JP2001348138A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device having roller interval detection means precisely detecting the thickness of a paper sheet by effectively removing the fluctuation component from roller interval detection information. SOLUTION: Correction roller interval data (fluctuation component) d1 is obtained based on the roller interval detection information sampling the output of a paper thickness detection circuit 330 when no paper sheet passes between roller pair 215 so that roller interval detection information d2 from the paper thickness detection circuit 330 when the paper sheets pass between the roller pair 215 is corrected by the correction roller interval data d1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a printer and a copying machine.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a printer or a copying machine, a technique has been proposed in which the thickness of a sheet as a transfer material is measured and the result is reflected in image forming process conditions. Have been. Furthermore,
As a method for measuring the thickness, for example, an image forming apparatus has been proposed in which a sheet thickness is obtained from a displacement of a distance between rollers when the sheet passes through a pair of conveying rollers.

[0003]

However, there is a need for an improvement in the proposed technology in which the paper thickness is detected by removing these vibration components from the viewpoint of the existence of various vibrations in the apparatus. As the vibration, for example, in the apparatus, there are vibration due to driving of motors and vibration due to driving of solenoids and clutches.

[0004] In any environment, it is desirable to propose a method for removing fluctuation components caused by various vibrations in order to improve the accuracy of paper thickness detection in any environment. This also means that any fluctuation can be dealt with at any timing, so that there is a degree of freedom in the control timing of each component in the apparatus, which contributes to the realization of a high-throughput image forming apparatus.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of accurately detecting a paper thickness by effectively removing a fluctuation component from detection information of a roller interval.

[0006]

In order to solve the above-mentioned problems, according to the present invention, an output of a roller interval detecting means when a sheet does not pass between a pair of rollers is corrected based on sampled roller interval detecting information. Correction means for obtaining roller interval data (fluctuation component) for use and correcting the roller interval detection information from the roller interval detection means when the paper passes between the roller pairs with the correction roller interval data. It is characterized by the following.

[0007] Thus, the fluctuation component can be clearly separated from the output of the roller interval detecting means, whereby the accuracy of paper thickness detection and the like can be improved. Furthermore, even if there is a timing that causes a fluctuation during the detection of the paper thickness, the fluctuation can be separated, so that the control timing of each component for the image forming operation can be freely set, and a high throughput can be achieved. Printer can be realized.

The roller interval detecting means includes a transformer having a movable core displaced by a change in the interval between the pair of rollers and a fixed core opposed to the movable core. It is characterized by detecting an interval between pairs.

Normally, the paper thickness is obtained from the roller interval detection information when the paper passes between the roller pairs.

The roller pair is a registration roller in the transport direction for synchronizing the transport direction between the sheet and the image. The roller pair detects the sheet passing state from the roller interval detection information detected by the roller interval detecting means, and detects the paper passage. A control unit for controlling the registration roller so as to synchronize the conveyance direction with the image is provided.

The roller pair is a wrapped jam detection roller pair for detecting the wrapped state of the paper roller.
The image forming apparatus further includes a discriminating unit that discriminates the winding of the sheet by detecting a sheet passing state from the roller interval detection information detected by the roller interval detecting unit. As the roller pair, a fixing roller pair for fixing an image on a sheet is preferable.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments.

(First Embodiment) FIG. 1 is a block diagram of a printer 200 as an image forming apparatus including a printer controller 103 and a printer engine 104 according to a first embodiment of the present invention.

In FIG. 1, reference numeral 101 denotes a display, and 102 denotes a host computer. A printer controller 103 converts image data transmitted from the host computer 102 into an image signal so that raster scanning can be performed, and controls a printer engine 104 through an interface. The printer controller 103 and the printer engine 104 are both housed in the same printer housing.

The components in the printer controller 103 are as follows.

Reference numeral 103a denotes a display unit disposed on the surface of the printer housing, 103b denotes an operation unit disposed on the surface of the printer housing, 103c denotes a controller CPU, and 103d denotes a CPU.
ROM to be accessed by 103c; 103e: CPU 10
Reference numeral 3c denotes a RAM to be accessed.

