JPH05303265A - Image forming device - Google Patents

Abstract

PURPOSE:To clearly and efficiently form an electrostatic latent image on a photosensitive drum and a visible image on a paper and to miniaturize a device by forming an exposing means of a line head and a scanning driving circuit and specifying the peak of the spectral sensitivity of the photosensitive drum. CONSTITUTION:The exposing means 13 is formed of the line head where plural end face light emission type electronic light emitting elements 30 are arrayed and disposed and the scanning driving circuit, and the peak of the spectral sensitivity of the photosensitive drum 11 is adjusted to the wavelength peak 590+ or -70nm of the emitted light of the element 30. Then, the electrostatic latent image is plotted on the photosensitive drum 11 which is electrostatically charged to a specified potential by an electrostatic charger 12 by driving the exposing means 13 to perform scanning. In such a case, since the peak of the spectral sensitivity of the photosensitive drum 11 is adjusted to the wavelength peak 590+ or -70nm of the emitted light of the element 30, the electrostatic latent image is clearly and efficiently plotted. Therefore, the clear and accurate visible image is formed on the paper by allowing the latent image to pass through a developing and cleaning device 14 and a transfer device 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which forms an electrostatic latent image on a photosensitive drum by using an exposing means and then forms a visible image by using a developing device and a transfer device.

[0002]

2. Description of the Related Art A developing device and a waste toner collecting device including a scraping blade are arranged on both sides of a photosensitive drum with a transfer device interposed therebetween so that development and cleaning of residual toner on the photosensitive drum can be performed independently. In contrast to the independent cleaning type image forming apparatus (FIG. 6), the applicant of the present invention is a so-called simultaneous development type cleaning type which simultaneously performs development and cleaning.
The image forming apparatus shown in FIG.
72).

The image forming apparatus 10P shown in FIG. 6 has a charger 12P, an exposure unit 13P, and a developing unit 14P (developing roller 1) which are arranged around the photosensitive drum 11P along the rotation direction thereof.
4R), a transfer device 15P, a waste toner collecting device 16P, and a charge eliminating lamp 17P. Reference numeral 18 is a heat fixing device.

In such an apparatus 10P, as shown in FIG. 8A, the surface of the photosensitive drum 11P is charged to a predetermined charging potential Vo (for example, -650V) by the charger 12P, and then the light is irradiated from the exposing means 13P. An exposed portion (electrostatic latent image) is formed. The residual potential Vr of the exposed portion is, for example, −
Although it is 50 V, the potential (Vo) of the unexposed portion is the charging potential V
It remains o.

Therefore, the exposed portion is at the developing position (the position where the photosensitive drum 11P and the developing roller 14R have the minimum clearance).
To the developing bias potential Vb (for example, -5
The toner applied with 00V) is adsorbed by the electric field action, and a visible image is formed. Since the absolute value of the potential (Vo) of the unexposed portion is larger than the developing bias potential Vb, the toner is not adsorbed.

This visible image is transferred onto the paper P having a potential Vd (+300 V, for example) transferred and charged by the transfer device 15P. However, a part of the toner T4 remains attached to the photosensitive drum 11P as shown in FIG. 4, and is collected by the waste toner collecting device 16P. After that, the surface of the photosensitive drum 11P is uniformly discharged by being irradiated with light from the discharge lamp 17P, and becomes, for example, −50V.

On the other hand, in the apparatus 10 of the simultaneous cleaning system for development shown in FIG. 7, a charger 12, an exposure unit 13P, a developing / cleaning unit 14, a transfer unit 15, a residual toner equalizing unit 19 (power source) are provided around the photosensitive drum 11. 25) and are arranged. The developing / cleaning device 14 includes a blade 14 that is in contact with the toner supply roller 14R1, the developing roller 14R2, and the developing roller 14R2 by a spring 14S.
It is formed including B and the like. The developing roller 14R2 contacts the photosensitive drum 11. In addition, both rollers 14R1,1
A developing bias potential Vb is applied to the 4R2 from the developing bias power source device 20. Therefore, the supplied toner T1 becomes the potential Vb and becomes the adhered toner T2 on the developing roller 14R2.

