JP2019108218A - Image formation device, method, and program of discriminating recording material using image formation device - Google Patents

Abstract

A multi-layered sheet and an envelope are discriminated from a relationship between a relative position of a recording material in a conveying direction and a transmitted wave component, and an image is formed by automatically applying image forming conditions suitable for the recording material. In addition, the present invention provides an image forming apparatus in which the frequency of downtime is reduced and usability is improved. SOLUTION: The detection result of the transmitted wave of the ultrasonic wave transmitted in a pulse shape with the leading and trailing edge position detecting means of the recording material is associated with the leading and trailing edge position of the recording material, and the transmitted wave intensity increases from the leading edge position to the trailing edge of the recording material. , Decrease, or within the threshold range, the type of recording material and the envelope and multi-feed are determined. Further, by calculating the intensity according to the frequency component of the transmitted wave, the presence or absence of the sheet stacking surface on the conveyed recording material or the number of times of superposition is estimated. From the information, the leading and trailing edge position information of the recording material, and the detected sub-scanning length, a determination is made as to whether an envelope or double feed is present. [Selection diagram] FIG.

Description

  The present invention relates to an image forming apparatus such as, for example, a multi-function printer, a laser beam printer, a facsimile, and a printing apparatus using an electrophotographic method or an electrostatic recording method.

Conventionally, one characteristic is that an image forming apparatus by electrophotography or electrostatic recording method can transfer, fix and output a toner image formed on an image carrier to various media (recording materials). There is.
However, if the process of transferring and fixing the toner image to the recording material represented by paper etc. is not performed in an appropriate condition range according to the surface property, basis weight, thickness, surface resistance, etc. of the recording material, transfer failure or fixing It may lead to defects, hot offsets, etc.
Therefore, recording materials that have a different basis weight, thickness, size, etc. from the recording material generally considered to have a high usage ratio, such as a basis weight of more than 90 g / m ² or less than 60 g / m ² , postcards, envelopes, etc. In order to perform good printing on a recording material, it is conventional to make paper settings corresponding to the characteristics of the recording material.
For example, in the case of a copying machine, it is currently the case that a paper type considered to correspond is selected by a setting item such as 'paper type' displayed on a print setting screen displayed on an operator screen such as a liquid crystal touch panel. It is common.

  On the other hand, with the widespread use of electrophotographic image forming apparatuses from office applications to light printing applications and general home applications, although the ratio among all users is not high, the frequency of special recording materials is relatively high. The number of users using it tends to increase.

  As described above, selecting the paper type on the setting screen in accordance with the recording material to be used requires the user or operator to refer to the manual and to have some experience. In addition, if the selection is incorrect, it is necessary to retake it, and improvement in usability is desired.

  Therefore, for the purpose of improving the usability of the image forming apparatus and achieving more reliable operation, a means (hereinafter also referred to as a media sensor) for automatically determining the thickness, basis weight, surface property and the like of the recording material is provided. By doing this, there have been technical proposals relating to an image forming apparatus that automatically determines the sheet type.

  Patent Document 1 has means for irradiating a recording medium with an ultrasonic wave, means for receiving a transmitted wave, and means for receiving a reflected wave, and recording is performed by processing the transmitted wave intensity and the reflected wave intensity. Determine the thickness and type of media.

  Patent Document 2 has means for irradiating light to a recording material, and means for detecting transmitted light and reflected light, identifies the type of recording material by arithmetic processing of obtained optical information, and image processing. Control the formation conditions.

Further, there have been proposed a method and apparatus for detecting and warning double feeding from the viewpoint of preventing double printing, or double feeding detecting means which also detects the thickness and basis weight of the recording material.
According to Patent Document 3, double feeding detection is performed by utilizing the fact that the transmission wave intensity is significantly reduced compared to the strength at the time of normal recording material conveyance or non-sheet passing when double feeding of the recording material.

  In patent document 4, burst wave intensity of an ultrasonic wave is different at the time of double sending and non-double sending, and double feeding detection is performed based on the value which integrated the burst wave.

  As described above, the transmission component and the reflection component of the irradiated ultrasonic waves and light are measured, and the thickness and basis weight of the recording material are estimated by comparing the measured value with the threshold value set in a specific procedure, and the sheet lamination state The determination of is being made.

Japanese Patent Application Publication No. 2004-107030 Japanese Patent Application Publication No. 2007-233186 Japanese Patent Laid-Open No. 2000-25986 JP 2009-292549

  However, in an image forming apparatus having a media sensor as described above, when envelope printing is to be performed, it is recognized as a thick medium, and as a result of applying a fixing temperature higher than necessary, wrinkles, curls, etc. may be caused. .

  Or, particularly when using a media sensor that doubles as a double feed detection function, an error occurs by determining that the envelope is double feed, and the user is forced to perform error processing, manual sheet type selection, reprinting, etc., resulting in usability. It may lead to a situation contrary to improvement.

  That is, even if the media sensor is installed, envelope printing becomes difficult if manual setting such as manually selecting the 'envelope' on the paper setting screen or turning off the double feed detection function is not performed. There is.