FIG. 2 is a mechanical configuration diagram of the printer 200.

The printer 200 includes a printer main body 201 as a main body and an optional paper feeder 202 as an option.

Reference numeral 203 denotes a front cover. When the front cover is opened, an MPT (Multi-Purpose Tray) 2 serving as a manual feed tray is provided.
04 can be used. 205 denotes the manual paper feed tray (M
(PT) 204 is a flag of a sensor for detecting the presence of a sheet. Reference numeral 206 denotes a paper feed roller for conveying paper on a manual paper feed tray (MPT) 204 into the printer.

Reference numeral 207 denotes a standard paper feed tray PCT (Pap
er Cassette Tray). Reference numeral 208 denotes a flag of a sensor that detects the presence of a sheet on the standard paper feed tray (PCT) 207. Reference numeral 209 denotes a paper feed roller for conveying the paper on the standard paper tray (PCT) 207 to the inside of the printer.

Reference numeral 210 denotes an optional paper feed tray OP
T (Optional Paper cassette Tray). Reference numeral 211 denotes a sensor flag for detecting the presence of a sheet on the optional tray (OPT) 210. Reference numeral 212 denotes an OPT paper feed roller for conveying paper on an optional tray (OPT) 210 to the inside of the printer.

Reference numeral 213 denotes a standard paper feed tray (PCT) 207.
And rollers for transporting the paper fed from the optional paper feed tray (OPT) 210 further into the printer.

The paper fed from any of the manual paper feed tray (MPT) 204, the standard paper feed tray (PCT) 207, and the optional paper feed tray (OPT) 210 comes into contact with the registration shutter 214 at the leading end, and is conveyed. The orientation is corrected. Further, by driving the pair of registration rollers 215,
The sheet is transported further downstream. Registration roller 215
Immediately after the flag 215 of a sensor called a TOP sensor
a to synchronize the paper conveyed with the image. The sheet is further guided by a transport guide 216 to a transfer nip sandwiched between a photosensitive drum 219 and a transfer roller 221.

A known toner cartridge 217 includes a primary charging roller 218, a photosensitive drum 219, and a developing cylinder 220 therein.

The writing of the electrostatic latent image is performed by irradiating a predetermined laser beam on a polygon mirror 224 rotated and driven by a motor 223 and irradiating the photosensitive drum 219 with a return mirror 225 in the scanner unit 222. .

After the sheet has passed the toner transfer position, the sheet is transferred to the fixing roller 22 by the conveying belt mechanisms 226a to 226e.
7 and a pressure roller 228, where the toner image is fixed on a sheet.

A paper discharge sensor 229 detects the presence of paper immediately after the fixing device.

The sheet that has passed through the fixing device is further conveyed by a sheet discharging roller 230. Face up tray 231
Is open as shown in the figure, the sheets are stacked on the tray 231. When the tray 231 is closed, the paper reaches the rollers 232 and is stacked on the face-down tray 233.

Reference numeral 234 denotes an upper door. When the upper door is opened upward, the toner cartridge 217 can be taken in and out.

FIG. 3 is an electrical configuration diagram of the printer engine according to the first embodiment.

Reference numeral 301 denotes an electric circuit unit of the printer engine. 302 is a microprocessor, 30
3 is the core. The microprocessor 302 includes a CPU 304 provided in the core 303, a ROM 30
5. RAM 306 and gate arrays (hereinafter abbreviated as GA) 307a to 307d connected to the core 303,
Have.

Reference numeral 308 denotes a manual paper feed tray (MPT) 20
No. 4 paper presence sensor, 309 is a manual feed tray (MP
T) 204 is a paper feed roller drive solenoid; 310 is a paper presence sensor of a standard paper feed tray (PCT) 207;
Is a paper feed roller drive solenoid of the standard paper feed tray (PCT) 207, 312 is an optional paper feed tray (OPT) 2
Reference numeral 313 denotes a paper presence sensor, and reference numeral 313 denotes a solenoid for driving a paper feed roller of an optional paper feed tray (OPT) 210.
Each roller rotates by driving a solenoid while the main motor 314 is rotating.

