JP3851076B2 - Printing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printing apparatus having a function of detecting a conveyance state of printing paper.
[0002]
[Prior art]
As a printing apparatus capable of high-speed printing, for example, there is a dot printer mainly used for business use. Such a conventional dot printer includes a roller that contacts the printing paper and rotates by an angle corresponding to the moving distance of the printing paper, and a tachometer that rotates together with the roller, and outputs a voltage output from the tachometer. The configuration is such that jamming of the printing paper is detected by monitoring.
[0003]
[Problems to be solved by the invention]
However, the conventional dot printer has a problem in that it cannot accurately judge the conveyance state of the printing paper.
[0004]
In other words, with the recent development of printing technology, printing apparatuses are also required to increase printing speed and at the same time improve printing quality. For example, it is required to eliminate printing misalignment during double printing. For this purpose, it is necessary to accurately grasp the movement distance of the printing paper and perform alignment. In addition, with regard to jamming of printing paper, it is not sufficient to detect that the printing paper being transported is completely stopped, and jamming is detected immediately when the transport speed becomes slower than the allowable error, There is a demand for minimizing waste of printing paper and printing time.
[0005]
However, in the configuration in which the printing paper conveyance status is determined based on the output voltage of the tachometer as in the conventional dot printer, a jam can be detected when the printing paper being conveyed is completely stopped. However, it is impossible to accurately detect the conveyance speed and conveyance distance of the printing paper. As a result, the conveyance device is not controlled in accordance with the actual conveyance state of the printing paper, and the printing quality has not been improved from the viewpoint of the conveyance accuracy of the printing paper.
[0006]
DISCLOSURE OF THE INVENTION
The present invention has been conceived under the circumstances described above, and an object of the present invention is to provide a printing apparatus that can accurately determine the conveyance status of printing paper.
[0007]
It is another object of the present invention to provide a printing apparatus that can accurately control the stop position of the printing paper.
[0008]
In order to solve the above problems, the present invention takes the following technical means.
[0009]
According to the first aspect of the present invention, a paper transport unit that transports printing paper at a predetermined speed set in advance along a predetermined path, and a movement distance detection unit that detects an actual movement distance of the printing paper; A determination unit for determining whether or not the actual movement distance detected by the movement distance detection unit is less than a movement distance to be conveyed by the sheet conveyance unit by a predetermined distance or a predetermined ratio; If it is determined that the actual movement distance is less than a predetermined distance or a predetermined ratio or more than the movement distance to be conveyed by the paper conveyance unit, the conveyance speed by the paper conveyance unit is changed to a speed lower than the predetermined speed. The actual conveyance distance of the printing paper is conveyed by the paper conveyance unit based on the determination result of the paper conveyance control unit that conveys the printing paper and the determination unit that is determined after the conveyance of the printing paper by the paper conveyance control unit. When less than or more than a predetermined proportion given distance than can travel, and the abnormality processing unit that performs a predetermined abnormality processing as abnormal transport of the printing paper, characterized by comprising a printing device is provided .
[0010]
According to a preferred embodiment, the abnormality processing by the abnormality processing unit includes an abnormality occurrence display or warning or abnormality cancellation guidance .
[0011]
According to another preferred embodiment, the movement distance detecting unit includes a roller that contacts the printing paper and rotates by an angle corresponding to the movement distance of the printing paper, rotates by the same angle as the roller, and is centered on the rotation center. A rotating body in which a large number of detected portions are formed at a predetermined pitch on a concentric circle, and a detecting portion that outputs a detection signal each time the printing paper moves a predetermined distance by detecting the detected portions; And a movement distance calculation unit that calculates an actual movement distance of the printing paper based on a detection signal from the detection unit.
[0012]
According to another preferred embodiment, the paper transport unit uses a stepping motor as a drive source, and the detection unit outputs a detection signal each time the printing paper moves by a distance corresponding to one step of the stepping motor. .
[0014]
According to the present invention, when the actual moving distance of the printing paper is smaller than the moving distance to be conveyed by the paper conveying unit by a predetermined distance or more or a predetermined ratio or more, the conveying speed by the paper conveying unit is higher than the predetermined speed. When the printing paper is conveyed by changing to a lower speed, and the actual movement distance of the printing paper is less than a predetermined distance or a predetermined ratio more than a movement distance to be conveyed by the paper conveyance unit in this conveyance, Since a predetermined abnormality process is performed as a printing paper conveyance abnormality, it is possible to accurately determine the printing paper conveyance status.
[0016]
Other features and advantages of the present invention will become more apparent from the following description of the embodiments of the invention.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.
