GB2251083A

GB2251083A - "An image printer"

Info

Publication number: GB2251083A
Application number: GB9125342A
Authority: GB
Inventors: Dong-Ho Lee
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1990-12-22
Filing date: 1991-11-28
Publication date: 1992-06-24
Also published as: ITMI913174A1; FR2670712A1; GB9125342D0; IT1252695B; KR930006968B1; KR920013049A; DE4140884A1; ITMI913174A0

Abstract

There is disclosed an electrophotography processor employing an LED array 4, wherein the distance between the LED head array 4 and the light-sensitive drum 9 may be kept constant by a mounting means with resilient bias means. <IMAGE>

Description

22310.33 AN IMAGE PRINTE, R The present invention relates to

electrophotography, and more particularly to image printers employing an LED head array.

Referring to Figure 1 of the accompanying diagrammatic drawings, which illustrates a conventional image printer, a control circuit causes a scanning unit 10 to direct a succession of light beams over a lightsensitive drum 11 according to printing data provided by an external computer (not shown). If the surface of the light-sensitive drum 11 that is charged with a constant voltage by an electrical charging means 12 is illuminated with the light beams,the voltage of the portions receiving the light beams is reduced so as to form an electrostatic latent image. Thereafter, the light- sensitive drum 11 is rotated and attracts the toner of a developing means 13 to develop the electrostatic latent image.

Meanwhile, paper supplied from a paper supplying means 14 is delivered b register rolls to an image transferring means 15, which transfers y 1:1 the visible image formed by the toner onto the paper.

Thereafter, the paper stuck to the surface of the light-sensitive drum by electrostatic force is separated by a separator 16 conveyed to a fixing means 17. Here, the toner on the paper is fixed by means of the heat of a heating roll 21 and the pre5sure of a compression roll 22, and then the paper is conveyed to a tray. The residual toner is removed from the surface of the drum by a cleaner 23 and collected into a waste toner holder. The electrostatic latent image is removed by the light beams of a latent image removing lamp 24.

2 - Such an image printer generally uses a laser scanning unit for forming an electrostatic latent image on the light-sensitive drum. This considerably increases the volume of the printer. Moreover, if the printer receives external shocks, disturbances, etc., a lens or mirror inside the laser scanning unit may be displaced, so as to prevent a picture of proper quality from being obtained.

In order to solve such a problem, there has been proposed an image printer employing an LED head array for exposing the light-sensitive drum to light beams. However, the LED head array is directly mounted on the body housing or a bracket attached to the housing, so that it is very difficult to maintain precisely the distance between the LED head and light-sensitive drum.

Preferred embodiments of the present invention aim to provide a device for keeping a precise distance between the LED head and light sensitive- drum in an image printer employing an LED head array.

According to a first aspect of the present invention, there is provided an image printer comprising:

a light-sensitive drum; an LED array for illuminating a surface of said drum; mounting means on which said LED array is mounted; position fixing means disposed between said mounting means and said drum to determine the position of said LED array relative to said drum surface; and resilient bias means to urge said LED array towards said drum surface.

Said resilient bias means rnay comprise a plate spring or a coil spring.

Preferably, said position fixing means comprises a low-friction device 10 which in use bears against the light-sensitive drum or a part connected thereto.

Preferably, said low-friction device comprises a roller.

Preferably, said low-friction device is mounted on a free end of a bracket.

Preferably, an image printer according to any of the preceding aspects of the invention may comprise a housing having two parts at least one of 1 1 which is moveable with respect to the other to open the printer, thereby to allow access to parts inside the printer, and said mounting means is provided on one of said parts.

Said mounting means may comprise a bracket provided on said one part.

Said LED array may be mounted on a free end of said bracket.

Preferably, said parts are respectively lower and upper parts of said housing.

Preferably, said one part is said upper part.

An image printer according to any of the preceding aspects of the invention may include means for adjusting the position of said position fixing means, thereby to adjust the position of said LED array relative to said drum surface.

Preferably, said position fixing means comprises a pair of position fixing members. each disposed at a respective end of said LED array.

For a better understanding of the invention. and to show how the same may be carried into effect, reference will now be made, by way of example, to Figures 2 to 4 of the accompanying diagrammatic drawings, in which:

Figure 2 is a schematic diagram of one example of an image printer according to the present invention, 117 Figure 3 is a perspective view of one example of a part of an image printer as shown in Figure 2; and Figure 4 is a side view of onp example of another part of the image printer shown in Figure 2.