A TOP sensor 315 detects the behavior of the flag 215a, and a discharge sensor 316 detects that the paper has been discharged from the printer.

Reference numeral 317 denotes an interface between the optional sheet feeding device and a checker exclusively connected to the printer main body. This checker is used by a service technician to check the status of the printer or perform a predetermined operation.

Reference numeral 318 denotes a switch for instructing a test print for outputting a test image for checking the operation of the printer. A switch 319 detects the open / closed state of the door 234 and turns off the high voltage circuit inside the printer when the door 234 is open. A jumper 320 indicates the type of power supply of the printer.

An external interface circuit 321 allows the printer engine 104 to communicate with the printer controller 103. 322 is an electric circuit of the scanner unit 222, 323 is an electric circuit for controlling charging, development, transfer, and high voltage of the fixing film, and 324 is an electric circuit of the fixing device.

Reference numeral 325 denotes a fan for cooling the inside of the printer.

Reference numeral 330 denotes a paper thickness detection circuit as roller interval detection means.

The printer engine 104 outputs a BD signal on / BDO to the controller 103 through an external interface (I / F). This is a signal indicating that the polygon mirror 224 has a predetermined phase. When an image forming operation is performed on each sheet, horizontal scanning is performed when an image of one frame is received in a raster form via VDO and / VDO. Line synchronization signal. The first BD signal for each frame is called a TOP signal.

FIG. 4 shows a paper thickness sensor 4 constituting the paper thickness detection circuit 330 in the printer engine according to the first embodiment.
00 is shown. In this embodiment, the present invention is applied to a registration roller pair 215 in the transport direction that synchronizes the transport direction between the sheet and the image as a roller pair that is urged to abut each other and has a paper transport function. The distance between the rollers of the pair of registration rollers 215 is detected by the paper thickness sensor 400.

As the paper thickness sensor 400, a tuned sensor composed of a transformer 404 whose output changes due to a change in mutual inductance depending on the distance between the fixed core 404b and the movable core 404a is used. Movable core 404a
And the fixed core 404b include a primary winding 404c and a secondary winding 4
One core sharing the same core 04d is formed, and the mutual inductance between the primary winding 404c and the secondary winding 404d is determined by the distance between the movable core 404a and the fixed core 404b.

A support member 402 is provided as an interlocking means for displacing the movable core 404a in conjunction with a change in the roller interval between the pair of registration rollers 215. The support member 402 is rotatably supported by the rotating shaft 401, one end of one of the pair of registration rollers 215 is supported, and the other end supports the movable core 404a.

When the sheet S1 enters, the lower roller of the registration roller pair 215 is lowered by the thickness of the sheet S1, and
The support member 402 rotates clockwise about the rotation shaft 401. The support member 402 is urged counterclockwise by a spring mechanism 403 so that the registration roller pair 21
5 is urged in the direction of contact.

FIG. 5 is a circuit diagram showing details of the paper thickness detection circuit 330.

In the drawing, reference numeral 501 denotes the paper thickness sensor 40.
0 is always applied to the primary winding 404c, and oscillates when a current flows through the primary winding 404c. On the other hand, the mutual inductance of the transformer 404 is determined according to the distance D between the ferrite cores 404a and 404b, and the AC pulse value generated in the secondary winding 404d is determined accordingly. For example, the relationship is such that when the distance of D is short, the value of the AC pulse voltage L decreases, and conversely, when the distance of D increases, the value of L increases. Further, the relationship between D (distance) and L (voltage value) is almost linear.

The peak value L of the AC pulse value is shaped by a detection circuit 502 and converted into a DC voltage value.
The output is amplified N times by the amplifier 503, and the output value (L · N) is used as final paper thickness output information.

FIG. 6 shows the waveform of the paper thickness detection circuit output (LN) related to the paper thickness detection processing in the printer of the first embodiment.

According to the present invention, correction roller interval data (fluctuation component) is obtained based on roller interval detection information obtained by sampling the output of the sheet thickness detection circuit 330 when the sheet does not pass between the registration roller pair 215. The roller interval detection information from the sheet thickness detection circuit 330 when the sheet S passes between the pair of registration rollers 215 is corrected by the microprocessor 302 as correction means based on the correction roller interval data.

