JPH11133790A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fixing speed for an envelope and an OHP sheet by setting the second fixing speed at which the envelope or OHP sheet is fixed, and, further, setting the speed within the specific range of a first fixing speed used for plain paper. SOLUTION: A fixing device has settings for the first fixing speed at which plain paper is fixed and the second fixing speed at which an envelope or OHP sheet is fixed. Furthermore, the second fixing speed is set within the range of 1/1.6-1/1.8 of the first fixing speed. From device specifications relating to the printing speed of the printer, the fixing speed for printing on the plain paper is determined, for example, 100 mm/sec. To fix the envelope at the same fixing speed as that used for the plain paper, it is necessary to increase the setting temperature of the fixing unit. To make the temperature constant, it is necessary to decrease the fixing speed in order to prevent cold offset on the envelope. From the result, the setting center of the fixing temperature is specified to 150 deg.C at 55 mm/sec. which corresponds to the 1/1.8 of the fixing speed used for the plain paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printing device,
In particular, it relates to setting of a fixing speed of a fixing device.

[0002]

2. Description of the Related Art In the prior art, switching of the fixing speed of a fixing device differs depending on the type of paper used, so that fixing may be incomplete at the same speed. The fixing speed has been switched.

In many cases, the fixing speed of an envelope, an OHP sheet, or a thick paper is set to half the fixing speed of plain paper.

[0004]

However, in order to increase the overall speed of the printing apparatus, it is better to use a little faster, and if a large amount of printing is performed continuously even with a slight time difference, a large time difference occurs. There is.

[0005]

SUMMARY OF THE INVENTION The present invention is characterized in that an optical device for forming a latent image, a charging device, a photosensitive device,
In a printing apparatus including a developing device for developing a latent image and a fixing device, the fixing speed of the fixing device is a first fixing speed for fixing plain paper, and a second fixing speed for fixing an envelope or an OHP sheet. And the second fixing speed is set in a range of 1 / 1.6 to 1 / 1.8 of the first fixing speed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.

The printing apparatus main body 25 includes developing units 1 to 4, an optical unit 5, a charging unit 8, a photosensitive belt 22, a transfer drum 21, a registration roller 12, a transfer roller 13, a static eliminator 15, a fixing unit 19, and a paper discharge. The rollers 18 and the paper feed cassette 6 are main components.

Next, the operation of the printing device 25 will be described.

The charger 8 uniformly charges the photosensitive belt 22 in response to a print start signal from a host (not shown).

The optical unit 5 draws a latent image on the photosensitive belt 22 according to print data sent from the host,
The drawn latent image is developed by any one of the developing devices 1 to 4, and the colored particles in the developing device are applied on the photosensitive belt 22.

The photosensitive belt 22 is rotated by a drive source (not shown) to transfer the colored particles on the photosensitive belt 22 onto the transfer drum 21.

Excessive colored particles remaining on the transfer drum 21 are removed by a cleaner a20, and excess colored particles remaining on the photosensitive belt 22 are removed by a cleaner b23. 8 is charged.

In the case of color printing, this process is repeated three or four times while switching the developing device.

On the transfer drum 21, a visible image is formed by colored particles of a single color or a plurality of colors, and when the desired transfer is completed, or in advance, the paper 27 is transferred from the paper feed cassette 6.
Is pulled out by the feed roller 10 and the registration roller 1
Wait at 2.

At a timing when the position of the visible image formed on the transfer drum 21 coincides with the transfer position on the sheet, the sheet waiting at the registration roller 12 starts to be conveyed again, and At 13 the visible image is transferred to the paper side.

The paper is peeled off from the transfer drum 21 by the static eliminator 15, the colored particles are fixed on the paper by the fixing device 19, and are discharged to the paper discharge tray 28.

FIG. 2 is a sectional view of the fixing device 19 according to the present invention, and FIG. 3 is a plan view of the fixing device 19 according to the present invention.

A heating roller 127 and a pressure roller 128 are respectively mounted on pipe-shaped cores 127-1 and 128-1 on a 1.5 mm-thick silicon rubber 127-JIS having a JIS hardness of 40 degrees.
2. An elastic roller covered with 2,128-2, having a heater 129 of 400 W and a heater 1 of 300 W
30.

The heating roller 127 is provided around the heating roller 127.
Cleaning roller having heat-resistant fibers coated on a metal core for removing offset toner attached to the surface of 27
131, a temperature sensor 132 for detecting the temperature of the surface of the heating roller 127, and an oil application unit 133 for applying silicone oil stably.

The heating roller 1 is provided on the surface of the pressure roller 128.
A cleaning pad 134 for removing the offset toner transferred from the heater 27 and a fuse 135 for cutting off the current when the heaters 129 and 130 are abnormally heated due to a failure of the temperature sensor 132 or the like. Both sides are protected by covers 146 and 147 for safety.

The oil application unit 133 includes the heating roller 1
27, an oil supply felt 142 for supplying the silicone oil supplied from the oil bottle 141 by capillary action, and an oil blade 143 for regulating the amount of the silicone oil applied to the surface of the heating roller 127 to a certain amount. It is fixed to a heating roller frame 144 holding a heating roller 127, a temperature sensor 132 and the like.

By rotating the heating roller 127 in the direction of the arrow, an oil film of silicone oil is formed on the surface of the heating roller 127, and the releasability between the toner and the surface of the heating roller 127 is improved.

The paper 137 on which the unfixed toner image 136 is formed is conveyed by the entrance guide 138 to the pressure contact portion between the heating roller 127 and the pressure roller 128 from the direction of the arrow.
Then, after the toner is fixed on the sheet by the heat and pressure from both rollers, the toner is discharged in the direction of arrow B according to the guides 139 and the discharge guide 140 which also serve as the case of the cleaning roller 131.