[0018]
FIG. 1 is a conceptual explanatory diagram illustrating the overall configuration of a printing apparatus according to the present invention. The printing apparatus includes a hopper 1, sheet pressing rollers 2 a and 2 b, a platen roller 3, a printing unit 4, a tractor 5, a guide roller 6, and a stacker 7.
[0019]
The printing paper 8 made of continuous paper is conveyed by the tractor 5 from the hopper 1 to the stacker 7 along a predetermined path. The tractor 5 is driven via a belt 12 by a stepping motor 11. Printing is performed on the printing paper 8 by the printing unit 4.
[0020]
FIG. 2 is a front view of the tractor 5. FIG. 3 is a plan view of the tractor 5. 4 is a cross-sectional view taken along arrow AA in FIG. 2 to 4 mainly show a detection mechanism for detecting the transport distance of the printing paper 8, and the other parts are schematically shown. A large number of protrusions 16 projecting from the conveying belt 15 of the tractor 5 are fitted into holes formed at the end portions in the width direction of the printing paper 8 to convey the printing paper 8 in the direction of the arrow in FIG.
[0021]
A disc-shaped roller 17 made of an elastic material such as natural rubber or synthetic rubber contacts the printing paper 8 and rotates by an angle proportional to the moving distance of the printing paper 8. At this time, since the lid 18 attached to the tractor 5 so as to be openable and closable is closed, the lid 18 favorably suppresses the lifting of the printing paper 8 and ensures the contact state between the printing paper 8 and the roller 17. . In FIG. 3, the lid 18 is omitted.
[0022]
A rotary code wheel 20 is fitted and fixed to the rotary shaft 19 that supports the roller 17, and the rotary code wheel 20 rotates integrally with the roller 17. The rotating code wheel 20 has a large number of projecting portions 20 a projecting radially from the center, and transmissive photoelectric sensors 21 are disposed on both sides of the rotating code wheel 20 in the axial direction. The photoelectric sensor 21 includes a light projecting unit 21a and a light receiving unit 21b. If nothing exists between the light projecting unit 21a and the light receiving unit 21b, the light from the light projecting unit 21a is received by the light receiving unit 21b. Is received by. Therefore, if the roller 17 rotates with the movement of the printing paper 8 and the rotating code wheel 20 rotates together with the roller 17, the protruding portion 20a of the rotating code wheel 20 blocks light from the light projecting portion 21a. A state where the printing paper 8 is not shut off and a state where the printing paper 8 is not blocked are alternately generated, and a detection signal having a cycle inversely proportional to the moving speed of the printing paper 8 is output from the light receiving unit 21b.
[0023]
FIG. 5 is a conceptual explanatory diagram of the printing unit 4. The printing unit 4 includes a print head 31, a linear motor 32, a linear encoder 33, a moving body 34, a belt 35, pulleys 36a and 36b, a guide rod 37, and coil springs 38a and 38b.
[0024]
Stoppers 39 a and 39 b that are slidably fitted to the guide rod 37 are provided at the distal end of the movable body 34, and the print head 31 and the movable body 34 are movable along the guide rod 37. The coil springs 38a and 38b are slidably fitted to the guide rod 37. The linear motor 32 reciprocates the moving body 34 in the direction of the arrow in FIG. As the moving body 34 moves, the belt 35 connected to the moving body 34 moves, and as the belt 35 moves, the print head 31 connected to the belt 35 moves in the opposite direction to the moving body 34. . Therefore, when the moving body 34 moves to the right in FIG. 5, the print head 31 moves to the left, and the coil spring 38b is sandwiched between the print head 31 and the stopper 39b of the moving body 34 and compressed. Conversely, when the moving body 34 moves to the left in FIG. 5, the print head 31 moves to the right, and the coil spring 38a is sandwiched between the print head 31 and the stopper 39a of the moving body 34 and compressed. .
[0025]
FIG. 6 is a front view of the main part of the linear motor 32. FIG. 7 is a plan view of the main part of the linear motor 32. The linear motor 32 includes a plurality of pairs (six pairs in the present embodiment) of permanent magnets 41a and 41b facing each other with a predetermined interval, and there is movement between these pairs of permanent magnets 41a and 41b. The coil support 42 of the body 34 is located. A plurality (six in this embodiment) of coils 43 are arranged on the coil support portion 42, and each coil 43 is located in a gap between each pair of permanent magnets 41a and 41b. Of these coils 43, two coils 43 at both ends function as constant speed coils, and the remaining four coils 43 function as inversion coils. The reversing coil is a coil for mainly applying a propulsion force or a braking force to the print head 31 when the print head 31 accelerates or decelerates to reverse the moving direction. The constant speed coil is a constant speed coil. This is a coil for mainly applying a propulsive force to the print head 31 when traveling at high speed. When the direction of movement of the print head 31 is reversed, the coil spring 38 a or the coil spring 38 b is compressed and deformed by the propulsive force applied by the linear motor 32. Thereby, the elastic restoring force of the coil spring 38a or the coil spring 38b acts on the print head 31, and the moving direction of the print head 31 is instantaneously reversed.
