JP2002103721A - Printing on printing sheet positioned by sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To print image data on a printing sheet while positioning accurately. SOLUTION: A printing sheet P is guided by mean of guides 29a and 29b and sub-scan fed such that the opposite side ends are located, respectively, above a left groove 26a and a right groove 26b. In this regard, a carriage 31 equipped with a photoreflector 33 is located at a position shown by a dashed line. The photoreflector 33 detects the printing sheet P, if any, at the connecting part 26d of the left groove 26a and a downstream side groove 26r. When the front end of the printing sheet P is detected by the photoreflector 33, sub-scan feeding is stopped and printing is started at the upper end part Pf (lower end on Fig. 1) of the printing sheet P by means of a part of nozzles located above the downstream side groove 26r.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for recording dots on the surface of a recording medium using a dot recording head, and more particularly, to a technique for accurately positioning a printing sheet and performing printing.

[0002]

2. Description of the Related Art In recent years, as an output device of a computer,
2. Description of the Related Art Printers that eject ink from nozzles of a print head are widely used. FIG. 15 is a side view showing the periphery of a print head of a conventional printer. The printing paper P is supplied to upstream paper feed rollers 25p, 2 arranged upstream of the platen 26o.
5q and the downstream paper feed rollers 25r and 25s arranged downstream of the platen 26o are fed in the direction of arrow A and stopped at a predetermined position. And the printing paper P
Is supported on the platen 26o so as to face the head 28o. Thereafter, a large number of ink droplets Ip are ejected from the print head toward a predetermined position on the platen 26o while feeding the print paper little by little in the direction of arrow A. The ink droplets Ip land on the printing paper P on the platen 26o, and an image is recorded on the printing paper.

[0003]

In the above-described printer, as shown in FIG. 15, when the printing paper is shifted from an assumed position indicated by a broken line, an image is not formed at an assumed position on the printing paper. Further, an image to be formed near the edge of the printing paper may run off the printing paper. In such a case, as shown in FIG. 15, the ink droplets deviate from the end of the printing paper to be landed and land on the platen, and the printing paper passing on the platen thereafter becomes dirty.

[0004] The present invention has been made to solve the above-mentioned problems in the prior art, and has as its object to provide a technique for accurately positioning a printing sheet and performing printing.

[0005]

Means for Solving the Problems and Their Functions and Effects In order to solve at least a part of the above-mentioned problems, the present invention employs the following constitution. The dot recording apparatus of the present invention is a dot recording apparatus that records dots on the surface of a print medium using a dot recording head provided with a plurality of dot forming elements that eject ink droplets. A main scanning drive unit that drives the dot recording head with respect to the print medium to perform main scanning, and drives at least a part of the plurality of dot forming elements to form dots during the main scanning. A head drive unit, a sub-scanning drive unit that performs sub-scanning by driving the print medium in a direction that intersects the main scanning direction, a detection unit that detects the presence or absence of the print medium at a predetermined detection point, and each unit. And a control unit for controlling. The detection unit is provided at a position that does not intersect the trajectory of the ink droplet ejected from the dot forming element during the main scanning. According to this aspect, by detecting the print medium by the detection unit, the print medium can be accurately positioned, dots can be recorded, and an image can be formed on the print medium.

[0006] In the above dot recording apparatus, it is preferable to perform the following printing. That is, the sub-scan of the print medium is started from a state where there is no print medium at the detection point. Then, when the detection unit detects the printing medium, the sub-scanning of the printing medium is stopped at a predetermined sub-scanning position in the sub-scanning direction. Thereafter, in a state where the print medium is at the predetermined sub-scanning position, the main scanning is started while ejecting ink droplets from the dot forming elements. According to such printing, the printing medium can be positioned based on whether or not the leading end of the printing medium has reached a predetermined detection point. Therefore, the printing medium can be accurately positioned in the sub-scanning direction.

Preferably, the detecting section includes a light emitting section that emits light toward a predetermined detection point, and a light receiving section that receives light reflected by the light hitting the print medium.
With this configuration, the print medium can be detected without contacting the print medium, and there is no hindrance in recording dots on the print medium.

It is preferable that the detection unit is provided so as to be driven integrally with the dot recording head during the main scanning. With this configuration, the dot recording head and the detection unit do not interfere with each other in the main scanning.

In the sub-scanning direction, the position of the detection unit is set at a position near the dot forming element located at the downstream end in the sub-scanning direction among the dot forming elements used for printing. Is preferred. With such an embodiment, the presence or absence of the print medium can be detected in the vicinity of the dot forming element for printing the leading end of the print medium, and the print medium can be positioned. Therefore, the print medium can be accurately positioned with respect to the dot forming element for printing the leading end of the print medium.

It is preferable that the dot recording apparatus includes a platen that extends in the main scanning direction so as to face the dot forming element in at least a part of the main scanning path, and supports a print medium. Then, it is preferable to adopt the following configuration. That is, the platen has a downstream groove portion extending in the main scanning direction at a position facing the dot forming element located at the downstream end in the sub-scanning direction among at least a plurality of dot forming elements. Shall be. The detection point of the detection unit is a predetermined position within the opening of the downstream groove and within the range where the dot forming element exists in the sub-scanning direction. According to this aspect, it is possible to detect that the leading end of the recording medium is located at the opening of the downstream groove, and to start recording dots near the leading end of the recording medium by the dot forming element.

