JP2943229B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that performs image exposure using a light emitting element array.

[Prior art] Many conventional image forming apparatuses form a high-quality image by scanning a laser with a polygon scanner, but the trend is to reduce the size of the image forming apparatus using an LED array (light emitting diode array). And USP-47347
34, light shielding means is provided between adjacent light emitting elements of the LED array, and light emitted from the light emitting elements is condensed on the latent image carrier by the condensing lens array to provide high image quality. An image forming apparatus for forming an image has been proposed.

[Problems to be Solved by the Invention] However, the above-described conventional technology requires a high-precision and expensive condenser lens array for the LED array, and has a problem that the structure is complicated, large, and expensive. . In addition, there is a problem that the light amount is lost due to the condensing lens array, and a sufficient light amount cannot be obtained unless a large current is supplied to the LED array.

Therefore, the present invention solves such a problem,
An object of the present invention is to provide a small-sized and low-cost image forming apparatus using a light emitting element array having a simple structure and a thin shape. Still another object is to provide an image forming apparatus with high resolution and high image quality.

[Means for Solving the Problems] An image forming apparatus according to the present invention is an image forming apparatus for forming an electrostatic latent image on a latent image carrier by exposing an image with a light emitting element array. In addition to performing image exposure while being in close contact with a carrier, the light emitting element array is provided with a light emitting portion, and further, an optical block portion and a protective film are disposed on the light emitting portion.

Further, the image forming apparatus according to the present invention is characterized in that the light blocking portion is disposed so as to overlap a part of the light emitting portion.

Further, the image forming apparatus according to the present invention is characterized in that the light blocking portion is disposed so as to overlap a part of the light emitting portion.

Further, the image forming apparatus of the present invention is characterized in that a surface potential of at least a portion of the light emitting element array near a connection portion with the latent image carrier is substantially equal to a surface potential of the latent image carrier.

[Operation] According to the above configuration of the present invention, the condenser lens array attached to the light emitting element array is omitted, and not only the structure is simplified, but also a small and thin image forming apparatus is provided. be able to. Further, light loss due to light transmittance of the condenser lens array can be reduced. Further, a high-resolution image can be formed according to the size of the light emitting elements and the adjacent pitch.

 Hereinafter, the present invention will be described in detail with reference to examples.

Embodiment FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention, in which a latent image carrier 1 has organic or inorganic photoconductivity on a conductive support 2. After the photosensitive layer 3 is charged using a charger 4 such as a corona charger or a charging roller, a plurality of light emitting elements 5 are arrayed in the axial direction of the latent image carrier 1. Each of the light emitting elements 5 of the light emitting element array 6 formed on the same line or in a staggered manner is selectively switched in accordance with an image to irradiate the photosensitive layer 3 with light. An electrostatic latent image is formed by obtaining a potential contrast thereon. The light emitting element array 6 is disposed so as to bring the light emitting element 5 close to the latent image carrier 1, and the gap between the light emitting element array 6 and the latent image carrier 1 is 0 to 0.
By setting it to 500 [μm], high-resolution image exposure is possible. In particular, when the light emitting element array 6 is brought into close contact with the latent image carrier 1, the surface potential at least in the vicinity of the contact portion of the light emitting element array 6 is set to a value equivalent to the surface potential of the latent image carrier 1, and light emission is performed after image exposure. Variations in the potential of the latent image carrier 1 due to contact can be prevented by preventing the electrostatic latent image from being destroyed due to contact or the like between the element array 6 and the latent image carrier 1. Next, the latent image carrier 1 on which the electrostatic latent image has been formed is developed with the developing device 7 to adhere the toner 8 to the image portion to visualize the electrostatic latent image, and is transferred to a corona transfer device or a transfer roller. Table 9
Is used to transfer an image by the toner 8 onto the recording paper 10 and fix the toner on the recording paper 10 using heat and pressure to obtain a desired image on the recording paper 10. On the other hand, the toner 8 remaining on the latent image carrier 1 after the transfer is removed by the cleaning device 11 and the process is started again after charging. However, the light emitting element array 6 is small and thin, and other members are arranged adjacently. Even if it is provided, the optical path will not be blocked, so that a toner collecting member (not shown) for sending the toner collected by the cleaning device 11 to the developing device 7 and reusing the toner is provided to further reduce the size of the image forming apparatus. It is also possible to reduce running costs. 300 [DP] with an image forming apparatus as shown in FIG.
When a line image, a character image, and a solid image were continuously formed over 10,000 sheets using the light emitting element array of [I], a line image of 300 [DPI] was formed stably without thickening, and the resolution of the line pair image Was sufficiently large, and there was no tailing or background fogging at the edge of the image, and a high-density solid image having an OD value of 1.4 or more could be stably formed. In addition, the optical path length can be reduced compared to the conventional image forming apparatus using a laser, the polygon motor can be omitted, the optical lens can be omitted, and the optical path length can be reduced compared to the image forming apparatus using the conventional LED array. As a result, the size and cost of the image forming apparatus can be reduced.

