JP2005280194A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To print without information distorted. <P>SOLUTION: Differences between elements at a mutually corresponding time of time series data of a width direction position of a left end part of an endless belt 13 and time series data of the width direction position of the left end part when the endless belt 13 does not meander are calculated, whereby a meandering amount of a printing paper 14 is detected. Even if the printing paper 14 meanders because the endless belt 13 meanders, ink droplets discharged from nozzles of each printer head 15 can be hit on a suitable position. Consequently, the information can be printed without being distorted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing apparatus that sequentially prints on a print medium with a plurality of printer heads.

2. Description of the Related Art Conventionally, for example, a printing apparatus that includes a plurality of printer heads each capable of printing different colors and sequentially prints on a printing paper by using the plurality of printer heads is known.
In addition, some of such printing apparatuses are configured to prevent a print image from being disturbed by meandering of printing paper. For example, in Patent Document 1, a registration mark is printed on both edges of printing paper when printing the first color, and at the position of the printed registration mark when printing each color after the second color. Based on this, the position of each printer head is appropriately moved so that the color overlapping position of each color is appropriate.
JP-A-10-35021

  However, in the above prior art, the registration mark is printed simultaneously with the printing of the first color. Therefore, when the printing paper meanders, the meandering state is reflected in the printing result of the registration mark. The registration mark is meandered and printed. Therefore, at the time of printing for the second color and thereafter, there is a problem that the position of each printer head is moved based on the position of the meandering registration mark, and as a result, information such as characters and images is distorted and printed.

  An object of the present invention is to solve the above-mentioned unsolved problems of the conventional printing apparatus, and an object thereof is to provide a printing apparatus capable of printing information without distortion.

  In order to solve the above-described problem, a printing apparatus according to a first aspect of the present invention includes a plurality of printers disposed on different positions along a conveyance direction on a print medium that is conveyed by an endless belt stretched around a plurality of rollers. A printing apparatus that sequentially prints with a head, a data generation unit that generates print data to be printed by each printer head, and a time series that can detect time-series data of the width direction position of the end in the width direction of the endless belt Based on the data detection means and the detected time series data, the time series data of the width direction end of the endless belt and the width of the end in the width direction when the endless belt is not meandering Based on the meandering amount calculation means for calculating the difference between the elements in the time corresponding to the time-series data of the direction position, and the calculated difference and the print data generated by the data generation means. There is characterized in that a head control means for operating the printer head.

In the printing apparatus according to the second aspect of the invention, the head control unit controls the position of each printer head with respect to the width direction of the endless belt based on the difference calculated by the meandering amount calculation unit. And a print execution unit for printing the print data on each printer head whose position is controlled.
According to the first or second invention, when the print medium meanders due to the endless belt meandering, the time series data of the width direction position of the end part in the width direction of the endless belt and the endless belt does not meander The meandering amount of the endless belt can be detected appropriately by calculating the difference between the elements in the time corresponding to the time-series data of the width direction position of the end in the width direction. That is, the component included in the time-series data of the width direction position of the endless belt, that is, the component due to the meandering of the endless belt and the component due to the shape error of the end portion of the endless belt in the width direction is removed, and the endless belt is removed. It is possible to detect only the component due to meandering. Therefore, the meandering amount of the print medium can be detected by detecting the meandering amount of the endless belt, and even if the meandering of the print medium, the ink droplets ejected from the nozzles of each printer head are landed at an appropriate position. As a result, information can be printed without distortion.

  Furthermore, in the printing apparatus according to the third aspect of the invention, the printing apparatus includes a state detection unit that detects a position and a rotation state of the print medium with respect to the endless belt, and the head control unit detects the print detected by the state detection unit. Each printer head is operated based on the position and rotation state of the medium, the difference calculated by the meandering amount calculation means, and the print data generated by the data generation means.

  In the printing apparatus according to the fourth aspect of the invention, the head control means determines whether the difference calculated by the meandering amount calculation means and the position and rotation state of the print medium detected by the state detection means. And a position control means for controlling the position and rotation state of each printer head relative to the endless belt, and a print execution means for printing the print data on each printer head whose position and rotation state are controlled. It is characterized by.

