JP3133310B2 - Laser printer control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a control device for a laser printer having a photo interrupter device used for detecting a rotation amount, a rotation speed, and the like of a rotation shaft.

[0002]

[Prior art]

In the photo interrupter, a light emitting unit having a light source such as an LED and a light receiving unit having a light receiving element such as a photodiode are provided in one block facing each other, and a peripheral portion of a rotating disk is interposed therebetween. It has a configuration.

[0003] A slit is formed in a peripheral portion of the disc, and light reaching the light receiving section from the light emitting section is turned on / off intermittently by rotation of the disc. Then, the signal output from the light receiving element is shaped into a rectangular pulse signal, and the rotation amount and the rotation speed of the rotating shaft provided with the disk are measured using the pulse signal.

[0004]

[Problems to be solved by the invention]

However, in the conventional photointerrupter, since the width of the slit formed in the disk is constant from the center side to the peripheral side, the positional relationship between the light emitting unit and the block of the light receiving unit and the disk is changed in the radial direction of the disk. In the case of misalignment, the pulse width changes even if the rotation of the disk is constant, depending on where the photo interrupter detects the slit on the disk. There are disadvantages that are difficult to apply.

[0005]

[Object of the invention]

The present invention has been made in view of the above problems, and uses a photointerrupter device in which the output pulse width does not change even when the relative distance between the rotating plate and the light emitting unit and the block of the light receiving unit changes. It is an object of the present invention to provide a control device of a laser printer having a reliable and highly accurate detection accuracy.

[0006]

[Means for Solving the Problems]

In order to achieve the above object, a control device for a laser printer according to the present invention includes a heat roller driven by a drive motor and a pressing roller, and fixes the continuous sheet inserted between the rollers while holding the sheet continuously. A fixing unit, and a tractor unit that conveys the continuous paper, wherein the tractor unit is driven by the drive motor, a driven shaft that is driven to rotate by the drive shaft, the driven shaft, A continuous paper laser printer configured to convey the continuous paper while controlling a conveyance speed of the tractor unit and a conveyance speed of the fixing unit, the endless belt being bridged between the driven shaft and the endless belt. A rotating plate that has a radial slit and forms a part of a photo-interrupter around a rotation axis that is rotated in conjunction with the driven shaft; A sensor for detecting a continuous paper transport speed, which has a light emitting portion and a light receiving portion on both sides of the transfer region, and constitutes a part of the photo interrupter, is provided. Time measuring means for measuring the time of the HIGH level of the pulse to be performed and the time of the LOW level of the pulse, and detects the transport speed of the continuous paper based on the measurement of the time measuring means, and detects the transport speed based on the transport speed. The driving motor is controlled.

[0007]

[Action]

According to the above configuration, since a radial slit is formed in the rotating plate, even if an error occurs in the mounting position in the radial direction with respect to the rotating plate, detection deterioration due to the mounting position error can be avoided, and the pulse HIGH The time measurement means that measures the time of the level and the time of the LOW level of the pulse improves the accuracy of detecting the transport speed, so that when transporting continuous paper, highly reliable speed detection can be performed. As a result, the continuous paper can be conveyed in a sluggish manner.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described with reference to the drawings. Fig. 1 ~
FIG. 3 shows an embodiment of a laser printer having a photointerrupter device according to the present invention.

Here, a laser beam printer which prints print data from a host computer as a printer main body on continuous paper in accordance with an electrophotographic process of exposing a photosensitive drum to a photosensitive drum, developing an exposed image, transferring the image to paper, and fixing the image is described. Is shown.

First, a mechanical configuration of the printer will be described with reference to FIGS. 1 and 2.

In this printer, as shown in FIG. 1, the photosensitive drum 11 is centered from a feed port 1 where continuous paper FP is supplied to a discharge port 2 where a printed sheet is discharged. Process unit 10, a tractor unit 20 having an endless belt 21 having a projection engaged with a paper feed hole, and a fixing unit 3 having a pair of rollers 31, 32 for thermocompressing the transferred toner image.
0 is arranged in order.

