CN101393730B - gamma voltage conversion device - Google Patents

Abstract

The gamma voltage conversion device comprises a gamma voltage conversion circuit, an amplifier and a gamma voltage adjusting circuit. The gamma voltage conversion circuit is used for generating a first gamma voltage which accords with a first gamma curve according to the gray scale signal. The amplifier includes a first input terminal for receiving the first gamma voltage, a second input terminal and an output terminal. The amplifier outputs the first gamma voltage or the second gamma voltage of the second gamma curve as the gamma driving voltage according to the first input end and the second input end. The gamma voltage adjusting circuit is coupled between the second input end and the output end of the amplifier and is used for controlling the amplifier to output a first gamma voltage or a second gamma voltage as a gamma driving voltage according to the gray scale signal and the gamma curve selection signal.

Description

Gamma voltage conversion device

【Technical field】

The present invention relates to a gamma voltage conversion device, more specifically, a gamma voltage conversion device capable of converting a grayscale signal into a gamma voltage conforming to a gamma curve or another gamma curve .

【Background technique】

Please refer to Figure 1. FIG. 1 is a schematic diagram illustrating a gamma curve. In Figure 1, the gamma curve gamma A is suitable for a 3-volt liquid crystal panel, the horizontal axis represents the grayscale signal D _IN , the vertical axis represents the gamma driving voltage V _OUT , and the grayscale signal D _IN is 6 bits (6bits) digital signal. Therefore, the user can know the magnitude of the gamma driving voltage V _OUT corresponding to the gray scale signal D _IN according to the gamma curve gamma A disclosed in FIG. 1 , so as to drive a 3-volt liquid crystal panel.

Please refer to Figure 2. FIG. 2 is a schematic diagram of a gamma voltage conversion device 200 in the prior art. As shown in FIG. 2 , the gamma voltage conversion device 200 includes a gamma voltage conversion circuit 210 and an operational amplifier OP.

The gamma voltage conversion circuit 210 is used to output a gamma voltage V _GA conforming to the gamma curve gammaA to the operational amplifier OP according to a grayscale signal D _IN , and the operational amplifier OP then outputs a gamma driving voltage V _OUT to drive 3 Volt LCD panel. The grayscale signal D _IN is a 6-bit digital signal.

The gamma voltage conversion circuit 210 includes a decoder 211 , sixty-four switches SW _{A1 -SWA64} , and a resistor series 212 .

The resistor series 212 is coupled between a reference voltage source V _REF and a bias voltage source V _SS (ground terminal). The resistor series 212 includes sixty-five resistors R _{A0 -RA64} connected in series, each of which has a predetermined resistance value and is used to provide a resistor divider (resistor divider V ₁ -V shown in FIG. 2 ). ₆₄ ) (a total of sixty-four resistive voltage divisions are provided), and the corresponding relationship between the resistive voltage division provided by each resistor and the grayscale signal D _IN conforms to the gamma curve gamma A. For example, when the grayscale signal D _IN is [000000], according to the gamma curve gamma A corresponding to the resistance voltage division is V ₁ , when the grayscale signal D _IN is [000001], according to the gamma curve gamma The resistor divider voltage corresponding to A is V ₂ . When the gray scale signal D _IN is [111111], the resistor divider voltage corresponding to gammaA according to the gamma curve is V ₆₄ .

The decoder 211 is used for receiving the grayscale signal D _IN and decoding corresponding decoding signals D ₀₁ -D ₀₆₄ accordingly. As the aforementioned gray-scale signal D _IN has six bits, when the gray-scale signal D _IN is [000000], only the decoding signal D ₀₁ is logic “1” and the other decoding signals are logic “0”; when the gray-scale signal When D _IN is [000001], only the decoding signal D ₀₂ is logic "1", and the rest of the decoding signals are logic "0". When the grayscale signal D _IN is [111111], only the decoding signal D ₀₆₄ It is logic "1", and other decoding signals are logic "0".