  The present invention relates to an image forming apparatus using a media sensor for estimating the thickness and basis weight of a recording material by detecting and calculating the amplitude and frequency components of a transmitted wave of an ultrasonic wave irradiated to the recording material. By performing double-feeding of a single-layer sheet and discrimination of an envelope from the relationship between the relative position in the conveyance direction of the transport direction and the transmission wave component, image formation is performed by automatically applying an image forming condition suitable for a recording material. It is an object of the present invention to provide an image forming apparatus in which the frequency of downtime occurrence is reduced and usability is improved.

  In order to achieve the above object, an image forming apparatus according to the present invention is provided on a recording material conveyance path, and includes detection means for detecting an end portion of the recording material, and ultrasonic wave transmission means provided on the recording material conveyance path. Ultrasonic wave receiving means provided on the recording material conveyance path corresponding to the ultrasonic wave transmitting means and receiving a transmitted wave transmitted from the ultrasonic wave transmitting means and transmitted through the recording material, and detected by the ultrasonic wave receiving means Calculating means for detecting the amplitude of the recorded waveform and performing calculation, and the ultrasonic wave transmitting means is provided along the recording material conveyance direction in the process in which the recording material is conveyed on the recording material conveyance path A pulse wave is transmitted so that a plurality of ultrasonic waves are irradiated, and the calculation means is arranged to move from the front end area to the rear end area of the recording material in the conveyance direction in the process of the recording material being conveyed on the recording material conveyance path. Several to go On the basis of the intensity of the transmitted wave or frequency components in Tokoro, and performs determination between the double feed and the envelope of the recording material.

According to the present invention, ultrasonic waves are applied to a plurality of locations in the recording material transport direction, and the transport wave component and the positional relationship between the transport direction and the transport length of the recording material allow double feeding of the envelope and single layer recording material. If it is determined that the image is an envelope, transfer and fixing in the envelope mode are performed.
In the past, despite the aim of improving usability by equipping a media sensor, it is detected as a multifeed error at the time of envelope printing, causing downtime, and the user is strong in error processing, manual resetting, and reprinting. Will be greatly improved.

Principal part sectional view of an image forming apparatus to which the present invention is applied Control block diagram of the image forming apparatus of FIG. 1 The figure which represented the ultrasonic wave waveform oscillated from the ultrasonic wave transmitter 12 in the Example of this invention. The figure which represented the waveform which detected the ultrasonic wave irradiated with respect to the single layer recording material in Example 1. The figure which represented the waveform which detected the ultrasonic wave irradiated to the sheet | seat 2 sheet overlapping area of the envelope in Example 1 FIG. 7 is a diagram showing a waveform obtained by detecting an ultrasonic wave applied to a three-sheet overlapping region of an envelope in the first embodiment. FIG. 6 is a diagram showing how an envelope moves between the ultrasonic transmitter 12 and the ultrasonic receiver 13 in the first embodiment. FIG. 6 is a diagram illustrating movement of the recording material transported by double feeding between the ultrasonic transmitter 12 and the ultrasonic receiver 13 in the first embodiment. FIG. 6 is a flowchart showing the process of determining the type of recording material to be transported or double feeding in Embodiment 1. In Example 1 and Example 2, the figure which normalized and represented the frequency and the amplitude of the ultrasonic wave emitted from the ultrasonic wave transmitter 12 The figure which represented the intensity | strength relationship of a fundamental frequency component and the n-th harmonic component about the transmitted wave of the ultrasonic wave irradiated with respect to the single layer recording material in Example 2 The figure which represented the intensity | strength relationship of a fundamental frequency component and the n-th harmonic component about the transmitted wave of the ultrasonic wave irradiated to the 2-sheet overlapping area | region of an envelope in Example 2 The figure which represented the intensity | strength relationship of a fundamental frequency component and the n-th harmonic component about the transmitted wave of the ultrasonic wave irradiated to the 3-sheet overlapping area | region of an envelope in Example 2 The figure which represented the transmitted wave intensity of the ultrasonic wave irradiated with respect to the recording material in Example 2 according to the kind of recording material. In Example 2, the figure which represented relative intensity (alpha) ₂ of the second harmonic component of the transmitted wave detected according to the kind of recording material In the second embodiment, the relative intensity α ₂ of the second harmonic component of the transmitted wave detected during double feeding of the recording material is shown according to the type of recording material. In the second embodiment, the relative intensity α ₃ of the third harmonic component of the transmission wave detected during double feeding of the recording material is shown according to the type of recording material. In the second embodiment, the relative intensity α ₃ of the third harmonic component of the transmitted wave detected during triple feeding of the recording material is shown according to the type of recording material. FIG. 12 is a flowchart showing the process of determining the type of recording material to be transported or double feeding in Embodiment 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The first embodiment of the present invention will be described using FIGS. 1 to 9 and FIG. 14 and Table 1.

  In the present embodiment, first, the top sensor 11 detects the front and rear end position of the recording material. Then, the pulsed ultrasonic waves are applied to a plurality of locations in the recording material transport direction, each transmitted wave is detected by the ultrasonic receiver 13, and the peak-held amplitude for each pulse is used as the detected wave intensity of each pulse. .

  Then, whether the plurality of detected wave intensities increase, decrease, or fall within a predetermined threshold range over a specific length in the transport direction is compared with the transport length of the recording material and the size of the selected recording material. Thereby, the recording material to be conveyed is determined to be thin paper, plain paper, thick paper, an envelope, or multi-feed.

