Liquid crystal driving circuit, semiconductor integrated circuit device, reference voltage buffering circuit, and method for controlling the same
First Claim
1. A reference voltage buffering circuit provided in a source driver circuit for driving a liquid crystal element of a liquid crystal module, wherein:
- the reference voltage buffering circuit comprises two buffering circuits arranged in parallel to each other between an input-side node for receiving an externally produced reference voltage as an input voltage and an output-side node for sending out an output voltage; and
each buffering circuit of the two buffering circuits includes;
an operator for receiving the input voltage at one terminal and an output voltage of the operator itself at the other terminal, and operating so that the output voltage of the operator is substantially equal to the input voltage;
a capacitor including a first electrode and a second electrode and capable of storing a charge corresponding to a voltage difference between the input voltage and the output voltage of the operator;
a first node connected to the first electrode of the capacitor;
a second node connected to the second electrode of the capacitor;
a third node for receiving an output signal from the operator;
a first switching element provided between the second node and the third node;
a second switching element provided between the first node and the input-side node input side of the operator;
a third switching element provided between the first node and the output-side node; and
a fourth switching element provided between the third node and the output-side node.
2 Assignments
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Accused Products
Abstract
A source driver 4A arranged on a liquid crystal panel includes therein in-chip reference voltage wires 17 extending from one end to the other end of an LSI chip. The source driver 4A includes therein: branch reference voltage wires 17a branching off from in-chip reference voltage wires 17; reference voltage production buffers 31; a control circuit 30 for controlling the reference voltage production buffers 31; a reference voltage production resistor section 32 for subdividing the reference voltage into values of n steps; voltage level selection circuits 34 each for selecting one of the subdivided voltages; and output buffers 35. Since the reference voltages are supplied to each source driver 4 via wiring for connecting the in-chip reference voltage wires 17 in series with one another, the wiring structure for supplying the reference voltages can be simplified.
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Citations
23 Claims
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1. A reference voltage buffering circuit provided in a source driver circuit for driving a liquid crystal element of a liquid crystal module, wherein:
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the reference voltage buffering circuit comprises two buffering circuits arranged in parallel to each other between an input-side node for receiving an externally produced reference voltage as an input voltage and an output-side node for sending out an output voltage; and each buffering circuit of the two buffering circuits includes; an operator for receiving the input voltage at one terminal and an output voltage of the operator itself at the other terminal, and operating so that the output voltage of the operator is substantially equal to the input voltage; a capacitor including a first electrode and a second electrode and capable of storing a charge corresponding to a voltage difference between the input voltage and the output voltage of the operator; a first node connected to the first electrode of the capacitor; a second node connected to the second electrode of the capacitor; a third node for receiving an output signal from the operator; a first switching element provided between the second node and the third node; a second switching element provided between the first node and the input-side node input side of the operator; a third switching element provided between the first node and the output-side node; and a fourth switching element provided between the third node and the output-side node. - View Dependent Claims (2)
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3. A method for controlling a reference voltage buffering circuit, including two buffering circuits arranged in parallel to each other, each buffering circuit of the two buffering circuits including:
- an operator provided between an input-side node and an output-side node for operating so that an output voltage of the operator is substantially equal to an input voltage provided via the input-side node;
a capacitor including a first electrode and a second electrode;
a first node connected to the first electrode of the capacitor;
a second node connected to the second electrode of the capacitor;
a third node for receiving an output signal from the operator;
a first switching element provided between the second node and the third node;
a second switching element provided between the first node and the input-side node of the operator;
a third switching element provided between the first node and the output-side node; and
a fourth switching element provided between the third node and the output-side node, wherein;in each buffering circuit of the two buffering circuits, in an output mode in which a reference voltage is output from the buffering circuit, the third and fourth switching elements are placed in a conductive state while the first and second switching elements are placed in a non-conductive state; and in a charge storing mode in which the capacitor of the buffering circuit stores a charge, the third and fourth switching elements are placed in a non-conductive state while the first and second switching elements are placed in a conductive state. - View Dependent Claims (4, 5, 6)
- an operator provided between an input-side node and an output-side node for operating so that an output voltage of the operator is substantially equal to an input voltage provided via the input-side node;
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7. A liquid crystal driving circuit for driving a liquid crystal element on a liquid crystal panel, the liquid crystal driving circuit comprising:
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a plurality of source driver circuit devices on the liquid crystal panel, each source driver circuit device including; a plurality of input-side pads, each input-side pad receiving a reference voltage; a plurality of output-side pads, each output-side pad outputting the reference voltage; a plurality of in-chip reference voltage wires, each in-chip reference voltage wire directly connecting each input-side pad to each output-side pad to transmit the reference voltage; a plurality of branch reference voltage wires, each branch reference voltage wire branching off from each in-chip reference voltage wire and transmitting the reference voltage in parallel with each in-chip reference voltage wire; a plurality of buffers, each buffer coupled to each branch reference voltage wire and outputting an output voltage in response to the reference voltage transmitted by each branch reference voltage wire and capable of preventing an electric current from flowing via each branch reference voltage wire; and a selection circuit selecting a voltage for driving the liquid crystal element in response to output voltages of the plurality of buffers, a plurality of inter-chip reference voltage wire units, each inter-chip reference voltage wire unit interposed between any two adjacent source driver circuit devices of the plurality of source driver circuit devices and including a plurality of inter-chip reference voltage wires, each inter-chip reference voltage wire connecting each output-side pad of one source driver circuit device of the two adjacent source driver circuit devices to each input-side pad of the other source driver circuit device of the two adjacent source driver circuit devices; a reference voltage production circuit capable of producing a plurality of reference voltages to drive the plurality of source driver circuit devices; and a reference voltage providing wire unit capable of receiving the plurality of reference voltages and providing the plurality of reference voltages to one of the plurality of source driver circuit devices and including a plurality of reference voltage providing wires, each reference voltage providing wire coupled to each in-chip reference voltage wire via each input-side pad of the one of the plurality of source driver circuit devices to provide a reference voltage. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A semiconductor integrated circuit device provided in a liquid crystal module having a liquid crystal element, the semiconductor integrated circuit comprising:
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a plurality of input-side pads, each input-side pad receiving a reference voltage; a plurality of output-side pads, each output-side pad outputting the reference voltage; a plurality of in-chip reference voltage wires, each in-chip reference voltage wire directly connecting each input-side pad to each output-side pad to transmit the reference voltage; a plurality of branch reference voltage wires, each branch reference voltage wire branching off from each in-chip reference voltage wire and transmitting the reference voltage in parallel with each in-chip reference voltage wire; a plurality of buffers, each buffer coupled to each branch reference voltage wire and outputting an output voltage in response to the reference voltage transmitted by each branch reference voltage wire and capable of preventing an electric current from flowing via each branch reference voltage wire; and a selection circuit selecting a voltage for driving the liquid crystal element in response to output voltages of the plurality of buffers. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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Specification