JP2002072754A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus of which the throughput can be increased as much as possible when a recording material of small width is fed from a detachable paper feeder. SOLUTION: In a printer having a fixing apparatus provided with two heating bodies 133 and 134 which are different in length, an envelope paper feed option 114 is made detachable, and a paper width sensor 112 provided in the printer main body selects the two heating bodies 133 and 134. The envelope paper feed option 114 is provided with a paper width sensor 137 and the number of prints per unit time is made different according to whether or not the paper width sensor 137 detects a fed envelope.

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 for fixing a toner image transferred onto a recording medium by a heat fixing device, and has an image forming apparatus having a feeding device which is detachable from an image forming apparatus main body. About.

[0002]

2. Description of the Related Art In a conventional image forming apparatus using an electrophotographic process, a latent image formed by exposing a photosensitive drum such as a latent image carrier to image light is developed with toner of a developing means, and a visible image is developed. The unfixed toner image obtained by transferring the converted toner image to the recording paper via the transfer unit is fixed on the recording paper by the heat fixing device.

As a heat fixing device of an image forming apparatus, a heat fixing device of a heat roller type using a halogen heater or the like as a heat source,
A heat fixing device of a film heating type is used in which a heater having a planar (linear) heating element provided on a ceramic substrate is used as a heat source and a pressure roller is brought into pressure contact with the planar heating heater via a heat-resistant film. ing.

In recent years, with the increase in print speed,
The power supplied to the heat source is also increasing. Along with this,
The number of heating elements as a heat source is also increasing from one to a plurality.

Generally, in the case of a heat fixing type image forming apparatus, an A4 size width (210 mm) and a Letter size width (215.9) are used.
Ii) For paper having a width larger than that, printing can be performed at the maximum printing speed of the apparatus (minimum sheet interval determined by the apparatus).

However, in the case of narrow paper (for example, envelopes, postcards, etc.), the temperature at the end of the heating body is significantly higher than that at the center of the heating body.

Therefore, in the case of a sheet having a narrow width, it is necessary to perform control such as reducing the number of prints per unit time or reducing the number of prints according to the number of continuous prints.

In order to prevent a decrease in the number of printed sheets per unit time when printing a sheet of narrow width, the sheet width is detected by a sheet width sensor, and two heaters are used. In some cases, the heating element is switched according to the result detected by the paper width sensor to perform fixing.

[0009]

However, the following problems have been pointed out in the conventional image forming apparatus.

[0010] For paper determined to be narrow,
Even if a heating element having a short size in the longitudinal direction is used, the paper width sensor does not recognize the paper width as a numerical value, but recognizes whether the paper width is wider or narrower than a predetermined width, and therefore cannot determine how narrow the paper width is. However, there is a risk that the temperature at the end of the heating element with a short size in the longitudinal direction may significantly increase, so it is necessary to control the number of prints per unit time even for all wide paper. Had become.

Furthermore, in an apparatus that feeds only narrow paper in general, such as an envelope feeding option and a postcard feeder, it is necessary to always reduce the number of prints per unit time. It was also considered to invite.

An object of the present invention is to provide an image forming apparatus capable of improving the number of printed sheets as much as possible even when paper having a small size is fed.

[0013]

According to a first aspect of the present invention, there is provided an image forming means for transferring an unfixed visible image to a recording medium fed from a paper feeding unit, and a main unit for heating and fixing the unfixed image on the recording medium. A fixing device including a plurality of heating elements having different lengths in a scanning direction; a first sensor configured to detect whether a width of a recording medium conveyed to the fixing device corresponds to any of the plurality of heating elements; A second sensor for detecting a width of the recording medium fed from the paper feeding unit in an area narrower than the first sensor; and selecting the plurality of heating elements based on a detection signal from the first sensor. In addition, the present invention provides an image forming apparatus having control means for controlling the number of prints per unit time based on detection signals from the first and second sensors.

According to a second aspect of the present invention, in the first aspect, one of the second sensors is provided at a position narrower than the heating element having a minimum length.

According to a third aspect of the present invention, in the first aspect, a plurality of the second sensors are provided at different positions narrower than the heating element having a minimum length.

