JP2009251237A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which obtains an optimum image by providing sensors on the front and back of a recording medium, acquiring the movement of the recording medium on the upper and lower sides separately, determining the condition of the recording medium being passed, and controlling the alteration of parameters necessary for image forming conditions. <P>SOLUTION: The image forming apparatus has displacement information acquiring means for emitting measurement light to a recording medium being conveyed, acquiring light reflected from the recording medium by means of a two-dimensional sensor array, and measuring an amount of two-dimensional movement. In the image forming apparatus, the displacement information acquiring means are disposed on the front and back of the recording medium and in the sidewise and lengthwise directions relative to the direction of conveyance of the recording medium. The displacement information acquiring means acquire the movement of the front and back of the recording medium which is special paper. According to the result of the acquired movement, a predetermined process is performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheet conveying and toner fixing portion of an image forming apparatus, and more particularly to an image forming apparatus such as a copying apparatus, a facsimile, a scanner, or the like that passes a bag, an envelope, a release paper, a medicine bag, a folded sheet, or the like. is there.

In an electrophotographic image forming apparatus, an electrostatic latent image formed by irradiating optical image information onto a uniformly charged photoconductor is developed with toner supplied from a developing device. After the image is transferred onto a recording medium fed from a paper feeding device, the recording medium is conveyed into a fixing unit and fixed by heating and pressurization.
Conventionally, the types of recording media that enter the fixing unit can be classified into thick paper, thin paper, thick envelopes, etc., from key input by a user, a dedicated paper feed tray, and the like. According to the classification, the temperature of the fixing unit, the conveyance speed of the recording medium, and the like are controlled so that the best image can be obtained by changing parameters suitable for the recording medium.
However, if the actual recording medium does not match the situation at the time of designing the fixing unit, or if the environment or properties are unexpected, that is, undesignated thick paper, thin paper, envelope, double origami, medicine bag In the case of release paper or the like, the recording medium may behave differently from the assumed situation, and as a result, wrinkles, creases, and missing images may occur. At that time, secondary damage such as cost loss due to damage to the recording medium and damage to other parts of the machine due to the damaged recording medium may occur.

For this reason, several proposals have been made together with related control techniques in order to avoid damage to the recording medium such as sheet wrinkling, folding, and image omission (see, for example, Patent Documents 1 to 7). ).
In Patent Document 1, an image can be recorded in a two-dimensional array, and the lateral movement of the recording medium such as the feeding speed and skew of the recording medium can be captured based on the information. Examples of an electrostatic printing apparatus and an electrophotographic apparatus having a recording medium feeding mechanism capable of correction are disclosed. Patent Document 2 discloses a system that can monitor a feeding state of a recording medium from a paper tray by a sensor having the same structure.
Furthermore, the above-described Patent Document 1 includes a structure in which an image sensor is attached obliquely to improve lateral sensitivity. In the above description, the sensor measures the feeding speed of the recording medium and the shift amount on both sides of the recording medium at a position parallel to the feeding direction of the recording medium.
Regarding the control, Patent Documents 3 and 4 disclose a method for adjusting the temperature applied to the recording medium from the fixing unit, Patent Documents 5 to 7 disclose a method for adjusting the nip pressure of the fixing roller, and the like. According to this, it is possible to function by inputting the output value of the sensor to the control unit.
JP 2006-208381 A JP-A-2005-41623 JP 2002-040873 A JP 2002-049282 A JP 2007-079160 A Japanese Patent Laid-Open No. 08-324841 Japanese Patent Laid-Open No. 05-232834

