Drive apparatus having a temperature detector

• US 4,923,285 A
• Filed: 12/21/1988
• Issued: 05/08/1990
• Est. Priority Date: 04/22/1985
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Inoue, Yutaka, Okada, Shinjiro, Ogino, Yoshitaka
• Primary Examiner(s): James, Andrew J.
• Assistant Examiner(s): Mai, Huy K.
• Application Number:
  US07/287,657
• Time in Patent Office: 503 Days
• Field of Search: 350/350 S, 350/332, 350/331 T, 340/713
• US Class Current: 345/101
• CPC Class Codes: G02F 1/133382 Heating or cooling of liquid crystal cells other than for activation, e.g. circuits or arrangements for temperature control, stabilisation or uniform distribution over the cell
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3685 Details of drivers for data electrodes
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers
• CPC Class Codes: G09G 5/222 Control of the character-code memory

Abstract

A drive apparatus has a ferroelectric LCD for displaying information, a thermo detector for detecting the temperature of the LCD, a driver for driving the LCD by a drive signal having a pulse width corresponding to an output from the thermo detector, and a computer for controlling the driver. When a plurality of display elements are to be driven, they can be divided into blocks and controlled in accordance with an average temperature of each block.

Claims

1. A display apparatus comprising:

a display element comprising a ferroelectric liquid crystal having a first and a second threshold value in accordance with the polarity of an applied voltage;

drive means for applying one polarity or another polarity voltage to said display element;

temperature detection means for detecting the temperature of said display element and outputting temperature data representative thereof; and

control means for (1) referring the temperature data to predetermined driving frequency data in accordance with a stored temperature, (2) extracting a designated one of the driving frequency data in accordance with a certain one of the temperature data, and (3) controlling said drive means so as to be able to apply one polarity or the other polarity voltage, exceeding the threshold value of the ferroelectric liquid crystal, to said display element at a selected driving period, and to apply a voltage between the first and the second threshold values of the ferroelectric liquid crystal to said display element at a non-selected driving period at a driving frequency represented by the designated driving frequency data.

2. An apparatus according to claim 1, wherein said drive means drives said display element in accordance with the average temperature of said display element detected by said temperature detection means.

3. An apparatus according to claim 1, further comprising:

input means for inputting data; and

pattern generating means for generating a pattern corresponding to data input from said input means, said drive means allowing a pattern corresponding to the data to be displayed by said display element.

4. An apparatus according to claim 3, wherein said input means comprises a plurality of key input switches, and said pattern generating means comprises a character generator for transforming character code data input by said key input switches into image data.

5. An apparatus according to claim 4, further comprising a character memory for storing character code data input at said input means, and wherein said drive means reads out the character code data from said character memory and transforms the character code data into image data by said character generator.

6. An apparatus according to claim 1, wherein said drive means comprises scanning signal output means for outputting a scanning signal for scanning said display element, signal output means for outputting a data signal to said display element, and setting means for setting the pulse widths of the scanning and data signals in accordance with an output from said temperature detection means.

7. A display apparatus comprising:

a display element comprising a ferroelectric liquid crystal having a first and a second threshold value in accordance with the polarity of an applied voltage;

drive means for applying one polarity or an other polarity voltage to said display element;

a plurality of temperature detection means each for detecting the temperature of said display element and outputting temperature data representative thereof; and

control means for (1) calculating an average temperature of said display element from the plurality of temperature data, (2) referring the average temperature to predetermined driving frequency data in accordance with a stored temperature, (3) extracting a designated one of the driving frequency data in accordance with a certain one of the temperature data, and (4) controlling said drive means so as to be able to apply one polarity or the other polarity voltage, exceeding the threshold value of the ferroelectric liquid crystal, to said display element at a selected driving period, and to apply a voltage between the first and second threshold values of the ferroelectric liquid crystal to said display element at a non-selected driving period at a driving frequency represented by the designated driving frequency data.

8. An apparatus according to claim 7, wherein said plurality of display elements are divided into a plurality of blocks, and said temperature detection means detects the average temperature for each of said plurality of blocks.