In such a device 10, as shown in FIG. 8B, a predetermined charging potential Vo (for example, −
The surface of the photosensitive drum 11 charged to 500 V is irradiated with light by the exposure unit 13P and the residual potential Vr (for example, −).
It becomes an exposed portion (electrostatic latent image) of 50V. The unexposed portion remains at the charging potential Vo. Here, the developing bias potential Vb
Is -250V, the toner T2 adhering to the developing roller 14R2 is attracted to the exposed portion of the potential Vr (-50V) to become the visible image toner T3. That is, it is developed.
At the same time, the residual toner T5 adhering to the unexposed portion of the potential Vo has a lower absolute value than that of the developing roller 14.
Adsorbed on the R2 side. That is, it is cleaned.

Hereinafter, the visible image toner T3 is transferred onto the paper P having the transfer charging potential Vd (for example, +300 V) at the transfer position. Toner T4 attached on the photosensitive drum 11
After passing through the brush (19) to equalize the potential, the exposed portion and the unexposed portion reach the charger 12 again.

Thus, the apparatus 10 of the simultaneous cleaning system of development shown in FIG. 7 reduces the running cost due to the reduction of the toner consumption amount and the waste toner collecting apparatus (16) including the scraping blade as compared with the apparatus 10P of FIG. ) Removal to make the apparatus compact and extend the life of the photosensitive drum 11, and further reduce the developing bias potential Vb due to the contact between the photosensitive drum 11 and the developing roller 14R2 and reduce the size of the power supply unit 20 thereof. Have. In addition, since the apparatus 10P performs non-contact development, but the contact development, the charging potential V
It is possible to reduce the potential of o.

By the way, as shown in FIG. 9, the exposure means 13P of each of the apparatuses 10P and 10 has a light emitting source 13R composed of a gas laser tube or a semiconductor laser and a polygon mirror 13PY.
It is formed of a laser optical system including a (motor 13M), an f-θ lens 13L, a beam direction changing mirror 13F, and the like.

[0012]

However, it has been pointed out that such exposure means 13P cannot achieve further downsizing of the apparatus, higher accuracy, and lower cost. That is, since the gas laser tube and the laser optical system are large and the degree of freedom in layout is small, the exposure means 13P serves as a brake in spite of the removal, especially in the simultaneous developing cleaning system in which the waste toner collecting device (16) is removed. It is not possible to achieve the expected dramatic reduction in device size.

Further, since the polygon mirror 13PY rotates at high speed together with the motor 13M, its vibration affects the accuracy of the formed image. The higher the precision, the greater the effect. Moreover, even if the accuracy of parts and assembly is increased,
The vibration suppression effect is small for the high cost and increased labor.

Further, noise caused by the high speed rotation of the polygon mirror 13PY and the motor 13M may be a problem. In addition, safety measures for the laser beam must be perfect.

An object of the present invention is to provide a small-sized image forming apparatus capable of performing image formation at high speed and with high accuracy while eliminating generation of vibration and noise.

[0016]

An image forming apparatus according to the present invention forms an electrostatic latent image by irradiating the peripheral surface of a photosensitive drum which has passed through a charging device with light from an exposing means, and then a developing device and a transfer device. In an image forming apparatus for forming the visible image on a sheet while passing through a container, a line head in which a plurality of light emitting wavelength peaks of an edge emitting electroluminescent device having an emission wavelength peak of 590 ± 70 nm are aligned and the line head is provided. And a scanning drive circuit for scanning and driving the head, and the spectral sensitivity of the photosensitive drum is formed to have a peak in a wavelength range of 590 ± 70 nm.