In FIG. 1, a cylindrical or belt-shaped latent image carrier 1 can be used.
Can be made of a conductive metal material such as aluminum, and the photosensitive layer 3 can be made of an organic or inorganic photosensitive material.

In FIG. 1, the present invention is not limited only by the configuration shown in FIG. Arrows indicate the rotation directions of the respective members, but do not limit the present invention. further,
The development method can also be used regardless of whether it is regular development or spot development.

FIG. 2 is a schematic cross-sectional view of a light emitting element array according to an embodiment of the present invention. The light emitting element array is provided on a base 21, and one or more diode layers 23 are formed on an electrode 22 to form a light emitting section 24. An electrode (not shown) connected to the switch is switched to cause the light emitting section 24 to emit light. Each light emitting unit 24 is provided with a light blocking unit 25 to prevent light from leaking to the adjacent light emitting unit 24, and furthermore, a protective film 26 is provided to protect the light emitting unit 24,
Further, a reinforcing portion 27 made of tempered glass or the like is provided to reinforce contact with the latent image carrier. Second
As shown in the figure, the light emitting section 24 is disposed so as to overlap a part of the optical block section 25 to prevent leakage of light to adjacent pixels and maintain high resolution. By increasing the thickness, a sufficient resolution can be obtained even if the light emitting element array is arranged with a gap to the latent image carrier, and the gap between the light emitting element array and the latent image carrier is preferably 500 [μm] or less. If the arrangement pitch of the light emitting portions 24 is about the same, the protective film 26 and the reinforcing portion 27 can be made of a material having a high refractive index to suppress leakage of light to adjacent pixels and perform high-resolution image exposure.

In FIG. 2, the layer structure and the material of the light emitting element array are not limited to those of the present embodiment. In particular, as the light emitting element material, GaP, GaAlAs, GaAsP
And inorganic light emitting materials such as TPD (tetraphenylbenzidine) and TPAS (tetraphenyldiaminostilbene), and light emitting materials such as semiconductor lasers.

Although the embodiments have been described above, the present invention can be widely applied not only to the above embodiments but also to an image forming apparatus using a magnetic toner widely, and is particularly effective when applied to a printer, a copier, a facsimile, and a display. .

[Effects of the Invention] As described above, according to the present invention, a small-sized and low-cost image forming apparatus having a simple structure can be provided by bringing a light emitting element array close to or in close contact with a latent image carrier. Further, the waste toner can be reused, and an image forming apparatus with low running cost can be provided. Further, the present invention has an excellent effect that a high-resolution and high-quality image forming apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of a light emitting element array according to the embodiment of the present invention. 1 ... Latent image carrier 5 ... Light emitting element 6 ... Light emitting element array

Claims (4)

(57) [Claims] An image forming apparatus for forming an electrostatic latent image on a latent image carrier by image exposure with a light emitting element array, wherein the light emitting element array is brought into close contact with the latent image carrier to perform image exposure, and The image forming apparatus according to claim 1, wherein the light emitting element array includes a light emitting unit, and a light blocking unit and a protective film provided on the light emitting unit. 2. The image forming apparatus according to claim 1, wherein said light blocking portion is provided so as to overlap a part of said light emitting portion. 3. An image forming apparatus according to claim 1, wherein said light emitting element array has a reinforcing portion at a contact portion with a latent image carrier. 4. The image forming apparatus according to claim 1, wherein a surface potential of at least a portion of the light emitting element array near a contact portion with the latent image carrier is substantially equal to a surface potential of the latent image carrier.