  According to these third and fourth aspects, the position and rotation state of the printer head with respect to the width direction of the print medium can be kept constant. Therefore, even if the position and rotation state of the print medium with respect to the endless belt deviates from the predetermined position and rotation state, the ink droplets ejected from the nozzles of each printer head are landed at an appropriate position on the print medium. Can do.

A line printer as an embodiment of a printing apparatus according to the present invention will be described below with reference to the drawings.
<First Embodiment>
<Configuration of line printer>
FIG. 1 is a side view and a plan view showing the appearance of the line printer of the first embodiment, and FIG. 2 is a block diagram showing the internal configuration of the line printer of the first embodiment. As shown in FIG. 2, the line printer 1 includes a CPU (Central Processing Unit) 2, a RAM (Random Access Memory) 3, a ROM (Read Only Memory) 4, an I / F (InterFace) 5, and a printing paper transport unit 6. The ink ejection unit 7, the belt meandering detection unit 8 and the belt reference position detection unit 9 are configured to be connected to each other via a bus 10 so as to be able to exchange data.

Among these, when a print execution command (described later) is output from the I / F 5, the CPU 2 reads various programs and data stored in the ROM 4, expands these various programs in a work area provided in the RAM 3, A print execution process, which will be described later, is executed to control each unit so that information such as images and characters according to a print execution command (described later) is printed.
The RAM 3 forms a work area for developing various programs executed by the CPU 2 and also forms a memory area for storing data related to the various programs. Then, when a read request is output from the CPU 2, the RAM 3 outputs the stored data to the CPU 2 in response to the read request.

Furthermore, the ROM 4 stores various programs and data executed by the CPU 2. Then, when a read request is output from the CPU 2, the ROM 4 outputs various stored programs and data to the CPU 2 in response to the read request.
The I / F 5 is connected to a personal computer (not shown) that outputs data of information to be printed by the line printer 1. When the information data is output from the personal computer (not shown), the I / F 5 issues a command (hereinafter also referred to as “print execution command”) to cause the line printer 1 to print information corresponding to the data. It outputs to CPU2.

  Further, as shown in FIG. 1, the printing paper transport unit 6 includes a driving roller 11 that can be driven to rotate by a servo motor (not shown), a driven roller 12 that has the same diameter as the driving roller 11, and a rotatable roller 12. And an endless belt 13 stretched between the rollers 11 and 12. Among these, the endless belt 13 is provided with a sheet adsorbing means (not shown) that adsorbs the printing sheet 14. Examples of the paper suction means include static electricity and air suction. Further, the circumferential length of the endless belt 13 is an integral multiple of the diameter of the drive roller 11.

When the print control command (described later) is output from the CPU 2, the printing paper transport unit 6 has an endless belt so that the front ends are aligned on a straight line extending from the index 22 (described later) in a direction orthogonal to the paper feed direction. After the printing paper 14 is attached to a specific position at the center of the driving roller 11, the driving roller 11 is rotationally driven at a constant speed, the endless belt 13 is rotated, and the printing paper 14 is conveyed.
The ink ejection unit 7 includes four printer heads 15 disposed above the endless belt 13. These printer heads 15 are arranged at different positions along the direction in which the printing paper is conveyed (hereinafter also referred to as “paper feeding direction”), and sequentially from the downstream side in the paper feeding direction, black, cyan, magenta. A plurality of nozzles capable of ejecting one of the yellow colors vertically downward are respectively formed on the lower surface. The plurality of nozzles are arranged such that the nozzles of the same printer head 15 are arranged in a direction orthogonal to the paper feeding direction, and the nozzles at different positions of different printer heads 15 are arranged in a line in the paper feeding direction. .

  The printer head 15 is formed so that the length in the direction orthogonal to the paper feeding direction is longer than the width of the printing paper 14, one end of which contacts the elastic member 16 and the other end contacts the drive shaft of the drive source 17. ing. The drive source 17 includes a stepping motor that moves the drive shaft back and forth according to the number of steps of the input step signal. When a movement command (described later) is output from the CPU 2, the printer head 15 inputs a step signal to the driving source 17 so that the printer head 15 moves in the longitudinal direction in accordance with the movement command (described later). .