9. An apparatus according to claim 8, wherein said control means discriminates a block to which a display element to be driven among said plurality of display elements belongs, and outputs a drive signal having a pulse width corresponding to the average temperature of the block to which the display element to be driven belongs.

10. An apparatus according to claim 7, further comprising:

input means for inputting data; and

pattern generating means for generating a pattern corresponding to data input from said input means, said control means allowing a pattern corresponding to the data to be displayed on said display elements.

11. An apparatus according to claim 10, wherein said input means comprises a plurality of key input switches, and said pattern generating means comprises a character generator for transforming character code data input by said key input switches into image data.

12. An apparatus according to claim 11, further comprising a character memory for storing character code data input at said input means, and wherein said control means reads out the character code data from said character memory and transforms the character code data into image data by said character generator.

13. An apparatus according to claim 7, wherein said control means comprises scanning signal output means for outputting a scanning signal for scanning said plurality of display elements, signal output means for outputting a data signal to said plurality of display elements, and setting means for setting the pulse widths of the scanning and data signals in accordance with an output from said temperature detection means.

14. A display apparatus comprising:

display means comprising a ferroelectric liquid crystal assuming a first and a second threshold value in accordance with the polarity of an applied voltage, a set of scanning electrodes and a set of data electrodes, thereby defining a plurality of display elements intersecting the set of scanning electrodes and the set of data electrodes;

drive means for applying a scanning signal in serial to the set of scanning electrodes, and applying data signals in parallel to the set of data electrodes;

temperature detection means for detecting the temperature of said display means and outputting temperature data representative thereof;

scanning means for outputting a scanning signal having a predetermined pulse width to scan said display means;

signal output means for outputting a data signal having a predetermined pulse width to said display means; and

control means for (1) referring the temperature data to predetermined pulse width data in accordance with a stored temperature, (2) extracting a designated one of the pulse width data in accordance with a certain one of the temperature data, and (3) controlling said scanning means and said signal output means so as to output the scanning signal having the designated pulse width and the data signal having the designated pulse width.

15. An apparatus according to claim 14, wherein said control means causes said scanning means and said signal outputting means to output the scanning signal and the data signal, respectively, having pulse widths in accordance with the output from said detecting means.

16. An apparatus according to claim 14, wherein said control means causes the scanning and data signals to have different amplitudes in accordance with the output from said detecting means.

17. An apparatus according to claim 14, wherein the scanning and data signals are three-value signals respectively.

18. A display apparatus comprising:

a display panel comprising a ferroelectric liquid crystal assuming a first and a second threshold value in accordance with the polarity of an applied voltage, a set of scanning electrodes and a set of data electrodes, thereby to define a plurality of display elements intersecting the set of scanning electrodes and the set of data electrodes;

drive means for applying a scanning signal in serial to the set of scanning electrodes, and applying data signals in parallel to the set of data electrodes;

temperature detection means for detecting the temperature of said display panel;

control means to control the drive means so as to produce a picture on the display panel, to decrease the maximum of the applied voltage to the display element, and to apply a voltage exceeding the threshold value of the ferroelectric liquid crystal to a display element on a selected scanning electrode, and to apply a voltage between the first and the second threshold values of the ferroelectric liquid crystal to a display element on a nonselected scanning electrode.

19. A display apparatus comprising:

display means comprising a ferroelectric liquid crystal assuming a first and a second threshold value in accordance with the polarity of an applied voltage, a set of scanning electrodes and a set of data electrodes, thereby defining a plurality of display elements intersecting the set of scanning electrodes and the set of data electrodes;

temperature detection means for detecting the temperature of said display means and outputting temperature data representing the same;

scanning means for outputting a scanning signal having a predetermined peak value of the voltage to scan said display means;

signal output means for outputting a data signal having a predetermined peak value of the voltage to said display means; and

control means for (1) referring the temperature data to predetermined peak value data in accordance with a stored temperature, (2) extracting a designated one of the peak value data in accordance with a certain one of the temperature data, and (3) controlling said scanning means and said signal output means so as to output the scanning signal having the designated peak value of the voltage and the data signal having the designated peak value of the voltage.