JP2000314618A - Sheet surface roughness detecting device and image forming apparatus provided with the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect the roughness of a sheet surface with simple and small constitution by contacting a contact means on a conveyed sheet surface and detecting such physical phenomena as vibration and sliding sound with a roughness detection means. SOLUTION: A sheet surface detector 24 is constituted by pinching a piezoelectric vibration sensor (roughness detection means, piezoelectric element) 20 with a molded sensor base 21 and a precopy guide (contact means, support means) 17 as a sheet metal such as aluminum and the like. The precopy guide 17 smoothly guides a sheet P to a copy nip part formed on a touching part of a sensing drum 1 and a copy roller 8 and is arranged in the position bending the angle of the sheet P during coming in and out the precopy guide 17 for 5 degrees to change copy image quality and improve the resolution. With this constitution, the vibration energy receiving of the precopy guide 17 by the sheet P surface roughness concentrates on the piezoelectric vibration sensor 20 so that the roughness of the sheet P surface can be measured with good sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet surface roughness detecting device for detecting the surface roughness of a sheet, and a copying machine, an ink jet printer, a thermal head printer, a dot impact printer, and a laser printer provided with the device. , A facsimile, and an image forming apparatus such as a composite device thereof.

[0002]

2. Description of the Related Art Conventionally, image forming apparatuses include plain paper, postcards,
An image is formed on a sheet such as a cardboard, an envelope, or a thin plastic sheet.

An electrophotographic printer, which is an example of an image forming apparatus, forms a toner image on a sheet by an image forming unit, and then heats and presses the sheet on a fixing unit to fix the toner image on the sheet. ing.

[0004] In another example, an ink jet printer forms an image on a sheet using ink ejected from an ink jet head.

Further, another example of a thermal head printer forms an image on a sheet by thermal transfer using an ink ribbon and a thermal head.

[0006]

However, in the image forming apparatus, it is necessary to form an optimum image according to the surface roughness of the sheet due to diversification of sheets.

As a countermeasure, for example, in the case of the above-mentioned electrophotographic printer, the fixing temperature of the fixing means is adjusted by setting the fixing temperature of the sheet having a rough surface, assuming that an image is formed on a sheet having a relatively poor surface. It is set to match.

For this reason, the conventional image forming apparatus is capable of fixing an image reliably even when the fixing temperature is lower than that of a sheet having a rough surface. In the case of forming a toner image, the toner image is fixed at an unnecessarily high fixing temperature of the fixing means, and wasteful power is consumed.

In the case of the above-mentioned ink jet printer, the ejection amount of ink ejected from the ink jet head is set on the assumption that an image is formed on a sheet having a relatively rough surface.

For this reason, in the case of a conventional ink jet printer, when an image is formed on a sheet having a relatively smooth surface, the image can be surely formed even if the discharge amount of ink is smaller than that of a sheet having a rough surface. Ink was unnecessarily ejected, and the ink was wasted.

Further, in the case of the above thermal head printer, the power supply to the thermal head is set in accordance with the sheet having a smooth surface, assuming that an image is formed on a sheet having a relatively smooth surface.

For this reason, in the conventional thermal head printer, since the fixing temperature determines the power supply to the thermal head in accordance with the sheet having a smooth surface, the transferability of the ink to a sheet having a rough surface is inferior.

Accordingly, it is necessary to detect the roughness of the sheet surface and form an image based on the detected information.

However, conventionally, there has not been a sheet surface roughness detecting device provided in an image forming apparatus to reliably detect the surface of a sheet.

The present invention relates to a sheet surface roughness detecting device which can be used by being mounted on a main body of an image forming apparatus for forming an image on a sheet, and an image forming apparatus having the device mounted on the main body.

[0016]

According to the present invention, there is provided a sheet surface roughness detecting device comprising: a contact means for contacting a surface of a sheet being conveyed; and a vibration generated by the contact means contacting the sheet being conveyed. Roughness detecting means for detecting physical phenomena such as sliding noise to detect the roughness of the sheet surface.

The sheet surface roughness detecting device detects physical phenomena such as vibration and sliding noise caused by contact of the contacting means with the surface of the sheet being conveyed by the roughness detecting means.