FIG. 9A shows the output waveform of the sheet thickness detection circuit 330 during the printing operation and when the sheet does not pass through the pair of registration rollers 215. d1 is correction roller interval data, which is a simple average of the output of the paper thickness detection circuit 330.

FIG. 7B shows an output waveform as roller interval detection information when a sheet is passing through the roller pair 215 during a printing operation. d2 is a paper thickness detection circuit 330
Shows the simple average of the output of

Assuming that the corrected paper thickness data is d3, d3
= D2-d1.

FIG. 7 is a diagram showing a part of the contents of the RAM 306 in the printer engine 104 according to the first embodiment. The storage area of d1, d2, and d3 described above is shown.

FIG. 8 is a flowchart showing a paper thickness detecting procedure in the printer engine 104 according to the first embodiment.

A program for realizing the procedure shown in this flowchart is stored in the ROM 305. This program is started for each sheet of paper in the printing operation each time one sheet is fed. Then, a process condition for image formation is determined according to the detected paper thickness. That is, it is controlled by the microprocessor 302 as a control means so as to detect the sheet passage state from the roller interval detection information detected by the sheet thickness detection circuit 330 and to synchronize the conveyance direction between the sheet and the image.

Hereinafter, the procedure for detecting the paper thickness will be described with reference to this flowchart.

First, time measurement by a time measurement program (not shown) is started (step 801). The control timing after this is measured based on this timing situation.

Next, until just before the fed sheet comes into contact with the registration shutter 214, the output of the sheet thickness detecting circuit 330 is taken in (802, 803), the average is calculated, and this is set as d1 (804). .

Next, the leading end of the sheet is moved to the registration roller pair 215.
(805).

Next, until the leading edge of the paper reaches the nip between the photosensitive drum 219 and the transfer roller 221, the output of the paper thickness detection circuit 330 is taken in (806, 807), and the average is calculated. d2 (808).

Finally, the paper thickness d3 is calculated from d2 and d1 (809).

(Second Embodiment) In the first embodiment, registration in the transport direction between a sheet and an image is performed by the leading edge detection sensor (TOP sensor) 215a. However, in the printer engine 104 of the second embodiment, Instead of the mechanism of the first embodiment, registration in the transport direction is performed by the following method.

More specifically, a method of accurately registering the paper and the image in the transport direction using the paper thickness detection circuit 330 described in the first embodiment has been proposed.

The microprocessor as a control means detects the state of passage of the registration roller pair 215 from the roller interval detection information detected by the sheet thickness detection circuit 330 and synchronizes the transport direction between the sheet and the image. 30
2 is controlled. More specifically, a steady state of the output of the sheet thickness detection circuit 330 shown after the leading edge of the sheet has passed through the registration roller pair 215 is recognized, and the sensor output is at a time earlier than this steady state period, and the sensor output has a peak value. Based on the timing shown. This peak value is
This is caused by overshoot of the roller displacement when the sheet comes into contact with the roller pair.

By the way, there are solenoids in the printer engine 104, and the vibration when driving them is
It may affect paper thickness detection.

The second embodiment of the present invention realizes that the fluctuation at the time of driving the solenoid is removed from the output of the paper thickness detecting circuit 330. The configuration of the second embodiment is the same as that of the first embodiment.
Therefore, the configuration will not be described in detail, and only the state of fluctuation removal by this solenoid drive will be described.

FIG. 9 is a diagram showing the output waveform of the sheet thickness detection circuit related to the sheet leading edge detection process in the printer engine 104 according to the second embodiment.

FIG. 7A shows an output waveform of the sheet thickness detection circuit when the first sheet is fed in a predetermined printing operation. The waveform shown in the period N1 is an output for a certain period after driving a predetermined sheet feeding solenoid.
The outputs in this period N1 are stored in time series.