However, with special paper (bags, envelopes, release paper, medicine bags, folded paper) that is a recording medium, measure the combination of the back and front, which are other parameters, to determine how the special paper behaves. It is necessary to control whether or not an abnormal state occurs by grasping whether it changes.
For this reason, the techniques disclosed in Patent Documents 1 to 7 do not cope with the control so that an abnormal state does not occur. That is, in the conventional technique, the fixing unit heats the recording medium having the toner image conveyed from the transfer unit with the nip pressure of the two rollers and the heat from the heater, thereby melting the toner and To settle.
At that time, temperature, pressure, special paper thickness, double paper such as envelopes, double paper such as folded recording media, medicine bags, etc., due to subtle differences in front and back friction force pressure, etc. In particular, with double paper (envelopes), double origami papers, medicine bags, and release papers, the overlapping positions of the upper and lower recording media may be displaced, leading to problems such as wrinkles, deformation, and folding.
Since the sensor in the prior art detects only the passing time of the recording medium, or detects the amount of movement of only one side of the recording medium, either the top or bottom of the recording medium, the speed fluctuation abnormal state above and below the recording medium Cannot be detected.
In other words, if the upper and lower recording media such as double paper, which is special paper, and the medicine bag move differently, and the top and bottom are moving separately, the movement cannot be caught and the copying work can be performed as it is. Continue to make poor quality copies or, as a result, make garbage that must be discarded for bad copies. Furthermore, there is a possibility that the separation claw, which is the separation mechanism of the fixing unit, may be damaged.
In view of the above situation, the object of the present invention is to provide sensors on the front side and the back side of the recording medium so that the movement of the recording medium is separately detected on the upper side and the lower side, and the state of the recording medium being passed It is an object of the present invention to provide an image forming apparatus that obtains an optimum image by performing parameter change control necessary for image forming conditions.

In order to solve the above-mentioned problem, the invention according to claim 1 irradiates measurement light to a recording medium being conveyed, and captures reflected light reflected from the recording medium by a two-dimensional sensor array. In the image forming apparatus provided with the displacement information acquisition unit capable of measuring a two-dimensional movement amount, the displacement information acquisition unit is set in the transverse longitudinal direction with respect to the conveyance direction of the recording medium and also with respect to the recording medium. An image forming apparatus provided on the front side and the back side, wherein the displacement information acquisition means captures the movement of the front and back surfaces of the recording medium, which is special paper, and performs predetermined processing according to the capture result. Features.
According to a second aspect of the present invention, in order to measure the amount of movement of the recording medium, a mode for performing test passing is provided, and a response to the behavior of the recording medium in the mode is fed back. The image forming apparatus according to claim 1, wherein the optimum sheet passing condition of the recording medium is stored in a memory, and the optimum sheet passing condition is called from the stored memory and used when necessary. And

  According to the present invention, paying attention to the movement of the recording medium (sheet) that actually enters the fixing unit, the sensors provided on the front side and the back side capture the movement of the separate recording medium on the upper side and the lower side, and When the difference is more than the standard amount, it is judged that the recording medium being passed is damaged, and the operation of the image forming apparatus is stopped or the next sheet is passed (the same condition is passed next). The parameter change control necessary for the image forming conditions (paper feed speed, fixing temperature, fixing roller pressure, paper sag) can be performed from the (paper), and an optimal image (output recording medium free from wrinkles, folds, etc.) can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing an image forming apparatus that can implement the present invention. In FIG. 1, an image forming apparatus A includes an image forming unit 8 including a photosensitive drum 3 and a transfer belt 7. A sheet (transfer paper) supporting a toner image conveyed from a transfer belt 7 is transferred to two rollers. It includes a fixing unit 4 that is heated by nip pressure and heat from a heater to melt toner and fix it on a recording medium (sheet).
Below the image forming apparatus A, there are a first paper feed tray (in this case, for A2 paper) 1 and a second paper feed tray (in this case, for A3 paper) 2 that form a paper feed unit. A manual feed table 10 is provided on the right side of the image forming unit 8, a paper feed tray (in this case, for A3 paper) 9 is provided below the image forming unit 8, and a left side of the fixing unit 4 is provided on the left side of the fixing unit 4. A copy tray 5 is arranged.
In FIG. 1, a thick solid line indicates a transfer paper conveyance path. A conveyance path branched from the conveyance path to the copy tray 5 is a conveyance path to a post-processing mechanism 6 such as a sorter. S1, S2, S3, and S4 are sensors arranged at appropriate positions on the conveyance path. A sensor is also arranged in the sensor mounting portion 11.
FIG. 2 is a schematic diagram showing the arrangement of sensors according to the present invention. FIG. 3 is a schematic perspective view showing a plurality of sensors arranged so as not to overlap each other. Referring to FIGS. 2 and 3, the sensor 21 and the sensor 22 are arranged so as to sandwich a sheet passing portion of a conveyance path of a sheet (transfer sheet) 20 that is a recording medium. In this case, the plurality of sensors are arranged so as not to overlap (sensors 23 to 29 in FIG. 3).