When the sheet surface is rough, physical phenomena are large. When the sheet surface is smooth, physical phenomena are small. The roughness of the sheet surface is detected by detecting the physical phenomenon change by the roughness detecting means. The front surface includes both the front surface and the back surface.

In the sheet surface roughness detecting device according to the present invention, the roughness detecting means has a piezoelectric element for detecting vibration of the contact means.

In the above-described sheet surface roughness detecting device, when the sheet surface is rough, the contact means is greatly displaced. When the seat surface is smooth, the contact means is slightly displaced. This displacement is expressed as an electrical change by the piezoelectric element. By this electric change, the roughness of the sheet surface is detected.

In the sheet surface roughness detecting device of the present invention, the roughness detecting means has a microphone for detecting a sliding sound between the sheet and the contacting means.

In the above-described sheet surface roughness detecting device, when the sheet surface is rough, the sliding noise between the sheet and the contact means increases. When the sheet surface is smooth, the sliding noise between the sheet and the contact means is reduced. The sliding sound is collected by a microphone, and the roughness of the sheet surface is detected based on the magnitude of the sound.

In the sheet surface roughness detecting device of the present invention, the contact means is also used as a support means for supporting a part of the sheet.

In the above-described sheet surface roughness detecting device, the contact means supports a part of the sheet and surely contacts the sheet.

In the sheet surface roughness detecting device according to the present invention, a support means for supporting a part of the sheet is disposed downstream of the contact means in the sheet conveying direction.

In the above-described sheet surface roughness detecting device, a part of the sheet is supported by the support means, and the sheet is reliably brought into contact with the contact means by utilizing the bending of the sheet.

In the sheet surface roughness detecting device according to the present invention, the contact means and the support means are disposed on both sides of the sheet.

According to the image forming apparatus of the present invention, any one of the first to fourth sheet surface roughness detecting devices is passed through the sheet surface roughness detecting device and the sheet surface roughness detecting device. Image forming means for forming a toner image on the sheet, fixing means for fixing the toner image on the sheet by heating and pressing the sheet on which the toner image is formed in the image forming means, and sheet surface roughness Temperature control means for controlling the temperature of the fixing means in accordance with the type of sheet detected by the detection device.

According to the image forming apparatus of the present invention, any one of the first to fourth sheet surface roughness detecting devices is passed through the sheet surface roughness detecting device and the sheet surface roughness detecting device. Image forming means for forming an image on the sheet by discharging ink on the sheet, and ink discharge amount control for adjusting the discharge amount of the ink according to the type of the sheet detected by the sheet surface roughness detecting device Means.

According to the image forming apparatus of the present invention, any one of the first to fourth sheet surface roughness detecting devices is passed through the sheet surface roughness detecting device and the sheet surface roughness detecting device. Forming means for forming an image on the sheet with an ink ribbon and a thermal head, and power control means for controlling power supplied to the thermal head in accordance with the type of the sheet detected by the sheet surface roughness detecting device And

In the image forming apparatus of the present invention, a supporting means for supporting a part of the sheet is provided between the contact means and the image forming means.

In the image forming apparatus according to the present invention, the contact unit is in contact with an image forming surface of the sheet.

[0033]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIGS.

An image forming apparatus using electrophotography, which is an example of an image forming apparatus provided with a sheet surface roughness detecting device according to an embodiment of the present invention in a main body, will be described with reference to FIG.

An image forming apparatus using electrophotography is configured, for example, as shown in FIG.

Reference numeral P denotes a sheet of paper, reference numeral 1 denotes a photosensitive drum, reference numeral 2 denotes a charging roller, reference numeral 3 denotes a laser exposure device, reference numeral 4 denotes a reflection mirror, reference numeral 5 denotes a developing sleeve, and reference numeral 6 denotes a developing sleeve. Denotes a toner, 7 denotes a toner container, 8 denotes a transfer roller, 10 denotes a cleaning blade, 11 denotes a waste toner container, 12 denotes a fixing device,
Reference numeral 13 denotes a paper cassette, reference numeral 14 denotes a paper feed roller, reference numeral 15 denotes a separation pad, reference numeral 16 denotes a high-voltage power supply,
Reference numeral 24 indicates a sheet surface roughness detecting device.

