JPH03149588A - Electrostatic charge removing device of image forming device - Google Patents

Abstract

PURPOSE:To prevent an erasure line of electrostatic charges from being irregular by deviating the center of an LED lamp upstream in the rotating direction of a photosensitive body about the center of the projection width of a case part for projection width specification. CONSTITUTION:The center of the LED lamp 9 is deviated upstream in the rotating direction of the photosensitive body 1 about the center of the projection width of the case 8a for projection width specification. Therefore, the low- brightness part of the LED lamp 9 on the surface of the photosensitive body 1 is cut at the case part on the upstream side in the rotating direction of the photosensitive body 1 with a little variation in projection width at the case part 8a and, therefore, a little variation in the quantity of light projection on the surface of the photosensitive body 1. Consequently, electrostatic charges on the surface of the photosensitive body are removed at the high-brightness part to make the erasure line of electrostatic charge flat.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a static charge removing device in an image forming apparatus such as an electrostatographic copying machine or a printer, and more specifically, to a case portion for regulating the light projection width in the direction of rotation with respect to a photoreceptor. The present invention relates to a static charge removing device in which LED lamps, which remove static charges on the surface of a photoreceptor by lighting them, are provided at predetermined intervals in the axial direction of the photoreceptor in a blank lamp case. [Prior Art] For example, in an electrostatographic copying machine, a static charge removal device is disposed upstream of a developing section to remove static charge from a specific area of the photoreceptor surface before the development process. It is possible to perform so-called "edge cut" development in which a margin is formed at the leading edge of the paper to prevent the paper from wrapping around the paper, development in which a part of the document is deleted, or so-called edit development in which only a part of the document is developed, or By removing static charges from unnecessary image areas that are outside the width of the paper to be transferred,
This makes it possible to prevent toner consumption in the unnecessary image area. As shown in FIG. 5, one of the LED lamps has a circular brightness distribution on the photoreceptor surface S, with high brightness at the center and decreasing toward the periphery. There is a type of so-called light-concentrating type. [Problems to be Solved by the Invention] In the static charge removing device using this condensing type LED lamp, the photoconductor surface S of the ED lamp 9 is
The electrostatic charge on the photoreceptor surface S within this range of light emission amount is removed. Static charge removal is not achieved sufficiently,
When developing a so-called solid black original where the static charge removal boundary line, that is, the static charge erase line, is uneven and development is formed on the entire surface, toner may be applied to the areas where the static charge has not been sufficiently removed. An image e is formed, and due to insufficient removal of this static charge, there are cases where the paper wraps around the photoreceptor due to poor development when cutting the leading edge, or when the image is cut in a specific area during edit development. Or, toner is wasted in unnecessary image areas. The present invention was devised in view of the above-mentioned circumstances, and aims to solve the above-mentioned disadvantages by an extremely simple improvement technique that only requires changing the arrangement of the LED lamps. [Means for Solving the Problems] In order to achieve the above object, the present invention provides an arrangement in which the lamp center of the LED lamp is positioned upstream in the rotational direction of the photoreceptor with respect to the center of the light projection width defined by the case portion for defining the light projection width. It is characterized by being biased to the side.

[Effect]