[0026]
FIG. 8 is an explanatory diagram of a pin block installed in the print head 31. The pin block 51 has a predetermined interval in a direction inclined with respect to both the moving direction of the print head 31 indicated by an arrow B in FIG. 8 and the direction orthogonal thereto, in other words, substantially on the diagonal line of the pin block 51. In addition, a plurality (12 in this embodiment) of printing pins 52 are installed at a predetermined pitch. A large number of pin blocks 51 are arranged in the print head 31 along the moving direction of the print head 31. The printing paper 8 is conveyed in the direction of arrow C in FIG. Printing is performed by driving the printing pin 52 so that the printing pin 52 presses the printing paper 8 against the platen roller 3 via an ink ribbon (not shown).
[0027]
FIG. 9 is a circuit block diagram of the control unit of the printing apparatus according to the present invention. The control unit includes an MPU 55, a ROM 56, a RAM 57, and an interface circuit 58. The MPU 55, ROM 56, RAM 57, and interface circuit 58 are connected to each other by a bus line. The interface circuit 58 is connected to the coil 43 of the linear motor 32, the photoelectric switch (not shown) of the linear encoder 33, the light receiving unit 21 b of the photoelectric sensor 21, and the stepping motor 11.
[0028]
An MPU (microprocessor unit) 55 controls the entire printing apparatus.
[0029]
A ROM (read only memory) 56 stores data such as a control program to be executed by the MPU 55 and setting values.
[0030]
A RAM (random access memory) 57 is used as a work area of the MPU 55 and stores various data.
[0031]
The interface circuit 58 controls transmission / reception of signals between the MPU 55 and the linear motor 32, the linear encoder 33, the photoelectric sensor 21, and the stepping motor 11.
[0032]
Next, the operation will be described. FIG. 10 is a flowchart for explaining the procedure of the paper feed process executed by the MPU 55. This routine is executed by the MPU 55 every predetermined time. First, the MPU 55 determines whether or not paper feeding is necessary (S1). That is, during printing, the conveyance of the printing paper 8 and the printing by the print head 31 are alternately performed, and it is checked whether or not the timing at which the conveyance of the printing paper 8 is necessary at this time.
[0033]
If paper feeding is necessary (S1: YES), the MPU 55 drives the stepping motor 11 at a predetermined normal speed (S2). Specifically, the MPU 55 supplies a drive pulse to the stepping motor 11 and drives the stepping motor 11 by a predetermined number of steps. In the present embodiment, when printing a normal character, the stepping motor 11 is driven by 24 steps to perform printing, and then is driven by 36 steps, so that printing is performed by 24 steps and 36 steps. Repeat alternately. Further, when printing image data, the operation of driving the stepping motor 11 by 24 steps and printing is repeated.
[0034]
Next, the MPU 55 determines whether or not the printing paper 8 has been conveyed for a predetermined distance (S3). Specifically, the MPU 55 counts the number of pulses of the detection signal from the photoelectric sensor 21 and calculates the actual moving distance of the printing paper 8 based on the counted number, which is, for example, 24 steps of the stepping motor 11. Find out if it corresponds to a minute. At this time, since the pulse may not be detected at the start and end of the count due to detection signal conversion or the like, an error tolerance range is set in advance, and the printing paper 8 is conveyed by 22 steps or more by two steps less. If so, it is recognized that the printing paper 8 has been conveyed a predetermined distance.
[0035]
If the printing paper 8 has not been conveyed for a predetermined distance (S3: NO), the MPU 55 drives the stepping motor 11 at a lower speed than the normal speed (S4). Specifically, the MPU 55 calculates the unconveyed distance and drives the stepping motor 11 by the number of steps corresponding to the distance. At this time, since the stepping motor 11 is driven at a low speed, the step-out of the stepping motor 11 can be eliminated, and the possibility that the printing paper 8 can be normally conveyed increases.
[0036]
Next, the MPU 55 determines whether or not the printing paper 8 has been conveyed for a predetermined distance (S5). The specific operation at this time is the same as step S3.
[0037]
If the printing paper 8 has been conveyed for a predetermined distance (S5: YES), the MPU 55 drives the printing unit 4 to perform printing (S6), and this routine ends.