The photosensitive drum 1 rotates in the direction of the arrow, and is uniformly charged by the charging device 2 supplied with a high voltage from the high voltage power supply 16. The laser light emitted from the laser exposure device 3 is reflected by the reflection mirror 4 and irradiates the photosensitive drum 1. Image information is formed on the photosensitive drum 1 as an electrostatic latent image.

The toner container 7 is filled with the toner 6, and an appropriate amount of the toner 6 is
Is supplied onto the photosensitive drum after receiving an appropriate charge.

The toner 6 on the developing sleeve 5 adheres to the electrostatic latent image on the photosensitive drum 1, and the latent image is developed and visualized as a toner image.

Paper feed roller 14 from paper cassette 13
Feeds the paper P one by one at a time. The separation pad 15 is arranged in contact with the paper feed roller 14,
The coefficient of friction, the contact angle, and the shape of the surface are adjusted so that only one sheet is fed each time paper is fed.

The paper fed from the paper feed roller 14 is guided by a transfer guide 17 to a contact portion between the photosensitive drum 1 and the transfer roller 8. In order to stabilize the behavior of the sheet, the sheet surface roughness detecting device 24 is provided at a position where the sheet surface roughness is always in contact with the sheet.

The visualized toner image on the photosensitive drum 1 is transferred onto a sheet by a transfer roller 8. The transfer residual toner remaining on the photosensitive drum 1 without being transferred is stored in a waste toner container 11 by a cleaning blade 10,
The photosensitive drum 1 whose surface has been cleaned repeatedly enters the next image forming process. Further, the paper P on which the toner image is formed is heated and pressed by the fixing device 12, and the toner image is permanently fixed. (First Embodiment) Next, the sheet surface roughness detecting device 24 will be described with reference to FIG.

The sheet surface roughness detecting device 24 includes a pre-transfer guide 17, a vibration / vibration sensor 20, a sensor base 21, and the like. The paper P is transported to the pre-transfer guide 17 by the paper feed roller 14 shown in FIG. 5 and a transport roller (not shown). The pre-transfer guide 17 includes the photosensitive drum 1 and the transfer roller 8.
Has a role of a guide member for smoothly guiding the sheet to the transfer nip portion formed at the abutting portion.

The pre-transfer guide 17 is made of a metal such as aluminum, a zinc-coated copper plate, and stainless steel, and is electrically grounded. The pre-transfer guide 17 may be integrated with the mold frame and insulated. From the viewpoint of the effects of the present invention, the pre-transfer guide 17 may be made of either a conductive material or an insulating material. However, from the viewpoint of image quality, it is preferable that the pre-transfer guide 17 has conductivity in order to remove static electricity from the paper.

The pre-transfer guide 17 also plays a role in adjusting the posture of the sheet entering the transfer nip. The transfer image quality changes depending on the angle at which the sheet enters, and in general, the resolution tends to be better when the sheet enters the transfer nip along the photosensitive drum 1. In the sheet surface roughness detecting device 24 of the present embodiment, the pre-transfer guide 17 is always arranged at a position where the pre-transfer guide 17 rubs against the non-printing surface side of the sheet during the conveyance of the sheet, and a part of the sheet entering the pre-transfer guide 17 is The angle formed by a part of the sheet exiting from the inter-transfer guide 17 is about 17
It is set to 5 degrees. In other words, the angle of the paper is about 5
It was arranged at the position where it was bent every degree.

The piezoelectric vibration sensor 20 has a diameter of about 18 m.
m, a commercially available piezoelectric element having a thickness of about 0.7 mm was used. Such a piezoelectric vibration sensor 20 may be simply fixed to a rubbing member such as the pre-transfer guide 17, but in order to measure vibration with higher sensitivity, the sheet surface roughness detecting device 24 of the present embodiment is The piezoelectric vibration sensor 20 is sandwiched between the molded sensor base 21 and the sheet metal pre-transfer guide 17.

With this configuration, the sheet surface roughness detecting device 24 concentrates the vibration energy of the pre-transfer guide 17 on the piezoelectric vibration sensor 20 and detects the vibration of the pre-transfer guide 17 that is in contact with the moving paper. The measurement can be performed with high sensitivity.