The processing unit 10 includes a charger 12 for charging the photoconductor on the photoconductor drum 11, a scanning optical system 13 for exposing the charged photoconductor to form an electrostatic latent image on the drum, A developing unit 14 for attaching toner to the formed latent image, a transfer charger 15 for charging the paper to transfer the toner image to the continuous paper FP, and a cleaning unit 16 for removing toner remaining on the drum. And a charge removing LED 17 for exposing the entire drum to remove charges.

The scanning optical system 13 is provided in the upper cover UC. The scanning optical system 13 continuously deflects a modulated beam from a semiconductor laser (not shown) by a polygon scanner 13a and converges the modulated beam by an fθ lens (not shown). The light is reflected by 13b to form a scanning line on the photosensitive drum 11, and an electrostatic latent image is formed for each dot as the drum rotates.

The developing unit 14 that supplies the toner includes a toner case 14 a in which the toner is accumulated, and a developing roller 14 that is provided at a lower end of the case and attaches the toner to the photosensitive drum 11.
b, and a piezoelectric sensor as a toner low sensor 14c for detecting the presence or absence of toner in the case.

The transfer charger 15 is fixed to an arm 15a rotatable about a pivot L1 by a cam mechanism. A pair of guide rollers 18a and 18b located on both sides of the continuous paper FP are integrally fixed to the arm 15a.

At the start of printing, it is necessary to idle the drum without feeding the paper until the exposed portion of the photosensitive drum 11 reaches the transfer position. In this case, by lowering the arm 15a and lowering the guide rollers 18a and 18b, the paper is separated from the photoconductor drum 11, thereby shortening the life due to the wear of the photoconductor and preventing the paper from being stained by residual toner. be able to.

The fixing unit 30 includes a heat roller 31 located on the upper side in the drawing, in which a halogen lamp for heating and a thermistor for temperature detection are provided, and a continuous paper FP inserted between the rollers.
And a pressing roller 32 for pressing the heat roller 31 against the heat roller 31 with a predetermined pressure.

An empty sensor 50 for detecting running out of paper is provided between the feeding port 1 and the transfer position P1.
A top sensor 52 for detecting the leading end of the sheet is provided below the fixing unit 30 and a jam sensor 53 for detecting a swelling of the center of the sheet due to a jam.

As shown in FIG. 2, between the fixing unit 30 and the tractor unit 20, skew sensors 51, 51 which contact both ends of the continuous paper and detect skew or cut of the paper are provided. A waste toner box 60 is provided on the side of the photosensitive drum 11.

As shown in FIG. 2, the tractor unit 20 includes two endless belts 21, 21 laid between a driven shaft 22 and a drive shaft 23.
Are driven from a main motor 40 via a feed clutch and a gear train provided in a box indicated by reference numeral 41 in the figure.

Note that the drive shaft 23 of the tractor unit 20 is
The gear train leading to
It is configured to convey at 50 mm / s, but has a built-in one-way clutch that spins with a predetermined resistance in accordance with the pulling speed when the paper is pulled at a higher speed.

The heat roller 31 is rotatably driven by a main motor 40 via an F clutch and a gear train, and is configured to feed the continuous paper FP at 75 mm / s when nipping the continuous paper FP. Therefore, the actual driving of the continuous paper FP is performed by the fixing unit 30, and the above-described tractor unit 20 mainly performs a function of applying a back tension to prevent skew of the paper.

A disk 25 as a rotating plate is attached to the driven shaft 22 on a rotating shaft 22 ′ interlocked via a chain 24. As shown in FIG. 3, the disk 25 has a plurality of fan-shaped slits 25a which are radially widened toward the circumferential side and are formed at predetermined intervals, and a light emitting portion provided therebetween. PFS (Paper feed senser) consisting of a light receiving unit
From 26, a signal corresponding to the moving amount of the sheet can be taken out according to the slit 25a. By shaping this signal, a rectangular PFS pulse can be obtained.

The PFS pulse is output once every 1/2 inch of the sheet, and the signal of the slit 25a detected from the PFS and the signal of the portion other than the slit are the two edges of the continuous sheet FP. Corresponds to the feed hole portion provided in and the portion other than the hole.

