JPH056110A - Electrostatic recording device - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the image quality when passing envelopes. [Structure] When the paper size detection sensor 13 detects that an envelope is passed, the CPU 12 causes the power pack 1
At 0, the switching circuit 102 switches the output of the output circuit 101, that is, the bias applied to the developing roller 51, and in the power pack 11, the switching circuit 112 causes the switching circuit 112 to transfer from the output of the output circuit 111, that is, from the charger wire 71 toward the photoconductor 1. Switch the current. The toner adhesion amount and the transfer current are set to 1.
05 to 1.15 times and 1.6 to 2.1 times. [Effect] It is possible to improve the transfer efficiency and increase the toner concentration without generating background stains, and obtain good print quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer material including a cut paper and an envelope by passing a transfer current to a transfer means to cause a toner image formed by adhering toner on an image carrier to a corona discharge. The present invention relates to an electrostatic recording device, such as a copying machine or a printer, which transfers an image onto a transfer material for paper to form an image.

[0002]

2. Description of the Related Art Conventionally, as a method for increasing the image density,
A method of providing a density adjusting volume on the operation portion and changing the bias applied to the developing roller is generally adopted. Also, in order to improve the transfer effect, a method of changing the transfer current depending on the paper thickness is well known.

[0003]

Recently, in electrostatic recording devices such as printers and copying machines, there is an increasing demand for printing using an envelope as an transfer sheet. In this case, since the copy medium called an envelope is formed by stacking two or four normal transfer sheets, the sheet thickness is large and air is present between the transfer sheets. In addition, there are also those in which irregularities are provided on the surface such as a raid finish.

For this reason, if an attempt is made to increase the density of the entire character to be copied by the density adjusting volume, the background part will be stained and good print quality cannot be obtained.

On the other hand, a sufficient transfer effect cannot be obtained only by switching the transfer current depending on the paper thickness, because air is present between the transfer papers.

It is an object of the present invention to solve the above problems in the prior art and to provide an electrostatic recording apparatus with improved image quality when an envelope is used as a transfer material.

[0007]

In order to solve the above-mentioned problems, the present invention provides a toner image formed by adhering toner on an image carrier by applying a transfer current to a transfer means. In an electrostatic recording apparatus that forms an image by transferring to a transfer material that passes through a transfer material that includes cut paper and an envelope by causing corona discharge, when the envelope is passed, the time when the cut sheet is passed is Also, the transfer current is increased 1.6 to 2.1 times and the toner adhesion amount is 1.
The invention according to claim 2 has a detecting means for detecting the passage of the envelope, and the detecting means detects the passage of the envelope. When the paper is detected, the control means performs the control.

[0008]

According to the invention of claim 1, when the envelope is passed, the transfer current is increased 1.6 to 2.1 times by the control means and the toner adhesion amount is increased by the control means than when the cut sheet is passed. Since the control is performed so as to be 1.05 to 1.15 times, the increase of the transfer current and the increase of the toner adhesion amount effectively make a synergistic effect, and the transfer efficiency is improved without causing the background stain, and the toner density Will increase.

According to the second aspect of the present invention, the control means carries out the control when the passage of the envelope is detected, so that the above-described operation can be performed without a human operation.

[0010]

1 shows a schematic structure of an image forming unit of a laser printer which is an example of an image forming apparatus to which the present invention can be applied. Around the periphery of the drum-shaped photoconductor 1, a charger 2 for uniformly charging the photoconductor 1 in the order of the rotation direction indicated by an arrow, and a laser beam 3 emitted by an optical system (not shown) based on the original image data. Exposure unit 4 on which
A developing device 5 that develops the electrostatic latent image formed on the photoconductor 1 by exposure with toner, a transfer charger 7 that transfers the toner image to a transfer paper 6 that is sent from a registration roller (not shown) at a timing, A separation charger 8 for separating the paper, a cleaning device 9 for removing the toner and the like remaining on the photoconductor 1 after transfer, and the like are provided.

The transfer paper on which the toner image has been transferred is sent to the outside after the unfixed toner image thereon is heat-fixed by a fixing device and a discharge roller (not shown), and the image is completed.

In such a printer, an envelope is used as a transfer material in addition to the cut sheet, and there is a strong need for printing on the envelope. Here, the cut sheet is, for example, Xerox 402.
4 and Ricoh T-6200 (both are trade names).

In order to pass the envelope through the paper, in this embodiment, as an example of the control means, the power packs 10 and 11 are provided with the switching circuits 102 and 112 in addition to the output circuits 101 and 111, respectively. For example, a CPU 12 that controls the entire connected printer is provided.

In the power pack 10, the switching circuit 102 is controlled by the CPU 12 to switch the output of the output circuit 101, that is, the bias applied to the developing roller 51. As a result, the potential difference between the photoconductor 1 and the developing roller 51 is switched, and the amount of toner attached to the photoconductor 1 is switched. However, as a method for controlling the switching of the toner adhesion amount, another method such as switching the output power of laser light may be used.