The switches S _WA1 -SW _A64 are used to transmit the voltage division of the resistors provided by the resistor series 212 to the operational amplifier OP according to the decoding signals D ₀₁ -D ₀₆₄ of the decoder 211 respectively. Each of the switches S _{WA1 -SWA64} includes a first terminal 1 , a second terminal 2 , and a control terminal C. As shown in FIG. The first end 1 of each switch among the switches SW _A1 -SW _A64 is coupled to the corresponding resistor in the resistor series 212 to receive the corresponding resistor voltage division, and the second terminal 1 of each switch among the switches SW _A1 -SW _A64 Terminal 2 is coupled to a first input terminal (positive input terminal) of the operational amplifier OP, and is used to transmit the received resistor divider (that is, the gamma voltage V _GA output by the gamma voltage conversion circuit 210 ) to the operational amplifier OP. The amplifier OP is used as the input voltage V _IN1 , and the control terminal C of each of the switches SW _A1 -SW _A64 is coupled to the corresponding output terminal of the decoder 211 to receive the corresponding decoding signal, so as to control the switch SW _A1 accordingly. The first terminal 1 and the second terminal 2 of ~SW _A64 are coupled. More specifically, all the switches SW _A1 -SW _A64 are short-circuited to the first input terminal of the operational amplifier. For example, when the grayscale signal D _IN is [000000], only the decoding signal D ₀₁ is logic “1” and the other decoding signals are logic “0”. Therefore, only the switch SW _A1 is turned on to divide the resistance The voltage V ₁ is transmitted to the first input terminal of the operational amplifier OP, which means that the gamma voltage V _GA output by the gamma voltage conversion circuit 210 at this time is V ₁ and used as the input voltage V _IN1 of the operational amplifier OP; When the signal D _IN is [000001], only the decoding signal D ₀₂ is logic "1" and the rest of the decoding signals are logic "0", so only the switch SW _A2 is turned on and the resistor divider voltage V ₂ is sent to the operational amplifier The first input terminal of the OP means that the gamma voltage V _GA output by the gamma voltage conversion circuit 210 at this time is V ₂ and used as the input voltage V _IN1 of the operational amplifier OP ... when the grayscale signal D _IN is [111111] , then only the decoding signal D ₀₆₄ is logic "1", and the rest of the decoding signals are logic "0", so only the switch SW _A64 is turned on to transmit the resistor divider voltage V ₆₄ to the first input terminal of the operational amplifier OP , which means that the gamma voltage V _GA output by the gamma voltage conversion circuit 210 at this time is V ₆₄ and serves as the input voltage V _IN1 of the operational amplifier OP.

The operational amplifier OP includes a first input terminal (positive input terminal), a second input terminal (negative input terminal), and an output terminal. The output terminal of the operational amplifier OP is coupled to the second input terminal (negative input terminal) of the operational amplifier OP, so that the operational amplifier OP forms a voltage follower (voltage follower), which is used for the second input terminal (negative input terminal) of the operational amplifier OP. The voltage V _IN1 received by an input terminal (positive input terminal) is buffered and then the output terminal of the operational amplifier OP outputs the gamma driving voltage V _OUT to enhance the driving capability. The input voltage V _IN1 of the operational amplifier is equal to the gamma driving voltage V _OUT , that is to say, the final output gamma driving voltage V _OUT is equal to the gamma voltage V _GA output by the gamma voltage conversion circuit 210 .

Therefore, according to the above, the gamma voltage conversion device 200 can convert the received grayscale signal into the gamma driving voltage V _OUT conforming to the gamma curve gamma A to drive the 3V liquid crystal panel.

However, due to the gamma voltage conversion device 200 of the prior art, the resistance value of each resistor in the resistor series has been set so that the corresponding resistor voltage division can conform to the gamma curve gamma A. However, the gamma curve required by other types of liquid crystal panels is not the gamma curve gamma A. For example, a 5-volt liquid crystal panel is suitable for the gamma curve gamma B. Therefore, the gamma voltage converting device 200 in the prior art is only applicable to a 3-volt liquid crystal panel but not to a 5-volt liquid crystal panel, causing inconvenience to users in the application of various liquid crystal panels.