[0011] The platen may further include a side groove provided at least in a range including a landing range of the ink droplet from the dot forming element in the sub-scanning direction and connected to the downstream groove. It is preferable to adopt the following configuration. That is, the dot recording apparatus further includes a guide section for positioning the print medium at a predetermined main scanning position in the main scanning direction during sub scanning. The predetermined main scanning position at which the guide portion positions the printing medium is located within the main scanning stroke of the dot recording head with respect to the main scanning direction of the printing medium, and one side end of the printing medium in the main scanning direction. The position is a position located on the opening of the side groove. And the detection point of the detection unit is
It is a predetermined position of the connection portion between the side groove and the downstream groove. According to this aspect, it is detected that the leading end of the recording medium is located at the opening of the downstream groove, and that the side end is located at the opening of the lateral groove, and recording of dots on the recording medium is started. can do.

It is preferable to provide a pair of side grooves, a first side groove and a second side groove. The first side groove and the second side groove are formed such that, when the print medium is at a predetermined main scanning position, one side end in the main scanning direction of the print medium is the first side groove. It is preferable that the second side groove is provided on the second side groove and the other side end is provided on the second side groove. According to this aspect, when it is detected that the leading end of the recording medium is positioned at the opening of the downstream groove and one side end is positioned at the opening of the first side groove, the other side is detected. The end will be located over the opening of the second lateral groove. Then, by confirming such an arrangement, it is possible to start recording dots on the recording medium.

Note that the present invention can be realized in various modes as described below. (1) Dot recording device, print control device, printing device. (2) Dot recording method, printing control method, printing method. (3) Computer programs for realizing the above devices and methods. (4) A recording medium on which a computer program for realizing the above apparatus and method is recorded. (5) A data signal embodied in a carrier wave, including a computer program for realizing the above apparatus and method.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in the following order based on embodiments. A. Overview of Embodiment: Overall configuration of device: Arrangement of printing paper: Upper end treatment: Printing on left and right edges: Lower edge processing: Modification:

A. Overview of Embodiment: FIG. 1 is a plan view schematically showing a structure around a platen of an ink jet printer according to an embodiment of the present invention. In FIG.
The printing paper P is fed in the sub-scanning direction from the upper side to the lower side in the direction of the arrow SS. At that time, the printing paper P is
a, 29b, and is fed in the sub-scanning direction so that both side edges Pa, Pb are located on the left groove 26a and the right groove 26b of the platen 26. On the other hand, when the printing paper P is fed in the sub-scanning direction onto the platen 26, the carriage 31 of the print head is arranged at a position indicated by a broken line.
The carriage 31 has a photo reflector 33 on a surface facing the platen 26. The photo reflector 33 is provided on the carriage 31 at a position slightly upstream (in the direction opposite to the arrow SS) of the nozzle at the downstream end in the sub-scanning direction. The photo reflector 33 detects whether or not the printing paper P exists at a predetermined point DP of a connection portion 26d between the left groove portion 26a and the downstream groove portion 26r.

The printing paper P is fed in the sub-scanning direction in the direction of arrow SS, and when the front end thereof is detected by the photo reflector 33, the feeding of the printing paper P in the sub-scanning direction is stopped. Then, of the nozzles on the print head, some of the nozzles on the downstream-side groove 26r are used to control the upper end Pf of the printing paper P.
(The lower end in FIG. 1) starts printing. The nozzle on the print head is located at the upper end Pf of the printing paper P.
Since it is provided further in the direction of the arrow SS than
An image can be formed without making a margin at the upper end of the printing paper P. In addition, since the nozzle used for printing is a nozzle located on the downstream groove 26r, even if the ink droplet comes off the printing paper P, the ink droplet is not discharged from the downstream groove 2r.
6r, and does not land on the central portion 26c of the platen 26. Therefore, the lower surface of the printing paper P is not stained by ink droplets that have landed on the central portion 26c of the platen 26. Also, for the left and right side edges of the printing paper P,
Similarly, at the time of main scanning, the left groove 26a and the right groove 26b
Printing is performed by the nozzle located above. Therefore, the left and right side edges can be printed without blanking without soiling the central portion 26c of the platen 26.

B. Apparatus Configuration: FIG. 2 is a block diagram showing the software configuration of the printing apparatus. In the computer 90, under a predetermined operating system,
An application program 95 is running. A video driver 91 and a printer driver 96 are incorporated in the operating system, and the application program 95 sends these drivers through these drivers.
The image data D to be transferred to the printer 22 is output. An application program 95 for retouching an image reads an image from the scanner 12 and displays the image on the CRT 21 via the video driver 91 while performing predetermined processing on the image. The data ORG supplied from the scanner 12 is read from a color original, and original color image data OR composed of three color components of red (R), green (G), and blue (B).
G.

This application program 95
When a print command is issued, the printer driver 96 of the computer 90 receives the image data from the application program 95, and receives the image data from the application program 95. The printer 22 can process the signals (here, cyan, magenta, yellow, light cyan, light magenta, and black for each color). Is converted to a multilevel signal). In the example shown in FIG. 2, the printer driver 96 includes a resolution conversion module 97, a color correction module 98, a halftone module 99, and a rasterizer 100.
Further, a color correction table LUT and a dot formation pattern table DT are also stored.

The resolution conversion module 97 converts the resolution of the color image data (composed of three colors of RGB) handled by the application program 95, that is, the number of pixels per unit length into a resolution that the printer driver 96 can handle. Convert. The color correction module 98 refers to the color correction table LUT and converts the resolution-converted image data into cyan (C), magenta (M), light cyan (LC), and light magenta (LC) used by the printer 22 for each pixel. LM), yellow (Y), and black (K).

