JPH115649A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate the kind of paper at a high speed and correctly so as to respond to the high-speed image forming process of an image forming apparatus body by judging the kind of paper according to the comparison between the detected driving torque and driving time with paper kind data stored in a storage means. SOLUTION: When paper sheets are stacked in a cassette and the cassette is installed in an image forming apparatus body, a lift motor is rotated, the rotation is transmitted to a torque detecting means 2, a gear 3, the lift torque is detected by the torque detecting means 2, and the rotation time of the lift motor is detected by a rotation time clocking means. The rotation time and a lift torque signal obtained by the detection are inputted to a control device, and the relational data is operated by a CPU of the control device. Thus obtained relational data is compared with the lift motor rotation time and the lift torque stored in a memory by the CPU, whereby the paper is automatically discriminated between plain paper and OH sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder of an image forming apparatus represented by an electrophotographic apparatus such as a copying machine, an LBP, a facsimile and the like.

[0002]

2. Description of the Related Art FIG. 10 shows an example of an image forming apparatus. In the figure, reference numeral 100 denotes an image forming apparatus main body, and 101 denotes a photosensitive drum, which is driven to rotate at a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow in the figure.

An original 110 is scanned by an optical lamp 102 and mirrors 103, 104, 105, 106, 10
The reflected light (hereinafter, image exposure) is bent by 7 and 108, and is irradiated on the photosensitive drum by the lens 109 so that the light is focused on the photosensitive drum. As a result, a latent image is formed on the photosensitive drum, and is then developed by the developing device 122 as a toner image. An image forming unit is formed by a photosensitive drum, a developing device, and the like.

On the other hand, a transfer material such as plain paper is stacked in a paper feed cassette 114 as transfer material stacking means.
Are separated and fed one by one by a pickup roller 121 and a separation roller pair 111, and are conveyed to a registration roller pair 113 by a conveyance roller pair 112. The transfer material S is sent to the transfer section 115 by the registration roller pair 113 at a timing when the leading end of the image on the photosensitive drum coincides with the leading end of the transfer material, and the toner image on the photosensitive drum is transferred onto the transfer material S.

The transfer material S onto which the toner image has been transferred is conveyed to the fixing device 117 by the conveying device 116, and the toner image on the transfer material is fixed on the transfer material by the heat and pressure of the fixing roller pair. Thereafter, the transfer material is separated from the fixing roller by the separation claw 118, and is discharged to the outside of the image forming apparatus main body by the discharge roller 119.

Incidentally, recent copying machines are required to support not only plain paper but also various kinds of materials such as OHP sheets and cardboard. In particular, OHP sheets are frequently passed through at a considerable frequency due to an increase in presentation opportunities and their importance.

However, the OHP sheet is different from ordinary plain paper, is made of PET (polyethylene terephthalate), and has a thickness different from that of plain paper. Specifically, the image process sequence represented by the transfer current and fixing conditions (specifically, fixing speed, fixing temperature, etc.) is changed from that of plain paper to obtain an optimal image regardless of the type of paper. Is controlled so that

For this reason, the paper to be conveyed is plain paper or OH
The image forming apparatus needs to be able to determine whether the sheet is a P sheet. As the method, a method in which a user inputs a paper type to be passed through an operation unit of the image forming apparatus, a method in which a sensor provided in the image forming apparatus automatically determines a paper type, and the like are generally used.

FIG. 11 and FIG. 12 show examples of the structure for automatic discrimination. FIG. 11 shows a case where a transmission type sensor 140 is provided, and a sheet passes between them. In this case, a band 142 such as white is colored at the tip of the OHP sheet 141,
The width of the band is detected by a transmission type sensor to determine whether the sheet is an OHP sheet or plain paper.

FIG. 12 shows another example, in which a transmission type sensor 140 is used.
And a sensor 143 with a lever-type actuator. In this case, when plain paper is passed, both the transmission type sensor 140 and the sensor with lever type actuator 143 detect the sheet. But OHP
When the sheet is passed, the sensor 143 with the lever-type actuator detects the sheet, but the transmission-type sensor 1
No. 40 cannot be detected because the sheet is transparent.

That is, when the sheet passes through the transmission type sensor 14,
Whether the sheet is plain paper or an OHP sheet is determined based on the presence or absence of the detection of 0.