【Content of invention】

The invention provides a gamma voltage converting device, which is used for generating a corresponding gamma driving voltage according to a gray scale signal. The grayscale signal and the gamma driving voltage conform to a first gamma curve or a second gamma curve. The Gamma voltage conversion device includes a Gamma voltage conversion circuit, an operational amplifier and a Gamma voltage adjustment circuit. The gamma voltage converting circuit is used for generating a first gamma voltage according to the gray scale signal. The grayscale signal and the first gamma voltage conform to the first gamma curve. The operational amplifier includes a first input terminal coupled to the gamma voltage conversion circuit for receiving the first gamma voltage, a second input terminal and an output terminal. The operational amplifier outputs the first gamma voltage or a second gamma voltage as the gamma driving voltage according to the first input terminal of the operational amplifier and the second input terminal of the operational amplifier. The grayscale signal and the second gamma voltage conform to the second gamma curve. The gamma voltage adjustment circuit is coupled between the second input terminal of the operational amplifier and the output terminal of the operational amplifier, and is used to control the operational amplifier to output the output according to the grayscale signal and a gamma curve selection signal. The first gamma voltage or the second gamma voltage is used as the gamma driving voltage.

【Description of drawings】

FIG. 1 is a schematic diagram illustrating a gamma curve.

FIG. 2 is a schematic diagram of a prior art gamma voltage conversion device.

FIG. 3 is a schematic diagram illustrating a di-gamma curve.

FIG. 4 is a schematic diagram of the gamma voltage conversion device of the present invention.

FIG. 5 is a schematic diagram illustrating an embodiment of a decoder of the present invention.

FIG. 6 is a schematic diagram illustrating an embodiment of another decoder of the present invention.

7, 8, and 9 are schematic diagrams illustrating the operation principle of the gamma voltage conversion device of the present invention when a grayscale signal is input.

[Description of main component symbols]

gamma A, gamma B Gamma curve

V _OUT gamma drive voltage

V _GA , V _GB gamma voltage

D _IN gray scale signal

B ₁ ~ B ₆ bits

OP Operational Amplifier

D ₀₁ ~ D ₀₆₄ , D _X1 ~ D _X37 decoding signal

G _S gamma curve selection signal

V _IN1 , V _IN2 input voltage

R _A0 ～R _A64 , R _B1 ～R _B37 , R _X , R _V resistance

V ₁ ~ V ₆₄ resistor divider

V _REF reference voltage source

V _SS bias source

S _WA1 ～SW _A64 , SW _B1 ～SW _B37 , S _WG switch

AND ₁ ~AND ₆₄ AND gates

INV ₁ ~ INV ₆ Inverter

200, 400 Gamma voltage conversion device

500 Voltage conversion circuit

210, 410 Gamma voltage conversion circuit

212, 412, 4212 Resistor series

421 variable resistance circuit

211, 411, 4211 Decoder

420 Gamma voltage adjustment circuit

【Detailed ways】

Please refer to Figure 3. FIG. 3 is a schematic diagram illustrating a di-gamma curve. In FIG. 3 , the gamma curve gammaA is suitable for a 3-volt liquid crystal panel, the gamma curve gamma B is suitable for a 5-volt liquid crystal panel, the horizontal axis represents the grayscale signal D _IN , the vertical axis represents the gamma driving voltage V _OUT , and The grayscale signal D _IN is a 6-bit digital signal. Therefore, the user can know the magnitude of the gamma driving voltage V _OUT corresponding to the gray scale signal D _IN according to the gamma curve gamma A disclosed in FIG. 3 , so as to drive a 3-volt liquid crystal panel; According to the gamma curve gamma B disclosed in FIG. 3 , the magnitude of the gamma driving voltage V _OUT corresponding to the gray scale signal D _IN can be known, so as to drive the 5V liquid crystal panel.

Please refer to Figure 4. FIG. 4 is a schematic diagram of a gamma voltage conversion device 400 of the present invention. As shown in FIG. 4 , the gamma voltage conversion device 400 includes a gamma voltage conversion circuit 410 , a gamma voltage adjustment circuit 420 , and an operational amplifier OP. The gamma voltage conversion device 400 can be used to select the gamma curve gamma A or gamma B to be used according to user settings, so that the output gamma driving voltage is used to drive a 3-volt liquid crystal panel or a 5-volt liquid crystal panel panel.