The color-corrected data has a predetermined gradation value. The printer 22 expresses this gradation value by forming dots in a dispersed manner. When the halftone module 99 performs halftone processing on the data, the data becomes data that enables the printer 22 to express a gradation value by forming such dots. The halftone module 99 refers to the dot formation pattern table DT, sets the dot formation pattern of each ink dot according to the tone value of the image data, and executes this halftone processing. The processed image data is rearranged by the rasterizer 100 in the order of transfer to the printer 22, and output as final print data PD. The print data PD includes raster data indicating the recording state of dots during each main scan and data indicating the sub-scan feed amount. In the present embodiment, the printer 22 only plays a role of forming dots in accordance with the print data PD and does not perform image processing. However, these processes may be performed by the printer 22.

Next, a schematic configuration of the printer 22 will be described with reference to FIG. As shown in the drawing, the printer 22 includes a mechanism for transporting the printing paper P by a paper feed motor 23,
Guides 29a and 29 for guiding the printing paper P during transport
b (not shown in FIG. 3) and the carriage motor 24
A mechanism for reciprocating the carriage 31 in the axial direction of the platen 26, a mechanism for driving a print head 28 mounted on the carriage 31 to eject ink and form ink dots, a paper feed motor 23, and a carriage. The control circuit 40 controls the exchange of signals with the motor 24, the print head 28, and the operation panel 32.

A mechanism for reciprocating the carriage 31 in the axial direction of the platen 26 is provided in parallel with the axis of the platen 26, and an endless mechanism is provided between the carriage shaft 24 and the slide shaft 34 for slidably holding the carriage 31. And a position detecting sensor 39 for detecting the origin position of the carriage 31.

The carriage 31 has a cartridge 71 for black ink (K), cyan (C), and light cyan (L).
C), a magenta (M), light magenta (LM), and yellow (Y) ink cartridges 72 containing six color inks can be mounted. The print head 28 below the carriage 31 has a total of six ink ejection heads 61.
Through 66 are formed, and an introduction pipe 67 that guides ink from the ink tank to each color head is provided upright at the bottom of the carriage 31. When the cartridge 71 for black (K) ink and the cartridge 72 for color ink are mounted on the carriage 31 from above, the introduction pipe 67 is inserted into the connection hole provided in each cartridge, and the ejection heads 61 to 66 are discharged from each ink cartridge. Can be supplied to the printer.

FIG. 4 is an explanatory diagram showing the structure of the piezo element PE and the nozzle Nz in detail. In each of the heads 61 to 66 provided in the lower portion of the carriage 31, a piezo element PE which is one of the electrostrictive elements and has excellent responsiveness is arranged for each nozzle. Then, as shown in the upper part of FIG. 4, the piezo element PE is installed at a position in contact with the ink passage 68 that guides the ink to the nozzle Nz.
As is well known, the piezo element PE is an element that distorts the crystal structure due to the application of a voltage and converts electro-mechanical energy very quickly. In the present embodiment, by applying a voltage having a predetermined time width between the electrodes provided at both ends of the piezo element PE, the piezo element PE expands by the voltage application time as shown in the lower part of FIG. One side wall 68 is deformed. As a result, the volume of the ink passage 68 shrinks in accordance with the expansion of the piezo element PE, and the ink corresponding to the shrinkage becomes particles Ip and is ejected at a high speed from the tip of the nozzle Nz. Printing is performed by the ink particles Ip penetrating into the paper P mounted on the platen 26.

FIG. 5 is an explanatory diagram showing the arrangement of the ink jet nozzles Nz in the ink discharge heads 61 to 66. These nozzles are arranged from six nozzle arrays that eject ink for each color of black (K), cyan (C), light cyan (LC), magenta (M), light magenta (LM), and yellow (Y). 48 nozzles are arranged in a row at a constant nozzle pitch k. The “nozzle pitch” is a value indicating how many rasters (that is, how many pixels) the intervals of the nozzles arranged on the print head in the sub-scanning direction are. Here, the “raster” is a row of pixels arranged in the main scanning direction. The “pixel” is a square grid virtually defined on a print medium in order to define a position where an ink droplet lands and a dot is recorded. For example, the pitch k of the nozzles arranged at intervals of three rasters is four.

FIG. 6 is an explanatory diagram showing the electrical configuration of the photo reflector. As shown in FIG. 5, on the lower surface of the carriage 31, a photo reflector 33 is provided at the same position as the nozzle # 4 in the sub-scanning direction. The photo-reflector 33 may be provided near the nozzle # 1 located at the downstream end in the sub-scanning direction. For example, the photo-reflector 33 is several times the nozzle pitch upstream of the nozzle # 1. Is preferably provided. This photo reflector 33
As shown in FIG. 6, a light emitting diode 33d and a phototransistor 33t are provided integrally. The light emitting diode 33d emits light toward a predetermined detection point, and the phototransistor 33t receives the reflected light and converts a change in light amount into a change in current. The CPU 41 in the control circuit 40 determines whether or not a part of the printing paper P is at the detection point according to whether or not the phototransistor 33t receives the reflected light reflected by the printing paper P.

The photo reflector 33 corresponds to a "detection unit" in the claims. The light emitting diode 33d corresponds to a “light emitting unit” and the phototransistor 3
3t corresponds to a “light receiving unit”. The light emitting unit may be any one that can emit light toward a predetermined detection point, and may be a laser. Also, the light receiving section
Any type of light can be used as long as it can receive the reflected light reflected by the print medium, and can be a photodiode.

FIG. 7 is a plan view showing the periphery of the platen 26. The platen 26 moves the print head 2 in the main scan.
8 is provided longer than the width of the printing paper P in the main scanning direction MS so as to face each of the nozzles 8. Upstream of the platen 26, upstream paper feed rollers 25a, 2
5b is provided. While the upstream paper feed roller 25a is one drive roller, the upstream paper feed roller 2a
5b is a plurality of small rollers that rotate freely. Also, downstream of the platen, downstream paper feed rollers 25c and 25d
Is provided. The downstream paper feed roller 25c is a plurality of rollers provided on the drive shaft, and the downstream paper feed roller 25d is a plurality of freely rotating small rollers. The downstream paper feed roller 25c and the upstream paper feed roller 25a are
It rotates synchronously so that the outer peripheral speed becomes equal.