  Hereinafter, the present embodiment will be described in detail.

First, the operation of the entire image forming apparatus will be described using FIG. 1 and FIG.
FIG. 1 is a cross-sectional view of an essential part of a multifunction printer (MFP) 100 which is an image forming apparatus adopting an electrophotographic method. FIG. 2 is a block diagram showing a control configuration of the image forming apparatus of FIG.
In the figure, the data processing controller 90 converts image data input from the print server 200 or the like through the interface 70 into serial data of a format suitable for exposure scanning by the laser scanner unit 3.
The DC controller 80 functions as a control unit that controls engine hardware, and executes various controls in accordance with image data from the data processing controller 90, thereby performing image output. Hereinafter, the DC controller 80 may be referred to as a control unit 80. For various controls, main motor, photosensitive drum motor,
There is drive control of various motors 50 such as a motor for conveying a sheet, and control of the image forming unit 40. The control of the image forming unit 40 includes various bias output controls such as the scanner 3, charging, development, transfer, and the like, and energization control of the fixing heater. Further, the control unit 80 is provided with a ROM, a CPU, a RAM, and the like (not shown), and determines the type of the recording material to be conveyed and the double feeding described later.
The operation unit 60 includes a liquid crystal touch panel, a numeric keypad, an operation key, and the like, and the status of the image forming apparatus 100 is displayed, and a command can be input from an operator.
In the photosensitive drums 1a, 1b, 1c, and 1d, an organic photosensitive layer is formed on the surface layer of a conductor rotating body such as an aluminum cylinder. In this embodiment, driving is controlled at a peripheral speed of 180 mm / sec at the time of image formation, and a toner image is formed on the surface by an image forming process described later.
In this example, a yellow toner image is formed on the photosensitive member 1a, a magenta toner image is formed on the photosensitive member 1b, a cyan toner image is formed on the photosensitive member 1c, and a black toner image is formed on the photosensitive member 1d. Thereafter, the toner image is primarily transferred onto the intermediate transfer belt 6, and the toner image of the four colors is secondarily transferred onto the recording material through the transfer roller 14, and then output through the fixing device 20.

Hereinafter, the toner image forming process will be described by taking the yellow toner image formation as an example for simplicity.
When the photosensitive drum 1a starts driving, bias application control is performed on the primary charging roller 2a via a control circuit (not shown), and the surface is uniformly charged.
The laser scanner unit 3 includes a semiconductor laser 30a, a laser driver, a polygon mirror 31, an f-θ lens 32a, and the like. Driving control of the semiconductor laser 30a is performed by the image data corresponding to the yellow component, and an electrostatic latent image corresponding to yellow is formed on the surface of the photosensitive drum 1a.
The electrostatic latent image is imaged as a yellow toner image by the developing device 4a.
The yellow toner image is transferred onto the intermediate transfer belt 6 via the primary transfer roller 5a.
Similar to the yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are superimposed on the intermediate transfer member 6, respectively.
Thereafter, bias application control is performed on the secondary transfer roller 14 according to the type of recording material, whereby the toner image is transferred, passes through the fixing process by the fixing device 20, and is output onto the sheet discharge tray.
In the present embodiment, the recording material is accommodated on the cassette 41 or the multi tray 43, fed in synchronization with the image formation timing by the sheet feeding roller 9 or 19, and 180 mm / the same as the peripheral speed of the photosensitive drum 1. It is transported at a speed of sec.

The recording material fed is subjected to correction of the image formation timing and posture by the registration roller 10, and the top sensor 11 detects the end, that is, the leading end position and the trailing end position of the recording material.
In this embodiment, the ultrasonic transmitter 12 as a signal oscillation means and the ultrasonic receiver 13 as a signal reception means at a position 20 mm downstream of the top sensor 11 and at a position facing each other across the recording material conveyance path. Are arranged at a distance of 6 mm.

  In this embodiment, as described later, after the recording material is fed, the pulse transmission of the ultrasonic wave is started. Then, the intensity detected by the ultrasonic wave receiver 13 is measured at a plurality of locations in the transport direction from the front end region of the recording material to the rear end region, and discrimination of the type and double transport of the transported recording material Is done.

  A transfer bias is applied to the transfer roller 14 according to the determination result of the type or double feeding state of the recording material, and the toner image is transferred onto the recording material. Then, the recording material on which the toner image has been fixed is output onto the paper discharge tray by passing through the fixing device 20 including the heating unit 21 and the pressure roller 22 and the like.

FIG. 3 shows an ultrasound waveform output by the ultrasound transmitter 12.
In the present embodiment, a waveform for 10 waves is shown when an ultrasonic wave with an amplitude P 0 and a frequency of 30 kHz is pulse transmitted every 20 msec in 10 wave units from the ultrasonic wave transmitter 12.
That is, as described later, pulsed ultrasonic waves of 10 wave units are emitted from the transmitter 12 every 3.6 mm in terms of the transport direction length.

  When the peak hold value by the ultrasonic wave receiver 13 in the absence of the recording material is Pa, the ultrasonic wave transmitter 12 corresponds to what the detected value in the state through the recording material corresponds to Pa. The detection is continued by setting the amplitude of the ultrasonic wave emitted by the signal to be 2P0 for twice or 5P0 for five times.