The gamma voltage conversion circuit 410 is used for outputting a gamma voltage V _GA conforming to a gamma curve gammaA to the operational amplifier OP as an input voltage V _IN1 of the operational amplifier OP according to a grayscale signal D _IN . The gamma voltage conversion circuit 410 includes a decoder 411 , sixty-four switches SW _A1 -SW _A64 , and a resistor series 412 . The gamma voltage conversion circuit 410 is similar in structure and operation principle to the gamma voltage conversion circuit 210 , which will not be repeated here.

The operational amplifier OP includes a first input terminal (positive input terminal), a second input terminal (negative input terminal), and an output terminal. The first input terminal (positive input terminal) of the operational amplifier OP is used to receive the input voltage V _IN1 , the second input terminal (negative input terminal) of the operational amplifier OP is used to receive the input voltage V _IN2 , and the operational amplifier OP Output gamma drive voltage V _OUT . In FIG. 4 , the input voltage V _IN1 is equal to the gamma voltage V _GA output by the gamma voltage conversion circuit 410 . Due to the characteristics of the operational amplifier OP, the input voltage V _IN1 on its first input terminal (positive input terminal) is substantially equal to the input voltage V _IN2 on its second input terminal (negative input terminal).

The gamma voltage adjustment circuit 420 includes a gamma curve selection switch SW _G , a resistor R _X , and a variable resistance circuit 421 .

The variable resistance circuit 421 includes a decoder 4211 , a resistor series 4212 , and thirty-seven switches SW _B1 -SW _B37 .

The decoder 4211 is used to decode the decoded signals D _X1 -D _X37 according to the decoded signals D ₀₁ -D ₀₆₄ decoded by the decoder 411 .

The switches SW _B1 -SW _B37 are used to control the equivalent resistance of the whole resistor series 4212 to the operational amplifier OP according to the decoding signals D _X1 -D _X37 of the decoder 4211 respectively. More specifically, the resistor series 4212 can be regarded as a variable resistor R _V coupled between the second input terminal of the operational amplifier OP and the bias voltage source V _SS (ground terminal), and the switches SW _B1 ˜SW _B37 can be used to control the resistance value of the variable resistor RV. Each of the switches SW _B1 -SW _B37 includes a first terminal 1 , a second terminal 2 , and a control terminal C. The first terminal 1 of each of the switches SW _B1 -SW _B37 is coupled to the corresponding resistor in the resistor series 4212, and the second terminal 2 of each of the switches SW _B1 -SW _B37 is coupled to the bias voltage source V _SS (ground terminal), the control terminal C of each switch in the switches SW _B1 -SW _B37 is coupled to the corresponding output terminal of the decoder 4211 to receive the corresponding decoding signal, so as to control the first switch of the switches SW _B1 -SW _B37 One end 1 is coupled to the second end 2 .

The resistor series 4212 is coupled between the second input terminal (negative input terminal) of the operational amplifier OP and the switches SW _B1 -SW _B37 . The resistor series 4212 includes thirty-seven resistors R _{B1 -RB37} connected in series, each of which has a predetermined resistance. As mentioned above, the resistor series 4212 can be regarded as a variable resistor R _V , which is coupled between the second input terminal of the operational amplifier OP and the bias voltage source V _SS (ground terminal), and the switches SW _{B1˜SW B37} can be used to control the resistance value of the variable resistor R _V. For example, when the decoding signal D _X1 is logic “1” to turn on the switch SW _B1 , the resistance of the variable resistor R _V is equal to the resistance of the resistor R _B1 ; when the decoding signal D _X2 is logic “1” ” to turn on the switch SW _B2 , the resistance value of the variable resistor R _V is equal to the resistance value of the resistor (R _B1 +R _B2 ); when the decoding signal D _X3 is logic “1” to turn on the switch SW _B3 , it can The resistance value of the variable resistor R _V is equal to the resistance value of the resistor (R _B1 +R _B2 +R _B3 ); ... and so on; when the decoding signal D _X37 is logic "1" to turn on the switch SWB ₃₇ , the variable The resistance value of the resistor R _V is equal to the resistance value of the resistors (R _B1 +R _B2 +R _B3 +...+RB ₃₇ ).

