JPH07215535A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an image forming apparatus capable of monitoring the feeding state of a recording medium with a simple configuration. A paper feed sensor 12 and a paper discharge sensor 14 are provided in a paper carrying line as a recording medium, and their detection signals are sent to a single port of a monitoring means 25A via a single signal line 30. Input to P ₁ , and the monitoring means 25A is connected to port P
The input signal of ₁ is monitored in time series.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus,
In particular, the present invention relates to an image forming apparatus suitable for use in a page printer such as a laser beam printer.

[0002]

2. Description of the Related Art In recent years, laser beam printers have become widespread due to their excellent printing quality and low price.

FIG. 6 shows a typical conventional example. In FIG. 6, 9 is a multi-paper tray, 10 is a paper feed roller, 12 is a paper feed sensor, 2 is a drum, 5 is an exposure device, 6 is a developing device, 7 is a transfer device, 4 is a mirror, 3 is a scanner unit, Reference numeral 11 is a registration roller, 14 is a paper discharge sensor, 25 is a CPU, and 13 is a fixing device. The CPU 25 drives the paper feed roller 10 to feed paper from the tray 9 based on the print signal from the printer controller 26, and also supplies a laser light source (not shown) and a scanner motor (not shown) in the scanner unit 3. To operate. Then, the fed paper is conveyed by the registration roller 11 and the drum 2
The video signal is transmitted from the printer controller 26 to the CPU 25 in synchronism with the approach to the laser beam, and the laser beam scans the photosensitive drum 2 based on the video signal to form a latent image corresponding to the video signal. After that, the photosensitive drum 2
Toner is attached to the toner to form a visible image of the latent image, the image is transferred to the paper being conveyed by the transfer device 7, and further fixed by the fixing device 13. Reference numeral 8 is a cleaner device for collecting the toner remaining on the photosensitive drum 2, and reference numeral 15 is a stacking tray for discharging the paper on which the image is transferred.

[0004]

By the way, in such a conventional printer, the CPU 25 is
When the output signal of the paper feed sensor 12 changes (for example, changes from L to H), the leading edge of the paper is detected, and a vertical synchronization signal is output to the printer controller 26 to notify the image output timing. Further, the CPU 25 detects the trailing edge of the paper by returning the output signal of the paper feed sensor 12 to the original (for example, returning from H to L), and masks the video signal so that the margin of the trailing edge of the paper is not printed. Forcibly turn off the laser light output. Similarly, the output signal of the paper discharge sensor 14 changes (for example, changes from L to H) to detect the front end of the paper, and monitors whether a paper jam phenomenon has occurred. The output signal returns to the original (for example, returns from H to L) to detect the trailing edge of the paper,
The printer controller 26 is informed that the next paper is ready to be fed.

Therefore, the CPU 25 uses the sensors 12, 1
It was necessary to provide a total of two input ports corresponding to each of the four, which was a great cost burden.

An object of the present invention is to provide an image forming apparatus capable of monitoring the feeding state of a recording medium with a simple structure.

[0007]

An image forming apparatus of the present invention comprises a feeding means for feeding a recording medium, and a plurality of detecting means for detecting the position of the recording medium fed by the feeding means. An image having a monitoring unit that monitors the feeding state of the recording medium based on the detection results of the plurality of detecting units, and an image forming unit that forms an image on the recording medium fed by the feeding unit. In the forming apparatus, the monitoring unit is configured to monitor the detection results of the plurality of detection units in time series via a single port.

[0008]

In the image forming apparatus of the present invention, the detection results of the plurality of detecting means for detecting the position of the recording medium are time-sequentially monitored by the monitoring means through the single port.
Reduce the number of input ports in the monitoring means.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(First Embodiment) A first embodiment of the present invention is shown in FIGS. 1, 2 and 3.

This embodiment is an example of application to a laser beam printer similar to that shown in FIG. 6, in which optical sensors as shown in FIG. 1 are used as the paper feed sensor 12 and the paper discharge sensor 14, and the CPU 25 is used. Is one port P ₁ connected to the sensors (detection means) 12, 14 as shown in FIG.
Is provided.

First, the paper feed sensor 12 includes a light emitting element 12A such as a light emitting diode, a light receiving element 12B such as a phototransistor, and a flag 12C movably interposed in the optical path between these elements 12A and 12B. I have it. As shown in FIG. 2, the flag 12C has a fulcrum P _{0 at} its middle portion.
It is rotatably supported around its upper end 1
2C-1 is located on the conveyance line L of the paper (recording medium) S. Further, at the lower end thereof, a first light-shielding portion 12C-2 on the upstream side in the sheet feeding direction A, a second light-shielding portion 12C-3 on the downstream side in the sheet feeding direction A, and a light-transmitting portion positioned between them. Part 12C
-4 is formed.