The weak output voltage from the piezoelectric vibration sensor 20 is amplified about 300 times by an operational amplifier which is a kind of an amplifier. A control circuit 25 having an operational amplifier controls the fixing temperature of the fixing device 12 based on the output voltage.

FIG. 6 shows the result of extracting only the AC component representing the vibration from the waveform of the output voltage from the piezoelectric vibration sensor 20 and measuring the AC power for nine types of paper.

The rough paper is a paper having a rough surface, and is a paper having a rough touch.

The unit of the vibration energy is an arbitrary unit [A.
U]. If the actual surface properties of the paper are poor, the vibration of the pre-transfer guide 17 increases when the paper rubs against the pre-transfer guide 17, so that the vibration energy is measured to be large. Also, when the basis weight of the paper is large, the thickness generally increases, and the rigidity of the paper increases.

The transport direction of the sheet P is bent by about 5 degrees by the pre-transfer guide 17, but if the rigidity of the sheet is high, the contact pressure between the pre-transfer guide 17 and the sheet increases, and the vibration increases.

When the temperature control of the fixing device 12 is fixed at the same temperature, the surface property is poor, that is, the rougher the surface, the worse the toner image fixing property is. Also, the larger the basis weight of the paper, the worse the fixability of the toner image tends to be. That is,
By measuring the vibration of the pre-transfer guide 17, it is possible to measure the ease with which the toner image can be fixed to the paper.

In FIG. 6, plain paper, recycled paper A, recycled paper B,
There is glossy paper. Also. Paper having poor surface properties, that is, paper having a rough surface includes rough papers A to D and envelopes.

Even if the fixing temperature of the fixing unit 12 is lowered, the paper on which the toner image is sufficiently fixed on the paper is plain paper, recycled paper A, and recycled paper B. Although the rough paper A has a low surface weight despite its low basis weight, the fixing temperature cannot be lowered.

FIG. 3 shows a graph of the values shown in FIG. From this figure, it is found that the threshold value A is set to about 9.6.
The above is a normal paper type, and it is possible to distinguish both types. By setting the threshold B at about 11.5, it is possible to identify a paper having a threshold B or more and particularly poor fixability.

In the sheet surface roughness detecting device 24 of the above embodiment, the piezoelectric vibration sensor 20 is attached to the pre-transfer guide 17.
However, if a fixing member other than the pre-transfer guide 17 slides with the sheet, the separation pad, the conveyance guide, the fixing entrance guide, the CRG container (container containing toner), the mylar (product) The same effect can be obtained by attaching a vibration sensor to a light-shielding body, a frame, or the like made of N.I.

The above-described sheet surface roughness detecting device can use an existing member such as a guide member as a diaphragm and is composed of inexpensive components such as a piezoelectric element and an operational amplifier. The device configuration can be realized with a simpler configuration and at lower cost than an optical detection device that detects the roughness of a sheet surface based on reflected light.

(Second Embodiment) Next, based on FIG.
A sheet surface roughness detecting device 26 according to another embodiment will be described.

Reference numeral 20 denotes a piezoelectric vibration sensor, reference numeral 22 denotes a base formed by molding, and reference numeral 23 denotes polyethylene terephthalate (PET, trade name “Mylar”).
Each of the rubbing members formed by is shown.

The sheet surface roughness detecting device 24 of the first embodiment
Although the pre-transfer guide 17 is in contact with the opposite side of the sheet from the printing surface, the second embodiment is more preferable from the viewpoint of detection accuracy in changing the fixing control depending on the type of paper in an electrophotographic printer. , A sheet surface roughness detecting device 26 is provided.

In the second embodiment, the rubbing member 23 comes into contact with the printing surface of the paper.

In general, one side of a sheet of paper is referred to as a wire side and the other side is referred to as a felt side at the time of manufacture. In the case of plain paper having a basis weight of about 60 to about 80 g / m ² , the felt surface is the front surface and often becomes the printing surface. Since the felt surface of the plain paper and the felt surface of the wire surface are smoother, the toner is more easily fixed on the front surface of the paper than on the back surface of the paper.

