JPH02296261A - Image forming device - Google Patents

Abstract

PURPOSE:To stably obtain good printing quality by providing a photovoltaic body, an image forming means which projects and forms a light image on the photovoltaic body, and a toner developing means which adheres toner on a projecting and image forming part of the photovoltaic body. CONSTITUTION:An elecrostatic latent image carrier 1 is of a cylindrical shape and is rotated and driven in the direction of an arrow around an axis, a magnetic brush 2 facing the upper part of the outside periphery and an LED alley head 3 facing this on the inner side are provided for exposing, and further, a transferring roller 4 which transfers a toner visual image to a recording paper 5 is provided facing the lower part of the outer periphery. Then when a light image is projected and formed on the photovoltaic bodies 13 to 15, electricity is generated along the light image, an electrostatic latent image is formed by its electromotive force, and when toner is adhered to the electrostatic latent image, a toner image responding to the light image is formed. Thus a stable surface electric potential can be set independent of the developing bias, and the good image quality can be stably obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an image forming apparatus for projecting and forming a light image onto a photovoltaic body.

(b) Prior Art Generally, electrophotographic apparatuses that utilize corona discharge are widely known as electrophotographic apparatuses. FIG. 7 is a schematic diagram showing a corona discharge type electrophotographic apparatus, in which an electrostatic latent image carrier 3
A charger 31 and a developer 3 for performing processes such as corona charging, exposure and development, transfer, static elimination, cleaning, etc.
2, a transfer device 33, an erasing lamp 34, a cleaning device 35, etc. are arranged, and while the electrostatic latent image carrier 30 is rotated, the charger 3
After being charged in step 1 and projecting a light image to form an electrostatic latent image, development step 8? ,': A toner image is formed at F32, transferred to a recording paper 37 by a transfer device 33, and fixed by a fixing device 36, residual static electricity is erased by an erasing lamp 34, and a cleaning device The process of removing residual toner is repeated in step 35). Therefore, it has the disadvantage that both its structure and process are complicated. For this reason, in recent years, an electrophotographic method that does not use corona discharge has been proposed (Imaging Electronics Society, Vol. 16, No. 5, 198
7).

FIG. 8 is a schematic diagram showing an electrophotographic apparatus that does not utilize corona discharge, in which a magnetic brush 41 is arranged on the upper part of the outer peripheral surface of the electrostatic latent image carrier 40, and a transfer roller 42 is arranged in the lower part of the outer peripheral surface of the electrostatic latent image carrier 40. , an LED array head 43 is arranged inside an electrostatic latent image carrier 40.

The electrostatic latent image carrier 40 includes a transparent support 40a made of glass, a transparent electrode 4υb on the outer periphery, and a photoconductive layer 40c constituting a photosensitive area.
A developing bias is applied between the transparent electrode 40b and the magnetic pole roller 41a forming the magnetic brush 41. The conductive toner is placed on the magnetic pole roller 41a.
A so-called magnetic brush 41 is formed by being attracted around the sleeve 41b placed over the outer periphery of the photoconductive layer 40C, and faces the outer circumferential surface of the photoconductive layer 40C. When the toner is applied to the layer 40c and an electrostatic latent image is formed on the photoconductive layer 40c, the toner is attracted to the surface of the photoconductive layer 40c from the magnetic brush 41, a toner image is formed, and the toner is transferred to the transfer roller 42. Then, the image is transferred onto the recording paper 44.

The residual toner on the surface of the electrostatic latent image carrier 40 is removed by the scraping force of the magnetic brush and the magnetic force of the magnetic pole roller 41. Therefore, charging and exposing the electrostatic latent image carrier 40,
Development and cleaning are performed substantially simultaneously by the magnetic brush 41 and head 43, which has the advantage of greatly simplifying the structure and process.

(c) Problems to be solved by the invention] In electrophotographic devices that do not use Rona discharge, charging is performed using a developing bias applied during development, but there are two different phenomena: charging and development. It was difficult to achieve both, and it was difficult to consistently obtain good printing quality.

(d) Means for Solving the Problems The present invention provides a photovoltaic body, an imaging means for projecting and forming a light image onto the photovoltaic body, and a toner attached to the projection and imaging portion of the photovoltaic body. The image forming apparatus is equipped with a toner developing means.

(E) Operation When a light image is projected onto the photovoltaic body, power is generated along the light image, and an electrostatic latent image is formed by the electromotive force.

Therefore, when toner is applied to the electrostatic latent image, a toner image corresponding to the optical image is formed.

(F) EXAMPLES The present invention will be specifically described below with reference to drawings showing examples thereof.

FIG. 1 is a schematic diagram of an electrophotographic apparatus using an electrostatic latent image carrier according to the present invention, in which 1 is the electrostatic latent image carrier according to the present invention, 2 is a magnetic brush, and 3 is an LED array. A head, 4 a transfer roller, and 5 a recording paper.