When the print control command (described later) is output from the CPU 2, the ink ejection unit 7 outputs the timing, the number of times, and the dot size (for example, L size, M size, and S size) according to the print control command (described later). The ink droplets are ejected to the respective nozzles by size), and information corresponding to a print control command (described later) is printed on the printing paper conveyed by the endless belt 13.
Further, the belt meandering detection unit 8 includes a photo sensor 18 arranged corresponding to the printer head 15 on the most upstream side in the paper feeding direction. The photosensor 18 includes a light emitting diode disposed on the upper surface side of the left end of the endless belt 13 and a light receiving element disposed on the lower surface side. The photosensor 18 detects the degree of obstruction of the left end of the endless belt 13 between the light emitting diode and the light receiving element by causing the light receiving element to detect light emitted from the light emitting diode, as shown in the graph of FIG. In addition, time-series data of the position in the width direction of the left end portion of the endless belt 13 is detected based on the detected degree. Here, in the graph of FIG. 3, the elapsed time t after the front end of the printing paper 14 passes just below the uppermost printer head 15 is a positive value on the horizontal axis, and meanders to the right in the paper feeding direction. The amount (hereinafter also referred to as “left end meandering amount”) is a positive value on the vertical axis. Further, the photosensor 18 detects the amount of change in the position in the width direction of the left end due to the shape error of the left end of the endless belt 13 measured in advance from the time-series data of the detected position in the width direction. The time series data of the meandering amount of the endless belt 13 is obtained by subtracting the elements at the time corresponding to each other in the time series data (hereinafter also referred to as “unique profile”) of the position in the width direction of the left end when not meandering. Is detected.

  When the time series data of the meandering amount of the endless belt 13 in the vicinity of the most upstream printer head 15 is detected by the photo sensor 18, the belt meandering detection unit 8 detects each printer head based on the detection result. The time-series data of the meandering state of the endless belt 13 immediately below 15, that is, the amount of meandering of the endless belt 13 at each elapsed time since the conveyance of the printing paper 14 is started, The meandering amount (hereinafter also referred to as “printing paper meandering amount”). Specifically, the meandering state of the printing paper 14 just below the downstream printer head 15 is the same as the meandering state of the printing paper 14 just below the uppermost printer head 15 from the uppermost printer head 15. It is calculated by delaying the distance to the downstream printer head 15 by the time of the division result obtained by dividing the distance to the rotational speed of the endless belt 13.

  The belt reference position detection unit 9 detects an index 22 formed at the right end of the endless belt 13 and that the index 22 has passed through the vicinity of the most upstream printer head 15 in the paper feeding direction. 23. Then, when the index detection sensor 23 detects the passage of the index 22, the belt reference position detection unit 9 outputs a command for starting the conveyance of the printing paper 14 (hereinafter also referred to as a “printing paper conveyance start command”) to the CPU 2. .

<Contents of print execution processing>
Next, the print execution process executed by the CPU 2 will be described with reference to the flowchart of FIG. This print execution process is executed whenever a predetermined time elapses when a print execution command is output from the I / F 5. First, in step S 101, the print execution command is output from the I / F 5. Print data including the timing, number of times, and dot size at which ink droplets are ejected for each nozzle is generated so that the corresponding information is printed on the print paper transported by the print paper transport unit 6. Data is stored in the RAM 3.

Next, the process proceeds to step S102, where it is determined whether or not a print sheet conveyance start command is output from the belt reference position detection unit 9, and if it is output (Yes), the process proceeds to step S103 and is not output. In this case (No), this determination is repeated.
In step S 103, a print control command for causing each nozzle to eject ink droplets at a timing, number of times, and dot size corresponding to the print data stored in the RAM 3 is output to the printing paper transport unit 6 and the ink ejection unit 7.

  Next, the process proceeds to step S104, in which the print image 14 is prevented from being disturbed due to the meandering of the print paper 14, and the belt according to the print execution command output from the I / F 5 is appropriately printed on the print paper. The printer heads 15 are sequentially moved based on the time-series data of the printing paper meandering amount detected by the meandering detection unit 8, and then this calculation process is terminated. Specifically, a command for moving the printer head 15 by the amount of printing paper meander (hereinafter also referred to as “movement command”) is output to each printer head 15. Here, if the detected printing paper meandering amount is a positive value, a movement command for moving the printer head 15 to the right in the paper feeding direction by the amount of the printing paper meandering amount is output, and a negative value is output. If the value is a value, a movement command for moving the printer head 15 to the left in the paper feeding direction by the amount of the printing paper meandering amount is output.