The print head 28 is composed of the upstream paper feed rollers 25a and 25b and the downstream paper feed rollers 25.
It reciprocates on the platen 26 sandwiched between c and 25d in the main scanning. The printing paper P is transferred to the upstream paper feed roller 25.
a, 25b and the downstream side paper feed rollers 25c, 25d, and a portion therebetween is supported by the upper surface of the platen 26 so as to face the nozzle row of the print head 28. Then, sub-scan feed is performed by the upstream paper feed rollers 25a and 25b and the downstream paper feed rollers 25c and 25d, and images are sequentially recorded by ink ejected from the nozzles of the print head 28.

The platen 26 is provided with an upstream groove 26f and a downstream groove 26r on the upstream side and the downstream side in the sub-scanning direction, respectively. The upstream groove 26f and the downstream groove 26r are each provided longer than the width of the printing paper P in the main scanning direction. The downstream groove portion 26r is provided at a position facing a part of the nozzle group Nr on the downstream side including the nozzle at the downstream end of the nozzles N on the print head 28 (the nozzles indicated by oblique lines in FIG. 7). . However, the width of the downstream groove 26r is wider than the width of the nozzle group Nr in the sub-scanning direction. The upstream groove 26f is a part of the upstream nozzle group Nf (not shown in FIG. 7) including the nozzle at the upstream end of the nozzles on the print head 28.
It is provided at a position facing the. The width of the upstream groove 26f is larger than the width of the nozzle group Nf in the sub-scanning direction.

The platen 26 has an upstream groove 26.
f and the left groove 26a and the right groove 26b extending in the sub-scanning direction so as to connect both ends of the f and the downstream groove 26r.
Are provided. Left groove 26a and right groove 26b
Is provided in a range in the sub-scanning direction longer than the range in which ink droplets land from the nozzle row on the print head. The left groove 26a and the right groove 26b are provided such that the distance between the respective center lines (in the main scanning direction) is equal to the width of the printing paper P in the main scanning direction. When the printing paper P is at a predetermined main scanning position guided by the guides 29a and 29b, one side end Pa of the printing paper P in the main scanning direction is formed by the left groove 26a and the right groove 26b. It suffices if it is provided so as to be positioned on the right side groove 26b while being positioned on the right side groove 26b. Therefore, as described above, when the printing paper P is in the fixed position, the side edge of the printing paper P is in the left groove 26a except for the side edge on the center line of the left groove 26a and the right groove 26b. It may be provided so as to be located inside the center line of the right groove 26b.

The upstream groove 26f and the downstream groove 26
r, the left groove 26a and the right groove 26b are connected to each other to form a quadrilateral groove. An absorbing member 27 for receiving and absorbing the ink droplet Ip is disposed at the bottom thereof.

The printing paper P is supplied to the upstream paper feed roller 25.
When the sub-scan feed is being performed by a, 25b and the downstream paper feed rollers 25c, 25d, the paper passes over the openings of the upstream groove 26f and the downstream groove 26r.
On the platen 26, the guides 29a, 29 are arranged such that the left end Pa is located on the left groove 26a and the right end Pb is located on the right groove 26b.
It is positioned in the main scanning direction by b.

Next, the control circuit 40 of the printer 22 (FIG. 3)
) Will be described. Inside the control circuit 40, in addition to the CPU 41, the PROM 42, and the RAM 43, a PC interface 45 for exchanging data with the computer 90, and a drive for outputting ink dot ON / OFF signals to the ink ejection heads 61 to 66. A buffer 44 and the like are provided, and these elements and circuits are interconnected by a bus. The control circuit 40 receives the dot data processed by the computer 90, temporarily stores the dot data in the RAM 43, and outputs the dot data to the driving buffer 44 at a predetermined timing.

In the printer 22 having the hardware configuration described above, the carriage 31 is reciprocated by the carriage motor 24 while the paper P is conveyed by the paper feed motor 23, and at the same time, the piezo elements of each nozzle unit of the print head 28 are operated. By driving, each color ink droplet Ip is ejected to form an ink dot to form a multicolor image on the paper P.

In the printer of this embodiment, as described later, the upper end Pf of the printing paper P is
r, and the lower end Pr is printed on the upstream groove portion 26f, so that a printing process different from that of the middle portion of the printing paper is performed near the upper end and the lower end of the printing paper. In this specification, the printing process in the middle portion of the printing paper is called “intermediate process”, the printing process in the vicinity of the upper end of the printing paper is referred to as “top processing”, and the printing process in the vicinity of the lower end of the printing paper is referred to as “lower edge” Processing ". When the upper end processing and the lower end processing are collectively called, “upper / lower end processing”
Call.

The width W in the sub-scanning direction of the upstream groove 26f and the downstream groove 26r can be determined by the following equation.

W = p × n + α

Here, p is one feed amount [inch] of the sub-scan feed in the upper and lower end processing. n is the number of sub-scan feeds performed in each of the upper end processing and the lower end processing. α is a sub-scan feed error assumed in each of the upper end processing and the lower end processing. It is preferable that the value of α in the lower end processing (upstream groove 26f) is set to be larger than the value of α in the upper end processing (downstream groove 26r). If the width of the groove portion of the platen is determined by the above equation, it is possible to provide a groove portion having a width sufficient to receive ink droplets ejected from the nozzles during upper and lower end processing.