The electrostatic latent image carrier 1 has a cylindrical shape and is rotatably driven in the direction of the arrow around an axis (not shown).The electrostatic latent image carrier 1 has a cylindrical shape and is rotatably driven in the direction of the arrow around an axis (not shown). An LED array head 3 for exposure is disposed on the recording paper 5, and the LED array head 3 is placed facing the lower part of the outer peripheral surface to direct the toner image onto the recording paper 5.
A transfer roller 4 is provided to transfer the image to the image.

FIG. 2 is a partial structural view of a portion of the electrostatic latent image carrier 10 according to the present invention. In FIG. 2, reference numeral 11 indicates a transparent support made of glass or the like. On this transparent support 11, an electrode 12 mainly composed of microcrystalline silicon is laminated, and on top of this a first electrode 12 mainly composed of amorphous silicon is formed.
The photovoltaic layer 13, the second photovoltaic layer 14, and the third photovoltaic layer 15 are laminated, and a surface layer made of a-3iN is further formed on top of them.

In the above device, when light enters each photovoltaic layer 13, 14, 15 through the substrate 11 and the electrode 12, free carriers (electrons and/or holes) are generated within each layer, which are transferred to the electrode 11, the surface By collecting current in the layer 16, an electromotive voltage is generated.

The electrostatic latent image carrier used in the present invention is, for example, as follows.

First, second, and third photovoltaic layers 1 stacked in the direction of light incidence
The optical forbidden band width Eopt of each of 3b, 14b, and 15b becomes smaller sequentially from the light incident side as shown in FIG. To explain more specifically, the specific configurations of the first to third power generation layers are shown in Table 1.

The following is a blank table 1. That is, in each power generation layer, the power generation function is mainly performed in the respective ■-type layer, but as mentioned above, the first I-type layer 13b and the 21st-type layer are laminated sequentially from the light incident side. 14b and the 31st type layer 15b, each optical band gap Eoptb1
．． 75ev, ), 65ev, and 1.5ev. First I-type layer 13b second I-type layer 14b
Both are made of a-8iH, but by changing the production conditions, the content of (2) and the like can be changed, and the Eopt can be changed, albeit slightly. Also, the third type layer 15
Since b is an alloy of Si and Ge called a-8iGeitl, E and opt can be lowered to L5ev.

In the semiconductor power generation phenomenon, the incident light wavelength that contributes to power generation,
That is, the absorption wavelength depends on the optical band gap of the power generation region.

FIG. 4 shows the first, second, and third photovoltaic layers 1 in this example.
3b, 14b, and 15b each exhibit light absorption characteristics.

In this example, as shown in FIG. 3, there are multiple optical forbidden band widths when looking at the element as a whole, and since the arrangement is such that the band widths become smaller sequentially from the light incident side, the energy of the incident light is Those on the wavelength side effectively contribute to power generation in a relatively shallow region of the element, while those on the long wavelength side are not absorbed in the shallow region of the element and proceed to a relatively deep region of the element where they effectively generate power. As a result, a large power generation efficiency can be obtained as a whole of the device.

To manufacture the above embodiment, for example, the substrate 11 is placed in a reaction chamber,
This is carried out by appropriately filling the reaction chamber with a reaction gas to generate glow discharge. Electrode 12 Each photovoltaic layer 13
．． Since the compositions of 14 and 15 are different from each other, it goes without saying that the reactive gases are changed in the order of stacking. Table 2 shows the composition of the reactive gas for each layer.

Table 2 Below margin (The reaction gas contains H2 as a carrier gas, and the amount varies depending on the purpose. The substrate temperature and power also vary depending on the layer.) A red LED array head 3 (center wavelength 660 nm) is attached to the body from the inside (transparent support side).
, 16 d'Ot/mm) is turned on in response to an image signal, an electromotive force (positive potential with respect to the electrode 12 in this embodiment) of about 2 V is generated only in the portion of the carrier 1 where the light is incident. At the same time, when conductive toner is brought into contact with the carrier 1 from the surface layer 16 side without applying a page developing bias ('-10 V), the toner adheres only to the position where an electromotive force is generated (development).

Next, the carrier 1 moves and guides the recording paper 5 between it and the transfer roller 4 biased to +100V, and the toner image on the carrier 1 is transferred to the recording paper 5. Transferred recording paper “5”
is then transported to a fixing device (not shown) and is fixed there, thereby completing printing.

On the other hand, the carrier 1 is further rotated and development is performed again at the development position, and this cycle is repeated.

The printed sample thus obtained is the same image as the conventional electrophotographic sample.

Here, the wavelength distribution of the luminous intensity of various LEDs is shown in FIG. Although a Red-1 LED was used in this embodiment, it is of course possible to select the most suitable one depending on the electrostatic latent image carrier used. Furthermore, simultaneous irradiation with a plurality of lights may help further improve the performance of the recording apparatus. The sixth layer is the ■-shaped layer 14b (Eo
From this figure, which shows the absorption characteristics of light of 6600 people with pt=1.65ev), it can be seen that, for example, about 10% of the light with a wavelength of 660OA is absorbed in the second I-type layer 14blo00 people film.