The flag 12C rotates as shown in FIGS. 2 (a), 2 (b) and 2 (c) when the upper end portion 12C-1 is pushed by the paper S on the conveying line L.

That is, first, the upper end 12C-1 is the paper S.
When not pressed by, as shown in FIG.
The first light shielding portion 12C-2 is located between the elements 12A and 12B to shield light. The center of gravity of the flag 12C is determined so as to maintain such a posture when no external force is applied from the paper S. Then, when the upper end portion 12C-1 is pushed in the transport direction A by the tip of the paper S, first, as shown in FIG.
As shown in (b), the translucent portion 12C-4 has the elements 12A and 12B.
After being positioned between the elements and transmitting light, the second light blocking portion 12C-3 is positioned between the elements 12A and 12B to block light, as shown in FIG. After that, the paper S is fed, and the rear end is the upper end portion 12
When removed from C-1, the flag 12C returns to the state of FIG. 2A through the state of FIG. 2B.

On the other hand, the paper discharge sensor 14 is the paper feed sensor 12
Similarly, a light emitting element 14A such as a light emitting diode, a light receiving element 14B such as a phototransistor, and those elements 12
Flag 1 movably interposed in the optical path between A and 12B
4C and. The flag 14C has the same configuration as the above-mentioned flag 12C, and therefore its description is omitted.

Light receiving elements 12B, 1 of both sensors 12, 14
The output terminal of 4B is connected to the CPU via a single signal line 30.
25 is connected to the port P ₁ of the monitoring means 25A.

Next, the operation will be described.

First, as in the case of FIG. 6 described above, the print signal from the printer controller 26 (see FIG. 3A).
The printer engine that receives the reference (reference) drives the scanner motor (not shown), the fixing device 13, and the main motor in the scanner unit 3. After that, when each of the units becomes ready, the CPU 25 drives the paper feed roller 10,
Paper S is fed from the multi-paper tray 9. The paper S
Passes through a position facing the paper feed sensor 12. Before the arrival of the paper S, the paper feed sensor 12 uses the first light shielding unit 12C-2 of the flag 12C as shown in FIG.
12B is shielded from light, and when the paper arrives, the same figure (b)
The light is transmitted by the light transmitting portion 12C-4 as described above, and after reaching the light, the light is again shielded by the second light shielding portion 12C-3 as shown in FIG. Since the paper S has not reached the position facing the paper ejection sensor 14, the element 1 of the paper ejection sensor 14 is not yet reached.
The light is still shielded between 4A and 14B, and the pulse signal from the paper feed sensor 12 is input to the port P ₁ at time T ₁ as shown in FIG. 3C. The monitoring means 25A of the CPU 25 monitors this signal, detects that the leading edge of the paper S has reached the position facing the paper feed sensor 12, and detects the vertical synchronization signal for timing of writing an image (see FIG. 3).
(See (d)) printer controller 26 (see FIG. 6)
Send to. The monitoring means 25A measures the time from the output timing T _{0 of the} paper feed signal shown in FIG. 3B, and determines whether the elapsed time t ₁ up to the time point T ₁ is within a predetermined delay time. , Jam of paper S is detected.

After that, the paper S advances, and its leading end reaches a position facing the paper discharge sensor 14. At time T ₂ when the paper S reaches the position facing the paper ejection sensor 14, the paper ejection sensor 12 outputs a pulse signal similarly to the paper feed sensor 12 described above (see FIG. 3C). The monitoring means 25A of the CPU 25 monitors this signal and detects a jam of the paper S from its output timing. Further, the paper S progresses,
At the time point T ₃ when the rear end passes through the position facing the paper feed sensor 12, the flag 12C which has been in the state of FIG. 2C until then passes through the state of FIG. 2B and then the state of FIG. Then, the paper feed sensor 12 outputs the pulse signal again. The monitoring means 25A monitors this signal and detects that the rear end of the paper S has passed a position facing the paper feed sensor 12.
Based on the detection result, the CPU 25 forcibly turns off the output of the laser light in the recordable area on the paper S in order to secure a blank space at the trailing edge of the paper S for recording. After that, the paper S further advances, and the rear end of the paper S
At the time point T ₄ when the sheet passes the position opposite to, the sheet discharge sensor 14 outputs the pulse signal again. The monitoring means 25A of the CPU 25 monitors this signal and detects that the rear end of the paper S has reached the position facing the paper discharge sensor 14, and stops each operation unit or detects the next paper S. Prepare for paper feeding.