FIG. 4 is a schematic view showing a sensor installed in a space between the transfer unit and the fixing unit. FIG. 5 is a schematic view showing sensors arranged on the transport path. 4 and 5, this sensor is a sensor arranged in the sensor mounting portion 11 of FIG. 1, and the number of sensors to be arranged is 2 on the front side, 1 on the back side, 2 on the front side and 2 on the back side, etc. Is also possible. In FIG. 3 described above, a configuration with three front sides and four back sides is shown.
FIG. 4 shows a state in which the recording medium fed from the paper feeding unit 1 is conveyed to the fixing unit 4 through the nip between the photosensitive drum 3 and the transfer belt 7. In FIG. 4, for example, the sensors 21 and 22 described in FIG. 2 are arranged on the front side and the back side of the exit end of the transfer belt 7 and the entrance end of the fixing unit 4 in the recording medium conveyance direction.
FIG. 5 shows a state in which the recording medium fed from the paper feeding unit 1 is conveyed to the fixing unit 4 through the nip between the transfer belt 7 and the secondary transfer roller 30 of the secondary transfer unit. 5, for example, the sensors 21 and 22 described in FIG. 2 are arranged on the front side and the back side of the outlet end of the secondary transfer roller 30 in the recording medium conveyance direction. Note that the sensors in FIGS. 4 and 5 are described as a pair of sensors in the sensor of FIG.
FIG. 6 is a block diagram showing a simplified control unit of the sensor. In FIG. 6, a main controller 31 is a main controller including a CPU, which controls a motor, a clutch, various sensors, and the like of the image forming apparatus, and at the same time, transfer sheet behavior monitoring sensors 21, 22, 23, 24, 25, The transfer paper behavior monitoring sensor control unit 32 for controlling 26, 27, 28 and 29 is controlled.

FIG. 7 is a schematic view showing a non-contact sensor having an optical mouse structure in which a two-dimensional sensor array is attached obliquely to the sheet. FIG. 8 is a schematic view showing a non-contact sensor having an optical mouse structure in which a two-dimensional sensor array is attached in a direction perpendicular to the sheet.
7 and 8, the sheet, which is the recording medium being conveyed, is irradiated with the measurement light from the LED 33 of the sensor 21 which is the displacement information acquisition means, and the reflected light of the measurement light reflected from the sheet is reflected. The sensor 21 is captured by the two-dimensional sensor array 36 and the two-dimensional movement amount can be measured by the movement distance calculation unit 37.
The sensors 21 and 22 are provided in the longitudinal direction in the transverse direction with respect to the sheet conveyance direction, and also on the front side and the back side of the sheet. The sensors 21 and 22 are sheets of special paper such as double paper and origami. The movement of the front surface and the back surface is captured, and predetermined processing is performed according to the result of the capture.
7 and 8, the non-contact sensor 21 having an optical mouse structure includes a laser LED 33, a condenser lens 34, a reduction lens 35, a two-dimensional sensor array 36, and a movement distance calculation unit 37.
In FIG. 7, the two-dimensional sensor array 36 is attached to a movement distance calculation unit 37 so as to receive light obliquely with respect to a sheet (paper, special paper) 20 that is a recording medium. On the other hand, in FIG. 8, the two-dimensional sensor array 36 is attached to the movement distance calculation unit 37 so as to receive light perpendicular to the sheet (paper, special paper) 20 as a recording medium.
A non-contact sensor 21 having an optical mouse structure that detects a sheet (transfer paper) 20 that is a recording medium and that can detect the movement of the sheet 20 in the X-Y direction is provided on the upper and lower sides of the sheet 20 and the transfer paper 20. For example, four or more are arranged symmetrically in the horizontal direction between the photosensitive drum 3 and the fixing unit 4.