The resistor R _X is coupled between the output terminal of the operational amplifier OP and the second input terminal (negative input terminal); the gamma curve selection switch SW _G is also coupled between the output terminal of the operational amplifier OP and the second input terminal terminal (negative input terminal). The gamma curve selection switch SW _G controls whether to short-circuit the output terminal of the operational amplifier OP with the second input terminal (negative input terminal) according to the gamma curve selection signal G _S . If the gamma curve selection switch SW _G short-circuits the output terminal of the operational amplifier OP and the second input terminal (negative input terminal), the gamma voltage conversion device 400 of the present invention will use a gamma voltage that conforms to the gamma curve gamma A The gamma drive voltage V _OUT is output to drive the liquid crystal panel of 3 volts; if the gamma curve selection switch SW _G does not short-circuit the output terminal of the operational amplifier OP with the second input terminal (negative input terminal), then the gamma of the present invention The voltage conversion device 400 will drive a 5V liquid crystal panel by outputting the gamma driving voltage V _OUT conforming to the gamma curve gamma B, and the operation principle is described as follows.

Please continue to refer to Figure 4. In FIG. 4 , the gamma voltage adjustment circuit 420 and the operational amplifier OP can be equivalent to a voltage conversion circuit 500 . When the gamma curve selection switch SW _G selects to short-circuit the output terminal of the operational amplifier OP with the second input terminal, the gamma voltage conversion device 400 of the present invention can be equivalent to the gamma voltage equivalent of the prior art The device 200 converts the grayscale signal D _IN into a gamma driving voltage V _OUT in a manner conforming to the gamma curve gamma A to drive a 3-volt liquid crystal panel. And when the gamma curve selection switch SW _G selects not to short-circuit the output terminal of the operational amplifier OP with the second input terminal, the gamma driving voltage V _{OUT output} by the gamma voltage conversion device 400 of the present invention can be Generated according to the following formula:

V _OUT ＝(R _X /R _V )×VIN ₂ …(1)

V _IN2 ＝V _IN1 …(2)

V _IN1 = V _GA ... (3)

Where V _IN2 is the voltage on the second input terminal (negative input terminal) of the operational amplifier OP. At this time, the gamma driving voltage V _OUT can be adjusted according to the resistance value of the variable resistor R _V to conform to the gamma curve gammaB. The resistance value of the variable resistor R _V is controlled according to the decoding signals D ₀₁ ~ D ₀₆₄ decoded by the gray scale signal D _IN and then decoded again by the decoder 4211 D _X1 ~ D _X37 , so It can ensure that the gamma driving voltage V _OUT adjusted by the variable resistor R _V can conform to the gamma curve gamma B to drive a 5V liquid crystal panel.

In addition, it is worth noting that although the gray-scale signal D _IN is six bits, the resistor series 412 needs sixty-four (2 ⁶ ) resistors R _A1 ˜R _A64 to perform and Gamma for each gray-scale signal. The correspondence of the gamma curve gamma A to generate the corresponding gamma voltage V _GA ; and in the resistor series 4212 in the present invention, theoretically, the same number of resistors are required to be connected in series, but in the six-bit grayscale signal D _IN , the resistance values of the corresponding variable resistors R _V for gray scale signals of some levels are the same, so the resistance series 4212 and the decoder 4211 of the present invention do not need the same number of resistors, switches and decoders code signal, each gray-scale signal in the six-bit gray-scale signal D _IN can be effectively converted into a gamma driving voltage V _OUT conforming to the gamma curve gamma B to drive a 5-volt liquid crystal panel.