On the other hand, in the power pack 11, the switching circuit 1
12 is controlled by the CPU 12, and switches the output of the output circuit 111, that is, the transfer current flowing from the charger wire 71 toward the photoconductor 1.

The switching is controlled by the CPU 12 in this way, and as a signal therefor, the detection signal of the paper size detection sensor 13 is used as a detection means for detecting the passage of the envelope, or for example, it is not shown. If the operation section is provided with a key for passing envelopes, there is a method of using this signal. However, you can manually press C when passing envelopes.
The switching circuit may be switched via the PU.

2A and 2B show the installed state of the paper size detection sensor 13. As the paper size detection sensor 13, a conductive detection plate 14a provided at the tip of the paper feed cassette 14 and having a different shape for each paper size is provided on the main body 100 side when the cassette is mounted on the main body 100 side of the printer. A method of making a judgment by conducting the contact with a contact is generally used. However, other types may be used.

With the above-mentioned structure, when the envelope is passed as the transfer material, the toner adhesion amount and the transfer current are switched to make these values larger than those when the cut sheet is passed.
The transfer efficiency is improved while increasing the image density on the transfer paper.

However, when the transfer current becomes excessive, a so-called printing effect occurs as an adverse effect, and this tendency is also related to the toner adhesion amount. Further, if the toner adhesion amount becomes excessive, a pixel crushing phenomenon occurs. For this reason, it is not easy to determine the conditions under which the image quality is best when printing on an envelope as a synergistic effect due to the increase in the toner adhesion amount and the transfer current. From the experimental results, it was possible to set the respective values to 1.05 to 1.15 times and 1.6 to 2.1 times the values at the time of ordinary cut paper passing. In this experiment, Glbert New Tech is used as the transfer paper.
The envelope was used.

[0020]

[Table 1]

[0021]

[Table 2]

The characteristics peculiar to the printer used in this experiment do not have a great influence on the experiment result, and the above values are general and widely applicable.

From Table 1, it can be said that when the transfer current exceeds 43 μA (2.1 times that for cut paper), a print image is produced, and the larger the amount of toner adhering to the photoreceptor 1, the more likely the print image is produced. From this point, in order to maintain good image quality, the transfer current is set to 2.
The amount of toner adhered is 1.22 as well as it is kept below 1 time.
Need to be less than twice, but toner adhesion amount is 0.94m
When g / cm ² (about 1.2 times) or more, the collapse of pixels becomes noticeable, so it is preferable that the toner adhesion amount is 1.2 times or less.

Next, it can be seen from Table 2 that the number of envelope types that can be handled increases when the transfer current and the toner adhesion amount are simultaneously switched and increased, rather than when only the transfer current is switched and increased. It is considered that this is because uneven density between characters can be reduced by increasing the amount of toner attached when the envelope is passed. As a result, the toner adhesion amount is 1.05 times or more and the transfer current is 1.6 times or more in order to print favorably on various types of envelopes.

FIG. 3 is a flow chart of control by the CPU 12. Depending on whether the transfer sheet is an envelope, it switched as illustrated bias voltage V _B and the transfer current I _t as toner adhesion amount and the transfer current is respectively a suitable value within said range.

If the transfer current is set to a low value (about 1.8 times), the fatigue due to the charging of the portion where the photoconductor is directly charged in the portion other than the sheet passing width of the envelope is reduced.

If only the output value of the power pack is switched as in this embodiment, the device can be simplified by mounting the power pack on the same substrate.

[0028]

As described above, according to the present invention, in the invention of claim 1, the transfer current is 1.6 to 2.1 times larger when the envelope is passed than when the cut sheet is passed. In addition, by increasing the toner adhesion amount from 1.05 to 1.15 times, it is possible to improve the transfer efficiency and increase the toner concentration without generating background stain, and obtain good print quality.

According to the second aspect of the present invention, since the control means performs the control when detecting the passage of the envelope, no human operation is required, the operability is improved, and the print quality is deteriorated due to an erroneous setting. It can be prevented.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an image forming unit of a printer according to an embodiment.

FIG. 2 is a perspective view showing an installed state of a paper size detection sensor of the printer.

FIG. 3 is a flow chart when switching between a transfer current and a developing bias with a transfer paper.

[Explanation of symbols]

1 photoconductor (image carrier) 6 Recording paper (transfer material) 7 Transfer charger (transfer means) 12 CPU (control means) 13 Paper size detection sensor (detection means) 102 Switching circuit (control means) 112 Switching circuit (control means)

Claims (2)

[Claims] 1. A toner image formed by adhering toner onto an image carrier is transferred to a transfer material, which is a paper passing member, out of transfer materials including cut paper and envelopes by causing a corona discharge by applying a transfer current to a transfer means. In the electrostatic recording apparatus for forming an image, when the envelope is passed, the transfer current is increased by 1.6 to 2.1 times and the toner adhesion amount is set more than when the cut sheet is passed. An electrostatic recording apparatus, characterized in that a control means is provided for controlling to 1.05 to 1.15 times. 2. The static image pickup device according to claim 1, further comprising a detection unit that detects the passage of the envelope, and the control unit performs the control when the detection unit detects the passage of the envelope. Electronic recording device.