These automatic discriminating units are generally arranged near the conveying rollers for stably conveying the sheet (indicated by 123 in FIG. 10).

[0013]

However, in recent years,
There is a demand for downsizing and speeding up of the apparatus. As a result, the conventional example has the following disadvantages.

When the paper is conveyed at a high speed in accordance with the decrease in the distance from the automatic discrimination unit to the transfer unit for plain paper and OHP sheets, the time from the automatic discrimination unit to the transfer unit is reduced. And the result of the automatic discrimination may not be fed back to the change of the transfer condition in time.

Therefore, an object of the present invention is to automatically determine the type of paper in a cassette in which a large number of papers are stacked and stored,
The result is fed back to transfer conditions, fixing conditions, and the like, so that an optimum image can be obtained while achieving miniaturization and high speed of the apparatus and irrespective of the type of paper.

[0016]

According to a first aspect of the present invention, there is provided an image forming section for forming an image on a sheet, a feeding means for feeding the sheet to the image forming section,
An image forming apparatus main body including a push-up member driven by a driving unit; and a sheet fed by the feed unit mounted on a sheet mounting unit pushed up by the push-up member, and detachably attached to the apparatus main body. A driving torque detecting means for detecting a driving torque of the driving means, a driving time detecting means for detecting a driving time of the driving means, and a relation between the driving torque and the driving time. It is characterized by having storage means for storing paper type data, and judging means for judging the paper type by comparing the detected drive torque and driving time with the paper type data stored in the storage means. According to a second aspect of the present invention, the driving time is such that the sheet stacking unit with the replenished sheets is mounted on the image forming apparatus main body, and the sheet stacking unit is moved from the lowermost position to a position where the upper surface of the sheet can be fed by the feeding unit. It is characterized in that it is the time for being pushed up by the pushing up member.

A third aspect of the present invention is characterized in that the driving means comprises a driving motor and a gear train, and the torque detecting means is arranged in the gear train.

According to a fourth aspect of the present invention, there is provided an image forming apparatus including an image forming unit for forming an image on a sheet, a feeding unit for feeding the sheet to the image forming unit, and a push-up member driven by the driving unit. An image forming apparatus, comprising: a main body; and a sheet stacking unit configured to mount a sheet fed by the feeding unit on a sheet stacking unit pushed up by the push-up member and to be detachably attached to the apparatus main body. A light emitting means for emitting light toward the upper surface of the sheet in the sheet stacking means, and a light receiving means for receiving reflected light emitted from the light emitting means and reflected from the upper surface of the sheet in the sheet stacking means. And

A fifth aspect of the present invention is characterized in that the light receiving means is slightly deviated from regular reflection light emitted from the light emitting means and reflected from the sheet surface.

According to a sixth aspect of the present invention, there is provided an arithmetic means for calculating a ratio between the amount of light emitted from the light emitting means and the amount of light received by the light receiving means, and a paper corresponding to the ratio between the amount of light emitted and the amount of light received. Storage means for storing the seed data; and determining means for determining the paper type by comparing the ratio between the light emission amount and the received light amount calculated by the calculating means and the paper type data stored in the storage means. I do.

According to a seventh aspect of the present invention, there is provided an image forming apparatus including an image forming unit for forming an image on a sheet, a feeding unit for feeding the sheet to the image forming unit, and a push-up member driven by a driving unit. An image forming apparatus comprising: a main body; and a sheet stacking unit configured to mount a sheet fed by the feeding unit on a sheet stacking unit pushed up by the push-up member and to be detachably attached to the apparatus main body. A driving torque detecting means for detecting a driving torque of the driving means, a driving time detecting means for detecting a driving time of the driving means, a light emitting means provided near a front portion of the feeding means or the sheet stacking means, and a light emitting means for emitting light. A light receiving means for receiving the reflected light reflected from the upper surface of the sheet, and calculating a relational data between a product of a ratio of a light emission amount and a light receiving amount, a driving torque of the driving means and a driving time of the driving means. And calculation means, and having storage means for storing the relationship data, a determination means for determining the contrast to paper type relationships data stored on the calculated relation data storage means.

According to an eighth aspect of the present invention, the means for determining the paper type based on the relational data of the product of the ratio of the light emission amount and the light reception amount, the drive torque and the drive time of the drive unit in the seventh invention, Means for determining the paper type from the relation data between the driving torque and the driving time of the driving means as second determining means;
The first judging means and the second judging means are switched and used depending on the sheet stacking amount of the sheet stacking means.