<Operation of line printer>
Next, the operation of the line printer 1 of the present embodiment will be described based on a specific situation.
First, it is assumed that data of information to be printed is output from a personal computer (not shown), and a print execution command corresponding to the data is output by the I / F 5. Then, the CPU 2 executes print execution processing. As shown in FIG. 4, first, in step S101, print data including the timing, number of times, and dot size at which ink droplets are ejected is generated for each nozzle. The printed data is stored in the RAM 3.

  Here, it is assumed that the index 22 passes near the index detection sensor 23. Then, a print sheet conveyance start command is output from the belt reference position detection unit 9, the determination in step S102 is “Yes”, and a print control command corresponding to the print data stored in the RAM 3 is output in step S103. . At the same time, the belt meandering detection unit 8 detects time-series data of the position in the width direction of the left end portion of the endless belt 13, and subtracts the elements at the time corresponding to each other of the unique profile from the detected time-series data. Time series data of the meandering amount of the endless belt 13 in the vicinity of the upstream printer head 15 is detected. That is, among the components included in the time series data of the position in the width direction of the endless belt 13, that is, the component due to the meandering of the endless belt 13 and the component due to the shape error of the left end portion of the endless belt 13, the component due to the shape error is removed. Only components due to endless belt meandering are detected. Then, based on the detected time series data, time series data of the printing paper meandering amount is set. Next, in step S104, the time series data of the printing paper meandering amount is read from the belt meandering detection unit 8 for each printer head 15, and a movement command corresponding to the read time series data is sent to each printer head 15. After being sequentially output to each, this calculation process ends.

  Then, after the printing paper 14 is stuck to a specific position of the endless belt 13 by the printing paper transport unit 6, the driving roller is driven to rotate at a constant speed, the endless belt 13 is rotated, and the stuck printing paper 14 is moved. It is conveyed below the printer head 15. At the same time, each of the printer heads 15 is appropriately moved in the longitudinal direction according to the movement command output from the CPU 2 by the ink ejection unit 7, and at the same time, the number of times and the dot size from each nozzle according to the printing control command. Information corresponding to the print control command, that is, information corresponding to data output from a personal computer (not shown) is appropriately printed on the printing paper ejected with the ink droplets and conveyed by the endless belt 13.

  As described above, according to the line printer 1 of this embodiment, when the endless belt 13 meanders and the printing paper 14 meanders, the time-series data of the width direction position of the left end portion of the endless belt 13 and the endless belt 13 are The meandering amount of the printing paper 14 can be detected appropriately by calculating the difference between the elements in the time corresponding to the time-series data of the position in the width direction of the left end when not meandering. Therefore, the amount of meandering of the printing paper 14 can be detected by detecting the amount of meandering of the endless belt 13, and even if the printing paper 14 meanders, the ink droplets ejected from the nozzles of the respective printer heads 15 are appropriately set. The position can be landed, and as a result, information can be printed without distortion. Further, compared with a method of printing an unnecessary mark on the printing paper 14 in order to detect the meandering state of the printing paper 14, a printer head for printing the mark can be omitted, the apparatus can be downsized, and the manufacturing cost can be reduced. Can be reduced.

  In this embodiment, the example in which the photo sensor 18 is arranged only in the vicinity of the most upstream printer head 15 is shown, but the present invention is not limited to this. For example, as shown in FIG. 5, a photo sensor 18 is configured in the vicinity of each printer head 15 so that the time series data of the position in the width direction of the left end portion of the endless belt 13 are simultaneously detected by the photo sensor 18. May be. By doing so, the meandering state of the printing paper 14 immediately below each printer head 15 can be detected with high accuracy, and as a result, information can be printed without distortion.