Please refer to Figure 5. FIG. 5 is a schematic diagram illustrating an embodiment of the decoder 411 of the present invention. As shown in FIG. 5 , the decoder 411 can be implemented by sixty-four AND gates (AND gates) AND ₁ -AND ₆₄ and six inverters INV ₁ -INV ₆ . In this way, the decoder 411 can correctly decode the desired decoding signals D ₀₁ to D ₀₆₄ according to the six-bit (B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B ₆ ) grayscale signal D _IN .

Please refer to Figure 6. FIG. 6 is a schematic diagram illustrating an embodiment of the decoder 4211 of the present invention. As shown in FIG. 5 , the decoder 4211 can be implemented by a plurality of OR gates. In this way, the decoder 4211 can correctly decode the desired decoding signals D _X1 -D _X37 according to the decoding signals D ₀₁ -D ₀₆₄ .

Please refer to Figures 7, 8, and 9. 7 , 8 , and 9 are schematic diagrams illustrating the operation principle of the gamma voltage conversion device 400 of the present invention when a grayscale signal is input. In FIGS. 7, 8, and 9, the input grayscale signal D _IN is set to [000100]. In FIG. 7 , it can be seen that when the grayscale signal D _IN is [000100], only the decoded signal D ₀₅ is logic “1” of the decoded signal decoded by the decoder 411 . Therefore, in the gamma voltage conversion circuit 410, the switch SW _A5 is turned on, and the resistor voltage _V5 corresponding to the resistor series 412 is output as the gamma voltage V _GA , and is transmitted to the first operational amplifier OP. An input terminal is used as the input voltage V _IN1 . In FIG. 8, it can be seen that when only the decoding signal _D05 is logic “1”, the decoding signal decoded by the decoder 4211 is only the decoding signal _DX5 being logic “1”. 1". Therefore, in the gamma voltage adjustment circuit 420, the switch SW _B5 is turned on, and the resistance corresponding to the resistor series 4212 is (R _B1 +R _B2 +R _B3 +R _B4 +R _B5 ) as a variable The resistance value of resistor R _V. Therefore, in FIG. 9, if the gamma curve selection switch SW _G selects to short-circuit the output terminal of the operational amplifier OP with the second input terminal, the gamma voltage conversion device 400 of the present invention will output a value of _V5 gamma driving voltage V _OUT , and the gamma driving voltage V _OUT of V ₅ and the gray scale signal D _IN with the value [000100] conform to the gamma curve gamma A; on the contrary, if the gamma curve selection switch SW _G selects no When the output terminal of the operational amplifier OP is short-circuited with the second input terminal, the gamma driving voltage V _{OUT output} by the gamma voltage conversion device 400 of the present invention can be calculated according to formulas (1), (2) and (3 ) to calculate:

V _IN1 =V _GA =V ₅ ;

V _IN2 =V _IN1 ;

V _OUT =(R _X /R _V )×V _IN2 =[R _X /(R _B1 +R _B2 +R _B3 +R _B4 +R _B5 )]×V ₅ ;

The gamma driving voltage V _OUT calculated according to the above formula and the gray scale signal D _IN with a value of [001000] conform to the gamma curve gamma B.

To sum up, the gamma voltage conversion device provided by the present invention can be used to select different gamma curves according to user settings to drive different liquid crystal panels, without having to design all types of liquid crystal panels. The corresponding gamma voltage conversion device can reduce production cost and provide greater convenience for users.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (7)

1. a gamma voltage conversion apparatus is used for according to a GTG signal, produces a corresponding gamma driving voltage, and this GTG signal and this gamma driving voltage meet one first gamma curve or one second gamma curve, and this gamma voltage conversion apparatus comprises:

One gamma voltage change-over circuit is used for producing one first gamma voltage according to this GTG signal, and this GTG signal and this first gamma voltage meet this first gamma curve;

One operational amplifier comprises:

One first input end is coupled to this gamma voltage change-over circuit, is used for receiving this first gamma voltage;

One second input end; And

One output terminal, this operational amplifier is according to this first input end of this operational amplifier and this second input end of this operational amplifier, export this first gamma voltage or one second gamma voltage with as this gamma driving voltage, this GTG signal and this second gamma voltage meet this second gamma curve; And