FIG. 4 shows that when recording material is irradiated with 10 ultrasonic waves with an amplitude of 2 P0 and a frequency of 30 kHz from the ultrasonic transmitter 12 when GF-C081 (81 g / m ² ) made by Canon Inc. is transported as the recording material. The waveform which tripled the amplitude of the waveform detected by the sound wave receiver 13 is shown. The peak hold value of this waveform is about 0.17 Pa when converted to an amplitude P0 and an amplification factor of 1.

  FIG. 5 shows that when a 70 g envelope made of King Corporation, a long type 3K, is transported as a recording material, an ultrasonic wave of 10 waves with an amplitude of 5 P0 and a frequency of 30 kHz is irradiated to the overlapping area of two sheets. The waveform which doubled the amplitude of the waveform detected by the signal generator 13 is shown. The peak hold value of this waveform is about 0.09 Pa.

  FIG. 6 shows that when a 70 g envelope made of King Corporation, a long type, is transported as a recording material, the ultrasonic wave of 10 waves with an amplitude of 5 P0 and a frequency of 30 kHz is applied to the three sheet overlapping region (flap portion) of the sheet. 8 shows a waveform obtained by amplifying the amplitude of the waveform detected by the ultrasonic receiver 13 by four times. The peak hold value of this waveform is about 0.045 Pa.

  FIG. 14 shows how many times the peak hold value of the transmission wave can be detected for the paper type and the intensity (Pa) when the recording material is absent.

  FIG. 7 shows how the vicinity of the tip of the envelope moves in the arrow direction between the ultrasonic transmitter 12 and the ultrasonic receiver 13 which constitute the media sensor in this example.

  Of the ultrasonic pulses oscillated every 20 msec in the drawing, the transmission intensity of the recording material at the leading end position is P1 and thereafter P6 is shown.

  FIG. 8 shows a state in which the vicinity of the front end of the recording material which has been double-fed and transported moves in the arrow direction between the ultrasonic transmitter 12 and the ultrasonic receiver 13 in the present embodiment.

FIG. 9 is a flowchart showing the type of recording material to be conveyed (thin paper, plain paper, thick paper, envelope) and the flow for determining double feeding when a print job is executed in this embodiment.
When envelope printing is performed in the image forming apparatus 100 in the present embodiment, the recommended transport direction is the direction in which the flap is on the leading end side in the transport direction.

  The type of recording material and the procedure for determining double feed will be described below with reference to the flowchart shown in FIG. The processing of the flowchart is realized by the CPU of the control unit 80 reading and executing a program stored in the ROM.

  The control unit 80 feeds the recording material at the start of the job (S802).

  When the control unit 80 detects a signal that the tip of the recording material passes through the top sensor 11 (S 803), the control unit 80 causes the ultrasonic wave transmitter 12 to pulse ultrasonic wave of 10 waves with an amplitude P 0 and a frequency of 30 kHz every 20 msec. See FIG. 3) (S804).

The control unit 80 sets a peak hold value of a waveform obtained by detecting the i-th transmission wave from the start of transmission by the ultrasonic wave receiver 13 as Pi (S805).
Next, from the pulse transmission, the peak hold value of 4 pulses emitted from when the recording material front reaches between the ultrasonic transmitter 12 and the ultrasonic receiver 13 is averaged to be Pa (S806).

The control unit 80 determines whether the detection level has reached less than 0.6 Pa after the start of the ultrasonic wave transmission (S807).
Then, when the detection level reaches less than 0.6 Pa (S807: Y), the value is taken as P1, ie, the peak hold value of the transmitted wave at a position within 3.6 mm from the leading edge of the recording material.
After the detection of P1, the transmitted light intensity is detected with the transmission intensity set to 2P0 (see FIG. 4) (S808).
S (1-4) = (P1 + P2 + P3 + P4) / 4 is calculated with an average of 4 pulses (P1 to P4) as S (1-4). The recording materials are classified into three types as shown in Table 1 according to the value of S (1-4) (S809).

  The relationship between the type of recording material and the peak hold value is shown in FIG.

If it is determined in S807 that the detection level has not reached 0.6 Pa, the process returns to S805.
The control unit 80 determines whether S (1-4) calculated in S809 is less than 0.1 Pa and determines that it is not less than 0.1 Pa (S810: N), the conveyed recording material is plain paper or It is considered to be thin paper, and the process proceeds to S811. Thereafter, the image forming process is executed by the transfer bias control and the fixing control corresponding to the type (S811).

  If it is determined in the process of S810 that the recording material to be conveyed is other than plain paper or thin paper (S810: Y), the control unit 80 considers that the attenuation of the ultrasonic wave accompanying the transmission of the recording material is large. Then, after P5, the transmission intensity of the ultrasonic wave transmitter 12 is changed to 5P0, and sampling of the transmission wave intensity Pi is continued (see FIG. 5) (S812).

  Here, the condition for determining the recording material to be conveyed as an envelope, double feeding, or thick paper will be described.

FIG. 7 shows a state in which the front end of the recording material moves in the arrow direction between the ultrasonic transmitter 12 and the ultrasonic receiver 13 constituting the media sensor in this example when the envelope is conveyed.
In the figure, up to P6 is represented every 20 msec (3.6 mm), where P1 is the transmitted wave intensity detected at the leading edge position of the recording material.

