US4907859A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid crystal device and image forming apparatus utilizing liquid crystal device
Assignee: Canon Inc
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Filing: 1988-05-25
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Granted: 1990-03-13
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Expires: 2008-05-25
Abstract
Abstract An image forming apparatus comprising: a light signal generator which comprises an exposure light source and a light-path switching means capable of interrupting the transmission of light rays at arbitrary portions of the cross-sectional area of the path of the light rays emitted from the light source, and an image-bearing member so disposed as to be illuminated with light signals from said light signal generator, wherein the light signal generator comprises: the light-path switching means which in turn comprises scanning lines, data lines and a ferroelectric liquid crystal material having an operational temperature range in which the ferroelectric liquid crystal material behaves as a ferroelectric liquid crystal and driven by selective application of signals to the scanning lines and the data lines so as to assume either one of light-transmitting state and light-interrupting state, and temperature control means for controlling the temperature of the liquid crystal material within the operational temperature range by means of at least one of heating means and cooling means.
Inventors
- 👤 Yoshihiro Takada
- 👤 Nagao Hosono
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:24
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/133382
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
257 words
An electro-optical switching apparatus for forming an image comprising: (a) a light source for emitting light rays; (b) a light-path switching means comprising (i) a first base plate having scanning lines, (ii) a second base plate having data lines, (iii) a ferroelectric liquid crystal disposed between the first and second base plates, (iv) a driving means for driving the ferroelectric liquid crystal by selective application of signals to the scanning lines and the data lines so as to cause the ferroelectric liquid crystal to assume either one of light-transmitting state and light-interrupting state; (c) a temperature sensor for detecting the temperature of the ferroelectric liquid crystal and for generating an output response therefrom; (d) a heating means for raising the temperature of the ferroelectric liquid crystal, said heating means comprising a resistance heater disposed on one of the base plates; and (e) a temperature-controlling means which, during the operation of said light-path switching means, receives said output from the temperature sensor for comparing the detected temperature with a predetermined operational temperature within a temperature range providing a ferroelectric liquid crystal phase, for restoring the temperature of the ferroelectric liquid crystal when the detected temperature is lower than the predetermined operational temperature by causing the heating means to raise the temperature of the ferroelectric liquid crystal until said detected temperature is above said predetermined temperature and thereafter cooling the ferroelectric liquid crystal to a temperature below said predetermined temperature, and for causing the heating means to maintain the temperature of the ferroelectric liquid crystal to be substantially constant.
Claim 2
Dependent Claim
257 words
An electro-optical switching apparatus for forming an image comprising: (a) a light source for emitting light rays; (b) a light-path switching means comprising (i) a first base plate having scanning lines, (ii) a second base plate having data lines, (iii) a ferroelectric liquid crystal disposed between the first and second base plates, (iv) a driving means for driving the ferroelectric liquid crystal by selective application of signals to the scanning lines and the data lines so as to cause the ferroelectric liquid crystal to assume either one of light-transmitting state and light-interrupting state; (c) a temperature sensor for detecting the temperature of the ferroelectric liquid crystal and for generating an output response therefrom; (d) a heating means for raising the temperature of the ferroelectric liquid crystal, said heating means comprising a resistance heater disposed on one of the base plates; and (e) a temperature-controlling means which, during the operation of said light-path switching means, receives said output from the temperature sensor for comparing the detected temperature with a predetermined operational temperature within a temperature range providing a ferroelectric liquid crystal phase, for restoring the temperature of the ferroelectric liquid crystal when the detected temperature is lower than the predetermined operational temperature by causing the heating means to raise the temperature of the ferroelectric liquid crystal until said detected temperature is above said predetermined temperature and thereafter cooling the ferroelectric liquid crystal to a temperature below said predetermined temperature, and for causing the heating means to maintain the temperature of the ferroelectric liquid crystal to be substantially constant.
Claim 3
Dependent Claim
17 words
An image forming apparatus according to claim 1 wherein said temperature control means comprises a cooling fan.
Claim 4
Dependent Claim
27 words
An electro-optical switching apparatus according to claim 1, which further comprises an image bearing member having an electroconductive substrate and a photoconductive layer on the electroconductive substrate.
Claim 5
Dependent Claim
18 words
An electro-optical switching apparatus according to claim 3 wherein said photosensitive layer comprises a film of amorphous silicon.
Claim 6
Dependent Claim
26 words
An electro-optical switching apparatus according to claim 3 wherein said photosensitive layer comprises a laminar structure comprising a charge generation layer and a charge transportation layer.
Claim 7
Dependent Claim
19 words
An electro-optical switching apparatus according to claim 1, wherein said ferroelectric liquid crystal is a chiral smectic liquid crystal.
