCD brightness adjustment part in Figure 2.
`Figure 5 is a relation graph of the brightness voltage and resolution according to the present invention.
`
` *
`
` Description of reference numerals for important parts of the drawings
`100: control part
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`
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`200: LCD module
`300: data input part
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`
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`400: LCD brightness adjustment part
`500: LCD brightness adjustment part based on D/A converter
`510: latch buffer
`520: D/A converter
`
`
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`530: amplifier (OP-AMP)
`
`R1 – R2: resistor
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`
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`Q1, Q2: NPN transistor
`G: ground
`
`[Detailed Description of the Invention]
`The present invention is related to a brightness adjustment apparatus of a liquid crystal display (hereinafter referred to as an LCD), and particularly to
`the LCD brightness controller based on a digital-analog (D/A) converter which is appropriate for multi-step brightness adjustment of a high
`resolution LCD.
`
`In general, the existing LCD brightness controller is mostly in the form in which its brightness control voltage is controlled by using the resistor,
`transistor, etc., and if the resolution of an LCD is increased, consumption by the resistor, transistor, etc. is increased and resolution of brightness is
`relatively decreased.
`
`The prior art that results in the phenomenon described above is described in detail by referring to Figure 1.
`
`Figure 1 is a block diagram of the existing LCD brightness controller, wherein it is largely divided into and comprised of a data input part (300) that
`generates data for LCD brightness adjustment, a control part (100) that receives data applied from the data input part (300) to control an entire system,
`an LCD brightness adjustment part (400) that is intended to control LCD
`brightness according to the brightness control signal of the control part (100), and an LCD module (200) that receives a brightness adjustment signal
`output from the LCD brightness adjustment part (400) either to control the brightness of an LCD (not illustrated) or to drive an LCD according to a
`control signal of the control part (100) for mutual exchange of data.
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`Skyworks Ex. 2008
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`TEUK 1995-0008788 
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`A detailed configuration of the LCD brightness adjustment part (400) consists of a first resistor (R1) that receives a certain positive voltage (Vcc)
`applied; a second resistor (R2) that is connected between an output terminal and a ground terminal (G) of the first resistor (R1); a sixth resistor (R6) to
`which a first brightness control signal (P1) of the control part (100) is applied; a fifth resistor (R5) to which a second brightness control signal (P2) of
`the control part (100) is applied; third and fourth resistors (R3, R4) to which an output signal of the first resistor (R1) is applied; and a second NPN
`transistor (Q2) wherein an output signal of the third resistor (R3) is applied to a collector terminal; an output signal of the sixth resistor (R6) is applied
`to a base terminal; and an emitter terminal is connected with a ground terminal (G); and a first NPN transistor (Q1) wherein an output signal of the
`fourth resistor (R4) is applied to a collector terminal; an output signal of the fifth resistor (R5) is applied to a base terminal; and an emitter terminal is
`connected with a ground terminal (CT) [sic: (G)].
`
`Operations of the existing LCD brightness adjustment apparatus configured as above are described by referring to Figure 2.
`
`After a data input part (300) sends data on the LCD brightness increase or decrease to a control part (100), a control part (100) turns on/off transistors
`(Q1, Q2) according to the LCD brightness adjustment data so that a main voltage source Vcc may output divided voltages as in the table (Figure 2)
`according to the combination of R1 with R2, R3, and R4 and supply them to an LCD module (200). At this time, the drive voltage of an LCD is
`determined by the difference voltage between the main voltage source Vcc and the output voltage Vo of the LCD brightness adjustment part (400). If
`the control signals of a control part (P1 and P2) represent the logic of “0”, LCD brightness becomes the brightest. The LCD module ([LIQUID
`CRYSTAL MODULE], 200) uses the data from a control part (100) and the control of a control signal and the output voltage of an LCD brightness
`adjustment part (400) as input to display on an LCD according to the brightness desired by a user.
`
`In the existing operation method of LCD brightness adjustment described above, as shown in the figure (Figure 1) and table (Figure 2), LCD
`brightness is adjusted based on the voltage division by resistors (R1 – R4) according to the ON and OFF of transistors (Q1, Q2), so if the resolution of
`brightness is raised, it results in the problem wherein more transistors and resistors are required and resolution of brightness becomes low.
`
`To solve the problem described above, an objective of the present invention is to provide a method of LCD brightness adjustment in which LCD
`brightness adjustment is appropriately made to achieve multi-step brightness adjustment with high resolution by using a digital-analog converter and
`an apparatus therefrom.
`
`To achieve the above objective, the present invention is intended to comprise a control part (100) that receives data from the data input part (300) to
`control an entire system; and an LCD module (200) that drives an LCD (not illustrated) according to a control signal of the control part (100) to
`exchange data, and an LCD brightness adjustment part (500) based on a D/A converter that receives a brightness control signal of the control part
`(100) and data of the LCD module (200) to apply an adjustment signal to the LCD module (200).
`
`The following describes a preferred embodiment example according to the present invention by referring to the attached drawings.
`
`Figure 3 is a block diagram of the brightness adjustment apparatus according to the present invention, wherein it is largely divided into and
`comprised of a data input part (300) that is used for LCD brightness control; a control part (100) that receives data of the data input part (300) to
`control an entire system; an LCD module (200) that drives an LCD (not illustrated) according to a control signal of the control part (100) to exchange
`data; and an LCD brightness adjustment part (500) based on a D/A converter that receives a brightness control signal of the control part (100) and
`data of the LCD module (200) to apply a brightness adjustment signal to the LCD module (200).