Further, FIG. 8 shows a state in which the vicinity of the front end when the recording material is double-conveyed and transported moves in the arrow direction between the ultrasonic wave transmitter 12 and the ultrasonic wave transmitter 13 in the present embodiment.
The S (1-4) represents the average of the four transmission wave intensities of ultrasonic waves in the vicinity of the leading end region (tip 0 to 18 mm, also referred to as the first region) of the recording material. S (5-8) represents an average value of four transmitted wave intensities irradiated to a region (also referred to as a second region) corresponding to around the tip of about 18 to 36 mm.
Here, the front end area (first area) of the recording material is an area where the flap is present in a folded state when the recording material is an envelope. Normally, an area of about 18 mm from the leading edge in the conveyance direction of the recording material is set, but the present invention is not limited to this value. The second area is an area starting from the end of the flap and going to the center. Normally, in the conveyance direction of the recording material, an area of about 18 mm to 36 mm from the front end after the first area is set, but this is also not limited to this value.

Here, in S813, in the case of S (1-4) <0.6S (5-8) (S813: Y), the control unit 80 is a factor that weakens the transmission wave intensity in the leading end region of the recording material, that is, the flap of the envelope It is considered that there is a state in which etc. is broken (S813).
Then, the control unit 80 executes the image forming process under the transfer and fixing conditions corresponding to the envelope (S816).
Thereafter, when detecting that the trailing edge of the recording material has passed the top sensor 11, the control unit 80 stops the pulse transmission of the ultrasonic wave (S817), (S818).

At S813, S (1-4)) 0.6S (5-8) (S813: N) and S (i- (i + 3))> 2S ((i-4)-(i-1) ) (Where i 5 5) (S 814: Y), the control unit 80 determines that there is a step that significantly reduces the transmission wave intensity from the leading end to the central region in the transport direction, that is, the sheets overlap. (S813), (S814).
In that case, the control unit 80 displays a double feed error display on the operation unit 60 (S815).

In the present embodiment, even if the recording material to be conveyed is double-fed, if the discharge is successful (S826: Y), the job is continued.
If discharge of the recording material which has been multi-fed fails (S826: N), the job is interrupted as a paper jam (S826), (S827). Note that, after the user performs the paper jam release process, the image formation is executed again on the image that did not end normally.

In addition, S (1-4) <0.1 Pa (S810: Y), and S (1-4)> 0.6 S (5-8) (S813: N), and S (i− (i +) 3)) If 2S ((i-4)-(i-1)) (where i 5 5) (S 814: N), the control unit 80 transmits the recording material to be conveyed significantly at least in the tip region It is determined that there is no step that changes the wave intensity (S814).
Then, the image forming process is executed with the transfer bias corresponding to the thick paper (the basis weight is more than 90 g / m ² ) and the fixing control temperature (S819).

Thereafter, when the trailing end of the recording material passes the top sensor 11, the control unit 80 stops the pulse generation of the ultrasonic wave (S820), (S821).
Then, let P (Z) be the peak hold value of the transmission intensity of the ultrasonic wave received by the ultrasonic receiver 13 at the end of the recording material. Here, i-1 satisfying P (i)> 2P (i-1) is Z (= i-1).
When S ((Z-3)-(Z)) ≦ 0.6 S ((Z-7)-(Z-4)) is satisfied (S822: Y), the control unit 80 controls the recording material by about 15 mm of the trailing edge of the recording material. It is determined that the area that significantly reduces the transmission intensity, that is, the state in which the flap of the envelope is folded, has passed the media sensor position (S822).
Then, the control unit 80 causes the operation unit 60 to display a message such as 'Please check the orientation of the envelope (the position of the flap)' (S823).

In addition, when the rear end of the recording material passes the top sensor 11, the control unit 80 stops the pulse transmission of the ultrasonic wave transmitter 12 (S817), (S818), (S820), and (S821).
Then, the control unit 80 determines whether or not the conveyance length of the recording material is within the range of ± 5 mm in light of the dimension of the recording material in the sub scanning direction selected from the image data or the selected print command ( S824). When the recording material is thick paper, (S814: N), S ((Z-3)-(Z)) ≦ 0.6 S ((Z-7)-(Z-4)) is not satisfied (S S822: N), perform this determination.
If not in the range, the control unit 80 causes the operation unit 60 to display a message such as 'Media size mismatch' (S825).

Also in the above case, if the discharge is successful, the job continues (S826).
If the discharge fails, the job is interrupted (S827).

  Then, if the dimension in the sub-scanning direction of the recording material to be conveyed is within the allowable range and the last recording material in the print job, the print job is completed (S828).

  If the recording material to be conveyed is not the last recording material, the next sheet feeding is continued, and the print job is continued (S828), (S829).

In the transfer bias control in this embodiment, constant current control in which control current values are made to correspond to respective paper types is executed for thin paper, plain paper, and thick paper, and constant voltage control is performed when it is determined to be an envelope.
In the fixing control, the control target temperature is varied according to the result of classification of the recording material type and the case of the envelope.
The fixing device 20 in the present embodiment is a so-called on-demand fixing device using a ceramic heater as a heat source. The fixing device 20 changes the fixing target temperature of the first job according to the temperature of the ceramic heater immediately before the start of the job. Further, the temperature rise of the pressure roller 22 is roughly estimated from the control integration time during the job, and the control temperature of the ceramic heater is varied.

