Data signal line driving circuit and image display apparatus

• US 6,437,768 B1
• Filed: 04/15/1998
• Issued: 08/20/2002
• Est. Priority Date: 04/23/1997
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sakai, Tamotsu, Kubota, Yasushi, Shiraki, Ichiro
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Kovalick, Vincent E.
• Application Number:
  US09/060,732
• Time in Patent Office: 1,588 Days
• Field of Search: 345/98, 345/99, 345/100, 345/204
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/0286 Details of a shift registers arranged for use in a driving circuit
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A shift register circuit, composed of a plurality of serially connected latch circuits, for sequentially transmitting a pulse signal in sync with a rising and a falling of a clock signal, and an output circuit for sequentially outputting a video signal to data signal lines in sync with the pulse signal outputted from the shift register circuit are provided. The shift register circuit is divided into a plurality of latch circuit groups, and the stage numbers of the latch circuits in each latch circuit group is set in such a manner to minimize the time difference between the pulse signal outputted from each latch circuit group and the video signal outputted in sync with the pulse signal. Consequently, the power consumption on the clock signal lines can be reduced while the time difference between the clock signal and the video signal can be prevented, thereby making it possible to provide a data signal line driving circuit and an image forming display apparatus which can realize a display of a satisfactory image.

Claims

1. A data signal line driving circuit comprising:

a shift register circuit for sequentially transmitting a pulse signal in sync with a clock signal, said shift register circuit being composed of a plurality of serially connected latch circuits; and

an output circuit for sequentially outputting data signals to data signal lines in sync with output signals outputted from said shift register circuit,

wherein,

said shift register circuit is divided into a plurality of blocks, each block including a number of stages (stage numbers) of latch circuits, where all the blocks have not-identical number of stages of the latch circuits, while some of the blocks may have an identical number of stages of the latch circuits with each other, and

stage numbers of the latch circuits included in said each block is set so as to compensate for a difference between the differing delays of the sequential output signals and the differing delays of the data signals.

10. The data signal line driving circuit of claim 1, wherein said data signal line driving circuit is composed of a polycrystalline silicon thin film transistor.

2. A data signal line driving circuit comprising:

a shift register circuit for sequentially transmitting a pulse signal in sync with a clock signal, said shift register circuit being composed of a plurality of serially connected latch circuits;

an output circuit for sequentially outputting data signals to data signal lines in sync with output signals outputted from said shift register circuit; and

wherein;

said shift register circuit is divided into a plurality of blocks, each block including a number of stages (stage numbers) of latch circuits, where all the blocks have a different number of stages of the latch circuits,

stage numbers of the latch circuits included in said each block is set so as to compensate for a difference between the differing delays of the sequential output signals and the differing delays of the data signals,

said output circuit includes an analog switch for outputting the data signal inputted from an external, and

said shift register circuit is arranged in such a manner that the stage numbers of the latch circuits included in said each block is monotonously increased with a distance from a signal input side.

3. A data signal line driving circuit comprising:

a shift register circuit for sequentially transmitting a pulse signal in sync with a clock signal, said shift register circuit being composed of a plurality of serially connected latch circuits;

an output circuit for sequentially outputting data signals to data signal lines in sync with output signals outputted from said shift register circuit;

wherein said shift register circuit is divided into a plurality of blocks, each block including a number of stages (stage numbers) of latch circuits, where ail the blocks have a different number of stages of the latch circuits;

wherein stage numbers of the latch circuits included in said each block is set so as to compensate for a difference between the differing delays of the sequential output signals and the differing delays of the data signals; and

a control section for supplying the clock signal to the block during a supply period covering at least an interval during which any of the latch circuits included in said block transmits the pulse signal, and for stopping the supply of the clock signal to said block during a non-supply period.

4. The data signal line driving circuit of claim 3, wherein, when the pulse signal is to be transmitted from one block to another block, said control section supplies the clock signal to both blocks, and when the pulse signal is transmitted throughout one block, said control section supplies the clock signal to said one block alone.

5. The data signal line driving circuit of claim 3, wherein said control section supplies the clock signal to a block including a particular latch circuit to which the pulse signal is to be transmitted next and the latch circuits at some stages before said particular latch circuit.

6. The data signal line driving circuit of claim 3, wherein said control section controls an output of the clock signal so that the clock signals respectively inputted into the latch circuits in adjacent blocks overlap for a period at least as long as a pulse width of the pulse signal.

7. The data signal line driving circuit of claim 3, wherein:

a clock signal control section is provided to said control section for each block of said shift register circuit to output the clock signal to each latch circuit in the block during the supply period; and

said each clock signal control circuit controls an output of the clock signal based on an output signal from the latch circuits in a preceding block and a next following block.

