JPH03197161A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To largely reduce the number of sensors to be installed, to simplify a circuit configuration and to decrease its cost by providing a single detector, and variously judging based on detection information of the detector. CONSTITUTION:A detector 3 as detecting means is disposed at a position of an upstream side from a thermal head 5 to the rotating direction F1 at the time of printing a platen drum 3, a detector 13 is formed of a plurality of detecting elements such as 7 optical sensors, and the sensors are so arranged in one row at a suitable interval to detect the maximum width of a sheet P to be used. A difference of quantity of reflected light reflected on the surface of the drum 3 and the quantity of reflected light reflected on the surface of the sheet P is detected to detect the presence or absence of the sheet P. The presence or absence of the sheet P is judged to judge whether the sheet is normally fed and conveyed or not. The length of the sheet P is detected from the front and rear end detection signals of the sheet P by the sensors to judge the sheet size. Further, various timings such as a timing of starting printing and a timing of sheet discharging operation are also judged based on detection information from the detector 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an image forming apparatus applied to electronic copying machines, laser printers, and the like.

(Prior Art) In a conventional image forming apparatus, various sensors are provided at appropriate locations, and various control processes related to image forming processing are performed based on various information from these sensors.

For example, when printing paper that is automatically fed from a paper feeder or manually fed by winding it around a platen drum, the paper feed sensor detects whether the paper has been fed properly. is provided. That is, when the paper feed sensor detects the leading edge of the paper within a certain period of time after the paper feeding operation is started, it is determined that the paper has been fed normally.

In addition, a paper detection sensor is installed near the printing position for printing on the paper wrapped around the platen drum, and when this paper detection sensor detects the leading edge of the paper being conveyed, the timing related to the printing process is determined. The timing for transporting paper is determined. In addition, a paper size detection sensor is installed near the manual paper feeder for manually feeding paper, for example on the manual stacker, so that when paper is fed manually, it is detected that the paper has been fed. At the same time, the size of the paper, so-called paper size, is also detected.

(Problems to be Solved by the Invention) As described above, conventional image forming apparatuses include a paper feed sensor to detect whether paper is fed normally, and a paper feed sensor that determines the timing for printing processing and paper conveyance processing. A paper size detection sensor for detecting the size of manually fed paper and a paper size detection sensor for detecting the size of manually fed paper have been provided separately. This not only increases the number of installed sensors, but also increases the circuit configuration depending on the type and number of installed sensors, resulting in a larger scale.Furthermore, the mechanical internal configuration of the device also increases. There was an issue that needed to be solved, which was that it was becoming more complex.

The present invention has been made in view of the above problems, and is an image forming apparatus that further reduces costs by reducing the types and number of installed sensors as much as possible and simplifying the circuit configuration associated with this. The purpose is to provide

[Structure of the Invention] (Means for Solving the Problems) The invention provided by the present application to achieve the above object includes a drum that rotates around a recording medium to be conveyed, and a rotating shaft that rotates in the axial direction of the rotating shaft of the drum. A detection means consisting of a plurality of detectors arranged in a direction along the drum to detect a recording medium on the drum, and control for performing a plurality of controls related to image formation based on detection information regarding the recording medium outputted from the detection means. means and
and an image forming means for forming an image on the recording medium on the drum under the control of the control means.

(Function) In the present invention, after a recording medium, which is an image-forming object, is wound around a drum, an image forming means forms an image on this recording medium under the control of a control means.

Further, the present invention has a detection means consisting of a plurality of detectors arranged in a direction along the axial direction of the rotating wheel of the drum, that is, in a direction perpendicular to the conveyance direction of the recording medium conveyed by the rotation of the drum, The control means makes various decisions based on the information from this detection means. That is, information from the detection means, for example, the presence or absence of a recording medium wrapped around the drum;
A decision regarding image formation is made based on the size of the recording medium or the timing of image formation by the image forming means, and the image forming means is controlled.

Therefore, various judgment processes can be performed based on information from a single detection means, and the associated mechanical elements and circuit configuration can be simplified to reduce costs.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to the drawings.

On the upper side of the image forming apparatus main body (hereinafter simply referred to as the apparatus main body) 1, there is a document table 20 formed of a glass plate or the like for placing a document, and a document cover 22 that can be opened and closed is provided above the document table 2o. It is provided.