FIG. 9 is a schematic view showing a case where the special paper is an envelope. FIG. 10 is a schematic view showing a case where the special paper is a double origami paper. FIG. 11 is a schematic view showing a case where the special paper is a medicine bag.
In the fixing unit 4 of FIG. 1, the recording medium that supports the toner image conveyed from the transfer belt 7 is heated by the nip pressure of two rollers and the heat from the heater to melt the toner, To settle.
At that time, due to temperature and pressure, the thickness of special paper, double paper such as envelopes, double paper such as folded paper, medicine bags, etc., due to subtle differences in front and back frictional force and pressure, etc. In particular, in the case of double paper (envelope (FIG. 9), double origami (FIG. 10), medicine bag in which the edges of two recording media are bonded together (FIG. 11)), and release paper, the upper and lower paper overlap positions. May shift and cause problems such as wrinkles, deformation, and breakage.
As shown in FIG. 1, a recording medium (transfer paper) receives an image such as toner on a transfer belt (transfer unit) 7 and is conveyed toward a fixing unit 4. The recording medium that has reached the fixing unit 4 is guided to the nip portion of the heated and pressurized roller of the fixing unit 4, and the toner is melted by heat and pressure to fix the toner image on the surface of the recording medium.
The recording medium fed between the rollers is transferred while maintaining a balance between the rollers and the transfer unit, and passes through the fixing unit 4. At this time, if the pressure and temperature for the special paper and the recording medium are not optimal, the recording medium may be deformed due to an excessive stress applied to the recording medium.
When the recording medium is deformed, the deformation occurs at the nip portion. However, the recording medium is not pulled even in the previous conveying portion, so that the wavy conveyance occurs, and in the case of double paper, the upper and lower recording media Behaves differently in speed and direction. This behavior is detected by a sensor, and the control side of the device recognizes that there is an abnormality in the recording medium, prevents any new recording medium from being conveyed further, and prevents damage to the recording medium (special paper). Can do.
In general, the recording media (including special paper) handled by users are often evaluated for behavior by the manufacturer of the image forming apparatus at the time of design, but other recording media (special paper) are also used. There are many cases where paper is passed, and in such a case, unexpected behavior may occur due to characteristics of the recording medium that are not taken into consideration at the time of design.

FIG. 12 is a flowchart for explaining the operation in the normal print mode. FIG. 13 is a table showing sensor output classifications when the sampling timing in the paper feed direction is 10 mm. FIG. 14 is a table showing the types of special paper as a table. First, the operation in the normal print mode will be described with reference to FIG.
In the normal print mode, when passing the special paper, the operator first selects the paper type according to the guide of the operation unit (not shown) and starts the paper feeding (S1). Next, the behavior of the sheet as the recording medium is monitored (S2). Here, printing is started (S31), and the calculation of the table of FIG. 13 is performed for all data (S4). The average value, standard deviation, maximum (Max), and minimum (Min) for each sensor are obtained from all the values of each sensor (S5). Then, the printing is finished (S6).
Next, an output determination is made as to whether or not the sensor output matches any state in the table of FIG. 13 (S7). If it does not match, it is normal, so it is determined whether or not there is a job remaining (S8), and if it remains, it is executed until the end of the job (S9). If there is a match in the output determination (S7), an abnormality has occurred, and the operator is asked to select whether to output the study mode as it is or not (S10). If the study mode is selected, the process proceeds to the study mode, and if not, the flow is executed as it is.