  In this embodiment, when it is determined that the recording material is thin paper, the constant current control value of the transfer bias is changed to 0.9 times that of the plain paper, and the fixing control temperature is 10 ° C. lower than the plain paper. A target temperature offset to the temperature is applied.

In the case of thick paper, the constant current control value of the transfer bias is changed to 1.15 times that of plain paper, and the fixing control temperature is offset to a temperature 10 ° C. higher based on the plain paper setting, and during continuous job Fixing ability is secured by widening the sheet feeding interval of the sheet.
When the recording material is determined to be an envelope, a voltage output at 1.1 times the constant current value applied to the plain paper is applied to the transfer roller 14 by the constant voltage control to transfer the toner image. As the fixing control temperature, the same target value as that for plain paper is applied.
Further, in the case of envelope sheet feeding, the feeding interval is widened compared to the plain paper, and control and adjustment of the feeding interval are executed according to the temperature of a plurality of sub thermistors not shown arranged in the longitudinal direction of the heating unit 21. As a result, suppression of the temperature rise in the non-sheet-passing portion, securing of the fixing property and prevention of the occurrence of wrinkles are performed.

  As described above, at the time of conveyance of the recording material, an ultrasonic pulse of 10 wave units is transmitted from the ultrasonic transmitter 12 toward the receiver 13 every 20 msec. According to the waveform intensity received by the receiver 13, the transmission intensity is varied, the transmission wave intensity Pi of the ultrasonic wave is measured, and calculation is performed to estimate the type of recording material, basis weight, and envelope This makes it possible to distinguish between double feed and double feed.

  As a result, an appropriate imaging process is automatically performed without manually setting the paper type. In particular, in the case of envelope printing, it is possible to provide an image forming apparatus excellent in usability and reliability, which is judged as a multi-feed error after paper feeding, and there is no need to perform error cancellation or manual resetting.

  Second Embodiment A second embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the front end region of the recording material is irradiated with ultrasonic waves, and when it is considered to be other than plain paper or thin paper from the attenuation level of the transmitted wave intensity detected, Determine the presence and number of times. As a result, it is determined whether the cardboard is in the envelope or the double feed.

Hereinafter, the procedure for estimating the number of sheet superpositions, the thick paper and the envelope, and the procedure for determining double feeding will be described from the frequency component of the detection wave with reference to the drawings.
FIG. 10 is a diagram showing a spectrum in which the amplitude intensity is normalized with respect to the frequency of the ultrasonic wave transmitted from the ultrasonic wave transmitter 12. In this embodiment, it is shown that the irradiation wave is a 30 kHz sine wave.

FIG. 11 detects the fundamental frequency by using the GF-C081 as a recording material, irradiating the ultrasonic wave, detecting the transmitted wave with the receiver 13, and then performing FFT analysis on the nth harmonic component of the fundamental frequency It is a figure showing the result standardized by intensity.
Here, it is expressed as α _{n =} A _n / A ₁ when the intensity of the fundamental frequency component of the intensity of A _1, n-th harmonic component and A _n.

In FIG. 12, using a long type 3 kraft, 70 g envelope, manufactured by King Corporation, as a recording material, the ultrasonic waves are applied to a region where two sheets are stacked, and the transmitted wave is detected by the receiver 13. relates _n, is a diagram showing the results of n = 1, 2, 3, 4.

In FIG. 13, using a long type 3 kraft, 70 g envelope, manufactured by King Corporation, as a recording material, the ultrasonic waves are applied to a region where three sheets are stacked, and the transmitted wave is detected by the receiver 13. relates _n, is a diagram showing the results of n = 1,2,3,4,5.

FIG. 14 shows GF-C081 (single sheet conveyance and multi-feed), NPI 52 g paper, NPI 128 g paper, Xerox 4200 20 lb paper, and 24 lb paper as a recording material, long 3 kraft envelope (2 stacked area and 3 sheets It is a figure at the time of using an overlap field. For each of them, ultrasonic waves are irradiated from the ultrasonic wave transmitter 12, and the peak hold value of the transmitted wave obtained by the ultrasonic wave receiver 13 is represented by a multiple of the peak hold value (Pa) detected when paper is absent. There is.
As can be seen from FIG. 14, the discrimination of double feeding is that when the recording material to be transported becomes thick (more than 90 g / m ² ), the transmitted waves in the one sheet portion and the two sheet overlapping region generated in the leading edge region If the peak hold value can not be detected reliably, there is a risk of false detection.

In the present embodiment, as described above, using the values of α ₂ and α ₃ among the frequency components of the transmission wave, in particular, the parameters expressed as the α _n , whether the recording material to be transported includes an overlapping boundary surface Determine if it is not.

FIG. 15 is a diagram showing α ₂ at the time of single sheet conveyance, using GF-C081, 52 g and 128 g NPI paper, and Xerox 4200 20 lb and 24 lb paper as recording materials.

FIG. 16 is a diagram showing α ₂ of the waveform detected by the ultrasonic receiver 13 when the various recording materials are respectively fed twice.
FIG. 17 is a diagram showing α ₃ of the waveform detected by the ultrasonic receiver 13 when the various recording materials are respectively fed twice.
FIG. 18 is a diagram showing α ₃ of the waveform detected by the ultrasonic receiver 13 when the various recording materials are respectively fed in triple.