[0038]
In step S5, if the printing paper 8 has not been conveyed for a predetermined distance (S5: NO), the MPU 55 notifies that a jam has occurred (S7) and ends this routine. This notification is performed by displaying, for example, characters or symbols indicating that a jam has occurred on a display screen (not shown) of a display device provided in the printing apparatus. Of course, in addition to this notification, a cancellation guidance or the like may be displayed. Further, an alarm sound such as a chime sound or a buzzer sound may be sounded instead of or in addition to the display by the display device.
[0039]
In step S3, if the printing paper 8 has been conveyed for a predetermined distance (S3: YES), the process proceeds to step S6.
[0040]
In step S1, if paper feeding is not necessary (S1: NO), this routine ends.
[0041]
Thus, the tractor 5 that conveys the printing paper 8 along a predetermined path, the roller 17 that contacts the printing paper 8 and rotates by an angle corresponding to the moving distance of the printing paper 8, and the same angle as the roller 17 The rotation code wheel 20 in which a large number of detected portions are formed at a predetermined pitch on a concentric circle with the rotation center as a center, and the detected portions of the rotary code wheel 20 are detected, thereby printing paper. Since the photoelectric sensor 21 that outputs a detection signal every time the 8 moves a predetermined distance, the conveyance status of the printing paper 8 can be accurately determined based on the detection signal from the photoelectric sensor 21.
[0042]
Further, by controlling the tractor 5 based on the detection result of the tractor 5 that conveys the printing paper 8 along a predetermined path, the photoelectric sensor 21 that detects the actual movement distance of the printing paper 8, and the photoelectric sensor 21. Since the MPU 55 for controlling the stop position of the printing paper 8 is provided, the actual moving distance of the printing paper 8 is fed back to the tractor 5, so that the stop position of the printing paper 8 can be controlled with high accuracy.
[0043]
In addition, when the actual moving distance detected by the photoelectric sensor 21 is smaller than the moving distance to be transported by the tractor 5 by a predetermined distance or more, the print paper 8 should be transported at a low speed by a distance corresponding to the difference. When an instruction is given to the tractor 5 and the tractor 5 transports the printing paper 8 in accordance with the instruction, the actual moving distance detected by the photoelectric sensor 21 is less than the moving distance to be conveyed by the tractor 5 by a predetermined percentage or more Since it is determined that an abnormality has occurred in the paper conveyance, the stop position of the printing paper 8 can be controlled with high accuracy, and the stepping motor 11 can be prevented from stepping out by low-speed driving, and the printing paper 8 can be conveyed normally. Becomes higher.
[0044]
In the above embodiment, the conveyance state of the printing paper 8 is detected by the combination of the rotary code wheel 20 and the photoelectric sensor 21, but as shown in FIG. 11, the combination of the linear scale 61 and the transmission type photoelectric sensor. Thus, the conveyance state of the printing paper 8 may be detected. The linear scale 61 is formed by forming a large number of linear slits 63 radially on a thin disk 62. The slits 63 are processed by a method such as etching, and are formed at a very fine pitch of, for example, about 80 μm on the circumference centered on the center of the disc 62.
[0045]
Alternatively, as shown in FIG. 12, the conveyance state of the printing paper 8 may be detected by a combination of a linear scale 71 and a reflective photoelectric sensor. The linear scale 71 is obtained by forming a large number of linear reflectors 73 radially on a disc 72. The reflectors 73 are provided, for example, by a method such as printing, and are formed on the circumference centering on the center of the disc 72 at an extremely fine pitch of about 80 μm, for example. The disc 72 is adapted to absorb light from the photoelectric sensor. Of course, an absorber that absorbs light from the photoelectric sensor may be provided instead of the reflector 73. In this case, what reflects light from the photoelectric sensor may be used as the disc 72.
[0046]
If such a linear scale 61 or linear scale 71 is used, detection can be performed with higher accuracy than when the rotary code wheel 20 is used. For example, when one step of the stepping motor 11 corresponds to a printing density of 180 dpi, the slit 63 or the reflector so that a detection pulse of one cycle is output from the photoelectric sensor every time the printing paper 8 moves 0.141 mm. If the pitch of 73 is set, a detection pulse of one cycle is obtained every time the stepping motor 11 is driven by one step, so that highly accurate detection can be performed and control becomes very easy. That is, by comparing the drive pulse of the stepping motor 11 with the detection pulse from the photoelectric sensor, the conveyance status of the printing paper 8 can be determined in units of one step of the stepping motor 11, so that the MPU 55 detects the detection pulse from the photoelectric sensor. By controlling the stepping motor 11 based on the above, the conveyance speed and conveyance distance of the printing paper 8 can be easily controlled with high accuracy. Therefore, it is possible to quickly detect a jam before the printing paper 8 is completely stopped due to a decrease in the conveyance speed of the printing paper 8.