`
`The detailed configuration of the LCD brightness adjustment part (500) based on a D/A converter includes a latch buffer (510) that receives LCD
`brightness adjustment data and a control signal applied by the control part (100); a D/A converter (520) that converts digital data output from the
`latch buffer (510) into an analog signal, and an amplifier (530) that receives an analog signal of the D/A converter (520) applied to amplify and
`output a brightness adjustment signal of the LCD module (200), wherein an output signal of the amplifier (530) is returned to the D/A converter (520)
`so as to set the range of an output voltage.
`
`The following describes in detail the operations of the brightness adjustment apparatus with the above configuration according to the present
`invention by referring to Figure 4 and Figure 5.
`
` data input part (300) sends data on LCD (Liquid Crystal Display) brightness increase or decrease to a control part (100). A control part (100)
`provides a control signal to a latch buffer (510) of an LCD brightness adjustment part (500) according to the data on LCD brightness increase or
`decrease from a data input part (300) to replace data. Data output of the replacement buffer (510) becomes digital data input of a D/A (digital-analog)
`converter (520) so that an analog voltage is output as in the table (Figure 4) according to the data. This analog output is amplified with an OP-AMP
`(530) and an output voltage Vo is transmitted to an LCD module (200) so that LCD brightness adjustment is enabled, and the output voltage Vo is
`returned to a D/A converter (520) so that a desired voltage range can be controlled. As in the table (Figure 4) and graph (Figure 5), the step of analog
`output is determined according to the number of digital data bits of a D/A converter (520), and adjustment step of LCD brightness, that is, resolution
`is determined according to the step of this analog. In the case of 4-bit data, 16 steps of LCD brightness adjustment can be made; in the case of 16-bit
`data, 256 steps of LCD brightness adjustment can be made; and in the case of 16-bit data, 64,000 steps of LCD brightness adjustment can be made. In
`addition, because the memory for data requires only one byte of memory that indicates current LCD brightness data, an extremely small amount of
`memory may be used for LCD brightness adjustment. In the case of 0V – 5V of an output voltage range and 8-bit data, for example, its output
`voltage Vo (brightness voltage) is approximately 5V as in the table (Figure 3) provided that LCD brightness data is 16-digit FFH so that its LCD
`brightness is the smallest; whereas in the case of the data of 16-digit OOH, its output voltage Vo becomes 0V so that its LCD brightness becomes the
`brightest.
`
`Since an LCD drive voltage is determined by the difference between a main power source supplied to an LCD and a brightness voltage Vo,
`brightness is adjusted by the brightness voltage Vo.
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`TEUK 1995-0008788 
`
`An LCD module (200) uses the output voltage from an LCD brightness adjustment part (500) as its input voltage to adjust the LCD brightness and
`receives data and a control signal from a control part (100) to display them.
`
`The LCD brightness controller based on a D/A converter according to the present invention that operates as described above is provided to adjust the
`LCD brightness using a D/A (digital-analog) converter and effectively eliminate the problem with low resolution of the existing brightness controller
`because it allows a user to easily adjust to the desired brightness and also to enable multi-step manipulation according to the number of data bits for
`brightness adjustment.
`
`(57) Scope of Claims
`
`Claim 1
`An LCD brightness controller based on a digital-analog converter characterized in that it comprises a data input part (300) for LCD brightness
`adjustment; a control part (100) that receives data from the data input part (300) to control an entire system; and an LCD module (200) that drives an
`LCD (not illustrated) according to a control signal of the control part (100) to exchange data; and an LCD brightness adjustment part (500) based on
`a D/A converter that receives a brightness control signal of the control part (100) and data of the LCD module (200) to apply an adjustment signal to
`the LCD module (200).
`
`Claim 2
`The LCD brightness controller based on a digital-analog converter recited in Claim 1 characterized in that the LCD brightness adjustment based on
`the D/A converter comprises a latch buffer (510) that receives LCD brightness adjustment data and a control signal applied by the control part (100);
`a D/A converter (520) that converts digital data output from the latch buffer (510) into an analog signal; and an amplifier (530) that receives an
`analog signal of the D/A converter (520) applied to amplify and output a brightness adjustment signal of the LCD module (200).
`
`Claim 3
`The LCD brightness controller based on a digital-analog converter recited in Claim 2 characterized in that the output signal of the amplifier (530) is
`configured to return to the D/A converter (520) so as to set the range of its output voltage.
`
`Drawings
`
`Figure 1
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`
`module
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`control part
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`data input part
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`Figure 2
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`Control Signal Transistor Status of Control Part
`P2
`P1
`Q2
`Q1
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`Brightness Adjustment Part Output Voltage Vo
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`Brightness
`Grade
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`TEUK 1995-0008788 
`
`
`Figure 3
`
`
`
`module
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`D/A
`converter 
`
`latch
`buffer
`
` 
`
`control part
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`data input part
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`Figure 4
`Digital Value (16-Digit Number)
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`Output Voltage Vo (Brightness Voltage)
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`Figure 5
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`Brightness Voltage
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`TEUK 1995-0008788 
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`Digital Value
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`f6!
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`TRANSPERFECT
`
`City of New York, State of New York, County of New York
`
`I, Mamiko Taniguchi, hereby certify that the following is, to the best of my
`knowledge and belief, a true and accurate translation of the document, “Korean
`Pat App. 1995-0008788,” from Korean into English.
`
`
`
`Sworn to before me this
`
`Friday, April 18, 2014
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`
`
`I'fie
`
`' M3ggtiimisslon Expires MAY 21, 2016
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`
`
`
`Stamp, Notary Public
`State of New York
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`Page 6
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