(Second Embodiment) FIGS. 4 and 5 show a second embodiment of the present invention.

[0021] In the first embodiment described above, the optical sensor (hereinafter, referred to as "photo-interrupter") a plurality (two) were used, by their output unit for wired OR connection, the input port P ₁ It was a reduction.
In the second embodiment, a plurality of sensor flags are provided in one photo interrupter, and the one photo interrupter can function as a plurality of detecting means, thereby reducing the input port P ₁ and It also aims to reduce the number of parts.

In FIG. 4, the photo interrupter 31 is provided with a flag 32 for paper feed detection and a flag 33 connected to a flag 33 for paper ejection detection via a rod 34. The respective intermediate portions of the flags 32, 33, 35 are rotatably supported around the axes O ₁ , O ₂ , O _3, and the upper end portion 32A of the flag 32 is on the transport line L at the paper feed detection position. , The upper end 33A of the flag 33 is located on the transport line L at the discharge detection position, and the lower end 33B of the flag 33 and the upper end 3 of the flag 35 are located.
5A are connected by a rod 35. Flag 3
As shown in FIG. 5, the lower end portions 32B and 35B of 2, 35 pass through the optical path between the light emitting element 31A such as the light emitting diode of the photo interrupter 31 and the light receiving element 31B such as the phototransistor 31, The position P _A to P _C can be rotated. The positions P _A and P _C are positions that do not block the optical path, and the position P _B between them is a position that blocks the optical path.

The flags 32 and 33 are rotated by being pressed by the paper on the transport line L. That is, first, when the upper end portion 32A of the flag 32 is not pushed by the paper, the flag 32 is maintained in the rotation posture as shown in FIG.
B is in position P _A. Then, when the upper end portion 32A is pushed in the transport direction A by the leading edge of the paper, the lower end portion 32B rotates to the position P _C via the position P _B , and thereafter,
When the paper passes, it returns to the posture shown in FIG. On the other hand, the flag 33 is similarly rotated by the paper on the transport line L. That is, the flag 33 has an upper end portion 33A.
4 is not pushed by the paper, the rotary posture as shown in FIG. 4 is maintained, the lower end portion 35B of the flag 35 is at the position P _C , and the upper end portion 33A of the flag 35 in the transport direction A by the leading end of the paper. When pressed, the lower end portion 35 of the flag 35B
B rotates through the position P _B to the position P _A , and then the paper passes to return to the posture shown in FIG.

Therefore, in the case of this embodiment, the photo interrupter 31 outputs a pulse signal to the port P ₁ of the CPU 25 at the same timing as in the first embodiment.

[0025]

As described above, in the image forming apparatus of the present invention, the detection results of the plurality of detecting means for detecting the position of the recording medium are monitored in time series by the monitoring means via the single port. With this configuration, the number of input ports in the monitoring means can be reduced and the configuration can be simplified.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a main part of a first embodiment of the present invention.

FIG. 2 is an operation explanatory view of the paper feed sensor shown in FIG.

FIG. 3 is a time chart for explaining the operation of the first exemplary embodiment of the present invention.

FIG. 4 is a schematic diagram of a main part of a second embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a main part of a second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a conventional image forming apparatus.

[Explanation of symbols]

 2 drum 3 scanner unit 4 mirror 5 exposure device 6 developing device 7 transfer device 10 paper feeding roller 11 registration roller 12 paper feeding sensor 12C-2, 32, 33, 35 sensor flag 13 fixing device 14 paper ejection sensor 25 CPU 25A monitoring means 30 signal line 34 rod 40 print controller

Claims (3)

[Claims] 1. A feeding means for feeding a recording medium, a plurality of detecting means for detecting the position of the recording medium fed by the feeding means, and the detection means based on the detection results of the plurality of detecting means. An image forming apparatus comprising: a monitoring unit configured to monitor a feeding state of a recording medium; and an image forming unit configured to form an image on the recording medium fed by the feeding unit, wherein the monitoring unit includes the plurality of units. An image forming apparatus, wherein the detection result of the detection means is monitored in time series through a single port. 2. The image forming apparatus according to claim 1, wherein the plurality of detection units are connected to the single port by a single signal line. 3. The image forming means, a latent image forming means for forming a latent image on a photoconductor using an electrophotographic process, a transfer means for transferring the formed latent image to the recording medium, and the recording medium. Thermal fixing means for fixing the image transferred to
The image forming apparatus according to claim 1, further comprising: