Light-emitting device and image forming apparatus

Patent metadata

Field	Value
Publication number	US-12085869-B2
Application number	US-202318319289-A
Country	US
Kind code	B2
Filing date	May 17, 2023
Priority date	May 27, 2022
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

An image forming apparatus includes a light-emitting chip, a substrate on which a plurality of light emitting chips are mounted, a controller, and a switch. The light-emitting chip includes a light-emitting portion, which emits light exposing a photosensitive drum surface based on supply of a driving current to the light-emitting portion, and a driving portion that drives the light-emitting portion. The controller controls the driving portion by transmitting a signal to the light-emitting chip and outputs a digital signal corresponding to a target amount of light of the light-emitting portion to the light-emitting chip. Based on a control signal from the controller, the switch switches a connection state between the voltage source and the D/A converter to a first state where the voltage source supplies the reference voltage to the D/A converter, and a second state where an electrical connection between the voltage source and the D/A converter is disconnected.

First claim

What is claimed is:

1. An image forming apparatus to form an image on a recording medium, the image forming apparatus comprising:
a photosensitive drum;
a light-emitting chip including a light-emitting portion configured to emit light for exposing a surface of the photosensitive drum based on supply of a driving current to the light-emitting portion according to an image signal, and including a driving portion configured to drive the light-emitting portion;
a substrate on which a plurality of light emitting chips are mounted; and
a controller configured to control the driving portion by transmitting a signal to the light-emitting chip and to output a digital signal corresponding to a target amount of light of the light-emitting portion to the light-emitting chip,
wherein the light-emitting chip further includes:
a voltage source configured to output a reference voltage,
a digital-to-analog (D/A) converter configured to convert the digital signal into a voltage corresponding to the digital signal based on the reference voltage output from the voltage source, and
a switch configured to switch, based on a control signal from the controller, a connection state between the voltage source and the D/A converter to a first state where the voltage source and the D/A converter are connected to each other and the voltage source supplies the reference voltage to the D/A converter, and a second state where an electrical connection between the voltage source and the D/A converter is disconnected.

2. The image forming apparatus according to claim 1 ,
wherein the D/A converter includes a resistor and is configured to supply the reference voltage to the resistor to generate the voltage corresponding to the digital signal,
wherein the first state is a state where the voltage source and the resistor are connected to each other and the voltage source supplies the reference voltage to the resistor, and
wherein the second state is a state where an electrical connection between the voltage source and the resistor is disconnected.

3. The image forming apparatus according to claim 1 , wherein, during execution of an image forming job for successively forming images on a plurality of recording media, the controller controls the switch to switch to the second state during a first period in a period between a first timing that is a timing when transmission of image data for a single page is completed and a second timing that is a timing when transmission of the image data for a next page is started.

4. The image forming apparatus according to claim 3 , further comprising a transmission portion configured to transmit a reference signal to the controller based on an instruction given by a user to instruct the image forming apparatus to start the image forming job,
wherein, based on reception of the reference signal transmitted from the transmission portion, the controller starts transmission of the image data, and
wherein the first timing is a timing when a first time elapses after the controller receives the reference signal.

5. The image forming apparatus according to claim 4 , wherein the second timing is a timing when a second time longer than the first time elapses after the controller receives the reference signal.

6. The image forming apparatus according to claim 3 , further comprising a detection portion configured to detect a front end of the recording medium,
wherein the detection portion is provided on a conveying path of the recording medium, and a start point of the first period is a third timing when a third time elapses after the detection portion detects the front end of the recording medium.

7. The image forming apparatus according to claim 6 , wherein an end point of the first period is a timing when a fourth time elapses after the detection portion detects a rear end of the recording medium.

8. The image forming apparatus according to claim 3 , wherein the controller is configured to control the switch to switch to the first state during a second period that is a period from when the transmission of the image data for the single page is started to when the transmission of the image data for the single page is completed.

9. The image forming apparatus according to claim 1 , wherein the light-emitting portion includes an organic electroluminescent (EL) film.

10. The image forming apparatus according to claim 9 ,
wherein the driving portion is a first driving portion, the image forming apparatus further comprising a second driving portion including the D/A converter and the switch, and
wherein the organic EL film is formed on the second driving portion, and the organic EL film and the second driving portion are integrated together.

11. A light-emitting device in which a plurality of light-emitting portions, configured to emit light based on supply of a driving current to the plurality of light-emitting portions according to an image signal, and a driving portion, configured to drive the plurality of light-emitting portions, are built, the light-emitting device comprising:
a voltage source configured to output a reference voltage;
a digital-to-analog (D/A) converter provided corresponding to each of the plurality of light-emitting portions and configured to convert a digital signal corresponding to a target amount of light of the plurality of light-emitting portions into a voltage corresponding to the digital signal based on the reference voltage; and
a switch provided corresponding to each of the plurality of light-emitting portions and configured to switch a connection state between the voltage source and the D/A converter to a first state where the voltage source and the D/A converter are connected to each other and the voltage source supplies the reference voltage to the D/A converter, and a second state where an electrical connection between the voltage source and the D/A converter is disconnected.

12. The light-emitting device according to claim 11 ,
wherein the D/A converter includes a resistor and is configured to supply the reference voltage to the resistor to generate the voltage corresponding to the digital signal,
wherein the first state is a state where the voltage source and the resistor are connected to each other and the voltage source supplies the reference voltage to the resistor, and
wherein the second state is a state where an electrical connection between the voltage source and the resistor is disconnected.

13. The light-emitting device according to claim 11 , wherein the plurality of light-emitting portions includes an organic electroluminescent (EL) film.

Assignees

• Canon Kk

Inventors

• Akagi Daisuke

Classifications

• G06K15/408

  Handling exceptions, e.g. faults (computer driven error handling and recovery for a printer G06F3/1234) · CPC title

• G06K15/1228

  involving the fast moving of a light beam in two directions (G06K15/1233 - G06K15/129 take precedence) · CPC title

• G03G2215/0412

  Electroluminescent elements, i.e. EL-array · CPC title

• G03G15/04036

  Details of illuminating systems, e.g. lamps, reflectors (lamp housings for copying cameras, reflex exposure lighting G03B27/542) · CPC title

• G03G15/04063 Primary

  by EL-bars · CPC title