C. FIG. 8 shows a state in which the printing paper P is first placed on the platen 26 in the ink jet printer.
It is a top view which shows arrangement | positioning of each part at the time of upper distribution. In FIG. 8, the printing paper P is indicated by an arrow S from above to below.
Sub-scan feed is performed in the direction of S. At that time, the printing paper P is
It is guided by guides 29a and 29b (see FIG. 7), and is fed in the sub-scanning direction so that both ends are located on the left groove 26a and the right groove 26b of the platen 26.

The printing paper P is located at the center 26c of the platen 26.
During the upward sub-scan feed, the carriage 31 of the print head 28 is disposed at a position on the platen 26 to the left as shown in FIG. And the carriage 31
Is located at the position shown in FIG. 8, the photoreflector 33 is located on a predetermined detection point DP at the connection portion 26d between the left groove 26a and the downstream groove 26r. In this position, the light emitting diode 33d of the photo reflector 33 can emit light toward the detection point DP. The detection point DP is a predetermined position within the range where the nozzles on the print head 28 exist in the sub-scanning direction. The CPU 41 can detect whether or not the printing paper P exists at the detection point DP by using the photo reflector 33.

Since the photo reflector 33 can detect the printing paper without contacting the printing paper, unlike the case of the contact type sensor, it does not interfere with the subsequent printing. Further, since the photo reflector 33 is provided on the carriage, it does not intersect with the trajectory of the ink droplet in the main scanning. Therefore, there is little possibility that the detection performance is deteriorated due to the ink being applied. Since the detection point DP of the photo reflector 33 is a predetermined position within the range where the nozzle exists in the sub-scanning direction, the printing paper P is arranged near the position of the printing paper P when the printing paper P is detected. Then, if ink droplets are ejected from the nozzles, an image can be formed at the leading end of the printing paper P without any blank space.

First, the printing paper P is fed in the sub-scanning direction in the direction of the arrow SS from the state where there is no printing paper P on the platen 26. When the leading end is detected by the photo reflector 33, the sub-scan feed of the printing paper P is stopped. In this embodiment, the photo reflector 33 is a nozzle # 4
Is provided at the position. The CPU 41 slightly feeds in the sub-scanning direction after the photo reflector 33 detects the printing paper P, and positions the nozzle at the downstream end in the sub-scanning direction (hereinafter, this nozzle is referred to as “lower end nozzle”). So that the upper end Pf of the printing paper P is located at a position several rasters upstream in the sub-scanning direction (a direction opposite to the arrow SS).
The sub-scan feed is stopped. As a result of the sub-scanning feed of the printing paper P as described above, the printing paper P is
The upper end (the upper end in FIG. 8 is located on the lower side in FIG. 8) is located on the downstream groove 26r. The left end P of the printing paper P
a is located on the left groove 26a, and the right end Pb is located on the right groove 26b.

Thereafter, as shown in FIG. 7, the carriage is moved to the right end side, and printing is started. That is, main scanning is performed while ink droplets are ejected from the nozzles. In addition, even if the sub-scan feed of the printing paper P is performed, the photo reflector 3
If the printing paper P cannot be detected at the detection point DP due to No. 3, the CPU 41 transmits an error signal to the computer 90 and stops printing.

D. Upper end processing: In this embodiment, an image is recorded without a margin up to the upper end of the printing paper. At that time, the printing paper P
The recording at the upper end Pf is performed by the nozzle Nr disposed at a position corresponding to the position on the downstream groove 26r in the sub-scanning direction. Then, as shown in FIG. 7, some of the nozzles Nr including the lower end nozzle are located downstream of the upper end of the printing paper P in the sub-scanning direction (arrow SS).
Direction). In other words, the printing paper P is arranged such that the upper end Pf of the printing paper P is located upstream of the lower end nozzle in the sub-scanning direction.

Theoretically, if the printing paper P is arranged with respect to the printing head 28 and the dot recording is started so that the lower end nozzle is located at a position near the upper end of the printing paper P, the printing paper P An image can be recorded without margins up to the upper end of P. However, during the sub-scan feed, an error may occur in the feed amount. Further, the ejection direction of the ink droplet may be shifted due to a manufacturing error of the print head 28 or the like. In this embodiment, the upper end Pf of the printing paper P is
However, the printing paper P is arranged so as to be located upstream of the lower end nozzle, and the upper end Pf of the printing paper P is printed. For this reason, even when the landing position of the ink droplet on the printing paper is shifted, no margin is generated at the upper end of the printing paper.

FIG. 9 is a side view showing the relationship between the print head 28 and the printing paper P at the start of printing. Here, in order to simplify the description, the number of nozzles will be described as eight. The central portion 26c of the platen 26 is provided in a range R26 from a position two rasters later from the nozzle # 2 of the print head 28 to a position two rasters earlier from the nozzle # 7. And Therefore, even when the ink droplets Ip are ejected from each nozzle in a state where there is no printing paper, the ink droplets from the nozzles # 1, # 2, # 7 and # 8 do not land on the platen 26.

In FIG. 7, the nozzle group Nr indicated by oblique lines of the print head 28 is a portion where nozzles # 1 and # 2 are located. A downstream groove 26r is provided below a portion through which the nozzles pass during main scanning. Then, the upper end P of the printing paper P is placed on the downstream groove 26r.
Printing starts when f is present. In the present embodiment, the upper end Pf of the printing paper P is used by using the nozzle # 2 just above the upper end Pf of the printing paper P and the nozzle # 1 outside the upper end Pf of the printing paper P. Is printed, an image can be printed without creating a margin at the upper end of the printing paper P. Further, since the printing paper P is positioned by using the photo reflector 33, the printing paper P can be accurately arranged with respect to the nozzles used for the upper end processing. Further, even when the position of the printing paper is shifted due to an error in the sub-scan feed, the nozzles # 1 and # 2 are located on the downstream groove 26r, so that the ink droplets land on the central portion 26c of the platen 26. Nothing.