Claim 8
Dependent Claim
27 words
An electro-optical switching apparatus according to claim 6, wherein said chiral smectic liquid crystal is produced from the smectic A phase in the course of temperature decrease.
Claim 9
Dependent Claim
18 words
An electro-optical switching apparatus according to claim 6, wherein said chiral smectic liquid crystal has a non-spiral structure.
Claim 10
Dependent Claim
26 words
An electro-optical switching apparatus according to claim 6, wherein said chiral smectic liquid crystal is a liquid crystal in a chiral smectic C or H phase.
Claim 11
Dependent Claim
270 words
An electro-optical switching apparatus for forming an image, comprising: (a) a light for emitting light rays; (b) a light-path switching means comprising (i) a first base plate having scanning lines, (ii) a second base plate having data lines, (iii) a ferroelectric liquid crystal disposed between the first and second base plates, and (iv) a driving means for driving the ferroelectric liquid crystal by selective application of signals to the scanning lines and the data lines so as to cause the ferroelectric liquid crystal to assume either one of light-transmitting state and light-interrupting state; (c) a temperature sensor for detecting the temperature of the ferroelectric liquid crystal and for generating an output response therefrom; (d) a heating means for raising the temperature of the ferroelectric liquid crystal, said heating means comprising a resistance heater disposed on the base plate; and (e) a temperature controlling means which, during the operation of said light-path switching means, receives said output from the temperature sensor for comparing said detected temperature with a predetermined operational temperature within a temperature range providing a ferroelectric liquid crystal phase, for restoring the temperature of the ferroelectric liquid crystal when the detected temperature is lower than the predetermined operational temperature by causing the heating means to raise the temperature of the ferroelectric liquid crystal until said detected temperature is above said predetermined temperature and thereafter cooling the ferroelectric liquid crystal to a temperature below said predetermined temperature and then heating the ferroelectric liquid crystal to a temperature above said predetermined temperature, and for causing the heating means to maintain the temperature of the ferroelectric liquid crystal to be substantially constant.
Claim 12
Dependent Claim
270 words
An electro-optical switching apparatus for forming an image, comprising: (a) a light for emitting light rays; (b) a light-path switching means comprising (i) a first base plate having scanning lines, (ii) a second base plate having data lines, (iii) a ferroelectric liquid crystal disposed between the first and second base plates, and (iv) a driving means for driving the ferroelectric liquid crystal by selective application of signals to the scanning lines and the data lines so as to cause the ferroelectric liquid crystal to assume either one of light-transmitting state and light-interrupting state; (c) a temperature sensor for detecting the temperature of the ferroelectric liquid crystal and for generating an output response therefrom; (d) a heating means for raising the temperature of the ferroelectric liquid crystal, said heating means comprising a resistance heater disposed on the base plate; and (e) a temperature controlling means which, during the operation of said light-path switching means, receives said output from the temperature sensor for comparing said detected temperature with a predetermined operational temperature within a temperature range providing a ferroelectric liquid crystal phase, for restoring the temperature of the ferroelectric liquid crystal when the detected temperature is lower than the predetermined operational temperature by causing the heating means to raise the temperature of the ferroelectric liquid crystal until said detected temperature is above said predetermined temperature and thereafter cooling the ferroelectric liquid crystal to a temperature below said predetermined temperature and then heating the ferroelectric liquid crystal to a temperature above said predetermined temperature, and for causing the heating means to maintain the temperature of the ferroelectric liquid crystal to be substantially constant.
Claim 13
Dependent Claim
17 words
An electro-optical switching apparatus according to claim 10 wherein said light-path switching means comprises coordinate designating means.
Claim 14
Dependent Claim
27 words
An electro-optical switching apparatus according to claim 10 which further comprises an image bearing member having an electroconductive substrate and a photoconductive layer on the electroconductive substrate.
Claim 15
Dependent Claim
17 words
An electro-optical switching apparatus according to claim 12 wherein said photosensitive layer comprises an amorphous silicon film.
Claim 16
Dependent Claim
26 words
An electro-optical switching apparatus according to claim 12 wherein said photosensitive layer comprises a laminar structure comprising a charge generation layer and a charge transportation layer.
Claim 17
Dependent Claim
19 words
An electro-optical switching apparatus according to claim 10, wherein said ferroelectric liquid crystal is a chiral smectic liquid crystal.
Claim 18
Dependent Claim
27 words
A electro-optical switching apparatus according to claim 15 wherein said chiral smectic liquid crystal is produced from the smectic A phase in the course of temperature decrease.
