# US 8,770,705 B2 · Droplet discharge detection device and image forming apparatus including droplet discharge detection device

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- Number: US 8,770,705 B2
- Document ID: US8770705B2
- Status: Granted
- Kind: B2
- Application number: 13/614,294
- Filed: 2012-09-13
- Published: 2013-03-28
- Granted: 2014-07-08
- Earliest claimed: 2011-09-26
- Assignees: Ricoh Company, Ltd.
- Applicants: Takeshi Mochizuki
- Inventors: Takeshi Mochizuki
- Web page: https://patentgrep.com/patent/US8770705B2

## CPC

- B41J 2/0451: {for detecting failure, e.g. clogging, malfunctioning actuator}
- G01N 21/49: within a body or fluid
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Disclosed is a droplet discharge detection device including a head array unit in which plural nozzles are arranged in a line; a light emitter configured to emit a light beam in a direction in which the nozzles are arranged, wherein the light emitter is disposed at a first end portion of the head array unit and the light emitter has an aperture for limiting a diameter of a light beam; and a light receiver configured to receive a scattered light beam of the light beam generated by a droplet, wherein the light receiver is disposed at a second end portion of the head array unit, the second end portion being opposite to the light emitter of the head array unit.

## Claims

### Claim 1

A droplet discharge detection device comprising:
a head array unit in which plural nozzles are arranged in a line;
a light emitter configured to emit a light beam in a direction in which the nozzles are arranged, wherein the light emitter is disposed at a first end portion of the head array unit and the light emitter has an aperture for limiting a diameter of a light beam; and
a light receiver configured to receive a scattered light beam of the light beam generated by a droplet, wherein the light receiver is disposed at a second end portion of the head array unit, the second end portion being opposite to the light emitter of the head array unit,
wherein, when a first direction in which the droplet is discharged from the nozzles is set to be an X direction, and when a second direction that is perpendicular to the X direction and that is perpendicular to the direction in which the nozzles are arranged is set to be a Y direction, a formula below is satisfied,
∫X1X2∫Y1Y2(Asc2+2Adf·Asc·cos[2π(Ldf−Lsc)/λ])dXPDdYPD>0,
wherein, in the formula, the YPD is a Y-coordinate of a position in the Y direction on a light receiving surface of the light receiver, the [Y1, Y2] is an effective detection range in the Y direction on the light receiving surface of the light receiver, the XPD is an X-coordinate of the position in the X direction on the light receiving surface of the light receiver, the [X1, X2] is an effective detection range in the X direction on the light receiving surface of the light receiver, the Ldf is a first optical path length of a diffracted light beam from a center of the aperture of the light emitter to the light receiving surface of the light receiver, the Adf is a first amplitude of the diffracted light beam, the Asc is a second amplitude of the scattered light beam, the Lsc is a second optical path length of the scattered light beam from the center of the aperture of the light emitter to the light receiving surface of the light receiver, and the λ is the wavelength of the light beam.

### Claim 2 (depends on 1)

The droplet discharge detection device according to claim 1,
wherein the light receiver is disposed at a position shifted in the Y direction so as to prevent the light beam from entering, wherein the diameter of the light beam has been limited by the aperture.

### Claim 3 (depends on 2)

The droplet discharge detection device according to claim 2,
wherein the light emitter is configured to be moved in the Y direction with respect to a nozzle position at which the nozzles are arranged.

### Claim 4 (depends on 2)

The droplet discharge detection device according to claim 2,
wherein a distance Yik between the line, the nozzles being arranged in the line, and an optical axis of the light beam is within a range from −0.3 mm to +0.3 mm, and
wherein a squared value of the Adf is less than 1.5×10−6 W/mm2.

### Claim 5

An image forming apparatus comprising:
a droplet discharge detection device,
wherein the droplet discharge detection device includes
a head array unit in which plural nozzles are arranged in a line;
a light emitter configured to emit a light beam in a direction in which the nozzles are arranged, wherein the light emitter is disposed at a first end portion of the head array unit and the light emitter has an aperture for limiting a diameter of a light beam; and
a light receiver configured to receive a scattered light beam of the light beam generated by a droplet, wherein the light receiver is disposed at a second end portion of the head array unit, the second end portion being opposite to the light emitter of the head array unit,
wherein, when a first direction in which the droplet is discharged from the nozzles is set to be an X direction, and when a second direction that is perpendicular to the X direction and that is perpendicular to the direction in which the nozzles are arranged is set to be a Y direction, a formula below is satisfied,
∫X1X2∫Y1Y2(Asc2+2Adf·Asc·cos[2π(Ldf−Lsc)/λ])dXPDdYPD>0,
wherein, in the formula, the YPD is a Y-coordinate of a position in the Y direction on a light receiving surface of the light receiver, the [Y1, Y2] is an effective detection range in the Y direction on the light receiving surface of the light receiver, the XPD is an X-coordinate of the position in the X direction on the light receiving surface of the light receiver, the [X1, X2] is an effective detection range in the X direction on the light receiving surface of the light receiver, the Ldf is a first optical path length of a diffracted light beam from a center of the aperture of the light emitter to the light receiving surface of the light receiver, the Adf is a first amplitude of the diffracted light beam, the Asc is a second amplitude of the scattered light beam, the Lsc is a second optical path length of the scattered light beam from the center of the aperture of the light emitter to the light receiving surface of the light receiver, and the λ is the wavelength of the light beam.