A ninth aspect of the present invention is characterized in that there is provided a control means for controlling an image forming process sequence in accordance with the determination of the paper type by the determination means.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a view showing a first embodiment of the present invention, and is a schematic sectional view of a cassette portion.

In the figure, 1 is a lifter motor, 2 is a torque detecting means, 3, 4, 5, and 6 are gears, 7 is a push-up member, 8 is a cassette as a transfer material loading means, 9 is paper as a transfer material,
Reference numeral 10 denotes a middle plate on which the transfer material is placed, and reference numeral 11 denotes a rotating shaft of the push-up member 7 having a plate shape.

The user sets paper 9 in the cassette 8,
When the cassette 8 is mounted on the main body of the image forming apparatus, the control device starts rotation of the lifter motor 1 based on a detection signal of a cassette detection sensor (not shown), and this rotation causes the torque detection means 2 and the gears 3, 4, and 5 to rotate. Then, the sector gear 6 is rotated.

The gear 6 and the push-up member 7 are integrally rotatable by a shaft 11. When the gear 6 rotates, the push-up member 7 rotates about the shaft 11, and the middle plate 10 in the cassette 8 is rotated. Lift.

Then, when a paper surface detection sensor (not shown) detects that the upper surface of the paper 9 has risen to a predetermined position, for example, a position where the upper surface of the paper 9 can be picked up so that the upper surface of the paper is in contact with the pickup roller, detection means (not shown) detects it. Based on the detection signal, the control device including the CPU 21 shown in FIG. 6 stops the rotation of the lifter motor 1 (FIG. 2). The rotation time from the start to the stop of the lifter motor is measured by the motor rotation time measuring means 22 shown in FIG.

Further, the torque detecting means 2 detects the load torque while the lifter motor 1 is rotating.

FIG. 3 is a diagram showing the relationship between the lifter motor rotation time and the lift torque. The horizontal axis indicates the lifter motor rotation time, and the vertical axis indicates the lift torque.

When the cassette is set in the main body of the image forming apparatus and the lifter motor starts to rotate, and the rotation time until the paper rises to a predetermined position and stops, the amount of paper loaded in the cassette decreases. As a result, the lift torque is increased. In addition, the density (weight per unit volume) of the plain paper and the OHP sheet is different because the material is different (the OHP sheet is larger). Therefore, the lift torque for a certain lifter motor rotation time, that is, the lift torque at a certain paper stacking amount is naturally larger for the OHP sheet.

Then, the relation data between the lifter motor rotation time and the lift torque for each paper type (for example, data A = (lift torque / lifter motor rotation time)) is used. is there.)
Is stored in the memory 23 as storage means.

When sheets are loaded on the cassette and mounted on the main body of the image forming apparatus, the lifter motor rotates as described above, and the rotation is transmitted to the torque detecting means 2, the gear 3 and the like, and the lift is performed by the torque detecting means. The torque is detected, and the rotation time of the lifter motor is detected by the rotation time timer. The rotation time and the lift torque signal obtained by this detection are input to the control device, and the CPU of the control device calculates the relevant data. The relational data obtained in this way and the relational data between the lifter motor rotation time and the lift torque stored in the memory are compared by the CPU to automatically determine whether the sheet is plain paper or OHP sheet. By storing data other than the above two types in the memory, various types of paper can be determined.

FIG. 5 shows a flowchart up to the determination of the paper type.

(Second Embodiment) FIG. 7 is a view showing a feature of the second embodiment, and is a schematic cross-sectional view of a sheet feeding section, in which a middle plate is raised by a lifter motor (not shown), and a sheet feeding standby is performed. The state of is shown. In the figure, reference numeral 15 denotes a reflection type sensor.

As shown in FIG. 9, the reflection type sensor 15
The light receiving unit is composed of a light emitting unit 15A and a light receiving unit 15B, and the light receiving unit is disposed at a position slightly shifted from the regular reflection light. That is, with respect to the perpendicular of the sheet surface passing through the sheet reflecting portion, the case where the light emitting path and the reflected light path are symmetrical is specular reflection. In the present embodiment, the light receiving means 15B is slightly deviated from the specular reflection.