One gamma voltage is adjusted circuit, be coupled between this output terminal of this second input end of this operational amplifier and this operational amplifier, be used for selecting signal according to this a GTG signal and a gamma curve, control this operational amplifier and export this first gamma voltage or this second gamma voltage with as this gamma driving voltage

Wherein, this gamma voltage adjustment circuit comprises:

One first resistance has one first resistance, is coupled between this output terminal of this second input end of this operational amplifier and this operational amplifier;

One second switch is coupled between this output terminal of this second input end of this operational amplifier and this operational amplifier, is used for selecting signal according to this gamma curve, this second input end of this operational amplifier is coupled to this output terminal of this operational amplifier; And

One variable resistance circuit is coupled between this second input end and a ground end of this operational amplifier, is used for producing one second resistance according to this GTG signal;

Wherein the relation of this second gamma voltage and this first gamma voltage can be expressed from the next:

V _G2=(1+R ₁/ R ₂) * V _G1, V wherein _G2Represent this second gamma voltage, V _G1Represent this first gamma voltage, R ₁Represent this first resistance, R ₂Represent this second resistance.

2. gamma voltage conversion apparatus according to claim 1 is characterized in that, this gamma voltage change-over circuit comprises:

One first code translator is used for receiving this GTG signal to produce a plurality of first decoded signals according to this;

One first resistance serial is coupled between a reference voltage source and the ground end, comprises the resistance of a plurality of series connection, and each resistance of this first resistance serial has a predetermined resistance, and the electric resistance partial pressure of a correspondence is provided according to this reference voltage source;

A plurality of first switches, each first switch comprises:

One first end is coupled to a resistance corresponding in this first resistance serial, is used for receiving this electric resistance partial pressure of the corresponding correspondence that this resistance provided;

One second end is coupled to this first input end of this operational amplifier; And

One control end, be coupled to this first code translator, be used for receiving in these a plurality of first decoded signals one first corresponding decoded signal, this first switch couples this first switch according to this first decoded signal that is received this first end to this second end of this first switch to transmit this corresponding electric resistance partial pressure this first input end to this operational amplifier;

Wherein these a plurality of first switches this electric resistance partial pressure that is sent to this operational amplifier is promptly as this first gamma voltage.

3. gamma voltage conversion apparatus according to claim 2 is characterized in that, this first code translator can be implemented with door by a plurality of.

4. gamma voltage conversion apparatus according to claim 3 is characterized in that, a plurality of input ends with door in this first code translator are used for receiving this GTG signal; An output terminal with door in a plurality of and door in this first code translator is used for exporting one first corresponding decoded signal.

5. gamma voltage conversion apparatus according to claim 1 is characterized in that, this variable resistance circuit comprises:

One second resistance serial is coupled to this second input end of this operational amplifier, comprises the resistance of a plurality of series connection, and each resistance of this second resistance serial has a predetermined resistance;

One second code translator is coupled to this first code translator, is used for receiving these a plurality of first decoded signals to produce a plurality of second decoded signals;

A plurality of the 3rd switches, each the 3rd switch comprises:

One first end is coupled to a resistance corresponding in this second resistance serial;

One second end couples this ground end; And

One control end, be coupled to this second code translator, be used for receiving one second corresponding in these a plurality of second decoded signals decoded signal, the 3rd switch couples this first end to this second end of the 3rd switch of the 3rd switch and holds so that this corresponding in this second resistance serial resistance is coupled to this ground according to this second decoded signal that is received;

Wherein in these a plurality of the 3rd switches is coupled to this ground end with this corresponding in this second resistance serial resistance, and this second resistance serial is located at this summation that is coupled to the resistance of the preceding resistance of this resistance of holding on this ground and is this second resistance.

6. gamma voltage conversion apparatus according to claim 5 is characterized in that, this second code translator can be implemented by a plurality of or door.

7. gamma voltage conversion apparatus according to claim 6 is characterized in that, the input end a plurality of or door of this in this second code translator is coupled to the correspondence of this first code translator and the output terminal of door; In this second code translator this output terminal a plurality of or door is used for exporting one second corresponding decoded signal.

Images