FIG. 10 is a plan view showing the relationship between the image data D and the printing paper P. In this embodiment, the image data D is set beyond the upper end Pf of the printing paper P to the outside of the printing paper P. Similarly, for the lower edge Pr, the left edge Pa, and the right edge Pb, the image data D is set to extend beyond the edge of the printing paper P to the outside of the printing paper P. Therefore, in the present embodiment, the relationship between the size of the image data D and the printing paper P, and the relationship between the assumed position of the image data D and the arrangement of the printing paper P during printing is as shown in FIG. Note that the left end P
a, the right and left ends Pb of the printer 22
In print paper P, the names of the actual left and right sides and the left and right ends Pa and Pb are reversed.

E. Printing on Left and Right Edges: FIG. 11 is an explanatory diagram showing printing on the left and right edges of the printing paper P. In the present embodiment, printing is performed so that no margin is provided at the left and right ends of the printing paper P throughout the entire recording of the image on the printing paper P, including the upper end processing and the lower end processing. At that time, the print head 2
In the main scanning, at one end, all nozzles are sent to a position beyond the edge of the printing paper P and located outside the printing paper P, and at the other edge, all the nozzles are also printed. The printing paper P over the other end of the paper P
Sent to a location outside of Then, not only when the nozzle Nz is on the printing paper P, but also when the nozzle Nz
Is located beyond the edge of the printing paper P and on the left groove 26a or the right groove 26b, the ink droplets are ejected from the nozzles Nz according to the image data D.

By performing such printing, even when the printing paper P is slightly shifted in the main scanning direction, it is possible to form an image without creating a margin on the left and right ends of the printing paper P. Further, the detection point DP of the photoreflector 33 is located at a connection portion 26d between the left groove 26a and the downstream groove 26r, and if the printing paper P cannot be detected at the detection point DP, the printing is stopped and therefore, the main scanning direction is set. The printing can be performed by arranging the printing paper P at a correct position. Since the nozzles for printing both side edges of the printing paper are the nozzles located on the left groove 26a or the right groove 26b, even when the ink droplets are displaced from the printing paper P, the ink droplets remain at the center of the platen 26. 26c
Without landing on the left groove 26a or the right groove 2
Lands at 6b. Therefore, the central portion 26c of the platen 26
The printing paper P is not stained by the ink droplets that land on the printing paper P.

F. Lower End Processing: FIG. 12 is a plan view showing the relationship between the upstream groove 26f and the printing paper P when printing the lower end Pr of the printing paper P. In the present embodiment, as in the case of the upper end, the image is recorded without margins up to the end of the printing paper P at the lower end. In FIG. 12, the nozzle group Nf of the portion of the print head 28 indicated by oblique lines is the portion where the nozzles for performing the lower end processing are located. An upstream groove 26f is provided below a portion through which the nozzles pass during main scanning. Then, when the lower end Pr of the printing paper P is located at the position indicated by the alternate long and short dash line on the upstream-side groove 26f, printing is performed on the lower end Pr, and then printing is terminated. At this time, some of the nozzles in the nozzle group Nf
Is located upstream in the sub-scanning direction from the lower end (the upper end in FIG. 12).

As in the case of the upper end processing, when the nozzle at the uppermost stream in the sub-scanning direction (hereinafter, this nozzle is referred to as an “upper nozzle”) is located at a position just below the lower end of the printing paper P, the dot at the lower end is Theoretically, the image can be recorded to the entire lower end of the printing paper. However, in this embodiment, when the lower end of the printing paper P is located downstream of the upper end nozzle, printing is performed on the lower end Pr of the printing paper P. Therefore, even when the landing position of the ink droplet on the printing paper is shifted, no margin is generated at the lower end of the printing paper.

FIG. 13 is a side view showing the relationship between the print head 28 and the printing paper P when printing the lower end Pr of the printing paper P. When printing the lower end Pr of the printing paper P,
The lower end Pr of the printing paper P is located on the upstream groove 26f. The printing of the lower end Pr of the printing paper P is performed using the nozzle # 7 just above the lower end Pr and the nozzle # 8 outside the lower end Pr of the printing paper P.
For this reason, the printer 22 of the present embodiment can print an image without making a margin at the lower end Pr of the printing paper P. Further, the printer 22 of this embodiment positions the printing paper P by using the photo reflector 33 when starting printing. For this reason, as long as the sub-scan feed after the start of printing is performed accurately, the printing paper P can be accurately arranged to the nozzles used in the lower end processing.
Further, even when the position of the printing paper is shifted due to an error in the sub-scanning feed, the nozzles # 7 and # 8 are not connected to the upstream groove 2.
6f, the ink droplets fall on the center 2 of the platen 26.
6c will not land.

G. Modifications: The present invention is not limited to the above-described examples and embodiments, and can be carried out in various modes without departing from the gist thereof. For example, the following modifications are also possible. is there.

G1. Modification Example 1 In the above embodiment, one detection unit is provided on the carriage 31. However, the detection unit can be provided in another part of the printer 22. For example, a detection unit may be provided at a position further away from the platen than the space through which the carriage 31 passes in the main scanning, independently of the carriage 31. With such an embodiment, the presence or absence of the printing paper at the detection point can be detected without moving the carriage 31. Further, even when a dimensional error occurs in the position of the carriage in the main scanning, the dimensional error is not affected. Further, a plurality of detection units corresponding to different detection points can be provided. If the detection units are provided on the left groove and the right groove, respectively, even if the printing paper is displaced in any direction of the main scanning direction, it can be detected.

