JP-7855932-B2 - Belt device and image forming apparatus

Inventors

• 古西 貴大

Assignees

• 株式会社リコー

Dates

Publication Date

20260511

Application Date

20220607

Claims (8)

1. A belt unit comprising a plurality of roller members and a belt member stretched over the plurality of roller members, and configured to be rotatable about the rotation center of one of the plurality of roller members, A pressurizing mechanism is provided that allows adjustment of the contact pressure of the belt member against an object by rotating the belt unit around the rotation center, Without being linked to the rotation of the belt unit by the pressurizing mechanism, an optical sensor is positioned opposite one of the roller members via the belt member, A belt device characterized by having the following features.
2. The belt device according to claim 1, characterized in that, when viewed in a cross-section perpendicular to the rotation center, the detection surface of the optical sensor is configured to be perpendicular to the virtual normal passing through the rotation center of one of the roller members.
3. As the belt unit rotates due to the pressurizing mechanism, the winding range of the belt member on one of the roller members is displaced. The belt device according to claim 1 or 2, characterized in that even if the belt unit rotates due to the pressurizing mechanism and the winding range is displaced, the optical sensor faces the one roller member via the belt member within the winding range.
4. The belt device according to claim 3, characterized in that the pressurizing mechanism is configured to rotate the belt unit within a predetermined rotation range.
5. The belt device according to claim 1 or 2, characterized in that the optical sensor is fixedly installed on the pressurizing mechanism.
6. The belt device according to claim 1 or 2, characterized in that multiple optical sensors are installed at intervals along the axial direction of the rotation center.
7. The belt member is a secondary transfer belt that presses against a secondary transfer opposing roller via the intermediate transfer belt which is the target object, The belt device according to claim 1 or 2, characterized in that, among the plurality of roller members, one roller member different from the one roller member is a secondary transfer roller that presses against the intermediate transfer belt via the secondary transfer belt, and the optical sensor is a reflective photosensor.
8. An image forming apparatus characterized by comprising the belt device described in claim 1 or claim 2.

Description

This invention relates to a belt device equipped with belt members such as a secondary transfer belt, an intermediate transfer belt, and a transfer belt, and to an image forming apparatus such as a copier, printer, facsimile, or a multifunction device thereof, that is equipped with the same. Conventionally, image forming apparatuses such as copiers and printers are known to be equipped with optical sensors (toner image detection sensors) that detect toner images formed on the surface of belt members such as intermediate transfer belts and secondary transfer belts (see, for example, Patent Document 1). In detail, the image forming apparatus described in Patent Document 1 has an intermediate transfer belt (belt member) that is stretched and supported by multiple roller members, and a toner image detection sensor (optical sensor) is installed opposite one of the tension rollers (roller members) via the intermediate transfer belt. The toner image formed on the surface of the intermediate transfer belt is detected by the toner image detection sensor, and adjustments such as image density and positional misalignment are made based on the detection results. This is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention.This is a diagram showing a magnified view of a portion of the image-making section.This is a schematic diagram showing the vicinity of the intermediate transfer belt and the secondary transfer belt device.This is a diagram showing the configuration of the secondary transfer belt device.(A) A diagram showing the secondary transfer belt unit rotated toward the intermediate transfer belt, and (B) A diagram showing the secondary transfer belt unit rotated toward the side away from the intermediate transfer belt.This is an enlarged view showing the optical sensor and the roller facing the sensor.This diagram shows the secondary transfer belt unit and the pressurizing mechanism.This diagram shows the sensor-facing roller and multiple optical sensors in the width direction.This is an enlarged view showing an optical sensor and a roller facing the sensor as a comparative example. The embodiments for carrying out this invention will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be simplified or omitted as appropriate. First, the overall configuration and operation of the image forming apparatus 100 will be explained using Figures 1 and 2. Figure 1 is a diagram showing the configuration of a printer as an image forming apparatus, and Figure 2 is an enlarged view showing a part of its image-forming section. As shown in Figure 1, an intermediate transfer belt 8 (intermediate transfer body) is installed in the center of the image forming apparatus 100 as an image carrier. Opposite the intermediate transfer belt 8, image forming units 6Y, 6M, 6C, and 6K corresponding to each color (yellow, magenta, cyan, and black) are arranged side by side. Furthermore, an operation display panel (operation display unit) is installed on the top of the image forming apparatus 100 for displaying information related to the printing operation (image forming operation) and for performing operations. Referring to Figure 2, the image-forming unit 6Y corresponding to yellow consists of a photoreceptor drum 1Y as the photoreceptor, and a charging unit 4Y, a developing unit 5Y, a cleaning unit 2Y, a lubricant supply device 3, a static elimination unit, etc., arranged around the photoreceptor drum 1Y. The image-forming process (charging, exposure, development, transfer, cleaning, and static elimination) is then performed on the photoreceptor drum 1Y, forming a yellow image on the drum. Furthermore, the other three image units, 6M, 6C, and 6K, have almost the same configuration as the yellow-compatible image unit 6Y, except for the color of the toner used, and each unit forms an image corresponding to its respective toner color. Below, we will omit explanations of the other three image units, 6M, 6C, and 6K, and focus only on the yellow-compatible image unit 6Y. Referring to Figure 2, the photoreceptor drum 1Y is driven to rotate counterclockwise by a drive motor. Then, at the position of the charging section 4Y, the surface of the photoreceptor drum 1Y is uniformly charged (this is the charging process). Subsequently, the surface of the photoreceptor drum 1Y reaches the irradiation position of the laser light L emitted from the exposure unit 7, and an electrostatic latent image corresponding to yellow is formed by exposure scanning in the width direction (the direction perpendicular to the plane of the paper in Figures 1 and 2, which is the main scanning direction) at this position (this is the exposure process). Subsequently, the surface of the photoreceptor drum 1Y reaches a position opposite the developing unit 5Y, where the electrost