Referring to Figures 3 and 4. there is shown a bracket 2 fixedly mounted on a body housing 1 and a resilient member, i. e. plate spring 3 connected to a free end of the bracket 2 by means of a bolt 8, etc. An LED head array 4 is mounted on the underside of the plate spring 3. A position fixing member 5 is mounted at each side of the LED head array 4 for fixing the position of the LED head array. This position fixing member 5 comprises an L-shaped bracket 6 and a roll 7 mounted on the lower end of the bracket. The roll 7 contacts the light-sensitive drum 9 so as to keep constant the distance between the LED head array and the light-sensitive drum. Instead of the roll 7, there may be used an alternative device with a very low friction coefficient.

The operational effects restiltinllo., from use of the device of Figures 3 and 4 are as follows.

Since the LED head array 4 is mounted on the underside of the plate spring 3, the position of the LED head array relative to the light- sensitive drum 9 may be resiliently maintained (and adjusted). Thus, when the upper body 1 of the image printer is closed, the rolls 7 mounted on the lower ends of the brackets 6 mounted at both sides of the LED head array 4 contact the surface of the light-sensitive drum 9 so that the distance between the lightsensitive drum 9 and the LED head array 4 is kept constant. Of course, as the light-sensitive drum 9 is rotated, the rolls 7 are also rotated. Adjusting the position of the rolls 7 adjusts the distance between the LED array 4 and the surface of the drum 9.

Figure 2 is a.view similar to Figure 1, but showing use of the LED head array 4 and mounting assembly as shown in Figures 3 and 4, mounted on upper, opening part of the image printer body. In Figures 1 and 2, like reference numerals denote like or corresponding parts, and as the general operation of the image printer of Figure 2 will readily be apparent to those -6 skilled in the art, a detailed description of the more conventional parts of Figure 2 will not be repeated.

Although the embodiment shown, by way of example, in Figures 3 and 4 employs a plate spring as a resilient member, there may be used an alternative resilient means -such as, for example, a coil spring inserted in the middle of the LED head array mounted on a suitable bracket, which is made longer.

1 The rolls 7 of the position fixing members mounted at both sides of the LED head array, which reduce the frictional forces during the rotation of the light-sensitive drum 9, may be substituted by an alternative device with a very low friction coefficient.

The above-described embodinients of the present invention may always keep constant the distance between the LED head array and the light- sensitive drum, thus preventing the degradation of printed picture quality.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

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Claims

1. An image printer comprising:

a light-sensitive drum; an LED array for illuminating a surface of said drum; mounting means on which said LED array is mounted; position fixing means disposed between said mounting means and said drum to determine the position of said LED array relative to said drum surface; and is resilient bias means to urge said LED array towards said drum surface.

2. An image printer according to claim 1, wherein said resilient bias means comprises a plate spring.

3. An image printer according to claim 1, wherein said resilient bias means comprises a coil spring.

An image printer according to claim 1, 2 or 3 wherein said position fixing means comprises a low-friction device which in use bears against the 25 light-sensitive drum or a part connected thereto.

An image printer according to claim 4, wherein said low-friction device comprises a roller.

5.

6. An image printer according to claim 4 or 5 wherein said low-friction device is mounted on a free end of a bracket.

7. An image printer according, to any of the preceding claims, comprising a housing having two parts at least one of which is moveable with respect to the other to open the printer, thereby to allow access to parts inside the printer, and said mounting means is provided on one of said parts.

8. An image printer according to claim 7, wherein said mounting means h comprises a bracket provided on said one part.

9. An image printer according to claim 8, wherein said LED array is mounted on a free end of said bracket.

10. An image printer according to claim 7, 8 or 9, wherein said parts are respectively lower and tipper parts of said housing.

11. An image printer according to claim 10, wherein said one part is said upper part.

12. An image printer according to any of the preceding claims, including means for adjusting the position of said position fixing means, thereby to adjust the position of said LED array relative to said drum surface.

13. An image printer according to any of the preceding claims, wherein said position fixing means comprises a pair of position fixing members, each disposed at a respective end of said LED array.

14.- An image printer substantially as hereinbefore described with reference to Figures 3 and 4 or Figures 2 to 4 of the accompanying drawings.