Second Embodiment
Next, the line printer 1 according to the second embodiment will be described.
This embodiment includes a paper sticking state detection unit capable of detecting the position and rotation state of the printing paper 14 with respect to the endless belt 13, and based on the detection result, the position and rotation state of each printer head 15 with respect to the endless belt 13. The point which controls is different from the first embodiment.
Specifically, as shown in FIG. 6, the paper sticking state detection unit includes a rotation state detection unit 24 and a position detection unit 25. Among these, the rotation state detectors 24 are provided at two positions on the side surface of the printer head 15 and separated from each other in the longitudinal direction. The rotation state detection unit 24 detects the rotation state of the printing paper 14 with respect to the endless belt 13 directly below each printer head 15 by irradiating light vertically downward and detecting reflected light of the irradiated light. To do.

  Further, the position detection unit 25 includes a light emitting diode disposed on the upper surface side of a position where the left end of the printing paper 14 passes and a light receiving element disposed on the lower surface side immediately before the printing paper 14 is attached. . And the position detection part 25 detects the degree by which the left end of the printing paper 14 interrupts | blocks between a light emitting diode and a light receiving element by making a light receiving element detect the light emitted from a light emitting diode, and it is in the detected degree. Based on this, the position of the printing paper 14 with respect to the endless belt 13 is detected. Although the example in which the position detection unit 25 detects the position of the left end portion of the printing paper 14 immediately before being attached to the endless belt 13 is not limited to this, for example, the position detection unit 25 is attached to the endless belt 13. You may make it detect when it is conveyed.

  Further, the printer head 15 is provided on a swing member 27 that is swingable (rotatable) about the vertical shaft 26 on the left end side of the endless belt 13. Further, the end of the swing member 27 located on the opposite side of the vertical shaft 26 has one side surface in contact with the elastic member 28 and the opposite side surface in contact with the drive shaft of the drive source 29. When the movement command is output from the CPU 2, the printer head 15 responds to the movement command and the detection results of the rotation state detection unit 24 and the position detection unit 25 with respect to the width direction of the printing paper 14. Step signals for moving the printer head 15 in the longitudinal direction or swinging (rotating) about the vertical axis 26 are input to the drive sources 17 and 29 so that the position and rotation state are constant.

In addition, this 2nd Embodiment includes many structures equivalent to the structure of the said 1st Embodiment, attaches | subjects an equivalent code | symbol to an equivalent structure, and abbreviate | omits the detailed description.
Thus, according to the line printer 1 of this embodiment, the position and rotation state of the printer head 15 with respect to the width direction of the printing paper 14 can be kept constant. Therefore, even if the position and rotation state of the printing paper 14 with respect to the endless belt 13 deviate from a predetermined specific position, the ink droplets ejected from the nozzles of the printer heads 15 land at appropriate positions on the printing paper 14. Can be made.

  As described above, the CPU 2 in FIG. 2 and step S101 in FIG. 4 constitute the data generation means described in the claims, and similarly, the photosensor 18 and the belt meandering detection unit 8 in FIG. 1 and the meandering amount calculation means, and the elastic member 16 and the drive source 17 in FIG. 1, the CPU 2 in FIG. 2, the printing paper transport section 6 and the ink ejection section 7, and steps S102 to S104 in FIG. 4 constitute the head control means. The elastic member 16 and the drive source 17 in FIG. 1, the CPU 2 and the ink ejection unit 7 in FIG. 2, and the step SS 104 in FIG. 4 constitute position control means, and the CPU 2, the printing paper transport unit 6, and the ink ejection unit in FIG. 7. Steps S102 and S103 in FIG. 4 constitute a print execution unit.

The printing apparatus of the present invention is not limited to the contents of the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.
In the above-described embodiment, an example in which the ink discharge unit 7 includes a plurality of line heads has been described. However, the present invention is not limited to this. For example, a small serial head that can move in a direction orthogonal to the paper feed direction. You may make it comprise including.