However, rough paper called rough paper is premised on the use of a fountain pen, and its surface is intentionally roughened in order to give a sense of quality. In such a sheet, the surface on the printing surface side is inferior to the surface on the non-printing surface side, and is a type of paper on which the toner is hardly fixed.

FIG. 7 shows the results of measuring the vibration energy on the printing surface and the non-printing surface of plain paper and rough paper by the sheet surface roughness detecting device 26 of the second embodiment.

From these results, it is clear that the plain paper has better surface properties on the printing surface side and the front surface is smooth,
There is little vibration when paper 3 rubs against paper. On the other hand, the rough paper has the opposite tendency, and the printing surface has poor surface properties, so that the vibration energy is large.

FIG. 4 shows a graph of the values shown in FIG. When the rubbing member 23 is provided on the side opposite to the printing surface, a margin A for distinguishing plain paper from rough paper is about 1.41.
On the other hand, when the rubbing member 23 is provided on the printing surface side, the margin increases to about 2.24, and the possibility of erroneous detection due to variations in sensors and papers is reduced.

This effect is particularly important in an image forming apparatus using a heat fixing device described below.

In a conventional electrophotographic image forming apparatus,
Since the fixing temperature was set so as to satisfy the fixing property on the printing surface side of the rough paper D, heat energy was given to the fixing unit more than necessary for plain paper. For example, in a conventional fixing device, in order to obtain sufficient fixability on rough paper, the temperature control temperature for cold start (normal temperature start) is set to about 190 degrees Celsius regardless of the type of paper.

According to the present invention, the type of paper is discriminated from the surface property of the printing surface side, and when it is determined that the paper is plain paper, the temperature control temperature of the cold start is set to about 170 degrees Celsius so that sufficient fixing can be performed on plain paper. The average power consumption during the start-up from the cold start to the target temperature control temperature can be reduced by about 12% while maintaining the performance.

Also, by lowering the temperature regulation temperature when the fixing unit is sufficiently warmed, the average power consumption is reduced from about 160 W to about 140 W, and it is possible to achieve an energy saving of about 20 W.

At this time, since the target temperature needs to be changed before the sheet enters the fixing device, it is necessary to arrange a rubbing member and a vibration sensor in the transport path before the sheet enters the fixing device.
The same effect can be obtained by changing the fixing control as well as by changing the power control in addition to the temperature control temperature change.

As shown in FIG. 8, instead of the piezoelectric vibration sensor 20, sound is sensed by a microphone 28 such as a condenser microphone, an electromagnetic pickup, a crystal microphone, or an electromagnetic microphone, and the fixing temperature of the fixing device 12 is adjusted. It may be controlled.

In this case, the main frequency component of the sound generated by the rubbing between the rubbing member and the paper is about 500 Hz or more and several kHz.
z or less, a commercially available microphone that can sense the sound in this band can be used to similarly place the paper near a member where vibration occurs due to sliding of the sheet, such as a guide member (not shown) that guides the sheet. Can be detected.

Further, the piezoelectric vibration sensor 20 is disposed relatively close to the photosensitive drum 1, and a leakage current of an AC high voltage such as a developing bias and a charging bias flows into the piezoelectric vibration sensor 20, and noise is added to the piezoelectric vibration sensor 20. In this case, the piezoelectric vibration sensor 20 is provided on a member remote from the photosensitive drum 1, the pre-transfer guide 17 is insulated from the piezoelectric vibration sensor 20, the base 22 is insulated from the piezoelectric vibration sensor 20, or the piezoelectric vibration sensor 20 is shielded. It is necessary to take noise countermeasures.

Further, the description has been given by taking the case of discriminating between plain paper and rough paper as an example. However, special paper such as transparency sheet and label paper can also be discriminated. Instead, the detection of special paper can be performed in a similar manner.

When the above-mentioned sheet surface roughness detecting device is used, not only an electrophotographic printer but also an ink jet printer discriminates between special paper and plain paper or OHP paper (paper used for an overhead projector) to determine the ink ejection amount. Can be changed.

