Image forming apparatus having an optical sensor for converting a toner adhesion amount and image forming method

Patent metadata

Field	Value
Publication number	US-9565319-B2
Application number	US-201514879177-A
Country	US
Kind code	B2
Filing date	Oct 9, 2015
Priority date	Oct 17, 2014
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

An image forming apparatus includes an image bearer to bear a black toner pattern formed with a black toner image under an increased exposure amount and an increased developing bias. A first optical sensor detects an amount of reflection light reflected by the black toner pattern on the image bearer. The first optical sensor includes a light-emitting element to emit light toward the black toner pattern on the image bearer and a light-receiving element to receive the reflection light reflected by the black toner pattern on the image bearer. A toner adhesion amount converter converts the amount of the reflection light detected by the first optical sensor into a toner adhesion amount of toner adhered to the image bearer and adjusts an image density according to the toner adhesion amount.

First claim

What is claimed is:

1. An image forming apparatus, comprising:
an exposure device configured to form an electrostatic latent image under an increased exposure amount;
a developing device configured to visualize the electrostatic latent image as a black toner image under an increased developing bias;
a rotatable image bearer configured to bear a black toner pattern formed with the black toner image;
an optical sensor, opposite the image bearer, configured to detect an amount of reflection light reflected by the black toner pattern on the image bearer,
the optical sensor including:
a light-emitting element configured to emit light toward the black toner pattern on the image bearer; and
a light-receiving element configured to receive the reflection light reflected by the black toner pattern on the image bearer; and
a toner adhesion amount converter, operatively connected to the exposure device, the developing device, and the optical sensor, configured to convert the amount of the reflection light detected by the optical sensor into a toner adhesion amount of toner adhered to the image bearer and adjust an image density according to the toner adhesion amount,

wherein the toner adhesion amount is calibrated based on at least one of a result of the optical sensor with a white reference plate provided inside the optical sensor and a plurality of toner patterns having different image densities, respectively, with the optical sensor that detects a specular reflection light and a diffuse reflection light.

2. The image forming apparatus according to claim 1 , wherein the exposure device and the developing device form the black toner pattern at least at one of a time when the light-emitting element of the optical sensor changes a light-emitting amount, a time when the optical sensor is replaced, and a time when the optical sensor is reinstalled.

3. The image forming apparatus according to claim 1 , further comprising another optical sensor, opposite the image bearer, configured to optically detect the amount of the reflection light reflected by the black toner pattern on the image bearer, the another optical sensor including:
a light-emitting element configured to emit light; and
a light-receiving element configured to receive the reflection light reflected by the black toner pattern on the image bearer.

4. The image forming apparatus according to claim 3 , wherein the exposure device and the developing device form the black toner pattern at least at one of a time when the light-emitting element of at least one of the optical sensor and the another optical sensor changes a light-emitting amount, a time when at least one of the optical sensor and the another optical sensor is replaced, and a time when at least one of the optical sensor and the another optical sensor is reinstalled.

5. The image forming apparatus according to claim 3 , wherein the exposure device and the developing device are configured to form a color toner image to be formed into a color toner pattern borne on the image bearer,
wherein the optical sensor configured to detect an amount of reflection light reflected by the color toner pattern on the image bearer, and
wherein the toner adhesion amount converter configured to convert the amount of the reflection light detected by the optical sensor into a toner adhesion amount of toner adhered to the image bearer and configured to adjust an image density according to the toner adhesion amount.

6. The image forming apparatus according to claim 5 , wherein the color toner pattern includes:
a first gradation pattern constructed of a plurality of graded color patches in a first color that is aligned in a rotation direction of the image bearer; and
a second gradation pattern constructed of a plurality of graded color patches in a second color that is aligned in the rotation direction of the image bearer.

7. The image forming apparatus according to claim 6 , wherein the first gradation pattern is aligned with the second gradation pattern in a main scanning direction perpendicular to the rotation direction of the image bearer.

8. The image forming apparatus according to claim 7 , wherein the optical sensor is configured to detect the first gradation pattern and the another optical sensor is configured to detect the second gradation pattern.

9. The image forming apparatus according to claim 6 ,
wherein the first gradation pattern is contiguous to the second gradation pattern in the rotation direction of the image bearer, and
wherein the optical sensor is configured to detect the first gradation pattern and the second gradation pattern.

10. The image forming apparatus according to claim 9 , wherein the color toner pattern further includes another first gradation pattern and another second gradation pattern contiguous to the another first gradation pattern in the rotation direction of the image bearer, and
wherein the another optical sensor is configured to detect the another first gradation pattern and the another second gradation pattern.

11. The image forming apparatus according to claim 1 , wherein the light-receiving element of the optical sensor includes a specular reflection light-receiving element configured to receive specular reflection light, and
wherein the toner adhesion amount converter is configured to convert an amount of the specular reflection light into the toner adhesion amount.

12. The image forming apparatus according to claim 1 , wherein when the amount of the reflection light is greater than a preset upper limit, the toner adhesion amount converter uses the amount of the reflection light detected by the optical sensor previously.

13. The image forming apparatus according to claim 1 , wherein the image bearer includes one of an intermediate transfer belt and a secondary transfer belt.

14. The image forming apparatus according to claim 1 , wherein the toner adhesion amount converter includes a potential controller.

15. The image forming apparatus according to claim 14 , further comprising a temperature-humidity sensor, operatively connected to the potential controller, configured to detect a temperature and a humidity of an environment of the image forming apparatus.

16. The image forming apparatus according to claim 14 , further comprising a toner density sensor, operatively connected to the potential controller, configured to detect a toner density of toner contained in the developing device.

17. The image forming apparatus according to claim 14 , wherein the image bearer includes a photoconductor.

18. The image forming apparatus according to claim 17 , further comprising a potential sensor, operatively connected to the potential controller, to detect a potential of an outer circumferential surface of the photoconductor after exposure by the exposure device.

19. An image forming method comprising:
detecting an amount of specular reflection light reflected by a background of an image bearer;
determining that the amount of the specular reflection light is not in a given range;
adjusting an amount of light emitted onto the image bearer;
forming a black toner patch on the image bearer with an increased amount of toner adhered to the image bearer;
detecting an amount of specular reflection light reflected by the black toner patch on the image bearer;
forming a plurality of toner patterns having different toner densities, respectively, on the image bearer;
detecting a latent image potential of each of the plurality of toner patterns;
detecting an amount of toner of each of the plurality of toner

Assignees

• Muto Tetsuya
• Akatsu Shinichi
• Yoshida Akira
• Gotoh Keita
• Uematsu Yuuichiroh
• Ricoh Co Ltd

Inventors

• Muto Tetsuya
• Akatsu Shinichi
• Yoshida Akira
• Gotoh Keita
• Uematsu Yuuichiroh

Classifications

• H04N2201/0094

  Multifunctional device, i.e. a device capable of all of reading, reproducing, copying, facsimile transception, file transception · CPC title

• H04N1/00037

  Detecting, i.e. determining the occurrence of a predetermined state (H04N1/00031 takes precedence) · CPC title

• H04N1/60

  Colour correction or control {(H04N1/54 takes precedence)} · CPC title

• H04N1/6044

  involving a sensor integrated in the machine or otherwise specifically adapted to read the test pattern · CPC title

• G03G15/0121

  for developing · CPC title