In the present embodiment, to determine from the results of FIGS. 15 and 16, alpha ₂ is conveyed one regardless of the paper type is less than 0.3, transporting two if greater than 0.3, and.
Further, from the results of FIG. 17 and FIG. 18, if α ₃ is less than 0.2, it is determined that double feeding, and if it is more than 0.2, triple feeding or more.

FIG. 19 is a diagram showing a flowchart for determining the type of recording material to be conveyed as thin paper, plain paper, thick paper, envelopes, or double feeding at the time of print job execution in this embodiment.
The type of recording material and the procedure for determining double feed will be described below according to the flowchart. The processing of the flowchart is realized by the CPU of the control unit reading and executing a program stored in the ROM.

  Since the flow from the execution of the first sheet feeding to the classification of the recording material type into thin paper, plain paper, and thick paper with the start of the job is the same flow as S801 to S811 in the first embodiment, the description is omitted. (S1801) to (S1811).

  In the present embodiment, when it is determined that the recording material to be conveyed is neither thin paper nor plain paper, the control unit changes the amplitude of the transmitted ultrasonic wave to 5P0 (S1812).

Then, the intensity A ₁ of the fundamental frequency component of the transmitted through the recording material transmitted light and the ratio A ₂ / A ₁ a is the alpha ₂ between the intensity A ₂ of the second harmonic component, the intensity A ₁ of the fundamental frequency component 3 Based on the calculated value of α ₃ which is the ratio A ₃ / A ₁ of the second harmonic component to the intensity A ₃ , the control unit 80 estimates the number of times of sheet stacking, and discriminates thick paper, envelope, and double feed. I do.

_Let α _n (i) be α _n calculated from the transmitted wave of the i-th ultrasonic pulse from the start of oscillation. As in the first embodiment, for the ultrasonic pulse transmitted every 20 msec, the pulse irradiated to the range of 0 to 3.6 mm of the recording material tip is specified from the signal received by the top sensor signal or the receiver 13, i It is assumed that = 1.

With respect to α ₂ (i), the vicinity of the leading end 0 to 18 mm of the recording material, ie, i = 1 to 4 is calculated. In three or more places, if α ₂ (i) <0.3, the control unit 80 determines that the recording material is a thick sheet, and executes transfer and fixing control (S 1813) and (S 1814).

In the case of α ₂ (i) ≧ 0.3 (S 1813: N) and α ₃ (i) ≧ 0.2 (i = 1, 2, _3, 4) and α ₃ (i) <0.2 (i ≧ 5: integer) (S1815: Y), the control unit 80 determines that the recording material is an envelope, and executes transfer and fixing control according to the envelope (S1813), (S1815), and (S1816).
Thereafter, when the trailing edge of the recording material passes the top sensor 11, the control unit 80 stops the pulse transmission of the ultrasonic wave (S1817), (S1818).

If the determination result in S1815 is No, and 5 ≦ i (integer) ≦ 15 and α ₃ (i) ≧ 0.2 at seven or more locations (S1820: Y), the control unit 80 determines that a double feed error occurs. , And displays (S1815), (S1819), (S1820), and (S1821).

In the present embodiment, when the recording material determined to be a multi-feed also successfully discharges the sheet, the subsequent job is continued (S1827) and (S1830).
However, if the double-feeding recording material discharge fails, the print job is interrupted as a paper jam (S1829).

Roughly, the determination result in S1815 is negative, and in 5 ≦ i (integer) ≦ 14, α ₃ (i) <0.2 (S1820: N) at 7 or more locations and detection at the rear end position of the recording material Control is performed in the case of α ₃ (i) ≧ 0.2 at _three or more places among four places of z−3 ≦ i (integer) ≦ z, assuming that the transmitted wave to be transmitted is i = z th (S1824: Y) The unit 80 determines that the envelope flap is on the rear end side and performs display (S1815), (S1819), (S1820), (S1822) to (S1824), (S1828).

  If the sheet is ejected successfully even if the flap of the envelope is in the opposite direction to the recommendation, the job continues (S1828), (S1827), and (S1830). If the delivery is unsuccessful, the control unit 80 interrupts the job as a paper jam (S1827), (S1829).

In addition, when the rear end of the recording material passes the top sensor 11, the control unit 80 stops the pulse transmission of the ultrasonic wave transmitter 12 (S1817), (S1818), (S1822), and (S1823).
Then, the control unit 80 determines whether or not the conveyance length of the recording material is within the range of ± 5 mm in light of the dimension of the recording material in the sub scanning direction selected from the image data or the selected print command ( S1825). In the case where S1820 is not satisfied, the control unit 80 sets the case where α ₃ (i) 0.2 0.2 is 2 or less among the four locations in z-3 ≦ i (integer) ≦ z (S1824: N), This determination is made.
Then, from the time from when the top sensor 11 detects the leading edge of the recording material to when detecting the trailing edge, the control unit 80 determines whether the dimension in the sub-scanning direction of the recording material matches the selected recording material dimension. If the sizes do not match, a message to that effect is displayed (S1825), (S1826).
Even in the case where the sizes do not match, the job continues if discharge is successful (S1827) and (S1830).
If it is the last recording material in the print job, the job is ended together with the output (S1832). If it is in the middle of a job, the next recording material is fed (S1831).
If the discharge is unsuccessful, the control unit 80 interrupts the job as a paper jam (S1829).

