Driver system of memory type gray-scale display panel

• US 4,193,095 A
• Filed: 02/07/1978
• Issued: 03/11/1980
• Est. Priority Date: 02/25/1977
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Mizushima, Masashi
• Primary Examiner(s): Richardson, Robert L.
• Application Number:
  US05/875,798
• Time in Patent Office: 763 Days
• Field of Search: 340/324 M, 358/240, 358/241
• US Class Current: 348/800
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2803 Display of gradations G09G3/288 takes precedence
• CPC Class Codes: H04N 3/12 by switched stationary formation of lamps, photocells or light relays

Abstract

A driver system of a display panel including a matrix of luminescent elements with a bi-stable operation condition comprises a circuit arrangement for combining a plurality of divided lighting periods to provide a gray-scale display and a circuit arrangement for increasing or decreasing the respective widths of the divided lighting periods in correlation with each other, whereby a control of luminance with gray-scale is provided.

Claims

1. In a driver system of a memory type display panel including a matrix of luminescent elements each having a bi-stable operation condition of lighting and non-lighting states with the lighting states beginning when a firing pulse is applied to the luminescent elements and continuing until an erase pulse is applied to the luminescent elements, in which a gray-scale luminance is provided to the display panel by the combination of a plurality of divided lighting periods, the lighting periods being provided in the lighting states of the luminescent elements, the improvement comprising circuit means for increasing or decreasing the respective widths of the divided lighting periods in correlation with each other to control the gray-scale luminance of the display panel.

2. A driver system according to claim 1, wherein said circuit means includes a first circuit for receiving a plurality of input signals for control of the respective widths of said divided lighting periods to produce a plurality of pulse width modulated signals having their pulse widths corresponding to the respective widths of said divided lighting periods, a second circuit for converting said pulse width modulated signals to triangular waveforms respectively, a third circuit for supplying a bias voltage to said triangular waveforms, fourth circuit for shaping the biased triangular waveforms into rectangular waveforms respectively, a fifth circuit for receiving said rectangular waveforms from said fourth circuit to produce a rectangular waveform signal, a sixth circuit for synchronizing said rectangular waveform signal with predetermined clock pulses, a seventh circuit for receiving an output from said sixth circuit to produce outputs having their predetermined duration times required for erase, and an eighth circuit for providing the outputs of said seventh circuit as erase signals at predetermined time instants.

3. A driver system according to claim 2, wherein said seventh circuit comprises a differentiation circuit which includes a capacitor and a resister.

4. A driver system according to claim 2, wherein said seventh circuit comprises a mono-stable multivibrator.

5. A driver system according to claim 1, further comprising:

means for providing erase timing pulses; and

means for producing erase pulses based on said erase timing pulses including means to advance or delay the erase pulses relative to the erase timing pulses to control the width of the divided lighting periods.

6. A driver system according to claim 5, wherein said means to advance or delay the erase pulses includes pulse width modulation means which receives the erase timing pulses and produces pulse width modulated signals having their pulse widths corresponding to the respective widths of the divided lighting period.

7. A driver system according to claim 6, further comprising means coupled to the output of said pulse width modulation means for producing a triangular waveform whose rise time is determined by the pulse width of the output pulses of said pulse width modulation means.

8. A driver system according to claim 7, further comprising threshold means coupled to the output of the triangular waveform producing means for producing an output pulse having a pulse width determined by the period of time which the triangular waveform exceeds a predetermined threshold.

9. A driver system according to claim 8, further comprising pulse width selection means coupled to the output of the threshold means for producing a pulse having a pulse width narrower than the pulse width of the output pulse of the threshold means to indicate the leading edge of the output pulse of the threshold means, and means for producing the erase pulse upon generation of the output pulse of the pulse width selection means.

10. A driver system according to claim 7, wherein the triangular waveform producing means is an integrator.

11. A driver system according to claim 8, wherein the threshold means is a Schmitt trigger.

12. A driver system according to claim 9, wherein the pulse width selection means is a differentiation circuit.

13. A driver system according to claim 9, wherein the pulse width selection means is a monostable multivibrator.