According to a fourth aspect of the present invention, in any one of the above-mentioned inventions, the control means receives a signal indicating that a recording medium is present from the second sensor and a signal indicating that no recording medium is present from the first sensor. It is characterized in that it is determined to be abnormal.

In a fifth aspect based on the fourth aspect, the control means interrupts the printing operation when the control means determines that there is an abnormality.

According to a sixth aspect of the present invention, in any one of the above aspects, the paper supply unit is a paper supply device that is detachable from the image forming apparatus main body.

According to a seventh aspect of the present invention, in any one of the above-mentioned aspects, the second sensor is provided in the sheet feeding section.

[0020]

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention and is a diagram showing a conceptual configuration of an image forming apparatus using an electrophotographic process. Is represented.

In the image forming apparatus main body shown in FIG.
Reference numeral 00 denotes a process cartridge detachable from the main body of the image forming apparatus. Inside the process cartridge 100,
A photosensitive drum 102 for forming an electrostatic latent image; a charging roller 111 for uniformly charging the photosensitive drum 102; and a toner for developing an electrostatic latent image formed on the photosensitive drum 102 with a laser beam. Developing device 110 is provided.

Reference numeral 101 denotes a scanner unit, which scans a laser beam obtained by converting image light into an on / off signal onto a photosensitive drum 102 (main scanning is performed in the axial direction of the photosensitive drum 102, and scanning is performed in the circumferential direction). (Referred to as sub-scanning). Reference numeral 103 denotes a transfer roller charger for transferring the toner image formed on the photosensitive drum 102 to a predetermined sheet, 104 denotes a fixing unit that dissolves the toner image on the sheet and fixes it on the sheet, and 106 denotes a toner image fixed. A roller for discharging the discharged paper outside the machine; 105, a discharge sensor for detecting that the paper has passed through the fixing device 104; 107, a registration sensor for detecting the leading edge of the paper; and 109, a paper size on which the paper is stacked Reference numeral 108 denotes a paper feed roller for feeding paper to the photosensitive drum 102 side.

Reference numeral 112 denotes a paper size (paper width) in the main scanning direction.
Is a sensor for detecting paper feed, 113 is a manual feed port, 11
Reference numeral 4 denotes a paper feeding device that can be attached to and detached from the image forming apparatus main body (here, an envelope paper feeding option). The fixing unit
Reference numeral 104 denotes a film heating type fixing device using a heater provided with a planar heating element on a ceramic substrate (referred to as a ceramic surface emitting heater). The ceramic substrate has a temperature detecting surface on a surface opposite to a surface on which the heating element is formed. Is provided.

FIG. 2 is a block diagram showing the configuration of the engine control unit 130 according to the present embodiment.

Reference numeral 131 denotes a ceramic surface heater provided inside the fixing device 104. The thermistor 132 detects the surface temperature of the ceramic heater 131, and a first thermistor 132 is formed on a ceramic substrate and generates heat when AC is supplied. A heating element 133 formed on a ceramic substrate;
And a second heat generating element 134 that generates heat by energizing.

Reference numeral 135 denotes an envelope feed option control unit for controlling the envelope feed option 114; 136, a paper presence / absence sensor of the envelope feed option 114; and 137, a paper width sensor of the envelope feed option.

Reference numeral 138 denotes another sheet feeding device, such as a large-volume sheet feeding cassette option.

The engine control unit 130 and the envelope feed option control unit 135 communicate with each other through four signal lines. Only when the Opt1-SEL signal becomes “true”, the envelope feed option control unit 135 can communicate with the engine control unit 130. The CMD signal represents a command from the engine control unit 130 to the envelope feed option control unit 135, and includes a reset command, a feed start command, and the like. ST
The S signal is a signal that informs the engine control unit 130 of the state of the envelope paper feed option 114 and the paper presence sensor 136.
And the status of the paper width sensor 137 are returned as a status. CLKCMD signal is CMD
It is used as a synchronous clock when transmitting and receiving signals and STS signals.

This communication method is similarly applied to other sheet feeding options.

Next, the control performed by the engine control unit 130 in this embodiment will be described with reference to FIG.

In FIG. 3, reference numeral 139 denotes a sheet stacked on the envelope feed option 114, and reference numeral 140 denotes a feed roller of the envelope feed option 114.