The halogen lamp 24 is for irradiating light onto the document, and the glue deflector 26 serves as a reflector that collects the light from the halogen lamp 24 onto the surface of the document.
It is set up to cover.

The light reflected from the original surface enters the lens 32 via mirrors 28, 30a and 30b. The light passing through the lens 32 is applied to a photoelectric converter 36 via mirrors 34a and 34b.

The photoelectric converter 36 photoelectrically converts the light reflected from the document to separate and output the image of the document as cyan, green, and yellow (or red, green, and blue) light color signals. It is mainly composed of image sensors and the like.

Further, a platen drum 3 is provided approximately at the center of the apparatus main body 1 . The periphery of the platen drum 3 is made of an elastic member such as black rubber, and has a support and transfer function similar to that of a so-called platen roller. Further, the circumferential length of the platen drum 3 is set to be longer than the length of the paper P serving as a recording medium. In addition, the platen drum 3 rotates in the direction F1 shown in FIG. Rotationally driven by a motor.

A thermal head 5 is provided below the platen drum 3. This thermal head 5 is attached to a heat sink 7. Further, an ink ribbon 9 is interposed between the thermal head 5 and the platen drum 3. The ink ribbon 9 is wound around the respective winding cores of the ink ribbon cartridges 11a and llb via a pinch roller 10. This ink ribbon cartridge lla, 11
Each winding core b is connected to a drive shaft of a ribbon motor via a drive force transmission mechanism (not shown), so that the ink ribbon 9 is transported in synchronization with the circumferential speed of the platen drum 3. Further, the pinch roller 10 is driven by a pinch roller solenoid (not shown).

Also, the left side of the platen drum 3, that is, the platen drum 3
A detection section 13 as a detection means is arranged at a position upstream of the thermal head 5 with respect to the rotation direction F1 during printing. This detection unit 13 is formed of a plurality of detectors, for example, seven optical sensors, and is configured to detect rotation of the platen drum 3 in a direction perpendicular to the conveyance direction in which the paper P wound around the platen drum 3 is conveyed. Each optical sensor is arranged in a line along the axial direction at appropriate intervals so as to be able to detect the maximum width of the paper P used. This optical sensor is a so-called reflective sensor, and detects the difference in the amount of reflected light reflected from the surface of the platen drum 3 and the amount of reflected light reflected from the surface of the paper P wound around the platen drum 3. By this detection, the presence or absence of paper P can be detected. Based on the information detected by the detection unit 13, it is determined whether there is paper wrapped around the platen drum 3, and it is determined whether the paper is being fed and transported normally, that is, whether a so-called jam has occurred. I try to do that. Further, when the paper P is fed manually, for example, the size of the fed paper P is detected based on the detection information from the detection unit 13, that is, the width of the paper P is detected from the detection signals of the plurality of optical sensors, and the width of the paper P is detected based on the detection information from the detection unit 13. Paper P detected by the optical sensor
Detects the length of paper P from the detection signals of the leading edge and trailing edge of
I try to judge the paper size.

Further, based on the detection information from the detection unit 13, various timings such as the timing related to the start of printing and the timing related to the paper ejection operation, which will be described later, are also determined.

Note that the detection unit 13 may be any suitable sensor such as a CCDCD.
It may also be configured using a beline image sensor.

A paper feed cassette 15 is attached to the lower side of the apparatus main body 1 so as to be freely attachable and detachable to the apparatus main body 1. This paper feed force cellar 15 accommodates paper P of a predetermined size.

Also, inside or near the paper feed cassette 15, there is a pickup roller 17 for taking out the paper P one by one, a cam motor (not shown) for driving the pickup roller 17, and a feed roller for transporting the paper P. , a feed motor for driving the feed roller, and a pair of transport rollers 2 for transporting the paper P.
1 are provided to ensure that the sheets P stored in the paper feed cassette 15 are fed to the platen drum 3 one by one.

The guide plate 23 holds the paper P fed from the paper cassette 15.
is guided to the paper clip 25.

This paper clip 25 is fixed to the surface of the platen drum 3, and is used to clip the leading edge of the paper P fed from the paper feed cassette 15, and wind and fix the paper P around the platen drum 3.

Further, pressure rollers 27 are provided at appropriate positions around the platen drum 3 so as to press the platen drum 3, and this pressure roller 27 prevents the paper P from floating up.