That is, as shown in FIG. 9, the ink jet printer 100 picks up the sheet P stacked on the sheet stacking tray 101 by the pickup roller 102 and then discharges the ink from the ink jet head 104 while conveying the sheet P by the conveying belt 103. Thus, an image is formed on the sheet P, and the sheet is discharged to the discharge tray 106.

When the ink jet printer 100 sends out the sheets in a stack from the sheet stacking tray 101,
The sheet is separated and fed by a sheet separation roller pair 105.

The sheet P fed from the sheet stacking tray 101 is detected by the sheet surface roughness detecting device 26 for the sheet surface roughness. Then, the control circuit 27 controls the amount of ink ejected from the inkjet head according to the roughness of the sheet surface. That is, control is performed such that the ink ejection amount is large when the sheet surface is rough, and reduced when the sheet surface is smooth.

The ink jet head 104 is composed of four color heads of yellow, magenta, cyan and black.

Further, even when the sheet surface roughness detecting device 24 of the first embodiment is used, the ink discharge amount can be controlled similarly.

Further, when the above-mentioned sheet surface roughness detecting device is used, a plain paper, an O
The sublimation amount of the ink can be changed according to the sheet such as HT (overhead transparency).

That is, as shown in FIG. 10, the thermal head printer 200 has a ribbon 205 and ink sheet 204 having a film 203 with ink 204 interposed between a guide plate 201 and a thermal head 202,
The ink 204 is thermally transferred to the sheet P by the heat of the thermal head 202 while simultaneously moving the sheet 05 and the sheet P, thereby forming an image on the sheet.

In this case, a sheet surface roughness detecting device 24 is disposed on the upstream side in the sheet conveying direction, and the sheet surface roughness detecting device 24 detects the surface roughness of the sheet. The power to be supplied to the thermal head 202 can be set according to the surface roughness of the sheet.
That is, when the surface of the sheet is rough, the power supplied to the thermal head 202 is increased and the viscosity of the ink is reduced, whereby good transferability can be obtained even with a rough sheet. When it is smooth, it can be adjusted to reduce it.

Further, even when the sheet surface roughness detecting device 26 of the second embodiment is used, the power supplied to the thermal head 202 can be controlled in the same manner.

[0087]

The sheet surface roughness detecting device according to the present invention comprises:
Physical phenomena such as vibration and sliding noise generated when the contact means comes into contact with the surface of the sheet being conveyed are detected by the roughness detecting means, so that the roughness of the sheet surface can be easily and compactly measured. With the configuration described above, it is possible to reliably detect.

In the sheet surface roughness detecting device of the present invention,
If a supporting means for supporting a part of the sheet is provided downstream of the contacting means in the sheet conveying direction, the sheet is surely brought into contact with the contacting means by utilizing the bending of the sheet, and the sheet surface roughness detecting device detects the sheet. Accuracy can be improved.

The image forming apparatus of the present invention has the above-described sheet surface roughness detecting device having a simple and compact structure.
The fixing temperature of the fixing means, without increasing the size of the entire apparatus,
By controlling the amount of ink ejected and the power supplied to the thermal head in accordance with the roughness of the sheet surface, a high-quality image can be formed.

Further, it is not necessary to raise the temperature of the fixing means unnecessarily, so that power consumption can be reduced.
The maintenance cost of the image forming apparatus can be reduced.

Further, it is possible to prevent unnecessary discharge of ink, to reduce consumption of ink, and to reduce maintenance cost of the image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a front view of a sheet surface roughness detecting device according to a first embodiment of the present invention.

FIG. 2 is a front view of a sheet surface roughness detecting device according to a second embodiment of the present invention.

FIG. 3 is a graph showing data of each type of sheet detected by the sheet surface roughness detecting device according to the first embodiment of the present invention.

FIG. 4 is a graph showing data of each type of sheet detected by the sheet surface roughness detecting device according to the first and second embodiments of the present invention.

FIG. 5 is a schematic front sectional view of an image forming apparatus including the sheet surface roughness detecting device according to the first embodiment of the present invention.

FIG. 6 is a diagram showing numerical data of each type of sheet detected by the sheet surface roughness detecting device according to the first embodiment of the present invention.

FIG. 7 is a diagram showing numerical values of data of each type of sheet detected by the sheet surface roughness detecting device according to the first and second embodiments of the present invention.