[0017]

In the present invention having the above-mentioned structure, the exposing means is driven to scan to form an electrostatic latent image on the peripheral surface of the photosensitive drum. On this occasion,
Since the peak of the spectral sensitivity of the photosensitive drum is set to 590 ± 70 nm, which is the same as the peak of the emission wavelength of the exposing means, a clear electrostatic latent image can be drawn with high efficiency. Moreover, since the exposure means is formed by the line head composed of the edge emitting electroluminescent element and the scanning drive circuit, the apparatus can be downsized and a high-precision image free from vibration and noise can be smoothly formed.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the present image forming apparatus (10) is basically the same as the conventional cleaning method (FIG. 7) in the simultaneous developing and cleaning system, and as shown in FIGS.
Is formed from a line head in which a plurality of edge emitting electroluminescent elements 30 are arranged in an array and a scanning drive circuit 40, and the peak of the spectral sensitivity of the photosensitive drum 11 is aligned with the emission wavelength peak of 590 ± 70 nm of the electroluminescent element 30. It has been configured.

The same components as those of the conventional example (FIG. 7) are designated by the same reference numerals, and the description thereof will be simplified or omitted.

First, an edge emitting electroluminescent device (30)
2, the dielectric layers 32 and 33 are formed on both surfaces of the light emitting layer (active layer) 31, and the drive signals Vp-Vn,
It has electrodes 34 and 35 which apply Va-Vb. Electrode 3
And potential difference | Vp-Vb |, | Va- applied between 4 and 35
If Vn | is higher than the threshold voltage, light is emitted from the end face, and if the potential difference | Vp-Va |, | Vn-Vb | is lower than the threshold voltage, no light is emitted.

Specifically, as shown in FIG. 4, each one end is connected to a common block electrode 34A, 34B, ..., 34N, and each other end is each common electrode 35-1 to 35-6,3.
5-7 to 35-12, a plurality of light emitting layers 31 connected to
A plurality of edge emitting electroluminescent elements 30 having -1 to 31-6, 31-7 to 31-12, ... Are arranged in the main scanning direction (left and right direction in FIG. 4) to form a line head.

Here, each edge emitting electroluminescent device 30 is provided.
Has an emission wavelength range of 500 to 730 nm as shown in FIG.
The peak is at 590 ± 70 nm. Incidentally, the emission wavelength range of a conventional semiconductor laser, for example, is 430 to 900 nm as shown by the dotted line, and its peak is about 78.
It is 0 to 800 nm.

Then, from the channel driver 42 of FIG. 4 forming a part of the scanning drive circuit 40 to each block electrode 3
The block drive signals BKa, 4A, 34B, ...
, BKn are applied, and the common driver 41 is applied.
To the common electrodes 35-1, 35-7, ..., 35-
, 35-6, 35-12, ..., The common drive signals COM1, COM2 ,.

Therefore, focusing on the leftmost block (34A) in FIG. 4, common drive signals COM1 to COM6 (Vp to Vn) and the block drive signal BKa (Vp to Vn) are shown in FIG. ), Each of the electroluminescent layers 31-1 to 31-6 emits light and does not emit light.
For example, the electroluminescent layer 31-1 has the common drive signal COM1.
Is the voltage Vp on the positive electrode side and the block drive signal BKa is the voltage Vb on the low voltage side. Therefore, the potential difference | Vp-Vb | exceeds the threshold value and light is emitted. However, the electroluminescent layer 31-5
Since the common drive signal COM5 is the voltage Vp on the positive pole side and the block drive signal BKa is also the voltage Va on the high voltage side, the potential difference | Vp-Va | becomes less than the threshold value, and thus no light emission occurs.

Here, the block drive signal BKa of the block electrode 34A is set to the voltage Vb (Va) on the low voltage side (high voltage side), and each common drive signal COM1, COM2, ..., COM.
If 6 is switched to the voltage Vp (Vn) on the positive electrode side (negative electrode side) in this order, each electroluminescent layer 31-1, 31-2, ...
The end faces 1-6 can be sequentially generated.

Thus, if the exposure means 13 composed of the line head (30) and the scanning drive circuit 40 is used, the size of the entire apparatus can be greatly reduced. However, as it is, since the emission wavelength peak of the edge-emitting type electroluminescent device 30 is a very short wavelength (590 ± 70 nm) as described above, a clear electrostatic image and visible image can be obtained if the photosensitive drum 11 is used as it is. Cannot form an image. Therefore, the spectral sensitivity of the photosensitive drum 11 is selected so that its peak is 590 ± 70 nm so that a clear and smooth image can be formed without changing the charging device 12, the developing / cleaning device 14, the transfer device 15, and the like. Is forming.