Most of the toner fixed at the pressure contact portion between the heating roller 127 and the pressure roller 128 remains on the paper 137, but a small amount of toner (offset toner) is
Attach to 27.

The offset toner is removed by the cleaning roller 131. However, it is difficult to completely remove the offset toner by the cleaning roller 131, and the offset toner that cannot be completely removed is removed by the heating roller 127 and the pressure roller 128. It accumulates on the surface and reduces the releasability of the roller surface.

If the oil supply felt 142 is contaminated with offset toner, the oil supply from the oil supply felt 142 to the heating roller 127 becomes insufficient.
The releasability of the roller surface is reduced.

Next, a control block of the printing apparatus main body 25 is shown in FIG.

The control block includes an I / F section for exchanging data with the host, an exposure / photosensitive / development / fixing section, a motor as a power source, a solenoid drive section, an operation / display section, a paper feed section, and several sections. It is composed of a sequence control unit that controls a detector and the like.

Further, it is a driving source for paper feeding, photosensitive, and fixing.
The speed of the driving unit of the motor a is switched according to the type of paper by a speed switching unit in the sequence control unit.

There are various types of paper 27 used in the printing device 25, such as OHP sheets, cardboard, envelopes, and postcards, in addition to plain paper.

Therefore, the fixing characteristics vary depending on the material of the paper to be used and the environmental conditions in which the printing device is used, and it is necessary to change the fixing temperature and the feeding speed of the paper in order to cope with various types of paper with the same printing device. Yes.

FIG. 5 shows the relationship between the fixing speed and the fixing temperature.

Here, the cold offset boundary line indicates a limit at which the amount of heat for fixing is insufficient and the toner is not fixed on the sheet.

The upper limit of the OHP indicates a limit at which the rigidity is reduced when heat is applied to the OHP sheet and the OHP sheet is wound around the fixing roller.

From the device specifications relating to the printing speed of the printing device, the fixing speed at the time of printing on plain paper is determined. In this case, the fixing speed is 100 mm / sec.

From the measurement results shown in FIG. 5, when the envelope is fixed at the same fixing speed as that of plain paper, it is necessary to increase the set temperature of the fixing device.

Normally, since the heat capacity around the fixing unit is large, the ability to follow up and down of the temperature is slow, and the temperature is controlled at a constant temperature to improve the printing speed.

When the temperature is kept constant, the fixing speed is reduced to eliminate the cold offset of the envelope.

Next, the upper limit of the fixing temperature is limited based on the measurement result of the OHP upper limit, and the intersection of the envelope with the cold offset boundary line becomes the fixing speed limit.

When the sheet reaches the fixing device 19, the temperature of the fixing device fluctuates instantaneously due to the temperature difference.

When the fluctuation range of various types of paper, such as plain paper, envelopes, and OHP sheets, was measured, the temperature fluctuation was ± 5 to ± 5.
It was confirmed that the range was ± 7 degrees.

From these results, it can be seen from FIG.
Thus, the set center value of the fixing temperature may be set to 150 ° C. at 55 mm / sec, which is 1 / 1.8 of the fixing speed of plain paper.

In the case of the range of ± 5 degrees, the set center value of the fixing temperature should be 157 ° C. at 65 mm / sec, which is 1 / 1.6 of the fixing speed of plain paper.

Since this relationship is considered to be similar in a linear system, even when the fixing speed of plain paper is changed, the ratio of the optimum fixing speed to an envelope, an OHP sheet, or the like remains unchanged. I can say.

[0045]

According to the present invention, an envelope of a fixing device or an OH
The fixing speed to the P sheet can be improved, and the printing speed of the printing device can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view of a printing apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a fixing device showing one embodiment of the present invention.

FIG. 3 is a plan view of a fixing device showing one embodiment of the present invention.

FIG. 4 is a control block diagram of the printing apparatus showing one embodiment of the present invention.

FIG. 5 is a measurement graph showing a relationship between a fixing speed and a fixing temperature.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Developing device 1, 2 ... Developing device 2, 3 ... Developing device 3, 4 ... Developing device 4, 5 ... Optical unit, 6 ... Paper cassette 1, 8 ... Charging device, 10 ... Paper roller 1, 12 ... Registration roller, 1
3: transfer roller, 15: static eliminator, 18: discharge roller, 1
9: fixing device, 20: cleaner a, 21: transfer drum, 2
2: photosensitive belt, 23: cleaner b, 25: printing device main body, 27: paper, 28: discharge tray, 127: heating roller, 127-1, 128-1: cored bar, 127-2, 12
8-2: Silicon rubber, 128: Pressure roller, 129,
130 ... heater, 131 ... cleaning roller, 132
... Temperature sensor, 133 ... Oil application unit, 134 ...
Cleaning pad, 135: fuse, 136: unfixed toner image, 138: entrance guide, 139: guide, 140: discharge guide, 141: oil bottle, 14
2 ... oil supply felt, 143 ... oil blade, 1
44 ... Heating roller frame.

Continuing from the front page (72) Inventor Katsuyoshi Onose 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Prefecture Inside the Taga Headquarters, Electrification Equipment Division, Hitachi, Ltd. Inside Hitachi Mechanical Co., Ltd.

Claims (1)

[Claims] An image forming apparatus comprising: an optical device for forming a latent image; a charging device; a photosensitive device; a developing device for developing the latent image; and a fixing device. A first fixing speed for fixing plain paper and a second fixing speed for fixing an envelope or an OHP sheet are set, and the second fixing speed is set to 1 / 1.6 to 1 of the first fixing speed. A printing device characterized by being set in the range of /1.8.