Further, the detection unit may be configured to move on the slide shaft 34 independently of the carriage 31. If the detection unit is moved so that the carriage and the detection unit do not interfere with each other at the time of printing, there is no hindrance at the time of printing. According to this aspect, the height dimension of the printer can be reduced as compared with the aspect in which the detection unit is provided at a position further away from the platen than the carriage 31 described above.

FIG. 14 is a plan view showing the periphery of a platen 26 according to a modification. The detection unit may be provided further downstream in the sub-scanning direction than the position where the carriage 31 reciprocates in the main scanning. Even in such an embodiment, by detecting the print medium by the detection unit (photoreflector 33a), it is possible to accurately position the print medium, record dots, and form an image on the print medium. However, in such an embodiment, when the upper end of the printing paper is arranged on the groove and printing is performed without a margin to the upper end of the printing paper by the nozzle on the groove, the printing paper is directed upstream in the sub-scanning direction. It is necessary to feed the printing paper in the opposite direction from the normal.

On the other hand, it is also possible to adopt a mode in which the detection unit is provided further upstream in the sub-scanning direction than the position where the carriage 31 reciprocates in the main scanning. In such an embodiment, if printing is started after a predetermined amount of sub-scan feed is performed after the detection unit detects the printing paper, if the printing paper is started so that the upper end of the printing medium is at an arbitrary position. Arrange,
Printing can be started. Therefore, after the detection of the printing paper, it is also possible to perform the sub-scanning so that the upper end of the printing paper is located on the groove, and to perform the edge printing with the nozzle on the groove from that state. As described above, if the detection unit is arranged downstream or upstream in the sub-scanning direction from the position where the carriage 31 reciprocates in the main scanning, the object of detecting the position of the print medium with a simple structure is achieved. And the size of the device can be reduced.

G2. Modification 2 In the above embodiment, both the upper end processing and the lower end processing are executed, but only one of them may be executed if necessary. Neither the upper end processing nor the lower end processing may be performed. The printing apparatus according to the present embodiment includes the upstream groove 26f and the downstream groove 26r on the upstream and downstream sides of the platen 26 in the sub-scanning direction, respectively, and includes the left groove 26a and the right groove 26b on the left and right. Any of these may be selectively provided. In such a case, printing at each end of the printing paper P is preferably performed at the end provided with the corresponding groove, and is preferably performed using a nozzle provided on each groove. Alternatively, the printing paper P may be accurately positioned on a platen having no groove, and margins may be provided on four sides to print an image at an accurate position in the printing paper P.

G3. Modification 3 In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced with hardware. You may. For example, the CPU 41
A part of the functions shown in FIG. 3 may be executed by the host computer 90.

A computer program for realizing such functions is provided in a form recorded on a computer-readable recording medium such as a floppy disk or a CD-ROM. The host computer 90 reads the computer program from the recording medium and transfers it to an internal storage device or an external storage device. Alternatively, from the program supply device to the host computer 90 via a communication path.
May be supplied with a computer program. When implementing the functions of a computer program,
The computer program stored in the internal storage device is executed by the microprocessor of the host computer 90. Further, the host computer 90 may directly execute the computer program recorded on the recording medium.

In this specification, the host computer 90 is a concept including a hardware device and an operation system, and means a hardware device that operates under the control of the operation system. The computer program is executed by such a host computer 9.
0 implements the functions of the above-described units. Some of the functions described above may be realized by an operation system instead of the application program.

In the present invention, the “computer-readable recording medium” is not limited to a portable recording medium such as a flexible disk or a CD-ROM, but may be an internal storage such as various RAMs and ROMs. It also includes a device and an external storage device fixed to the computer such as a hard disk.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a structure around a platen of an ink jet printer according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a software configuration of the printing apparatus.

FIG. 3 is a diagram illustrating a configuration of a mechanical part of the printing apparatus.

FIG. 4 is an explanatory diagram showing the structures of a piezo element PE and a nozzle Nz in detail.

FIG. 5 is a plan view showing an example of an arrangement of nozzle units for each color in the print head unit 60.

FIG. 6 is an explanatory diagram showing an electrical configuration of a photo reflector.

FIG. 7 is a plan view showing the periphery of a platen 26;

FIG. 8 is a plan view showing the arrangement of each unit when the printing paper P is first placed on the platen 26 in the inkjet printer.

FIG. 9 is a side view showing the relationship between the print head and the printing paper P at the start of printing.

FIG. 10 is a plan view showing the relationship between image data D and printing paper P.

FIG. 11 is an explanatory diagram illustrating printing on left and right ends of printing paper P.

FIG. 12 is a plan view showing the relationship between the upstream groove 26f and the printing paper P when printing the lower end Pr of the printing paper P.

FIG. 13 is a side view showing the relationship between the print head and the printing paper P when printing the lowermost end of the printing paper.

FIG. 14 is a plan view showing the periphery of a platen 26 according to a modification.

FIG. 15 is a side view showing the periphery of a print head of a conventional printer.