8. The data signal line driving circuit of claim 7, wherein said each clock signal control circuit starts an output of the clock signal based on an output signal from the latch circuit at or before a last stage in the preceding block, and said clock signal control circuit stops the output of the clock signal based on an output signal from the latch circuit at or after a second stage in the next following block.

9. The data signal line driving circuit of claim 3, wherein, when the block is in the non-supply period, said control section outputs a constant bias to each latch circuit in the block.

11. An image display apparatus comprising:

a matrix of pixels;

a plurality of data signal lines for supplying a video signal to be written into the pixels;

a plurality of scanning signal lines for supplying a control signal for controlling a writing action of video data into the pixels; and

a data signal line driving circuit for outputting the video signal to the data signal lines in sync with a clock signal,

said data signal line driving circuit comprising;

a shift register circuit for sequentially transmitting a pulse signal in sync with a clock signal, said shift register circuit being composed of a plurality of serially connected latch circuits; and

an output circuit for sequentially outputting said video signal as a data signal to each data signal line in sync with an output signal outputted from said shift register circuits,

 

wherein;

said shift register circuit is divided into a plurality of blocks, each block including a number of stages (stage numbers) of latch circuits, where all the blocks have a different number of stages of the latch circuits,

stage numbers of the latch circuits included in said each block is set so as to compensate for a difference between the differing delays of the sequential output signals and the differing delays of the data signals,

said output circuit includes an analog switch for outputting the data signal inputted from an external, and

said shift register circuit is arranged in such a manner that the stage numbers of the latch circuits included in said each block is monotonously increased with a distance from a signal input side.

12. An image display apparatus comprising:

a matrix of pixels;

a plurality of data signal lines for supplying a video signal to be written into the pixels;

a plurality of scanning signal lines for supplying a control signal for controlling a writing action of video data into the pixels; and

a data signal line driving circuit for outputting the video signal to the data signal lines in sync with a clock signal, said data signal line driving circuit comprising;

a shift register circuit for sequentially transmitting a pulse signal in sync with a clock signal, said shift register circuit being composed of a plurality of serially connected latch circuits;

an output circuit for sequentially outputting said video signal as a data signal to each data signal line in sync with an output signal outputted from said shift register circuits;

 

wherein

said shift register circuit is divided into a plurality of blocks, each block including a number of stages (stage numbers) of latch circuits, where all the blocks have a different number of stages of the latch circuits, and

stage numbers of the latch circuits included in said each block is set so as to compensate for a difference between the differing delays of the sequential output signals and the differing delays of the data signals; and

a control section for supplying the clock signal to the block during a supply period covering at least an interval during which any of the latch circuits included in said block transmits the pulse signal, and for stopping the supply of the clock signal to said block during a non-supply period.

13. The image display apparatus of claim 12, wherein, when the pulse signal is to be transmitted from one block to another block, said control section supplies the clock signal to both blocks, and when the pulse signal is transmitted throughout one block, said control section supplies the clock signal to said one block alone.

14. The image display apparatus of claim 12, wherein said control section supplies the clock signal to a block including a particular latch circuit to which the pulse signal is to be transmitted next and the latch circuits at some stages before said particular latch circuit.

15. The image display apparatus of claim 12, wherein said control section controls an output of the clock signal so that the clock signals respectively inputted into the latch circuits in adjacent blocks overlap for a period at least as long as a pulse width of the pulse signal.

16. The image display apparatus of claim 12, wherein:

a clock signal control section is provided to said control section for each block of said shift register circuit to output the clock signal to each latch circuit in the block during the supply period; and

said each clock signal control circuit controls an output of the clock signal based on an output signal from the latch circuits in a preceding block and a next following block.

17. The image display apparatus of claim 16, wherein said each clock signal control circuit starts an output of the clock signal based on an output signal from the latch circuit at or before a last stage in the preceding block, and said clock signal control circuit stops the output of the clock signal based on an output signal from the latch circuit at or after a second stage in the next following block.

18. The image display apparatus of claim 12, wherein, when the block is in the non-supply period, said control section outputs a constant bias to each latch circuit in the block.

19. The image display apparatus of claim 12, wherein said data signal line driving circuit is composed of a polycrystalline silicon thin film transistor.

20. The image display apparatus of claim 12, wherein at least said data signal line driving circuit is formed on a substrate on which the pixels are also formed.

21. The image display apparatus of claim 20, wherein each of said data signal line driving circuit and pixels is composed of a polycrystalline silicon thin film transistor formed over a glass substrate through a process carried out at 600°

C. or below.