Generally speaking, films with the same Eopt have a low absorption rate for long wavelength light, and films with a large Eopt have a low absorption rate for light of the same wavelength.

By taking these factors together, an optimal electrostatic latent image carrier can be formed.

Here, the surface layer 16 is formed to obtain the resolution necessary for the electrostatic latent image carrier, and thanks to this surface layer 16, printing at a high resolution of 16 dat/mm is possible. Of course, resolution may be obtained even without this layer depending on the performance of the third N-type layer 15c, but the conditions for forming this layer are extremely difficult and unstable, so it is desirable to form the surface layer 16.

Since this image recording device uses a photovoltaic layer as an electrostatic latent image carrier, the device is much simpler than a corona discharge type electrophotographic device (Figure 7) and can be made smaller and cheaper. . Also, although it does not use corona discharge, compared to recording devices that use a photoreceptor as an electrostatic latent image carrier (Figure 8), there is no need to supply surface potential using conductive toner, so the potential is stable. can be set independently of the developing bias, making it possible to stably obtain good image quality.

In addition, in the second embodiment, the electrode 1 is used as the electrostatic latent image carrier.
2, a transparent film coated with SnO□ on ITO is used, and a second photovoltaic layer is placed between the second photovoltaic layer 14 and the third photovoltaic layer 15 of the above embodiment as a photovoltaic layer. the same layer as 5
When a film with a total of 8 layers of sandwiched layers and photovoltaic layers was used, the electromotive voltage generated at the light irradiation area was approximately 5 μ.

In this state, when the conductive toner is brought into contact with the carrier without applying a negative bias (-8 .mu.), a print with greater contrast than in the previous example can be obtained.

Using the same carrier as in the second embodiment, a fluorescent lamp was used instead of the LED array as the irradiation light source, and a liquid crystal shutter array was used to switch this light, but the fluorescent lamp had a light emission wavelength. Unlike LEDs, the distribution has a width, so light is absorbed at each position of each photovoltaic layer. A printing experiment was conducted under the same conditions as in the second example. As a result, an image with better contrast than the second example was obtained.

The same carrier as in the second example was used, and an LED array that emitted Green, Red-1, and Red-2 at the same time was used as the irradiation light source. As a result of conducting a printing experiment under exactly the same conditions other than the above, a contrast I. between the second and third embodiments was obtained.

In the fifth embodiment, a photovoltaic layer is formed on the electrode-L of the second embodiment as an electrostatic latent image carrier, and the photovoltaic layer is formed on the substrate, the electrode, and the
N type layer, 81st type layer, 8th P type layer, 7th N type layer,...
The first P-type layer and the surface layer were formed in this order.

Then, light irradiation was performed from outside the carrier to the development start position. Other conditions were set the same as in the second example, but as a result of printing experiments, only images with low contrast could be obtained.

In the second embodiment, a two-component insulating toner is used as a substitute for the conductive toner, and the developing bias is 100V.
The other conditions were the same as in the second embodiment. As a result of printing experiments, a slightly smaller contrast was obtained than in the second example. Therefore, the developing bias was set to 5.
When the voltage was lowered to 0V, the overall concentration became high and fogging occurred.

(G) Effects of the Invention Since the present invention uses a photovoltaic body and an electrostatic latent image carrier, the device is much simpler than a corona discharge type electrophotographic device1), resulting in lower cost and smaller size. can. In addition, compared to recording devices that do not use corona discharge but use a photoreceptor as an electrostatic latent image carrier, there is no need to use conductive toner, so a stable surface potential can be maintained independently of the developing bias. Since the settings can be made, it is possible to stably obtain good image quality.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of the image forming apparatus of the present invention, FIG. 2 is an enlarged sectional view of the element structure of the electrostatic latent image carrier, and FIG. 3 is an energy band diagram of the electrostatic latent image carrier. Figure 4 is a light absorption characteristic diagram of each photovoltaic layer, Figure 5 is a relative luminous intensity distribution diagram of LED,
Figure 6 is a diagram of the light absorption characteristics of the power generation layer, Figure 7 is a schematic configuration diagram of a conventional image recording device that uses corona discharge, and Figure 8 is a schematic configuration diagram of a conventional image recording device that does not utilize corona discharge. It is a diagram. 1... Electrostatic latent image carrier, 2... Magnetic brush, 3...
・LED array head, 4...transfer roller, 5...
Recording paper, 13.14.15... Photovoltaic layer (photovoltaic body)
.

Claims (3)

[Claims] (1) An image comprising a photovoltaic body, an imaging means for projecting and forming a light image onto the photovoltaic body, and a toner developing means for attaching toner to the projection and imaging portion of the photovoltaic body. Forming device. (2) The image forming apparatus according to claim 1, wherein the toner is developed at the same time as the light image is projected onto the photovoltaic body. (3) The image forming apparatus according to claim 1, wherein the toner is developed after projecting and forming the light image on the photovoltaic body.