FIG. 8 is a front view of a sheet surface roughness detecting device according to another embodiment.

FIG. 9 is a schematic front sectional view of an ink jet printer including a sheet surface roughness detecting device according to a second embodiment.

FIG. 10 is a front view of a main part of a thermal printer including the sheet surface roughness detecting device according to the first embodiment.

[Explanation of symbols]

P sheet 1 Photosensitive drum (image forming means) 3 Laser exposure device 6 Toner 7 Toner container 8 Transfer roller 9 Image forming device 12 Fixing device (Fixing device) 13 Paper cassette 17 Guide before transfer (Contact device, Supporting device) 20 Piezoelectric vibration Sensor (roughness detecting means, piezoelectric element) 21 sensor base 22 base 23 rubbing member (contact means) 24, 26 sheet surface roughness detecting device 25, 27 control circuit (temperature control means, ink ejection amount control means) , Power control means) 28 Microphone (roughness detecting means) 100 Inkjet printer (image forming apparatus) 104 Inkjet head (image forming means) 200 Thermal head printer (image forming apparatus) 202 Thermal head (image forming means) 203 Film 204 ink 205 ribbon

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) 9A001 F term (reference) 2C061 AP03 AP04 AP07 AQ01 AQ04 AQ05 AQ06 BB10 HH03 HJ01 HK07 HK11 2F062 AA66 AA99 BB14 BC08 CC23 CC30 EE13 EE62EE HH05 HH14 JJ04 2F069 AA57 BB20 CC06 DD16 DD19 GG01 GG06 GG52 GG62 HH02 JJ13 LL03 2H027 DA32 DC02 DE03 DE04 DE07 EA12 ZA07 2H033 AA02 AA18 AA47 CA01 CA30 9A001 BB06 HH35 KK35 KK35KK

Claims (11)

[Claims] A contact means for contacting a surface of a sheet being conveyed; and a physical phenomenon such as a vibration and a sliding sound generated when the contact means comes into contact with the sheet being conveyed. A sheet surface roughness detecting device, comprising: a surface roughness detecting means for detecting a surface roughness. 2. The sheet surface roughness detecting device according to claim 1, wherein said roughness detecting means has a piezoelectric element for detecting vibration of said contact means. 3. The sheet surface roughness detecting device according to claim 1, wherein said roughness detecting means has a microphone for detecting a sliding sound between said sheet and said contacting means. 4. The sheet surface roughness detecting device according to claim 1, wherein said contacting means is also used as a supporting means for supporting a part of said sheet. 5. A rough sheet surface according to claim 1, wherein a supporting means for supporting a part of the sheet is disposed downstream of the contact means in a sheet conveying direction. Detector. 6. The sheet surface roughness detecting device according to claim 5, wherein said contact means and said support means are arranged on both sides of said sheet. 7. A sheet surface roughness detecting device according to claim 1, wherein said sheet surface roughness detecting device forms a toner image on a sheet passing through said sheet surface roughness detecting device. Fixing means for heating and pressing the sheet on which the toner image is formed in the image forming means to fix the toner image on the sheet; and a type of sheet detected by the sheet surface roughness detecting device. An image forming apparatus comprising: a temperature control unit configured to control a temperature of the fixing unit. 8. The method according to claim 1, wherein:
The sheet surface roughness detection device according to the item, an image forming unit that forms an image on the sheet by discharging ink onto a sheet that has passed through the sheet surface roughness detection device, and the sheet surface roughness detection device An ink discharge amount control unit that adjusts the discharge amount of the ink in accordance with the detected type of the sheet. 9. Any one of claims 1 to 4,
The sheet surface roughness detection device according to any one of the preceding claims, an image forming unit that forms an image on a sheet passing through the sheet surface roughness detection device by a thermal head, and the sheet detected by the sheet surface roughness detection device And an electric power control means for controlling electric power supplied to the thermal head according to the type of the image forming apparatus. 10. The image forming apparatus according to claim 6, wherein a support unit for supporting a part of the sheet is provided between the contact unit and the image forming unit. 11. The image forming apparatus according to claim 8, wherein the contact unit is in contact with an image forming surface of the sheet.