# US 7,611,221 B2 · Liquid ejection apparatus, image forming apparatus and ejection determination method

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- Number: US 7,611,221 B2
- Document ID: US7611221B2
- Status: Granted
- Kind: B2
- Application number: 12/044,879
- Filed: 2008-03-07
- Published: 2008-09-04
- Granted: 2009-11-03
- Earliest claimed: 2005-01-14
- Assignees: Fuji Photo Film Co., Ltd.
- Inventors: Tsutomu Kusakari; Tsutomu Takatsuka
- Web page: https://patentgrep.com/patent/US7611221B2

## CPC

- B41J 2/04561: {detecting presence or properties of a drop in flight}
- B41J 2/04581: {controlling heads based on piezoelectric elements}
- B41J 2/16579: {Detection means therefor, e.g. for nozzle clogging}
- B41J 2/2142: {Detection of malfunctioning nozzles (generating single droplets or particles on demand by pressure, e.g. electromechanical transducers B41J2/045, B41J2/05; jet deflection sensors B41J2/125; for cleaning purposes B41J2/16579)}
- B41J 2/2146: {for line print heads}
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS

## Abstract

The liquid ejection apparatus comprises: a liquid ejection head having a plurality of ejection ports which eject droplets of liquid; a light emitting device which emits a determination light beam intersecting with flight paths of the droplets ejected from at least two of the ejection ports to be examined; a light receiving device which receives the determination light beam having passed through the flight paths of the droplets and outputs a determination signal corresponding to an amount of received light; an ejection port selection device which selects the at least two of the ejection ports to be examined so that the at least two of the ejection ports are disposed on a line parallel to an optical axis of the determination light beam, and that a distance between the at least two of the ejection ports along the optical axis of the determination light beam is smaller than a prescribed specific distance; an ejection control device which performs ejection driving to eject the droplets at substantially same time from the at least two ejection ports selected by the ejection port selection device; and an ejection state judgment device which judges droplet ejection state of the at least two ejection ports according to the determination signal outputted by the light receiving device when the droplets ejected due to the ejection driving performed by the ejection control device pass through the determination light beam.

## Claims

### Claim 1

A liquid ejection apparatus, comprising:
a liquid ejection head having a plurality of ejection ports which eject droplets of liquid;
a light emitting device which emits a determination light beam intersecting with flight paths of the droplets ejected from at least two of the ejection ports to be examined;
a light receiving device which receives the determination light beam having passed through the flight paths of the droplets and outputs a determination signal corresponding to an amount of received light;
a first ejection port selection device which selects the at least two of the ejection ports to be examined with respect to ejection failure so that a distance between the at least two of the ejection ports selected by the first ejection port selection device along the optical axis of the determination light beam is larger than a prescribed specific distance;
a first ejection control device which performs ejection driving to eject the droplets at substantially same time from the at least two ejection ports selected by the first ejection port selection device;
a first ejection state judgment device which judges whether or not the droplets are ejected from the at least two ejection ports to be examined with respect to ejection failure according to the determination signal outputted by the light receiving device when the droplets ejected due to the ejection driving performed by the first ejection control device pass through the determination light beam;
a second ejection port selection device which selects the at least two of the ejection ports to be examined with respect to flight abnormality so that the at least two of the ejection ports are disposed on a line parallel to the optical axis of the determination light beam, and that a distance between the at least two of the ejection ports selected by the second ejection port selection device along the optical axis of the determination light beam is smaller than the prescribed specific distance;
a second ejection control device which performs ejection driving to eject the droplets at substantially same time from the at least two ejection ports selected by the second ejection port selection device; and
a second ejection state judgment device which judges a presence of an abnormality in at least one of a flight direction and a flight speed of the droplets ejected from the ejection ports to be examined with respect to flight abnormality according to the determination signal outputted by the light receiving device when the droplets ejected due to the ejection driving performed by the second ejection control device pass through the determination light beam.

### Claim 2 (depends on 1)

An image forming apparatus comprising the liquid ejection apparatus as defined in claim 1, which forms an image on a recording medium by means of the droplets ejected from the ejection ports.