Moreover, although the example which arrange | positions the printer head 15 longer than the width | variety of the printing paper 14 as a line head in the ink discharge part 7 was shown, it is not restricted to this. For example, a printer head 15 configured by connecting a plurality of sub printer heads shorter than the width of the printing paper 14 over the width of the printing paper 14 may be arranged.
Further, the printer head 15 is configured to be movable in a direction orthogonal to the paper feeding direction, and each printer head 15 is based on the meandering state of the left end portion of the endless belt 13 so that information is appropriately printed on the printing paper 14. Although an example of moving is shown, it is not limited to this. For example, the print data is corrected so that the print data corresponding to each nozzle is output from the adjacent nozzle based on the meandering state of the print paper 14 so that the information is appropriately printed on the print paper 14. It may be. Further, for example, it is determined whether there is a possibility that information printed by the downstream printer head 15 may be improperly overlapped with information printed by the upstream printer head 15, and may be improperly overlapped. In this case, the print data may be corrected so that printing of the overlapping portion is omitted.

  Also, the difference between the elements in the time corresponding to the time series data x1 of the left end meandering amount of the most upstream printer head 15 and the time series data x2 of the left end meandering amount of the downstream printer head 15 is simply. Although the example which calculates (DELTA) x was shown, it is not restricted to this. For example, a rotary encoder capable of detecting the rotation speed of the drive roller 11 is provided, and the rotation unevenness of the drive roller 11 is detected based on the detection result of the rotary encoder, and the most downstream printer is detected based on the detected rotation unevenness. The time series data x1 of the head 15 may be corrected, and the difference Δx may be calculated based on the corrected time series data x1. By doing so, the meandering amount when the same portion of the printing paper 14 passes directly under the printer head 15 during the time corresponding to the time-series data of the left end meandering amount x corresponding to the printer head 15. As a result, it is possible to more appropriately prevent the disturbance of the printed image due to the meandering of the endless belt 13.

It is the side view and top view which show the external appearance of 1st Embodiment. FIG. 2 is a block diagram illustrating an internal configuration of the line printer in FIG. 1. It is a graph for demonstrating the left end part meandering amount. It is a flowchart of a printing execution process. It is explanatory drawing for demonstrating the modification of this invention. It is the side view and top view which show the external appearance of 2nd Embodiment.

Explanation of symbols

1 is a line printer, 2 is a CPU, 3 is a RAM, 4 is a ROM, 5 is an I / F, 6 is a printing paper transport unit, 7 is an ink ejection unit, 8 is a belt meandering detection unit, and 9 is a belt reference position detection unit. 10 is a bus, 11 is a driving roller, 12 is a driven roller, 13 is an endless belt, 14 is printing paper, 15 is a printer head, 16 is a sub-printer head, 17 is a photo sensor, 22 is an index, and 23 is an index detection sensor. , 24 is a rotation state detector, 25 is a position detector, 26 is a vertical shaft, 27 is a swing member, 28 is an elastic member, and 29 is a drive source.

Claims (4)

A printing apparatus that sequentially prints on a print medium conveyed by an endless belt spanned by a plurality of rollers with a plurality of printer heads arranged at different positions along the conveyance direction,
Data generating means for generating print data to be printed on each printer head, time series data detecting means capable of detecting time series data at the width direction end of the endless belt in the width direction, and the detected time series data The time series data of the width direction position of the end portion in the width direction of the endless belt and the time series data of the position in the width direction of the end portion in the width direction when the endless belt is not meandering Meandering amount calculation means for calculating the difference between the elements, and head control means for operating each printer head based on the calculated difference and the print data generated by the data generation means. Characteristic printing device.   The head control means includes a position control means for controlling the position of each printer head with respect to the width direction of the endless belt based on the difference calculated by the meandering amount calculation means, and a printer head whose position is controlled. The printing apparatus according to claim 1, further comprising: a print execution unit that prints the print data.   State detection means for detecting the position and rotation state of the print medium with respect to the endless belt, and the head control means is calculated by the position and rotation state of the print medium detected by the state detection means and the meandering amount calculation means. The printing apparatus according to claim 1, wherein each printer head is operated based on the difference and the print data generated by the data generation unit.   The head control unit is configured to determine the position and rotation state of each printer head relative to the endless belt based on the difference calculated by the meandering amount calculation unit and the position and rotation state of the print medium detected by the state detection unit. The printing apparatus according to claim 3, further comprising: a position control unit that controls the print data; and a print execution unit that prints the print data on each of the printer heads whose position and rotation state are controlled.

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