FIG. 9B shows an output waveform of the sheet thickness detection circuit 330 when a sheet other than the last sheet passes through the registration roller pair 215 in a predetermined printing operation for continuously feeding sheets. The waveform shown in the period N2 is an output for a certain period after driving the same paper feed solenoid as that shown in FIG. That is, the displacement due to the vibration accompanying the solenoid drive is weighted by the displacement due to the sheet thickness.

In order to recognize the steady state of the output of the paper thickness detecting circuit 300, the output is subtracted by the amount of the output due to the vibration of the solenoid weighted in the period N2 (shaded area). The output due to the vibration is already sampled in the period N1 described in FIG. Then, a timing at which the output peaks, such as P, is obtained.

(Embodiment 3) In Embodiments 1 and 2,
Although the paper thickness detecting circuit 330 as the roller interval detecting means detects the interval between the pair of registration rollers 215, in the present embodiment, the wrapped jam detecting roller pair for detecting the wrapping state of the sheet around the roller is a specific example. Specifically, the distance between a pair of fixing rollers constituted by a fixing roller 227 and a pressure roller 228 of a fixing device for fixing an image on a sheet is detected.

Then, by detecting the paper passage state from the roller interval detection information detected by the paper thickness detection circuit 330, the winding of the paper is determined by the microprocessor 302 as the determination means.

The process of removing the fluctuation component of the output of the paper thickness detection circuit 330 is performed in the same manner as in the first and second embodiments. In the following description, the same portions as those in the first embodiment will be described. Is omitted, and only the jam detection procedure will be described.

FIG. 10 is a diagram showing a state of the jam for explaining detection of a jam around the pressure roller of the fixing device in the printer engine according to the third embodiment.

FIG. 9A shows a state in which the sheet S3 conveyed from the right side of the sheet is normally conveyed between the fixing roller 227 and the pressure roller 228.

FIG. 7B shows a state in which the paper passing through the fixing device is wound around the pressure roller from the middle of the paper. In the nip between the fixing roller 227 and the pressure roller 228, three sheets are sandwiched.

FIG. 11 shows the engine of the third embodiment.
9 is a flowchart illustrating a procedure for detecting a jam around a fixing device pressure roller. A program for implementing the procedure shown in this flowchart is in the ROM 305.

First, when the sheet is conveyed and the leading end is detected by the sheet discharge sensor 316 (1101), the program starts timing (1102).

Next, the data of the interval between the fixing roller 227 and the pressure roller 228 is sampled for a time during which the pressure roller 228 makes a half turn, and a simple average is calculated (1103).
This is the interval when only one sheet passes between the rollers.

Next, the roller interval is measured until the trailing edge of the sheet is detected by the sheet ejection sensor.
When the interval of one sheet exceeds the predetermined amount obtained in (1)
105, 1104), it is determined that the jam has occurred (11).
07).

However, if the trailing edge of the sheet is detected by the sheet discharge sensor earlier than the predetermined time (1105, 1106), this is also determined to be a wrapping jam (1107).

As described above, in the first embodiment,
The fluctuation component was measured until just before the detection of the paper thickness.

If the timing of occurrence of fluctuation is known as in the second embodiment, it is clear from which part of the output of the paper thickness detection circuit the fluctuation should be subtracted.

In the third embodiment, the number of sheets sandwiched between the fixing nips is observed. However, since the thickness of one sheet is measured based on the same sheet, the thickness is measured. However, this method does not depend on the type of paper.

(Other Embodiments) In the third embodiment, the fixing roller 22 is rotated for a half time of the pressing roller 228.
Although the interval data between the pressure roller 7 and the pressure roller 228 is required and is set as one sheet interval, if the thickness of the sheet is known, step 1103 of the third embodiment is omitted as shown in FIG. Can also detect jams. The paper thickness data of the paper may be detected by the paper thickness sensor 400 of the registration roller pair 215 as described in the first embodiment, may be detected in another part, or may be known in advance. May be stored in a memory.

[0085]

The roller interval detecting means according to the present invention measures the fluctuation applied during the sheet passing before the sheet is passed, and uses it as roller interval correction data, so that the separation between the fluctuation and the sheet thickness is obtained. High effect.

[Brief description of the drawings]

FIG. 1 is a block diagram of a printer including a printer controller and a printer engine according to a first embodiment of the present invention.