It is also possible to provide a learning function by a program as shown in the flowchart of FIG. When printing on special paper, the display on the operation unit of the device displays the types of sheets (paper) that are several programmed recording media. Ask the operator to choose the closest one.
For example, thin paper, origami (double paper), envelope (size), medicine bag, release paper, etc. (a table of special paper is shown in FIG. 14). As a result of the selection, the device shifts the control mode to the control condition of the device that does not damage the sheet the most in the selection, and performs the printing paper passing.
During the printing operation, if the sensor detects an abnormality due to deformation such as wrinkles or creases in the sheet (see the state in the table of FIG. 13), a message is sent from the operation unit to the operator, Continue copying the next transfer paper as it is, or shift to study mode.
By disposing four or more non-contact sensors that detect the XY movement of the sheet, which is a part for detecting the sheet, symmetrically between the top and bottom of the sheet and the lateral direction of the sheet, between the photosensitive drum and the fixing unit, 14 sheet stress in the sheet feeding direction and left and right direction, wrinkle condition, envelope, folded paper, release paper, medicine bag, release paper, etc. (table in FIG. 14) To be captured.

Usually, the aim of the sheet feeding mechanism is to convey overlapping sheets and one sheet by rollers at the same speed and the same distance. However, in order to feed the sheet straight, the roller mechanism has a shape such as a drum shape (medium thickness).
Depending on the shape, there may be a difference in the feeding amount of the upper sheet and lower sheet, and it moves up and down at locations (front, middle, and rear) corresponding to the shape of the roller on the surface of the sheet. The sheet speed may change, and the sheet may be wrinkled or the sheet may be pulled to the left and right of the roller and separated.
In addition, even when the sheet is conveyed while being bent along the conveyance path and is turned around, if either the entry posture or timing of the roller hits the roller first, the conveyance force acts on the sheet before entering the nip. When the difference is strong between the upper and lower sheets, and when the difference is strong, or when slip occurs at the nip, peeling of the release paper or wrinkle phenomenon of the double paper occurs.
The information is captured by the difference in the amount of movement captured by the sensor above and below the sheet and the difference depending on the sensor position. When the difference exceeds the allowable value, it can automatically recognize that the sheet has been damaged. Depending on the amount of the difference, by controlling the fixing unit, feeding the paper, and the speed of the image forming process according to the table shown in FIG. You can reduce quality jams and damage, and achieve a good quality copy.
Also, special paper is often more expensive or rare than plain paper, and the machine can recognize that it has been damaged and notify the operator, thus minimizing user losses.
In addition, if sheet wrinkles, double paper misalignment, release paper in-machine peeling, etc. occur continuously, there is a possibility of damage to post-processing mechanisms such as the fixing roller, sheet discharge mechanism, and sorter. If the machine can recognize it at the time, the spread of damage can be prevented.

FIG. 15 is a flowchart for explaining the operation in the study mode. FIG. 16 is a diagram showing the control values as a table. FIG. 17 is a schematic diagram showing the output value of the sensor in relation to FIG. Referring to FIG. 15, in the study mode, first, the operator selects whether to use the data taken immediately before or to re-read the data (S11).
In the case of re-acquisition of data, when passing the special paper, first, according to the guide of the operation unit (not shown), the paper type is selected, paper feeding is started, and the data shown in Table 2 is taken (S12). Next, the behavior of the sheet as the recording medium is monitored (S13).
When the data taken immediately before is used, the situation is selected from the sensor maintenance table (table of FIG. 13) (S14). The selection is determined from the sheet type and the failure mode in the table of FIG. 13, and the control value is determined.
Next, it is determined whether or not the control value exceeds the limit (S15). If not exceeded, the determined control value is set (S16), the operator inputs the name of the sheet (paper) to be registered (S17), and ends the study mode. If the control value exceeds the limit, the adjustment is impossible, so that the adjustment is not possible is displayed, and the operator determines whether to forcibly execute the last condition (S18).
In the study mode, the device determines what kind of abnormality has occurred from the sensor output and the paper type selected by the operator, so that the control values of the fixing unit (rotation speed, temperature control, nip width, etc.) ) Or change the sheet conveying speed of the entire device.