[Explanation of symbols]

 12 scanner 21 CRT 22 printer 23 paper feed motor 24 carriage motor 25a, 25b upstream paper feed roller 25c, 25d downstream paper feed roller 25p, 25q upstream paper feed roller 25r, 25s downstream Side paper feed roller 26 Platen 26a Left groove 26b Right groove 26c Central part 26d Connection part 26f Upstream groove 26o Platen 26r Downstream groove 27 Absorbing member 28 Print head 28o Print head 29a 29b Guide 31 Carriage 32 Operation panel 33, 33a Photoreflector 33d Light emitting diode 33t Phototransistor 34 Sliding shaft 36 Drive belt 38 Pulley 39 Position detection sensor 40 Control circuit 41 CPU 42 PROM 43 ... RAM 44 ... Driver Operation buffer 45 PC interface 60 Print head unit 61-66 Ink ejection head 67 Inlet tube 68 Ink passage 71 Cartridge 72 Color ink cartridge 90 Computer 91 Video driver 95 Application program 96 Printer Driver 97 Resolution conversion module 98 Color correction module 99 Halftone module 100 Rasterizer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41J 13/10 B41J 3/04 101Z 2C480 3F101 F-term (Reference) 2C056 EA16 EB13 EB44 EC07 EC12 EC34 FA04 FA10 HA29 HA33 HA37 JC10 JC15 KD06 2C058 AB15 AC07 AE02 AE09 GB04 GB13 GB31 GB47 2C059 DD07 DD13 DD32 2C087 AC07 CA02 CB02 2C187 AC08 2C480 CA01 CA36 CA40 EC10 3F101 FB00 FC18 LA07 LB03

Claims (10)

[Claims] 1. A dot recording apparatus for recording dots on the surface of a printing medium using a dot recording head provided with a plurality of dot forming elements for discharging ink droplets, wherein A main scanning drive unit that performs main scanning by driving with respect to a head driving unit that drives at least a part of the plurality of dot forming elements to form dots during the main scanning; A sub-scanning drive unit that performs sub-scanning by driving the print medium in a direction that intersects the main scanning direction; a detection unit that detects the presence or absence of the print medium at a predetermined detection point; and controls the units. And a control unit for controlling the scanning, wherein the detection unit is provided at a position that does not intersect with the trajectory of ink droplets ejected from the dot forming element during the main scanning. 2. The dot recording apparatus according to claim 1, wherein the control unit is configured to start the sub-scanning of the print medium from a state where the print medium is not present at the detection point; A function of stopping the sub-scanning of the printing medium at a predetermined sub-scanning position with respect to the sub-scanning direction when the printing medium is detected, and in a state where the printing medium is at the predetermined sub-scanning position, A function of starting the main scanning while discharging ink droplets from a dot forming element. 3. The dot recording apparatus according to claim 1, wherein the detection unit emits light toward the predetermined detection point, and emits light reflected by the print medium. A dot recording device, comprising: 4. The dot recording apparatus according to claim 1, wherein the detection unit is provided so as to be driven integrally with the dot recording head during the main scanning. 5. The dot recording apparatus according to claim 4, wherein the position of the detection unit is the downstream of the dot forming element used for printing in the sub-scanning direction with respect to the sub-scanning direction. The dot recording device is set at a position near the dot forming element located at the side end. 6. The dot recording apparatus according to claim 1, further comprising an extension in the main scanning direction so as to face the dot forming element in at least a part of a path of the main scanning. A platen supporting the print medium, wherein the platen is located at a position facing a dot forming element located at a downstream end in the sub-scanning direction of at least the plurality of dot forming elements, in the main scanning direction. A downstream groove provided in an extended manner, wherein the detection point is a predetermined position within an opening of the downstream groove and within a range in which the dot forming element exists in the sub-scanning direction. Dot recording device, which is the position. 7. The dot recording apparatus according to claim 6, wherein the platen further comprises:
A dot groove is provided at least in a range including a landing range of ink droplets from the dot forming element, and has a side groove connected to the downstream groove.The dot recording apparatus further includes: A guide portion for positioning the printing medium at a predetermined main scanning position in a scanning direction, wherein the predetermined main scanning position is such that the printing medium is moved by the main scanning of the dot recording head with respect to the main scanning direction. And the one side end of the print medium in the main scanning direction is a position located on the opening of the side groove, and the detection point is the side groove and the downstream. A dot recording device which is a predetermined position of a connection portion with a side groove. 8. The dot recording apparatus according to claim 7, wherein the side groove is provided as a pair of a first side groove and a second side groove, and the first side groove is provided in the first side groove. When the printing medium is at the predetermined main scanning position, one side edge of the printing medium in the main scanning direction is the first side groove and the second side groove. A dot recording device, wherein the dot recording device is located on the groove and the other side end is located on the second lateral groove. 9. A dot recording head provided with a plurality of dot forming elements for ejecting ink droplets, and a predetermined detection point provided at a position that does not intersect the trajectory of the ink drops of the dot forming elements during main scanning. A detection unit for detecting the presence or absence of the print medium, wherein a dot recording method using a dot recording apparatus that records dots on the surface of the print medium, wherein (a) the main scanning direction and A sub-scan, which is a scan for driving the recording medium in an intersecting direction, starting from a state where the print medium is not present at the detection point,
(B) stopping the sub-scanning of the printing medium at a predetermined sub-scanning position in the sub-scanning direction when the detection unit detects the printing medium; And starting the main scanning while ejecting ink droplets from the dot forming element in the sub-scanning position. 10. A dot recording head provided with a plurality of dot forming elements for discharging ink droplets, and a predetermined detection point provided at a position that does not intersect with the trajectory of the ink drops of the dot forming elements during main scanning. A detection unit for detecting the presence or absence of the print medium, and a computer program for causing a computer including a dot recording device that records dots on the surface of the print medium to record a dot is recorded. A computer-readable recording medium, a function of starting a sub-scan, which is a scan for driving the recording medium in a direction intersecting with the main scanning direction, from a state where the print medium is not present at the detection point; A function of stopping the sub-scanning of the print medium at a predetermined sub-scanning position with respect to the sub-scanning direction when the unit detects the print medium; In the state where the print medium is at the predetermined sub-scanning position, a computer program for causing the computer to realize the function of starting the main scanning while discharging ink droplets from the dot forming elements is recorded. Computer readable recording medium.