FIG. 2 is a machine configuration diagram of the printer according to the first embodiment.

FIG. 3 is an electrical configuration diagram of the printer according to the first embodiment.

FIG. 4 is a diagram illustrating a paper thickness detection mechanism in the printer according to the first embodiment.

FIG. 5 is a circuit diagram of a paper thickness detection circuit in the printer according to the first embodiment.

FIG. 6 is an output waveform of a paper thickness detection circuit related to the paper thickness detection circuit in the printer according to the first embodiment.

FIG. 7 is a diagram illustrating a part of the contents of a RAM in the printer according to the first embodiment;

FIG. 8 is a flowchart illustrating paper thickness detection in the printer according to the first embodiment.

FIG. 9 is an output waveform of a sheet thickness detection circuit relating to a sheet leading edge detection process in the printer according to the second embodiment.

FIG. 10 is a diagram illustrating a state of a jam for explaining detection of a jam around a fixing device pressure roller in the printer according to the third embodiment;

FIG. 11 is a flowchart illustrating detection of a jam around a fixing device pressure roller in the printer according to the third embodiment.

FIG. 12 is a flowchart illustrating detection of a jam around a fixing device pressure roller in a printer according to another embodiment.

[Explanation of symbols]

Reference Signs List 101 display 102 computer 103 printer controller 104 printer engine 200 printer 201 printer main body 202 optional paper feeder 215 registration roller pair 302 microprocessor (correction means, control means, determination means) 330 paper thickness detection circuit 400 paper thickness sensor 404 transformer 404a movable Core 404b Fixed core 404c Primary winding 404d Secondary winding 501 Oscillator 502 Detection circuit 503 Amplifier

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/00 518 G03G 15/00 518 3F048 15/20 109 15/20 109 3F102 21/14 21/00 510 21/00 510 372 F term (reference) 2F063 AA16 AA23 BA30 BB08 BC01 BC09 CB04 DA02 DA04 DD02 GA05 GA16 KA01 KA05 LA16 LA23 LA30 2F069 AA44 AA46 BB20 EE03 EE22 GG04 GG06 JJ13 PP06 2H0 EE02 A14 DC07 CA16 CA22 CA39 2H072 AA03 AA16 AA24 AB07 3F048 AA02 AA04 AA05 AB01 BA05 BB02 CA04 DA06 DC18 EB31 3F102 AA06 AA11 AB01 BB02 CB01 FA08

Claims (6)

[Claims] 1. An image forming apparatus comprising: a pair of rollers which are urged to abut each other and have a sheet conveying function; and a roller interval detecting means for detecting an interval between the rollers of the pair of rollers. The correction roller interval data is obtained based on the roller interval detection information from the roller interval detection unit when the paper does not pass through, and the roller interval detection unit when the paper passes between the roller pairs is obtained. An image forming apparatus provided with correction means for correcting the roller interval detection information according to the correction roller interval data. 2. The roller distance detecting means includes a transformer having a movable core displaced by a change in the distance between a pair of rollers and a fixed core facing the movable core, and measuring a mutual inductance of the transformer. An image forming apparatus for detecting an interval between a pair of rollers by using the image forming apparatus. 3. The image forming apparatus according to claim 1, wherein a sheet thickness of the sheet is obtained from the roller interval detection information when the sheet passes between a pair of rollers. 4. A roller pair is a registration roller in the transport direction for synchronizing the transport direction between the sheet and the image,
Control means for controlling the registration rollers so as to synchronize the conveyance direction between the sheet and the image by detecting the sheet passing state from the roller interval detection information detected by the roller interval detection means. The image forming apparatus according to claim 1. 5. A roller pair is a wrapping jam detection roller pair for detecting a wrapping state of a roller of a sheet. The wrapping state of the sheet is detected by detecting a sheet passing state from roller interval detection information detected by roller interval detecting means. The image forming apparatus according to claim 1, further comprising a determination unit configured to determine whether the image forming apparatus determines the image quality. 6. The image forming apparatus according to claim 5, wherein the roller pair is a fixing roller pair for fixing an image on a sheet.