Further, a manual paper feed device 29 for feeding paper manually is provided above the paper feed cassette 15 described above.
The paper P fed by the manual paper feeder 29 is transported by a pair of transport rollers 21 as described above, and is transferred to the paper clip 25 via the guide plate 23.

When the leading edge of the paper P is fixed to the platen drum 3 by the vapor clip 25, the platen drum 3 is rotated in the direction F.
1, the paper P is wound around the surface of the platen drum 3.

Further, the paper P wound around the platen drum 3 is conveyed according to the rotation of the platen drum 3 in the direction F1,
When this paper P passes through the printing area 6, the aforementioned thermal head 5 is pressed against the platen drum 3, so that image formation, that is, printing is performed.

The printing process for the first color is completed when the platen drum 3 rotates approximately once in the direction F1. At this time, the pressure applied to the thermal head 5 is temporarily released, the ink ribbon 9 is wound up, and the next color is located.

Next, the platen drum 3 rotates again in the direction F1, printing is performed by the thermal head 5, and the next color is printed in an overlapping manner.

In this way, for full color copying, yellow,
Overlapping printing is performed four times corresponding to each color of magenta, cyan, and black. Further, when the colors to be printed are yellow, magenta, and cyan, three overlapping printings are performed. Further, if the color to be printed is a single color such as black, one printing operation is performed.

A paper discharge tray 31, a pair of rollers 33 for transporting the paper to the paper discharge tray 31, and a guide plate 35 for guiding the paper to the pair of rollers 33 are provided above the paper feed cassette 15.

When discharging the paper P on which the printing process has been completed to the paper discharge tray 31, the platen drum 3 is rotated in the direction F1 until the rear end of the paper P reaches the guide plate 35. When the trailing edge of the paper P reaches the guide plate 35, the platen drum 3 is rotated in the direction F.
2, the rear end of the paper P is separated from the platen drum 3 by a separation claw (not shown), and the paper P is guided to the guide plate 35. Then, the paper P is transferred to the paper output tray 31 by a pair of rollers 33, and at this time, the leading edge of the paper P is released from the paper clip 25, and this paper P is transferred to the paper output tray 31.
1.

Also, on the left side of the platen drum 3 are a plurality of printed circuit boards 3.
7 is included. The printed circuit board 37 is provided with various circuit sections such as a judgment processing circuit for performing various judgment processes based on the detection information from the detection section 13. The cooling fan 39 is for cooling the inside of the main body 1 of the apparatus. Further, a power supply 41 supplies a predetermined power to each part.

Next, various circuit sections incorporated into the printed circuit board 37 will be explained with reference to FIG.

The main control unit 49 which has a built-in microcomputer etc. has an operation panel 5 which has a copy switch etc. for copying.
Connected to 0. This main control section 49 and sub-control section 51
Various command information, status information, etc. can be exchanged between them. The sub-control unit 51 is connected to the memory 5
2. Memory 53, input port 54 and output port 5
5 through pass lines. Paper feed sensor 56 for detecting that paper P is fed
is connected to the human-powered boat 54. Further, an OHP sensor 57 is connected to the input boat 54 for detecting that the fed recording medium is a so-called OHP sheet.

Further, various motors and solenoids are connected to the drive circuit 64. That is, the drive circuit 64 includes a cam motor 58.
．． A feed motor 59, a platen motor 60, a ribbon motor 61, and a pinch roller solenoid 62 are each connected.

This drive circuit 64 is connected to the sub-control unit 5 via an output port 55.
1, and this drive circuit 64 is connected to the sub-control unit 51.
The corresponding motor or solenoid is driven according to the control command from the controller. Further, the detection section 13 is connected to the sub-control section 51, and detection information from a plurality of optical sensors is provided to the sub-control section 51.

Next, the operation will be explained with reference to FIG.

First, when the operator turns on the copy switch on the operation panel 50 provided on the apparatus main body 1 at time tl shown in FIG. 3A, the cam motor 58 rotates as shown in FIG. 3(B). The pickup roller 17 is driven by this rotation of the cam motor 58.