[0047]
In the above embodiment, the entire printing apparatus is controlled by one MPU 55. However, a plurality of MPUs may be provided, and in this case, the function sharing of each MPU is arbitrary.
[0048]
In the above embodiment, continuous paper is used as the printing paper 8, but the present invention can be effectively used even when the printing paper is cut paper.
[0049]
Of course, the specific configuration of the printing apparatus in the above embodiment is merely an example, and the present invention is not limited to such a specific configuration.
[0050]
【The invention's effect】
As described above, according to the present invention, when the actual moving distance of the printing paper is smaller than the moving distance to be conveyed by the paper conveying unit by a predetermined distance or more or a predetermined ratio or more, the conveying speed by the paper conveying unit. Is changed to a speed lower than the predetermined speed, and the printing paper is transported, and even in this transport, the actual moving distance of the printing paper is a predetermined distance or more than the moving distance to be transported by the paper transport section or a predetermined ratio When the number is less than the above, a predetermined abnormality process is performed as a printing paper conveyance abnormality, so that the printing paper conveyance state can be accurately determined.
[Brief description of the drawings]
FIG. 1 is a conceptual explanatory diagram illustrating the overall configuration of a printing apparatus according to the present invention.
FIG. 2 is a front view of the tractor shown in FIG.
3 is a plan view of the tractor shown in FIG. 1. FIG.
4 is a cross-sectional view taken along the line AA in FIG. 3;
FIG. 5 is a conceptual explanatory diagram of a printing unit shown in FIG. 1;
6 is a front view of the main part of the linear motor shown in FIG. 5. FIG.
7 is a plan view of the main part of the linear motor shown in FIG. 5. FIG.
8 is an explanatory diagram of a pin block installed in the print head shown in FIG.
FIG. 9 is a circuit block diagram of a control unit provided in the printing apparatus shown in FIG. 1;
FIG. 10 is a flowchart for explaining a procedure of paper feeding processing executed by the MPU shown in FIG. 9;
FIG. 11 is a front view of a linear scale according to another embodiment.
FIG. 12 is a front view of a linear scale in still another embodiment.
[Explanation of symbols]
4 Printing Unit 5 Tractor 8 Printing Paper 11 Stepping Motor 12 Belt 17 Roller 20 Rotation Code Wheel 21 Photoelectric Sensor 31 Print Head 52 Printing Pin 55 MPU
56 ROM
57 RAM
61, 71 Linear scale 62, 72 Disc 63 Slit 73 Reflector

Claims (4)

A paper transport unit that transports print paper at a predetermined speed set in advance along a predetermined path;
A moving distance detecting unit for detecting an actual moving distance of the printing paper;
A determination unit for determining whether an actual movement distance detected by the movement distance detection unit is less than a movement distance to be conveyed by the paper conveyance unit by a predetermined distance or a predetermined ratio;
When it is determined by the determination unit that the actual moving distance of the printing paper is less than a predetermined distance or a predetermined ratio than the moving distance to be conveyed by the paper conveying unit, the conveying speed by the paper conveying unit is set. A paper conveyance control unit that changes the speed to be lower than the predetermined speed and conveys the printing paper;
According to the determination result of the determination unit determined after the conveyance of the printing paper by the paper conveyance control unit, the actual movement distance of the printing paper is a predetermined distance or more than the movement distance to be conveyed by the paper conveyance unit or An abnormality processing unit that performs a predetermined abnormality process as a conveyance abnormality of the printing paper when less than a predetermined ratio;
A printing apparatus comprising: The printing apparatus according to claim 1, wherein the abnormality processing by the abnormality processing unit includes an abnormality occurrence display or warning or abnormality cancellation guidance . The movement distance detector
A roller that contacts the printing paper and rotates by an angle corresponding to the moving distance of the printing paper;
A rotating body that is rotated by the same angle as the roller and in which a large number of detected parts are formed at a predetermined pitch on a concentric circle around the rotation center;
A detection unit that outputs a detection signal each time the printing paper moves a predetermined distance by detecting the detected portion;
The printing apparatus according to claim 1 , further comprising a movement distance calculation unit that calculates an actual movement distance of the printing paper based on a detection signal from the detection unit. The paper transport unit uses a stepping motor as a drive source,
The printing apparatus according to claim 3, wherein the detection unit outputs a detection signal every time the printing paper moves by a distance corresponding to one step of the stepping motor .

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