Claim 19
Dependent Claim
18 words
A electro-optical switching apparatus according to claim 15 wherein said chiral smectic liquid crystal has a non-spiral structure.
Claim 20
Dependent Claim
26 words
A electro-optical switching apparatus according to claim 15 wherein said chiral smectic liquid crystal is a liquid crystal in a chiral smectic C or H phase.
Claim 21
Dependent Claim
182 words
A liquid crystal apparatus, comprising: (a) a liquid crystal panel comprising a pair of electrode plates and a ferroelectric liquid crystal disposed between the electrode plates, the ferroelectric liquid crystal having a chiral smectic C temperature range in which the ferroelectric liquid crystal assumes chiral smectic C phase, (b) a temperature sensor for detecting the temperature of the ferroelectric liquid crystal, (c) a heating means for heating the ferroelectric liquid crystal, and (d) a temperature control means for controlling the temperature of the ferroelectric liquid crystal capable of effecting a first step of heating the ferroelectric liquid crystal to a prescribed temperature above the chiral smectic C temperature range by the heating means and then lowering the temperature of the ferroelectric liquid crystal, and a second step of heating the ferroelectric liquid crystal by the heating means when the temperature sensor detects a temperature below a prescribed temperature within the chiral smectic C temperature range and lowering the temperature of the ferroelectric liquid crystal when the temperature sensor detects a temperature above the prescribed temperature within the chiral smectic C temperature range.
Claim 22
Dependent Claim
182 words
A liquid crystal apparatus, comprising: (a) a liquid crystal panel comprising a pair of electrode plates and a ferroelectric liquid crystal disposed between the electrode plates, the ferroelectric liquid crystal having a chiral smectic C temperature range in which the ferroelectric liquid crystal assumes chiral smectic C phase, (b) a temperature sensor for detecting the temperature of the ferroelectric liquid crystal, (c) a heating means for heating the ferroelectric liquid crystal, and (d) a temperature control means for controlling the temperature of the ferroelectric liquid crystal capable of effecting a first step of heating the ferroelectric liquid crystal to a prescribed temperature above the chiral smectic C temperature range by the heating means and then lowering the temperature of the ferroelectric liquid crystal, and a second step of heating the ferroelectric liquid crystal by the heating means when the temperature sensor detects a temperature below a prescribed temperature within the chiral smectic C temperature range and lowering the temperature of the ferroelectric liquid crystal when the temperature sensor detects a temperature above the prescribed temperature within the chiral smectic C temperature range.
Claim 23
Dependent Claim
184 words
A liquid crystal apparatus, comprising: (a) a liquid crystal panel comprising a pair of electrode plates and a ferroelectric liquid crystal disposed between the electrode plates, the ferroelectric liquid crystal having a chiral smectic C temperature range in which the ferroelectric liquid crystal assumes chiral smectic C phase, (b) a temperature sensor for detecting the temperature of the ferroelectric liquid crystal, (c) a heating means for heating the ferroelectric liquid crystal, and (d) a temperature control means for controlling the temperature of the ferroelectric liquid crystal capable of effecting a first step of heating the ferroelectric liquid crystal and lowering the temperature of the ferroelectric liquid crystal when the temperature sensor detects a temperature above a prescribed temperature above the chiral smectic C temperature range, and a second step of heating the ferroelectric liquid crystal by the heating means when the temperature sensor detects a temperature below a prescribed temperature within the chiral smectic C temperature range and lowering the temperature of the ferroelectric liquid crystal when the temperature sensor detects a temperature above the prescribed temperature within the chiral smectic C temperature range.
Claim 24
Dependent Claim
184 words
A liquid crystal apparatus, comprising: (a) a liquid crystal panel comprising a pair of electrode plates and a ferroelectric liquid crystal disposed between the electrode plates, the ferroelectric liquid crystal having a chiral smectic C temperature range in which the ferroelectric liquid crystal assumes chiral smectic C phase, (b) a temperature sensor for detecting the temperature of the ferroelectric liquid crystal, (c) a heating means for heating the ferroelectric liquid crystal, and (d) a temperature control means for controlling the temperature of the ferroelectric liquid crystal capable of effecting a first step of heating the ferroelectric liquid crystal and lowering the temperature of the ferroelectric liquid crystal when the temperature sensor detects a temperature above a prescribed temperature above the chiral smectic C temperature range, and a second step of heating the ferroelectric liquid crystal by the heating means when the temperature sensor detects a temperature below a prescribed temperature within the chiral smectic C temperature range and lowering the temperature of the ferroelectric liquid crystal when the temperature sensor detects a temperature above the prescribed temperature within the chiral smectic C temperature range.
References Cited (Backward Citations)
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