FIG. 4 is a plan view showing the arrangement of each part in FIG. 3 in a plan view.

In FIG. 4, reference numeral 133 denotes a length in the longitudinal direction.
Reference numeral 134 denotes a first heating element which is slightly longer than the Letter paper width (2159.9 mm). Reference numeral 134 denotes a second heating element which has a shorter longitudinal length than the first heating element 133. ing. The length of the second heating element 134 is usually
It is about paper width (182 mm). Reference numeral 132 denotes a thermistor for detecting the temperature of the ceramic heater 131, which can be arranged on either the surface on the heating body side or the opposite surface.

The paper width sensor 112 of the image forming apparatus main body is
Heating element 1 outside the width of heating element 2 in the main scanning direction
It is arranged inside the width of.

Paper width sensor 1 of envelope feed option 114
37 is disposed inside the width of the second heating body 134 with respect to the main scanning direction. The specific position is such that when a sheet having a width smaller than the width of the second heating body 134 is continuously printed at the maximum throughput (minimum sheet interval) of the image forming apparatus,
The end of the second heating element 134 is set at a paper width position that is a boundary of whether or not the temperature rise is satisfied.

When the engine controller 130 receives a print signal after the envelope feed option 114 is designated as a paper feed port from a printer controller (not shown), the engine controller 130 sends a paper feed command to the envelope feed option controller 135. I do.

The envelope feed option control unit 1 receiving this message
35 drives the paper feed roller 140, and the loaded paper 1
39 is started. When the sheet is conveyed and the sheet width is wide, this is detected by the sensor 137, and
The envelope paper feed option control unit 135 recognizes that the paper is wide.

After a predetermined time from the start of sheet feeding, the engine control unit 130 receives an STS signal transmitted from the envelope sheet feeding option control unit 135 to the engine control unit 130, and
Paper width sensor 13 provided in envelope feed option 114
7 are obtained.

When a toner image is formed on the sheet by the photosensitive drum 102 and the transfer roller 103, and the time when the leading edge of the sheet reaches the sheet width sensor 112 of the image forming apparatus main body (a predetermined time from the start of sheet feeding) is reached. , The detection result of the sensor 112 is determined. The judgment result here is that the paper width =
If it is determined that the sheet is “narrow”, even if continuous printing is performed between the minimum sheets, the temperature of only the end portion of the second heating body 134 does not rise significantly, so that the engine control section sets the maximum through Print at the top.

As described above, in the present embodiment, the paper width sensor 137 is provided further inside the position of the paper width sensor 112 of the image forming apparatus main body with respect to the paper feeder of the image forming apparatus. Even when printing on narrow paper, high-speed printing can be performed as much as possible.

(Embodiment 2) FIG. 5 is a view showing Embodiment 2 of the present invention. The difference from FIG. 4 is that a second sensor 140 for detecting the paper width is provided for the envelope feeding option 114. Is further provided.

From the envelope feed option 114, an envelope,
There is a mail merge mode for sequentially printing three types of postcards and documents as one set. These three types of paper are different from each other.

In the present embodiment, by providing the second sensor 140, which is the second paper width sensor, in the envelope paper feed option, it is possible to perform printing at such a high speed as possible even for continuous printing with different paper widths. The purpose is to print.

If the engine control unit determines that the paper fed from the envelope feed option has a paper width narrower than that of the second sensor 140, the interval for feeding the next paper is maximized. .

When the width of the fed paper is between the first sensor 137 and the second sensor 140, the width is wider than the maximum paper interval at the maximum throughput and smaller than the maximum paper interval.

As described above, by providing the second sheet interval,
Further, the paper width can be detected with high accuracy, and as a result, printing can be easily performed at a throughput corresponding to the paper width.

(Embodiment 3) The present embodiment relates to the detection of a device abnormality.

The engine control unit 130 shown in FIG. 2 uses the STS signal from the envelope feed option 114 to control the paper width by the paper width sensor of the envelope feed option 114 after a predetermined time from the start of feeding the envelope feed option 114. Recognize whether it is wide or narrow.

It is assumed that the result is that the paper width = “narrow”.