When the paper is plain paper, light emitted from the light emitting side is irregularly reflected on the plain paper, and a predetermined percentage of light on the light receiving side returns to detect light reception.

However, when the paper is an OHP sheet, the light emitted from the light emitting side is very smooth because the surface is very smooth.
The light is almost specularly reflected on the OHP sheet, the light hardly returns to the light receiving side, and light reception cannot be detected.

As described above, by determining the ratio of the amount of received light / the amount of emitted light using the reflection type sensor, it is possible to discriminate between the plain paper and the OHP sheet in the cassette.

(Third Embodiment) A third embodiment is a combination of the first embodiment and the second embodiment.
It has a torque detecting means and a reflection type sensor.

In the first embodiment, when the number of sheets stacked in the cassette is small, the case of plain paper and the OH
The difference between the lift torque in the case of the P sheet and the lift torque is small,
The accuracy of the automatic determination may be reduced.

Therefore, it is desirable to switch between the system of the first embodiment and the system of the second embodiment in accordance with the amount of sheets loaded in the cassette.

In the above configuration, the amount of paper loaded in the cassette can be detected from the rotation time of the lifter motor as in the first embodiment. If the stacking amount is larger than the predetermined amount, plain paper or OHP is used according to the method described in the first embodiment, and if smaller, the method described in the second embodiment.
Automatic determination of a sheet is performed.

(Fourth Embodiment) The fourth embodiment is also a first embodiment.
This is a combination of the configuration of the second embodiment and the configuration of the second embodiment. The torque detection means detects the lift torque, and the reflection type sensor detects the light reception ratio (light reception amount / light emission amount).
Has been detected.

FIG. 4 is a diagram showing the relationship between the lifter motor rotation time, that is, the sheet stacking amount, and the product of the lift torque and the light receiving rate.

The horizontal axis indicates the lifter motor rotation time, and the vertical axis indicates the product of the lift torque and the light receiving rate. As described in the first embodiment, the OPH sheet has a larger lift torque than the plain paper at a certain paper loading amount.

However, as described in the second embodiment,
The light reception amount of the OHP sheet in the reflection type sensor is much smaller than that of plain paper.

For this reason, when the product of the lift torque and the light receiving rate is calculated, plain paper is larger than OHP sheet.

Then, for plain paper and OHP, the product of the lift torque and the light receiving rate and the lifter motor rotation time, that is,
The relationship with the paper stacking amount is stored in the memory of the image forming apparatus main body. Then, when the sheets are stacked in the cassette of the image forming apparatus and set in the image forming apparatus, the lift torque is detected by the torque detecting means, the light receiving rate is detected by the reflection type sensor, and the lifter motor rotation time is detected by the CPU. By comparing the stored lifter motor rotation time with the relation data of the product of the lift torque and the light receiving rate, it is automatically determined whether the sheet is plain paper or OHP sheet.

FIG. 8 shows a flowchart for determining the paper type as described above.

[0051]

As described above, according to the present invention,
The drive means for pushing up the sheet placement portion of the sheet stacking means is provided with a drive torque detecting means, and the drive time measuring means for the drive means is provided, so that the sheet type of the sheet can be determined based on the drive torque and drive time relation data. Or to provide a light emitting means provided near the feeding means for feeding the sheet and a light receiving means for reflected light from the sheet, to determine the paper type based on the relationship data of the ratio of the light emission amount and the light reception amount, Further, by determining the paper type based on the relationship data between the ratio of the light emission amount to the light reception amount, the product of the driving torque, and the driving time, the paper type can be determined quickly and accurately. It can respond to the forming process.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a first embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a side view of a main part of a sheet rising position of the image forming apparatus according to the first embodiment of the present invention;

FIG. 3 is a diagram showing a relationship between lift torque and lift time required for plain paper and OHP sheets.

FIG. 4 is a diagram showing the relationship between the light receiving rate, lift torque and lift time of plain paper and OHP sheets.

FIG. 5 is a flowchart of a first embodiment of the image forming apparatus according to the present invention.

FIG. 6 is a block diagram of a first embodiment of the image forming apparatus according to the present invention;

FIG. 7 is a side view of a main part of a second embodiment of the image forming apparatus according to the present invention.

FIG. 8 is a flowchart of an image forming apparatus according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating a reflection type sensor according to a second embodiment of the image forming apparatus according to the invention.

FIG. 10 illustrates an example of a conventional image forming apparatus.