In the present embodiment having such a configuration, the charger 1
In step 2, the exposure unit 13 is driven to scan on the photosensitive drum 11 charged to a predetermined potential to draw an electrostatic latent image. At this time, the peak of the spectral sensitivity of the photosensitive drum 11 is aligned with the emission wavelength peak of 590 ± 70 nm of the edge-emitting electroluminescent device 30, so that the electrostatic latent image can be clearly drawn with high efficiency.
Therefore, the developing / cleaning device 14 and the transfer device 15
A clear and highly accurate visible image can be formed on the paper by passing through.

According to this embodiment, however, the exposure means 13 is formed of the line head in which the plurality of edge emitting electroluminescent elements 30 are arranged in line and the scanning drive circuit 40, and the spectral sensitivity of the photosensitive drum 11 is increased. Since the peak is adapted to the emission wavelength peak of 590 ± 70 nm of the electroluminescent element 30, the electrostatic latent image on the photosensitive drum 11 and the visible image on the paper can be formed clearly and highly efficiently. The overall size of the device can be greatly reduced.

Further, the exposure means 13 includes a line head (3
0) and the scan drive circuit 40, the vibration and noise of the conventional example including the polygon mirror can be eliminated, and the degree of freedom in the layout of the apparatus is large.

Further, the peak of spectral sensitivity of the photosensitive drum 11 may be changed by replacing the exposure means 13 including the line head (30) and the scanning drive circuit 40. That is, it is not necessary to modify other components such as the charger 12, the developing / cleaning device 14, the transfer device 15, and the like.
Easy implementation and cost reduction.

In the above embodiments, the simultaneous cleaning system is used for development, but the present invention is also applicable to an image forming apparatus of independent cleaning system.

[0032]

According to the present invention, the exposure means is formed by the line head in which a plurality of edge emitting electroluminescent elements are aligned and the scanning drive circuit, and the peak of the spectral sensitivity of the photosensitive drum is determined by the electroluminescent element. Emission wavelength peak 590 ± 70
Since the structure is adapted to the nm, the electrostatic latent image on the photosensitive drum and the visible image on the paper can be clearly and efficiently formed, and the size of the entire apparatus can be significantly reduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is also a diagram for explaining an edge emitting electroluminescent device.

FIG. 3 is also a diagram for explaining the emission wavelength characteristic of the edge-emitting type electroluminescent device.

FIG. 4 is also a diagram for explaining a scan drive circuit.

FIG. 5 is also a diagram for explaining the scanning light emitting operation.

FIG. 6 is an overall configuration diagram showing a conventional example (1).

FIG. 7 is an overall configuration diagram showing a conventional example (2).

FIG. 8 is a diagram for explaining operations of conventional examples (1) and (2).

FIG. 9 is a diagram for explaining an exposure unit of a conventional example.

[Explanation of symbols]

 11 Photosensitive Drum 12 Charging Device 13 Exposure Means 14 Developing / Cleaning Device 14R2 Developing Roller 15 Transfer Device 20 Development Bias Power Supply Device 30 Edge-Emitting Electroluminescent Device (Line Head) 40 Scanning Drive Circuit

Claims (1)

[Claims] 1. An electrostatic latent image is formed on a peripheral surface of a photosensitive drum which has passed through a charging device by irradiating light from an exposing means, and thereafter, the visible image is formed on a sheet while passing through a developing device and a transfer device. In the image forming apparatus for forming a plurality of emission wavelength peaks of the exposure means,
The end surface light emitting type electroluminescent elements of m are arranged in line and a scanning drive circuit for scanning and driving the line head, and the spectral sensitivity of the photosensitive drum is 59.
An image forming apparatus, which is formed to have a peak in a wavelength range of 0 ± 70 nm.