The table of FIG. 16 shows parameters used for control. The parameters are used for transporting the next sheet. Usually, during continuous copying, the next sheet is already fed and images are being created in many cases, but in the study mode, one sheet is sent at a time. The operator can assign the condition to the tray or assign a button to the operation unit, call it when necessary, pass continuously, measure, and change the parameters.
In a normal printing operation, the operator is burdened to obtain control parameters. For this reason, the behavior of the special paper is measured in advance at the time of equipment introduction or maintenance work, and the control parameters obtained therefrom are stored in the memory in the product (main control unit 31 in FIG. 6). Therefore, the operator can use the parameters when printing on special paper, so that the operability is excellent and stable operation can be performed.
In this way, the sensor values are compared and recorded while guiding the operator. Also, by recording the control value together, the sensor value and control value for each special paper can be recorded, and the paper handling capability of the device can be improved.
There are various patterns that indicate abnormal behavior of the sheet, such as the device design layout and control conditions (paper passing speed, speed difference between the fixing unit and the transfer unit, etc.). Typical patterns are shown in the table of FIG. ing. FIG. 17 shows the sensor output values arranged in descending order in the X direction in relation to the table of FIG.
Although the present invention has been described above with reference to image forming apparatuses such as copying machines and printers, it can of course be applied to apparatuses having a mechanism for feeding paper, such as printing machines, paper folding machines, and bookbinding machines. .

1 is a schematic diagram illustrating an image forming apparatus that can implement the present invention. FIG. 2 is a schematic diagram showing the arrangement of sensors according to the present invention. It is a schematic perspective view which shows the some sensor arrange | positioned so that it may not mutually overlap. FIG. 4 is a schematic diagram illustrating a sensor installed in a space between a transfer unit and a fixing unit. It is the schematic which shows the sensor arrange | positioned in a conveyance path | route. It is a block diagram which simplifies and shows the control part of a sensor. It is the schematic which shows the non-contact sensor of the optical mouse structure where the two-dimensional sensor array was attached to the sheet | seat diagonally. It is the schematic which shows the non-contact sensor of the optical mouse structure where the two-dimensional sensor array was attached perpendicularly | vertically with respect to the sheet | seat. It is the schematic which shows the case where special paper is an envelope. It is the schematic which shows the case where special paper is double origami. It is the schematic which shows the case where special paper is a medicine bag. 6 is a flowchart for explaining an operation in a normal print mode. It is a figure which shows a sensor output classification | category when the sampling timing of a paper feed direction is 10 mm as a table | surface. It is a figure which shows the kind of special paper as a table | surface. It is a flowchart explaining operation | movement of study mode. It is a figure which shows a control value as a table | surface. It is a schematic diagram which shows the output value of a sensor in relation to FIG.

Explanation of symbols

  A image forming apparatus, 3 photosensitive drum, 4 fixing unit, 7 transfer belt (transfer unit), 20 recording medium (sheet, paper, special paper, envelope), 21 displacement information acquisition means (sensor), 22 displacement information acquisition means (Sensor), 31 memory (main control unit), 30 secondary transfer roller (secondary transfer unit), 32 sheet behavior monitoring sensor control unit, 36 two-dimensional sensor array, 37 moving distance calculation unit

Claims (2)

  Image formation provided with displacement information acquisition means capable of irradiating measurement light onto a recording medium being conveyed, capturing reflected light reflected from the recording medium with a two-dimensional sensor array, and measuring a two-dimensional movement amount In the recording apparatus, the displacement information acquisition unit is provided in a laterally longitudinal direction with respect to a conveyance direction of the recording medium and on the front side and the back side with respect to the recording medium, and the displacement information acquisition unit is a special sheet An image forming apparatus characterized in that the movement of the front and back surfaces of a medium is captured, and predetermined processing is performed in accordance with the captured result.   In order to measure the amount of movement of the recording medium, a mode for performing test paper passing is provided, and the optimum paper feeding of the recording medium is fed back by feeding back the response to the behavior of the recording medium in the mode. 2. The image forming apparatus according to claim 1, wherein the condition is stored in a memory, and the optimum sheet passing condition can be called from the stored memory and used when necessary.

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