FIG. 11 is a diagram showing a conventional transmission sensor.

FIG. 12 is a diagram showing a combination of a conventional transmission sensor and a lever sensor.

[Description of Signs] 1... Drive motor 2. Torque detecting means 3 to 6. Gear 7. Light receiving means 21 ... CPU 22 ... Time measuring means 23 ... Memory

Claims (9)

[Claims] An image forming unit for forming an image on a sheet;
A feeding unit for feeding a sheet to the image forming unit, an image forming apparatus main body including a push-up member driven by a driving unit, and a sheet placement unit pushed up by the push-up member by the feeding unit. In an image forming apparatus having a sheet stacking unit on which a sheet to be fed is placed and which is detachably attached to the apparatus main body, a driving torque detecting unit for detecting a driving torque of the driving unit, and a driving time of the driving unit are detected. A drive time detecting means, a storage means for storing paper type data corresponding to a relationship between the drive torque and the drive time, and a paper type by comparing the detected drive torque and drive time with the paper type data stored in the storage means. An image forming apparatus comprising: a determination unit configured to determine a type. 2. The driving time is such that the sheet stacking unit having replenished sheets is mounted on the image forming apparatus main body, and the sheet stacking unit is pushed up from a lowermost position to a position where the upper surface of the sheet can be fed by the feeding unit. 2. The image forming apparatus according to claim 1, wherein the time is a time when the member is pushed up. 3. The image forming apparatus according to claim 1, wherein the driving unit includes a driving motor and a gear train, and the torque detecting unit is disposed in the gear train. 4. An image forming unit for forming an image on a sheet,
A feeding unit for feeding a sheet to the image forming unit, an image forming apparatus main body including a push-up member driven by a driving unit, and a sheet placement unit pushed up by the push-up member by the feeding unit. In an image forming apparatus having a sheet stacking unit on which a sheet to be fed is placed and which is detachably attached to the apparatus main body, in the vicinity of a front portion of the feeding unit or the sheet stacking unit, facing an upper surface of the sheet in the sheet stacking unit. An image forming apparatus, comprising: a light emitting unit that emits light through the light emitting unit; and a light receiving unit that receives light reflected by the sheet and emitted from the light emitting unit. 5. The image forming apparatus according to claim 4, wherein the light receiving unit is slightly deviated from the regular reflection light emitted from the light emitting unit and reflected from the sheet surface. 6. An amount of light emitted from the light emitting means,
Calculating means for calculating the ratio of the amount of light received by the light receiving means to the amount of light received by the light receiving means; storage means for storing paper type data corresponding to the ratio of the amount of light emitted to the amount of light received; The image forming apparatus according to claim 4, further comprising a determination unit configured to determine a paper type by comparing the ratio of the amount and the paper type data stored in the storage unit. 7. An image forming unit for forming an image on a sheet,
A feeding unit for feeding a sheet to the image forming unit, an image forming apparatus main body including a push-up member driven by a driving unit, and a sheet placement unit pushed up by the push-up member by the feeding unit. In an image forming apparatus having a sheet stacking unit on which a sheet to be fed is placed and which is detachably attached to the apparatus main body, a driving torque detecting unit for detecting a driving torque of the driving unit, and a driving time of the driving unit are detected. Driving time detecting means, light emitting means provided near the front of the feeding means or sheet stacking means, light receiving means for receiving reflected light emitted from the light emitting means and reflected from the upper surface of the sheet, light emitting amount and light receiving Calculating means for calculating relational data between the product of the ratio of the quantity and the driving torque of the driving means and the driving time of the driving means, and storage means for storing the relational data;
An image forming apparatus, comprising: determining means for comparing the calculated relational data with the relational data stored in the storage means to determine a paper type. 8. The image forming apparatus according to claim 7, wherein
Means for determining the paper type based on the relationship data between the product of the ratio of the light emission amount and the received light amount, the drive torque, and the drive time of the drive means is used as first determination means, and the paper type is determined from the relationship data between the drive torque of the drive means and the drive time. Is provided as a second determination means, and the first load is determined by the sheet loading amount of the sheet loading means.
An image forming apparatus characterized in that the judgment means and the second judgment means are switched and used. 9. An image forming apparatus according to claim 1, further comprising control means for controlling an image forming process sequence in accordance with a determination of a paper type by said determination means. apparatus.