Next, as shown in FIG. 3(C), when the feed motor 59 rotates at time t5 while the pickup roller 17 is in contact with the paper P stored in the paper feed cassette 15, the feed roller is driven. . By driving this feed roller, only one sheet of paper P stored in the paper feed cassette 15 is fed to the conveyance roller 21 . The paper P fed in this manner passes through the paper feed sensor 56 and the OHP sensor 57 after a certain period of time has elapsed. When the paper feed sensor 56 detects the paper P fed from the paper feed cassette 15, the feed motor 59 is turned off at time t9 as shown in FIG. 3(C).

After the feed motor 59 is turned off and the aligning time with the paper grip 25 has elapsed, as shown in FIG.
), the ribbon motor 61 is reversed at time tll. At this time, the paper P guided to the guide plate 23
The leading edge of the paper P is transferred to the paper grip 25, so the paper grip 25 clamps the leading edge of the paper P and fixes it to the surface of the platen drum 3.

Next, as shown in FIGS. 3(G) and 3(H), when the operation of the ribbon motor 61 ends at time t13, the platen motor 60 is driven at time t15 to rotate the platen drum 3 in the direction F1. As the platen drum 3 rotates in the direction F1, the paper P passes through the detection section 13 and is conveyed to the printing area 6.

At this time, as shown in FIG. 3(H), the platen motor 60
A predetermined detection time T1 is set from the time t15 when the paper starts rotating, and if the detection unit 13 does not detect the paper P within this detection time T1, it indicates that the paper P is not being conveyed normally. Detect jam.

When the paper P reaches the printing area 6, the thermal head 5, which has been released from the small position at time t19 shown in FIG. 3(C), is pressurized at time t20 to prepare for printing. When the pressurization of the thermal head 5 is completed, Fig. 3 (G) and (H)
As shown in FIG. 2, at time t21, the ribbon motor 61 and the platen motor 60 are rotated, and at the same time, a voltage is applied to the thermal head 5 to perform printing.

During this printing process, when the detection unit 13 detects the trailing edge of the paper P at time t23 as shown in FIG. 3 CF), the subsequent paper P
Various timings are determined, such as the timing of conveyance control, the timing of printing end, the timing of non-pressure of the pinch roller 10, and the timing of paper ejecting operation. For example, when the trailing edge of the paper P is detected at time t23, since the distance from the detection unit 13 to the pinch roller 10 is known in advance,
t2 after a predetermined period of time has elapsed from time t23 according to this distance.
5, the timing for non-pressure of the pinch roller 10 is set.

Next, the operation when the paper P is manually fed using the manual paper feeding device 29 will be explained.

If paper P is fed manually, this paper P
The size of is unknown. First, when the copy switch on the operation panel 50 is turned on at time t1 as shown in FIG. 3(A), the cam motor 58 is reversed as shown by the dotted line in FIG. 3(B).

By reversing the rotation of the cam motor 58, the pickup roller 17 for manually feeding paper is lowered. As a result, the paper P manually fed from the manual paper feeder 29 is transferred to the paper grip 25, and the paper P is wound around the surface of the platen drum 3 and fixed. When the paper P wound around the platen drum 3 passes through the detection unit 13 in accordance with the rotation of the platen drum 3 in the direction F1, within the period from time t17 to time t18, as shown in FIG. 3(F), Detector 13
The size of the manually fed sheet P, that is, the length and width of the sheet P is determined based on the information detected by the .

Even when the paper P is manually fed using the manual paper feeder 29 as described above, the paper P that is manually fed is determined based on the detection information from the detection unit 13.
Since the size of the image is determined, printing processing can be performed appropriately.

[Effects of the Invention] As explained above, according to the present invention, by providing a single detection section, various judgments are made based on the detection information of this single detection section. The number of installed sensors can be significantly reduced, the circuit configuration associated with this can be simplified, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a side view of an image forming apparatus to which the present invention is applied, and FIG. 2 is a block diagram of a circuit section incorporated into the image forming apparatus.
FIG. 3 is a timing chart showing the operation of each part. 3...Platen drum 5...Thermal head 13...Detection section

Claims (1)

[Claims] Detection means consisting of a drum that rotates around which a recording medium to be conveyed is wound, and a plurality of detectors that are arranged along the axial direction of the rotating shaft of this drum and detect the recording medium on the drum. a control means for performing a plurality of controls related to image formation based on detection information regarding the recording medium outputted from the detection means; and forming an image on the recording medium on the drum under the control of the control means. An image forming apparatus comprising an image forming means.