Next, after a predetermined time has elapsed from the start of paper feeding of the envelope paper feeding option 114, the paper width sensor 1 of the image forming apparatus main body.
Twelve detection results are determined. As a result, the paper width = “wide”
Assume that

In this case, it can be clearly determined that there is an abnormality in the apparatus.

For example, the paper width sensor 112 and the paper width sensor 1
It is conceivable that one of the paper width sensors 37 failed. Under such circumstances, the engine control unit 130 cannot determine an accurate sheet width, and therefore, the fixing of the toner image can be performed using either the first heating body 133 or the second heating body 134. I can't judge whether to do it.

It is also conceivable that the sheet is skewed, and as a result, there is a possibility that a jam state that is difficult to remove occurs.

Therefore, in such a case, the engine control unit 130 interrupts the printing operation and stops driving the apparatus. At the same time, the operation panel or the printer controller may be notified that the image forming apparatus is in such a situation.

[0055]

According to the first aspect of the present invention, when the second sensor detects the absence of the recording medium, and when the second sensor detects the presence of the recording medium, the first sensor detects the absence of the recording medium. Since the difference in the width of the recording medium can be discriminated from the case, the number of prints per unit time can be made different, and the throughput of the small size width can be improved as much as possible.

Further, as in the invention according to claim 3, the second
By providing a plurality of sensors at different positions narrower than the heating element having the minimum length, the number of printed sheets per unit time can be further finely varied, and the throughput of the small size width can be further improved as much as possible. It can be improved.

According to the fourth and fifth aspects of the invention, it is possible to detect an abnormality in the apparatus such as an abnormality in the paper feeding state, and to interrupt the printing operation.

According to the sixth and seventh aspects of the present invention,
A sensor is provided for detecting the paper width in a paper feeding device that is detachable from the image forming apparatus main body, and this sensor position is arranged at a position different from the position of the paper width sensor of the image forming apparatus main body in the main scanning direction. In addition, the throughput of the small size width, which has been reduced only by the image forming apparatus main body, can be improved as much as possible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a control block diagram of the image forming apparatus of FIG.

FIG. 3 is a schematic diagram of a transport system from an envelope feeding option to a fixing device in FIG. 1;

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a plan view of a transport system from an envelope feeding option to a fixing device according to the second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Process cartridge 101 Scanner unit 102 Photoconductor drum 111 Charging roller 110 Developing device 103 Transfer roller charging device 104 Fixing device 106 Roller 105 Discharge sensor 107 Registration sensor, 109 Cassette 108 Paper feed roller 112 Sensor 113 Manual feed port 114 Paper feed device (Envelope feed option) 130 Engine control unit 131 Ceramic surface heater 132 Thermistor 133 First heating element 134 Second heating element 135 Feed option control unit 136 Paper presence sensor 137 Paper width sensor

Claims (7)

[Claims] An image forming unit configured to transfer an unfixed visible image to a recording medium fed from a paper feeding unit; and a plurality of heat sources having different lengths in a main scanning direction for heating and fixing the unfixed image onto the recording medium. A first sensor for detecting whether a width of a recording medium conveyed to the fixing device corresponds to one of the plurality of heating elements, and a recording sheet fed from the sheet feeding unit. A second sensor for detecting the width of the medium in an area smaller than the first sensor, and selecting the plurality of heating elements based on a detection signal from the first sensor; An image forming apparatus comprising: a control unit that controls the number of printed sheets per unit time based on the detection signal of (1). 2. The image forming apparatus according to claim 1, wherein one of the second sensors is provided at a position narrower than the heating element having a minimum length. 3. The image forming apparatus according to claim 1, wherein a plurality of the second sensors are provided at different positions narrower than the heating element having a minimum length. 4. The apparatus according to claim 1, wherein the control unit determines that an abnormality is detected when a signal indicating that a recording medium is present is input from the second sensor and a signal indicating that there is no recording medium is input from the first sensor. An image forming apparatus according to any one of claims 1 to 3. 5. The image forming apparatus according to claim 4, wherein the control unit interrupts the printing operation when it determines that there is an abnormality. 6. The image forming apparatus according to claim 1, wherein the paper feeding unit is a paper feeding device that is detachable from a main body of the image forming apparatus. 7. The image forming apparatus according to claim 1, wherein the second sensor is provided in the sheet feeding unit.