  As described above, detection of the front and rear end positions and pulse-like ultrasonic wave irradiation are performed on the recording material to be conveyed. Then, the basis weight of the recording material to be conveyed is estimated and the presence or absence of the superposition of the sheets or the number of times is determined from the change in amplitude of the ultrasonic waves transmitted through the recording material and the frequency component.

  Estimate the basis weight of the recording material from whether the estimated basis weight and the number of sheet superpositions increase, decrease, or fall within the threshold range from the leading end region to the rear end of the recording material conveyance direction, and from the conveyance length It is possible to automatically determine the envelope and the multi-feed.

  In Embodiments 1 and 2 described above, when the job is interrupted as a paper jam, the recovery operation is performed after the user cancels the paper jam. However, as an initial setting of the device, it is also possible to set it so as not to perform the recovery operation. In this case, if it is determined that a double feed has occurred, the job ends prematurely. When re-forming an image, the user may set the job again.

(Other embodiments)
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. Can also be realized. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.
Further, the present invention may be applied to a system constituted by a plurality of devices or to an apparatus comprising a single device.
The present invention is not limited to the above embodiments, and various modifications (including organic combinations of the respective embodiments) are possible based on the spirit of the present invention, which are excluded from the scope of the present invention is not. That is, the configuration in which each of the above-described embodiments and their modifications are combined is also included in the present invention.

11 top sensor 12 ultrasonic oscillator 13 ultrasonic receiver 80 DC controller 100 multifunction printer

Claims (11)

A detection unit provided on the recording material conveyance path for detecting an end of the recording material;
Ultrasonic wave transmitting means provided on the recording material conveyance path;
Ultrasonic wave receiving means provided on the recording material conveyance path corresponding to the ultrasonic wave transmitting means and receiving a transmitted wave transmitted from the ultrasonic wave transmitting means and transmitted through the recording material;
Calculating means for detecting the amplitude of the waveform detected by the ultrasonic wave receiving means and performing an operation;
The ultrasonic wave transmitting means transmits a pulse wave so that a plurality of ultrasonic waves are irradiated in the conveyance direction of the recording material in the process of conveying the recording material on the recording material conveyance path.
The calculating means is based on the intensity or frequency component of the transmitted wave at a plurality of locations from the leading end region to the trailing end region of the recording material in the conveyance direction in the process of the recording material being conveyed on the recording material conveyance path. An image forming apparatus characterized by performing discrimination between double feeding of the recording material and an envelope;   The calculating means is configured to transmit the intensity of the transmitted wave transmitted through the first area including the substantially front end portion of the recording material through the second area of the recording material which continues to the first area in the transport direction. The image forming apparatus according to claim 1, wherein the recording material is determined to be an envelope when it is detected that the strength of the wave has decreased.   The computing means is characterized in that when the significant difference in intensity of the transmitted wave is detected from a substantially front end portion to a substantially central region in the conveyance direction of the recording material, it is determined that the recording material is double fed. The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 2, wherein when the computing unit determines that the recording material is an envelope, the image forming process is executed in accordance with a condition corresponding to the envelope.   The computing means is characterized in that the type of the recording material is determined to be thin paper, plain paper or thick paper according to the intensity of the transmitted wave transmitted through the first area including the substantially front end portion of the recording material. The image forming apparatus according to any one of claims 1 to 4, wherein   6. The image forming apparatus according to claim 5, wherein the intensity of the signal transmitted by the ultrasonic wave transmission unit is changed according to the type determined by the calculation unit. Said computing means multifeed the envelope of said recording material based on a comparison alpha _{n =} A _n / A ₁ between the intensity A _n of the intensity A ₁ and the n-th harmonic component of the fundamental frequency component included in the transmission wave The image forming apparatus according to claim 1, wherein the determination is made. The image forming apparatus according to claim 7, wherein α ₂ and α ₃ are used as the α _n . Using α ₂ for the transmitted wave transmitted through the first area including the substantially front end portion of the recording material, and α ₃ for the transmitted wave transmitted through the second area of the recording material following the first area in the transport direction The image forming apparatus according to claim 8, A detection unit provided on the recording material conveyance path for detecting an end of the recording material;
Ultrasonic wave transmitting means provided on the recording material conveyance path;
Ultrasonic wave receiving means provided on the recording material conveyance path corresponding to the ultrasonic wave transmitting means and receiving a transmitted wave transmitted from the ultrasonic wave transmitting means and transmitted through the recording material;
A recording material determination method using an image forming apparatus having an arithmetic unit that detects the amplitude of the waveform detected by the ultrasonic wave receiving unit and executes an operation;
The step of transmitting a pulse wave such that a plurality of ultrasonic waves are irradiated in the conveyance direction of the recording material in the process of the recording material being conveyed on the recording material conveyance path;
The recording means performs the recording based on the intensities of the transmitted waves at a plurality of locations from the front end area to the rear end area in the conveyance direction of the recording material while the recording material is conveyed on the recording material conveyance path. A method of discriminating a recording material using an image forming apparatus, comprising: a step of discriminating between double feeding of material and an envelope.   The program for making a computer perform the determination method of Claim 10.

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