Driving method for a liquid crystal display apparatus

• US 5,864,328 A
• Filed: 08/30/1996
• Issued: 01/26/1999
• Est. Priority Date: 09/01/1995
• 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: Kajimoto, Koichi
• Primary Examiner(s): LAO, LUNYI
• Application Number:
  US08/705,824
• Time in Patent Office: 879 Days
• Field of Search: 345/87, 345/94, 345/95, 345/96, 345/98, 345/204, 345/208, 345/209, 345/210, 345/211, 345/212, 345/89, 345/90, 345/92
• US Class Current: 345/95
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat panels
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 3/367 with a nonlinear element in series with the liquid crystal cell, e.g. a diode, or M.I.M. element
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A driving method for LCD apparatuses allows the dividing-driving method, which is effectual against the residual image phenomenon, or the burning phenomenon, to be applicable to drivers which are provided in the conventional LCD apparatuses of the passive type and are driven by the voltage averaging method. By the method, among voltages inputted to the scanning electrode driving circuit, levels of voltages which are inputted also to the data electrode driving circuit are switched to different levels at fixed timings, while levels of voltages inputted only to the data electrode driving circuit are switched to different levels at fixed timings. With this, waveforms of the signals outputted by the respective driving circuits are adjusted, thereby resulting in that a waveform of a difference signal of the scanning signal and the data signal is adjusted.

Claims

1. The method for driving a liquid crystal display apparatus, the liquid crystal display apparatus comprising a scanning electrode group having scanning electrodes, a data electrode group having data electrodes, and pairs of liquid crystal elements and two-terminal non-linear elements connected with each other in a series, each intersection of the scanning electrodes and the data electrodes having one of the pairs, the method comprising the steps of:

(a) switching levels of driving voltages in first and second driving voltage groups at respective fixed timings for each of at least two division periods, said at least two division periods constituting one selection period in which one of the scanning electrodes in the scanning electrode group is selected, a combination of the driving voltages in the second driving voltage group being different from that of the first driving voltage group;

(b) generating a scanning signal and a data signal, the scanning signal being generated by a scanning electrode driving circuit in accordance with the first driving voltage group and applied to the scanning electrode in a line-sequential manner so that one of the scanning electrodes is selected during each selection period, the data signal being generated by a data electrode driving circuit in accordance with the second driving voltage group and applied to each data electrode of the data electrode group; and

(c) applying the scanning signal to the selected scanning electrode while applying the data signal to the data electrode group, so as to drive the liguid crystal elements, connected between the selected scanning electrode and the data electrodes, through the two-terminal non-linear elements of the respective pairs,

wherein the step (a) comprises the steps of;

switching levels of driving voltages in the first driving voltage group so that only level of the driving voltages which are commonly included in the first and second driving voltage groups are switched; and

switching levels of the driving voltages in the second driving voltage group except those which are commonly included in the first and second driving groups.

2. The method as set forth in claim 1, wherein, in the step (a), each selection period is divided into two division periods,

a first two driving voltages are included commonly in the first and second driving voltage groups, and one level of the first two driving voltages is switched in the latter half division period of the selection period, and

a second two driving voltages are exclusively included in the second driving voltage group and one of the second two driving voltages is switched in the former half division period of the selection period.

3. A liquid crystal display apparatus comprising:

a scanning electrode group having scanning electrodes, a data electrode group having data electrodes, and pairs of liquid crystal elements and two terminal non-linear elements connected with each other in series, each intersection of the scanning electrodes and the data electrodes having one of the pairs;

a scanning electrode driving circuit for generating a scanning signal in accordance with a first driving voltage group composed of a plurality of driving voltages, the scanning signal being applied to the scanning electrode so that one of the scanning electrodes is selected one by one for each selection period;

a data electrode driving circuit for generating a data signal to be applied to each data electrode, the data signal being generated in accordance with a second driving voltage group composed of a plurality of driving voltages, a combination of the driving voltages of the second driving voltage group being different from that of the first driving voltage group;

a control circuit for switching levels of the driving voltages of the first and second driving voltage groups, at respective fixed timings for each of at least two division periods, the at least two division periods constituting one selection period;

a switching control section for generating a switching control signal; and

a driving voltage generating section for generating the driving voltages of the first and second driving voltage groups and for switching the levels of the driving voltages in response to the switching control signal,

wherein said driving voltage generating section includes a voltage switching section for switching levels of driving voltages in the first driving voltage group so that only the levels of the driving voltages included in both the first and second driving voltage groups are switched, and for switching levels of the driving voltages in the second driving voltage group except those included commonly in the first and second driving groups.

4. The liquid crystal display apparatus as set forth in claim 3, wherein so as to switch two driving voltages, said voltage switching section includes:

a P-channel field effect transistor for outputting one of the driving voltages when shifting to an ON state in response to the switching control signal of a high level; and

an N-channel field effect transistor for outputting another driving voltage when shifting to an ON state in response to the switching control signal of a low level.

5. A device for driving a liquid crystal display apparatus, the liquid crystal display apparatus comprising a scanning electrode group having scanning electrodes, a data electrode group having data electrodes, and pairs of liquid crystal elements and two-terminal non-linear elements connected with each other in series, each intersection of the scanning electrodes and the data electrodes having one of the pairs, the device comprising:

means for switching levels of driving voltages in first and second driving voltage groups at respective fixed timings for each of at least two division periods, said at least two division periods constituting one selection period in which one of the scanning electrodes in the scanning electrode group is selected, a combination of the driving voltages in the second driving voltage group being different from that of the first driving voltage group;

means for generating a scanning signal and a data signal, the scanning signal being generated by a scanning electrode driving circuit in accordance with the first driving voltage group and applied to the scanning electrode in a line-sequential manner so that one of the scanning electrodes is selected during each selection period, the data signal being generated by a data electrode driving circuit in accordance with the second driving voltage group and applied to each data electrode of the data electrode group; and

means for applying the scanning signal to the selected scanning electrode while applying the data signal to the data electrode group, so as to drive the liquid crystal elements, connected between the selected scanning electrode and the data electrodes, through the two-terminal non-linear elements of the respective pairs,

wherein the means for switching comprises;

first means for switching levels of driving voltages in the first driving voltage group so that only the levels of the driving voltages which are commonly included in the first and second driving voltage groups are switched; and

second means for switching levels of the driving voltages in the second driving voltage group except those which are commonly included in the first and second driving groups.

6. The device as set forth in claim 5, wherein each selection period is divided into two division periods,

a first two driving voltages are included commonly in the first and second driving voltage groups, and one level of the first two driving voltages is switched in the latter half division period of the selection period, and

a second two driving voltages are exclusively included in the second driving voltage group and one of the second two driving voltages is switched in the former half division period of the selection period.