The PFS pulse is used for detecting a paper transport amount and a transport speed.

The detection of the transport amount is performed by counting the number of PFS pulses, and the detection of the transport speed is performed by measuring the time of the HIGH level and the LOW level of the pulse.

In a conventional photointerrupter, for example, a rising portion of a pulse is used so that a detection accuracy does not change even when a pulse width changes due to a positional shift between a disk and a detector. It was necessary to perform speed detection by measuring the time between the two.

However, the control is complicated to detect and measure the pulse rise.

In the apparatus of this embodiment, the slit 25a is formed in a radial shape, so that even if the disk 25 and the substrate provided with the PFS 26 are relatively displaced due to an assembling error or the like, the output pulse width is Since there is no error, the reliability is high even if speed detection is performed by measuring the time of each of the HIGH level and the LOW level.

Therefore, the control can be simplified.

Further, when detection is performed only at the rising edge,
While the judgment is made in one cycle of the combination of LOW and HIGH, one cycle can be divided into two in the configuration of the embodiment, so that the accuracy of speed detection can be increased if the number of slits is the same. .

Further, when detecting the case where the disk does not move at all, the limit time at which the signal should change can be made shorter than before, so that the determination can be made in a short time.

[0032]

【The invention's effect】

As described above, according to the control device of the laser printer having the photointerrupter device of the present invention, even if the rotating plate, the light emitting device, and the light receiving unit are relatively displaced due to an assembling error or the like, the output pulse width is reduced. In addition to being able to be consistent, the time of the high level of the pulse and
Since the LOW level time is measured, it is possible to detect the rotation speed finely even with respect to the temporal fluctuation during one pulse, and it is possible to perform highly reliable speed detection, which is further improved. Detection accuracy can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view of a laser printer including a photointerrupter device according to the present invention.

FIG. 2 is a plan view of a paper transport portion of the laser printer shown in FIG.

FIG. 3 is a plan view showing a disk of the photointerrupter device.

[Explanation of symbols]

 25: Disk (rotating plate) 25a: Slit 26: PFS (light emitting unit, light receiving unit)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Kita 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Optical Industry Co., Ltd. (72) Inventor Takaaki Yano 2-36-9 Maeno-cho, Itabashi-ku, Tokyo No. Asahi Optical Co., Ltd. (72) Ryoji Honda 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Optical Co., Ltd. (72) Tsutomu Sato 2-36-9 Maenocho, Itabashi-ku, Tokyo No. Asahi Optical Industry Co., Ltd. (72) Inventor Shoji Kamasako 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Optical Industry Co., Ltd. (56) References JP-A 1-275077 (JP, A) JP-A-58-218615 (JP, A) JP-A-59-84164 (JP, A) JP-A-2-69275 (JP, A) JP-A-63-200551 (JP, U) (58) Int.Cl. ⁷ , DB name) G01D 5/00-5/62 G 01P 1/00-3/80

Claims (1)

(57) [Claims] A fixing unit having a heat roller driven by a drive motor and a pressing roller for fixing the continuous sheet inserted between the rollers while holding the sheet, and a tractor unit for conveying the continuous sheet. A drive shaft that is driven to rotate by the drive motor, a driven shaft that is driven to rotate by the drive shaft, and an endless belt that is stretched between the drive shaft and the driven shaft. A laser printer for continuous paper that transports the continuous paper while controlling the transport speed of the tractor unit and the transport speed of the fixing unit, wherein a rotary shaft that rotates in conjunction with the driven shaft A rotating plate having a radial slit with the center of rotation as a center and constituting a part of the photo interrupter is provided, and has a light emitting portion and a light receiving portion on both sides of the rotating region of the rotating plate, and photo A sensor for detecting a continuous paper transport speed which constitutes a part of the interrupter is provided, and also measures the HIGH level time of the pulse output from the continuous paper transport speed detection sensor and the LOW level time of the pulse. A control device for a laser printer, comprising a time measuring means, detecting a transport speed of the continuous paper based on the measurement of the time measuring means, and controlling the drive motor based on the transport speed.