# US 5,703,666 A · Electroluminescent device for illuminating a liquid crystal display

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,703,666 A
- Document ID: US5703666A
- Status: Granted
- Kind: A
- Application number: 08/512,697
- Filed: 1995-08-08
- Granted: 1997-12-30
- Earliest claimed: 1991-08-29
- Assignees: Canon Kabushiki Kaisha
- Inventors: Toshihiro Saika; Hidemasa Mizutani; Noriyuki Kaifu; Toshio Kameshima
- Web page: https://patentgrep.com/patent/US5703666A

## CPC

- H04N 1/0316: {illuminating the scanned image elements through the plane of the photodetector, e.g. back-light illumination}
- G02F 1/133603: {with LEDs}
- H04N 1/0313: {Direct contact pick-up heads, i.e. heads having no array of elements to project the scanned image elements onto the photodectors}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

A liquid crystal device has a light source and liquid crystal elements which selectively transmit light emitted by the light source. The liquid crystal device comprises: the light source, being an electroluminescent device, having a transparent electrode disposed on a light output side of the light source, an electrode opposite to the transparent electrode, and an electroluminescence emission layer interposed between the transparent electrode and the opposite electrode; voltage supply means connected to the transparent electrode in order to feed a reference voltage to the transparent electrode; and driving voltage application means for applying a driving voltage to the opposite electrode. The driving voltage application means comprises a separate excitation type driving circuit using the capacitance of the electroluminescent device itself to produce an alternating current, and pulse generating means for generating a pulse responsive to an input signal to turn on and off a switch of the separate excitation type driving circuit. The pulse generating means includes a multivibrator and a capacitor and a resistor determine the width of the pulse.

## Claims

### Claim 1

A liquid crystal device having a light source and liquid crystal elements which selectively transmit light emitted by the light source, said liquid crystal device comprising:
the light source, being an electroluminescent device, having a transparent electrode disposed on a light output side of the light source, an electrode opposite to the transparent electrode, and an electroluminescence emission layer interposed between the transparent electrode and the opposite electrode;
voltage supply means connected to the transparent electrode in order to feed a reference voltage to the transparent electrode; and
driving voltage application means for applying a driving voltage to the opposite electrode,
said driving voltage application means comprising a separate excitation type driving circuit using a capacitance of said electroluminescent device itself to produce an alternating current, and pulse generating means for generating a pulse responsive to an input signal to turn on and off a switch of said separate excitation type driving circuit,
wherein said pulse generating means comprises a multivibrator and a capacitor and a resistor determine a width of the pulse.

### Claim 2

A liquid crystal device having a light source and liquid crystal elements which selectively transmit light emitted by the light source, said liquid crystal device comprising:
the light source, being an electroluminescent device, having a transparent electrode disposed on a light output side of the light source, an electrode opposite to the transparent electrode, and an electroluminescence emission layer interposed between the transparent layer and the opposite electrode;
a voltage source connected to the transparent electrode in order to feed a reference voltage to the transparent electrode; and
a driving circuit for applying a driving voltage to the opposite electrode,
said driving voltage application means comprising a separate excitation type driving circuit using a capacitance of said electroluminescent device itself to produce an alternating current, and pulse generating means for generating a pulse responsive to an input signal to turn on and off a switch of said separate excitation type driving circuit,
wherein said pulse generation means comprises a multivibrator and a capacitor and a resistor determine a width of the pulse.