According to the above characteristic configuration, the low brightness portion of the LED lamp relative to the photoreceptor surface is located on the upstream side in the rotational direction of the photoreceptor, with almost no change in the amount of light emitted due to the case portion, or even a change in the amount of light emitted onto the photoreceptor surface. The electrostatic charges on the surface of the photoreceptor are removed at the high-brightness areas, and the erased lines of the electrostatic charges become flat. [Embodiment] Hereinafter, an embodiment of the present invention will be described based on the drawings. FIG. 1 shows an example of an image forming apparatus of a so-called center-based copying type (where the center of the width of the document storage stand and the center of the width of the document are aligned). Fig. 2 shows the outline of the image forming section B of the copying machine equipped with the above-mentioned electrostatic charge removing device A. The image forming section B includes a charging section 2, an exposing section 3, a static charge removing device A, a developing section 4, a transfer section 5, a paper separating section 6, and a cleaning section 7 around the photoreceptor 1. It consists of an arrangement. As shown in FIGS. 1 and 3-4, the static charge removing device A is installed inside an intermediate blank lamp case B whose light projection range covers the entire axial direction of the photoreceptor 1. , a large number of LED lamps 9 are provided at predetermined intervals in the axial direction of the photoreceptor 1, and the LED lamps 9 remove static charges on the surface S of the photoreceptor 1 when lit. A partition member 10 for regulating the amount of light projected is provided between the LED runs 19 outside the range corresponding to the smallest size transfer target paper a. Specifically, case portions 8a of the blank lamp case 8 on both sides in the rotational direction of the photoreceptor l have a function of regulating the amount of light projected by the LED lamp 9 in the rotational direction of the photoreceptor l. On the other hand, the LED lamp 9 is of a condensing type in which the luminance distribution on the surface S of the photoreceptor exhibits a circular luminance distribution with high luminance at the center and decreasing toward the periphery. Although not shown in the drawings, the arrangement pitch of the LED lamps 9 arranged within a range corresponding to the minimum size transfer target paper a is determined by adjusting the arrangement pitch of the LED lamps 9 arranged between the partition members 10.
The pitch is set slightly larger than the arrangement pitch of the lamps 9. According to the above configuration, by lighting up all of the LED lamps 9, static charges over the entire surface of the photoreceptor S are removed, and thus, for example, the photoreceptor at a portion corresponding to the leading edge of the transfer target paper a is removed. By removing the static charge on the surface S,
A so-called leading edge cut development is performed to form a margin at the leading edge of the paper. Furthermore, depending on the size of the transfer target paper a, by lighting the LED lamps 9 in a range outside the paper width to remove static charges in unnecessary image areas, wasteful consumption of toner in the unnecessary image areas can be avoided. Prevented. In addition, if the static charge removing device A is configured such that a partition member IO is provided between all of the LED runs 19, it is possible to perform development in which a part of the original is deleted or so-called edit development in which only a part of the original is developed. . In the static charge removing device A having the above configuration, in the present invention, the lamp center of the LED lamp 9 is biased upstream in the rotational direction of the photoreceptor l with respect to the center of the amount of light projected by the case portion 8a for regulating the amount of light projected. It has characteristics in points. According to this configuration, the amount of light emitted by the case portion 8a is kept approximately constant, and therefore, the amount of light emitted from the LED lamp 9 to the photoreceptor surface S is hardly changed. The portion d where the low brightness portions overlap can be substantially canted by the case portion 8a on the upstream side in the rotational direction of the photoreceptor 1, and as the LED lamp 9 is turned on, the surface S of the photoreceptor is Since the static charge is removed in the high-brightness area, the erasure line of the static charge on the photoreceptor surface S becomes clear and fluffy, and the formation of a linear toner image due to insufficient removal of the static charge is prevented. Definitely prevented. [Effects of the Invention] As explained above, according to the static charge removing device of the present invention,
This is an extremely simple arrangement in which the LED lamp for removing static charge is biased toward the case part on the upstream side in the rotation direction of the photoconductor with respect to the case part for regulating the amount of light emitted in the rotation direction of the photoconductor. The change makes it possible to flatten the erased line of static charge on the photoreceptor surface, reliably preventing the formation of toner images caused by insufficient removal of conventional static charge. It's arrived.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the static charge removal device, Fig. 2 is a schematic overall view of the image forming section of the copying machine, Fig. 3 is a detailed sectional view of the static charge removal device, and Fig. 4 is an explanatory diagram of static charge removal. , FIG. 5 is an explanatory diagram of static charge removal according to a conventional example. l...Photoreceptor, 8...Blank lamp case, 8a
- Case part for regulating the amount of light emitted, 9... LED lamp, S... Photoreceptor surface.

Claims (1)

[Claims] Inside a blank lamp case that has a case part that regulates the width of light emitted in the direction of rotation relative to the photoconductor, concentrating LED lamps that remove static charge on the surface of the photoconductor when lit are placed at predetermined intervals in the axial direction of the photoconductor. In the static charge removing device in the image forming apparatus, the lamp center of the LED lamp is biased upstream in the rotational direction of the photoconductor with respect to the center of the light projection width by the case portion for defining the light projection width. A static charge removing device in an image forming apparatus, characterized in that: