JP2011201021A - Printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine whether printing can be performed or not in accordance with information related to staining of a face to be printed, and to decrease waste of a medium to be printed.SOLUTION: When a printing starting signal is inputted from a PC 70, a printer detects the staining of the face Pa to be printed of a printing paper P by a media sensor before a printing is performed by a recording head, analyzes the information related to the staining by a staining analyzing part, and determines whether the printing on the face Pa to be printed can be performed or not based on the analysis result by a printing possibility determining part.

Description

  The present invention relates to a printing apparatus that performs printing on a printing surface of a printing medium.

  Conventionally, in a printing apparatus such as a printer that prints on a printing surface of a printing medium such as printing paper, a user prints an image or a character on one side instead of a printing medium that is blank on both sides and has no dirt. In some cases, the printing medium that is no longer needed or the blank surface on the opposite side of the printing medium on which misprints such as images and characters are printed may be used as the printing surface. When the print medium is stored, the print medium may be stored such that the surface on which the misprint is printed is the print surface. Further, when the printing medium is stored in the paper feed tray, the printing surface may be stained unexpectedly, and the printing medium with a dirty printing surface may be stored without noticing that fact.

  As described above, Patent Document 1 discloses that the printing surface of the printing medium can be detected when the printing surface of the printing medium is dirty as described above. A printing apparatus having a sensor is disclosed, and the printing apparatus detects a stain on a printing surface of a printing medium by a sensor before printing is performed, and stops printing when the dirt is detected. Yes.

JP-A-9-188015 (FIG. 2)

  However, in the printing apparatus of Patent Document 1, printing is stopped even if the stain on the printing surface of the print medium is a slight stain that does not affect the image or characters to be printed, resulting in printing. Printing on a possible print medium is not performed, and the print medium is wasted.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a printing apparatus that can determine whether printing is possible or not according to information on stains on a printing surface, and can reduce waste of a printing medium with reference to this determination.

  The printing apparatus of the present invention includes a printing unit that prints on a printing surface of a printing medium, a stain detection unit that detects information on the stain on the printing surface before printing by the printing unit, and the stain detection Printing enable / disable determining means for determining whether or not printing on the printing surface is possible based on information on the stain on the printing surface detected by the means.

  According to the printing apparatus of the present invention, the printing surface of the print medium is dirty enough to cause troubles such as difficulty in seeing printed images and characters even if printing is performed, or printing is performed even if printing is performed. It is possible to determine whether or not printing is possible, as well as determining whether the print surface has such a slight stain that does not cause problems such as difficulty in seeing the printed image or characters. In this way, even if the print surface is soiled, it is possible to print on the print surface if there are few problems after judging how much this stain affects the image or characters to be printed. It can be judged. Therefore, waste of the printing medium can be reduced with reference to this determination.

  The printing control unit further controls the printing unit, and the printing control unit causes the printing unit to print on the printing surface when the printing availability determination unit determines that printing is possible. Is preferred. According to this, it is possible to automatically print on the printing surface when there are few troubles after determining how much dirt affects the image or characters to be printed.

  Furthermore, it is preferable that the stain detection unit detects a stain position on the printing surface. According to this, by detecting the position of the stain on the printing surface, it is possible to determine how much the stain affects the printed image or characters.

  At this time, it is preferable that the printing availability determination unit determines that printing is possible when the position of the stain on the printing surface is outside a predetermined area. According to this, even if the printing surface is dirty, if the printing surface is outside the specified area that greatly affects the image or characters to be printed, the printing surface will be stained even if it is printed. Does not significantly affect the image or characters to be printed.

  The predetermined area is preferably a print area printed by the printing unit. According to this, even if the printing surface is dirty, the position of the printing surface is outside the printing area, and there is no area where the printing image or characters overlap with the dirt. Even if it performs, a stain | pollution | contamination does not have a direct influence on the image or character which is printed.

  Further, the stain detection means may detect the size of the stain on the printing surface. According to this, by detecting the size of the stain on the printing surface, it is possible to determine how much the stain affects the image or characters to be printed.

  At this time, it is preferable that the printing availability determination unit determines that printing is possible when the size of the stain on the printing surface is less than a predetermined size. According to this, even if there is a stain on the printed surface, if the size of the printed surface is small, even if printing is performed on the printed surface with the stain, the stain will greatly affect the image or characters to be printed. There is nothing.

  Further, the print control means detects that the stain position of the printing surface is within the print area of the print data printed by the printing means by the stain detection means, and prints by the print availability determination means. When it is determined that it is possible, the printing unit is controlled to correct the input print data in accordance with the dirt on the print surface, and printing is performed on the print surface based on the corrected print data. Is preferably performed. According to this, the print data is corrected so as to clarify the difference between the image and characters that overlap with the stain when printed, according to the stain on the printing surface, and overlaps with the stain when printed. Printing can be performed while making it easy to see images and characters and reducing the influence of dirt on the printed images and characters.

  Even if the print surface is soiled, it can be determined whether printing is possible based on how much this stain affects the printed image or characters. Since printing can be performed, waste of the printing medium can be reduced.

1 is a schematic perspective view of a printer according to an embodiment. 2 is a schematic plan view of the inside of the printer main body. FIG. 2 is a block diagram illustrating an electrical configuration of a printer. FIG. 6 is a flowchart from printing start to printing end. It is a figure explaining the analysis method of the stain | pollution | contamination of a printing surface, (a) is a case where a stain | pollution | contamination is linear, (b) is a case where a stain | pollution | contamination is a lump. It is a top view of the printing surface for demonstrating the judgment of the propriety of printing according to the position of dirt. 4A and 4B are plan views of a printing surface for explaining determination of whether or not printing is possible according to the size of a stain. FIG. 5A is a case where the print data is one image, and FIG. Is the case. It is a block diagram which shows the electric constitution of the printer in a modification. It is a top view of the printing surface for demonstrating the example of a change of the printing data according to the shape of dirt. It is a top view of the printing surface for demonstrating changing a printing area | region according to the position of dirt. It is a top view of the printing surface for demonstrating the example of a change of the printing data according to the color of dirt.

  Next, an embodiment of the present invention will be described. FIG. 1 is a schematic perspective view of the printer according to the present embodiment. FIG. 2 is a schematic plan view of the inside of the printer body.

  As shown in FIGS. 1 and 2, a printer 1 (recording apparatus) is mounted on a carriage 2 configured to be reciprocally movable along a predetermined scanning direction (left and right direction in FIG. 2), and the carriage 2. A recording head 3 (printing means) for printing on the printing paper P (printing medium), a paper feeding mechanism 4 for feeding the printing paper P in a paper feeding direction (vertical direction in FIG. 2) perpendicular to the scanning direction, and paper feeding A media sensor 5 that detects the paper width of the printing paper P conveyed by the mechanism 4 and a control device 50 (see FIG. 3) that controls the entire printer 1 are provided.

  The printer 1 has a substantially rectangular parallelepiped printer body 6 in which a carriage 2, a recording head 3, a paper feed mechanism 4, a media sensor 5, a control device 50, and the like are accommodated.

  A part of the lower half of the printer main body 6 is opened forward, and a paper feed tray 7 for storing the printing paper P and a printing paper P on which images, characters, and the like are recorded are provided in the opened portion. A paper discharge tray 8 to be discharged is provided. The printing paper P in the paper feed tray 7 is transported to the recording head 3 in the printer main body 6 by a transport roller (not shown) that is rotationally driven by a motor, and images, characters, and the like are recorded by the recording head 3. After that, it is discharged to the front discharge tray 8.

  The carriage 2 is configured to be able to reciprocate along two guide shafts 17 extending in parallel with the scanning direction (left-right direction in FIG. 2). An endless belt 18 is connected to the carriage 2, and when the endless belt 18 is driven to travel by the carriage drive motor 19, the carriage 2 moves in the scanning direction as the endless belt 18 travels. It has become.

  The printer 1 is provided with a linear encoder 10 having a large number of light transmitting portions (slits) arranged at intervals in the scanning direction. On the other hand, the carriage 2 is provided with a transmission type position detection sensor 11 having a light emitting element and a light receiving element. The printer 1 can recognize the current position in the scanning direction of the carriage 2 from the count value (number of detections) of the light transmitting portion of the linear encoder 10 detected by the position detection sensor 11 while the carriage 2 is moving. Yes.

  A recording head 3 is mounted on the lower surface of the carriage 2. The recording head 3 reciprocates in the scanning direction integrally with the carriage 2 and prints on the printing paper P. As the recording head 3, one that performs printing on the printing paper P by a known method such as an ink jet method, a laser method, or a thermal transfer method is used.

  A reflective media sensor 5 having a light emitting element and a light receiving element is mounted on the side surface of the carriage 2. The media sensor 5 detects the paper width of the printing paper P according to whether or not the light emitted from the light emitting element is received by the light receiving element while reciprocating in the scanning direction integrally with the carriage 2. In addition, the media sensor 5 prints on the printing paper P that is emitted from the light emitting element while being reciprocated in the scanning direction integrally with the carriage 2 and is conveyed downward (paper feeding direction) in FIG. 2 by the paper feeding mechanism 4. The stain on the printing surface Pa can also be detected from the reflectance of the light reflected by the surface Pa when the light receiving element receives the light.

  The paper feed mechanism 4 includes a first feed roller 12 disposed upstream of the recording head 3 in the paper feed direction, and a second feed roller 13 disposed downstream of the recording head 3 in the paper feed direction. is doing. The first feed roller 12 and the second feed roller 13 are rotationally driven by a first feed motor 14 and a second feed motor 15, respectively. The paper feeding mechanism 4 feeds the printing paper P from the upper side of FIG. 2 toward the recording head 3 by the first feeding roller 12, and images, characters, etc. are sent by the recording head 3 by the second feeding roller 13. The recorded printing paper P is sent downward in FIG.

  Next, the electrical configuration of the printer 1 centering on the control device 50 will be described with reference to the block diagram of FIG. The control device 50 of the printer 1 shown in FIG. 3 includes a central processing unit (CPU) and a ROM (Read Only Memory) in which various programs and data for controlling the overall operation of the printer 1 are stored. ) And RAM (Random Access Memory) that temporarily stores data processed by the CPU.

  As shown in FIG. 3, the control device 50 includes a head control unit 51, a carriage control unit 52, a paper feed control unit 53, a stain analysis unit 54, and a printability determination unit 55. . The functions of the head control unit 51, carriage control unit 52, paper feed control unit 53, stain analysis unit 54, and printability determination unit 55 are executed by the CPU with various control programs stored in the ROM of the control device 50. Is realized. Note that the dirt analysis unit 54 and the media sensor 5 in the present embodiment correspond to the dirt detection means in the present invention.

  The head control unit 51 controls the recording head 3 based on the print data input from the PC 70 and the print enable signal input from the print availability determination unit 55, and prints on the printing paper P on the recording head 3. Let it be done.

  The carriage control unit 52 controls the carriage drive motor 19 based on the stain detection start signal or the printable signal input from the printability determination unit 55 to reciprocate the carriage 2 in the scanning direction. The media sensor 5 is scanned back and forth.

  The paper feed control unit 53 controls the first feed motor 14 and the second feed motor 15 of the paper feed mechanism 4 on the basis of the stain detection start signal or the print enable signal input from the printability determination unit 55, and The printing paper P is fed in the paper feeding direction by the first feeding roller 12 and the second feeding roller 13.

  In the printer 1 of the present embodiment, during the printing operation, the head control unit 51 controls the recording head 3 and the carriage control unit 52 controls the carriage drive motor 19 to perform printing while moving the recording head 3 in the scanning direction. An operation of performing printing on the printing surface Pa of the paper P, and an operation of the paper feed control unit 53 controlling the first feed motor 14 and the second feed motor 15 to feed the print paper P by a predetermined amount in the paper feed direction. By repeating alternately, a desired image, character, or the like is printed on the printing surface Pa of the printing paper P.

  Here, the user prints printing paper P that is no longer necessary after printing images or characters on one side, or printing misprints such as images or characters on one side, instead of printing paper P that is blank on both sides and has no stains. The white paper surface on the opposite side of the printed paper P may be used as the printing surface Pa. However, the printing paper is stored in the paper feed tray 7 that stores the printing paper P that is fed through the lower surface of the recording head 3 by the paper feed mechanism 4. When storing P, the printing paper P may be stored such that the surface on which an image, characters, or the like is printed is the printing surface Pa. Further, when the printing paper P is stored in the paper feed tray 7, the printing surface Pa may be stained unexpectedly, and the printing paper P with the dirty printing surface Pa may be stored without noticing that fact. .

  If the printing operation is performed as it is, printing is performed on the dirty printing surface Pa of the printing paper P. At this time, if the print surface Pa is very dirty, the stain may affect the printed image or characters, which may cause problems such as difficulty in viewing the printed image or characters. If the surface Pa is lightly soiled, the soiled image does not affect the printed image or character, and the printed image or character may be difficult to see. As described above, even if the printing surface Pa of the printing paper P is dirty and printing is performed on the dirty printing surface Pa, the printing does not necessarily affect the printed image or characters. .

  Therefore, in the present embodiment, the control device 50 includes a stain analysis unit 54 and a print availability determination unit 55 in addition to the head control unit 51, the carriage control unit 52, and the paper feed control unit 53, and print paper. Based on the information regarding the stain on the P printing surface Pa, it is determined whether or not printing on the printing surface Pa is possible.

  The stain analysis unit 54 analyzes information related to stains on the printing surface Pa based on the reading result obtained by the media sensor 5 reading the entire printing surface Pa of the printing paper P conveyed in the paper feeding direction, and the analysis result is obtained. This is sent to the printability determination unit 55.

  When a print start signal is input from the PC 70, the printability determination unit 55 sends a stain detection start signal to the carriage control unit 52 and the paper feed control unit 53. Then, the operation of moving the carriage 2 in the scanning direction by the carriage control unit 52 and the operation of transporting the printing paper P by a predetermined amount in the paper feeding direction by the paper feeding control unit 53 are alternately repeated. The moving media sensor 5 reads the entire printing surface Pa of the printing paper P conveyed in the paper feeding direction, and detects the stain on the printing surface Pa of the printing paper P. Then, the printability determination unit 55 determines whether printing can be performed on the analyzed printing surface Pa based on the analysis result by the stain analysis unit 54. When the printability determination unit 55 determines that printing on the print surface Pa is impossible because the stain on the print surface Pa greatly affects the image or character to be printed, the print control signal is transmitted to the head control. The data is sent to the section 51, the carriage control section 52 and the paper feed control section 53.

  Similarly, based on the analysis result by the stain analysis unit 54, the printability determination unit 55 has no stain on the analyzed print surface Pa, or the stain on the analysis print surface Pa is an image or character to be printed. Therefore, when it is determined that printing on the printing surface Pa is possible, a printable signal is sent to the head control unit 51, the carriage control unit 52, and the paper feed control unit 53.

  The operation of the printer 1 from the start of printing to the end of printing will be described below with reference to FIG. 4 before describing the smear detection method and the printability determination criteria. As shown in FIG. 4, first, when a print start signal is input from the PC 70 (S <b> 1), the printer 1 cleans the entire printing surface Pa of the printing paper P fed from the paper feed tray 7 with the media sensor 5. In addition, if the stain analysis unit 54 detects the presence or absence of stains and stains, analysis of information regarding the stains is started (S2), and the analysis result is sent to the printability determination unit 55. At this time, the printing paper P sent in the paper feeding direction by the paper feeding mechanism 4 at the time of detecting the dirt is sandwiched between the second feeding roller 13 and a driven roller (not shown) at the rear end by the control of the paper feeding control unit 53. Stopped without being discharged.

  Then, the printability determination unit 55 determines whether or not the print surface Pa is dirty (S3). If it is determined that the print surface Pa is not dirty (S3: No), the print enable signal is sent to the head. It is sent to the control unit 51, the carriage control unit 52, and the paper feed control unit 53.

  Then, the second feed motor 15 is controlled by the paper feed control unit 53, and the printing paper P that has been stopped while the rear end is sandwiched between the second feed rollers 13 is fed in the direction opposite to the paper feed direction, and the leading end thereof is It moves to a position sandwiched between the first feed rollers 12. Then, the above-described printing operation is performed on the printing surface Pa of the printing paper P, a desired image or character is printed on the printing surface Pa (S4), and the printed printing paper P is discharged to the paper discharge tray 8. (S5).

  Further, when the printability determination unit 55 determines that the print surface Pa is dirty (S3: Yes), the printability determination unit 55 performs the printing based on the analysis result sent from the stain analysis unit 54. It is determined whether printing on the surface Pa is possible (S6). When the printability determination unit 55 determines that printing is possible (S6: Yes), a printable signal is sent to the head control unit 51, carriage control unit 52, and paper feed control unit 53.

  Then, the second feed motor 15 is controlled by the paper feed control unit 53, and the printing paper P that has been stopped while the rear end is sandwiched between the second feed rollers 13 is fed in the direction opposite to the paper feed direction, and the leading end thereof is It moves to a position sandwiched between the first feed rollers 12. Then, the above-described printing operation is performed on the printing surface Pa of the printing paper P, a desired image or character is printed on the printing surface Pa (S4), and the printed printing paper P is discharged to the paper discharge tray 8. (S5).

  If the printability determination unit 55 determines that printing is not possible (S6: Yes), a print disable signal is sent to the head control unit 51, carriage control unit 52, and paper feed control unit 53. Then, the head control unit 51 keeps the ejection operation of the recording head 3 stopped, and the carriage control unit 52 keeps the movement of the carriage 2 stopped, and keeps the printing operation temporarily stopped. Then, the printing paper P that has been stopped by the paper feed control unit 53 having its rear end held between the second feed rollers 13 is discharged to the paper discharge tray 8. Thereafter, a new printing paper P is fed from the paper feed tray 7, and the above-described stain detection and analysis are performed on the printing surface Pa of the printing paper P.

  Next, a method for detecting a stain on the printing surface Pa will be specifically described. The carriage 2 is moved in the scanning direction, and the media sensor 5 is scanned in the scanning direction integrally with the carriage 2. Then, when the media sensor 5 is not opposed to the printing paper P, the light emitted from the light emitting element is not received by the light receiving element, but when the media sensor 5 is opposed to the printing paper P, the light emitted from the light emitting element is emitted from the printing paper P. Is reflected by the printing surface Pa, and the reflected light is received by the light receiving element. The media sensor 5 detects the presence / absence of the printing paper P and the paper width from the presence / absence of light received by such a light receiving element.

  When the media sensor 5 faces the printing surface Pa of the printing paper P and the facing area is a blank area, the media sensor 5 has a high light reflectance and outputs a high output value. Further, the media sensor 5 is opposed to the printing surface Pa of the printing paper P, and when the facing area is dirty, the light reflectance is lower than that of the blank area and outputs a low output value. . The media sensor 5 scans the carriage 2 in the scanning direction, and the paper feeding mechanism 4 conveys the printing paper P in the paper feeding direction, so that the light receiving element as described above for the entire printing surface Pa of the printing paper P is obtained. Are output to the dirt analysis unit 54. In this way, the media sensor 5 can detect the presence or absence of the printing surface Pa of the printing paper P after detecting the presence or absence of the printing paper P.

  Then, the stain analysis unit 54 detects the position of the stain in the scanning direction of the printing surface Pa from which the low output value is output by the media sensor 5, and the position detection sensor 11 at the timing when the stain is detected by the media sensor 5. It is possible to analyze from the count value of the linear encoder 10. Further, the stain analysis unit 54 can analyze the position of the stain in the paper feed direction of the printing surface Pa from the transport amount of the print paper P by the paper feed mechanism 4 until the scan time when the media sensor 5 detects the stain. . In this manner, the stain analysis unit 54 can analyze the planar position of the stain with respect to the printing surface Pa.

  Further, as the time during which the media sensor 5 outputs a low output value becomes longer, the dirt analysis unit 54 increases the count value of the linear encoder 10 detected by the position detection sensor 11 at that time, and the dirt in the scanning direction becomes dirty. If it is large, it can be analyzed. Further, the stain analysis unit 54 can analyze that the stain is large in the paper feed direction when the area where the media sensor 5 outputs a low output value is continuous in the paper feed direction. In this way, the stain analysis unit 54 can analyze the planar size of the stain with respect to the printing surface Pa.

  In addition, when the area where the media sensor 5 outputs a low output value is continuous with respect to the scanning direction and the paper feed direction, the dirt analysis unit 54 is configured such that the dirt is linear or It is possible to analyze the shape of dirt such as a lump. As described above, the stain analysis unit 54 can analyze the information about the stain such as the shape, size, and position of the stain on the printing surface Pa based on the detection result of the media sensor 5.

  Specifically, for example, as shown in FIG. 5A, when there is a linear stain in the central area of the printing surface Pa, the stain analysis unit 54 relates to the paper feed direction by the media sensor 5 (1). In the scanning up to the position), since the printing surface Pa is not stained, a high output value is detected in the entire scanning direction. Then, in the scanning from (2) to (4) by the media sensor 5, the stain analysis unit 54 detects a low output value in a dirty region for a short time after detecting a high output value at first. Detect high output values. At this time, the position of the printing surface Pa in the scanning direction when the stain analysis unit 54 detects a low output value is gradually shifted to one side in the scanning direction. Next, in the scan after the position (5) in the paper feed direction by the media sensor 5, the stain analysis unit 54 detects a high output value in the entire scan direction because there is no stain on the print surface Pa.

  From this point, the stain analysis unit 54 is slightly shifted in position in the scanning direction on the printing surface Pa of the printing paper P shown in FIG. 5A by the scanning from (2) to (4) by the media sensor 5. Since it is detected that there is a very short stain and the detected stain is at the center of the printing surface Pa, it is analyzed that there is a linear stain formed obliquely at the center of the printing surface Pa.

  Further, for example, as shown in FIG. 5B, when there is a blocky stain in the central area of the printing surface Pa, the stain analysis unit 54 reaches the position (1) regarding the paper feed direction by the media sensor 5. In this scanning, since the printing surface Pa is not soiled, a high output value is detected in the entire scanning direction. And in the scanning from (2) to (4) by the media sensor 5, the stain analysis unit 54 detects a low output value at different times after detecting a high output value at the beginning, Subsequently, a high output value is detected. At this time, the time for detecting a low output value during the scanning in (3) is longer than in the scanning in (2) and (4) by the media sensor 5. Next, in the scan after the position (5) in the paper feed direction by the media sensor 5, the stain analysis unit 54 detects a high output value in the entire scan direction because there is no stain on the print surface Pa.

  From this, the stain analysis unit 54 has a certain width in the scanning direction on the printing surface Pa of the printing paper P shown in FIG. 5B by the scanning from (2) to (4) by the media sensor 5. Since the presence of dirt is detected and the detected dirt is in the center of the printing surface Pa, it is analyzed that there is a blocky dirt in the center of the printing surface Pa.

  Various criteria are conceivable for the criteria for determining whether or not the printing is possible based on the analysis result by the stain analysis unit 54. Several criteria will be described below. For example, as a criterion for judgment, there is a criterion for making a judgment based on only the information about the stain on the printing surface Pa and not considering the influence of the stain on the printed image or character according to the print data. In addition, there is a criterion for determining in consideration of how much the information regarding the stain affects the printed image or character according to the print data.

  1) First, as an example of determining from the position of the stain on the print surface Pa, it is assumed that the stain analysis unit 54 has analyzed that the stain 80 exists in the central region 74 of the print surface Pa as shown in FIG. At this time, if one image is printed on the entire printing surface Pa, a highly important object (a subject in the case of a photograph) is arranged in the central area 74 of the image, and around the central area 74 Those having a lower importance (such as the background) than the central region 74 are arranged. At this time, if there is a stain in the printed area with the high importance, the printed image will have a large effect, but even if there is a stain in the printed area with the low importance, the printed image The effect on is not so great. Accordingly, the printability determination unit 55 determines that printing is not possible when the dirt 80 is present in the central area 74 of the printing surface Pa, and determines that printing is possible when the dirt 81 is present outside the central area 74. .

  Further, as shown in FIG. 6, it is assumed that the stain analysis unit 54 has analyzed that the print data on the printing surface Pa is outside the print area 73 where the print data 73 is actually printed. At this time, since the stain 82 is outside the print area 73 of the printing surface Pa, even if printing data is printed on the printing surface Pa, the printed image does not overlap with the printed image, and the printed image itself Dirt does not directly affect Therefore, the printability determination unit 55 determines that printing is not possible when there is a stain 80 (or stain 81) in the print area 73 of the print surface Pa, and when there is a stain 82 outside the print area 73, It may be determined that printing is possible.

  Here, the print area 73 is an area where images, characters, and the like are actually printed, and indicates a different area for each print data. However, a printable area based on margin information that does not differ depending on the print data. It may be.

  The area for determining whether printing is possible is not limited to the central area 74 or the printing area 73 of the printing surface Pa, and may be an arbitrary area. For example, when two images are printed side by side on the printing surface Pa, it is sufficient that the two specific regions overlapping the two images are printed without any trouble such as it is difficult to see the central region 74. The printability determination unit 55 determines that printing is not possible on the printing surface Pa when there is dirt in the specific area, and determines that printing is possible when there is dirt outside the specific area.

  Further, the case where an image is printed has been described as an example of determining whether printing is possible from the position of the stain on the printing surface Pa. However, the image is not limited to an image as long as it is a target to be printed on the printing surface Pa, such as characters.

  2) As an example of judging from the size of the stain on the print surface Pa, as shown in FIG. 7A, the stain analysis unit 54 analyzes that there is a relatively large dirt 83 in the print surface Pa. Suppose. At this time, if one image 75 is to be printed over the entire printing surface Pa, the size of the stain 83 is very small with respect to the size of the image 75, and thus the influence on the printed image is not so great. . However, when a plurality of small images 76 such as thumbnails are printed on the printing surface Pa, the size of the stain 83 is larger than the size of one image 76, so that the printed image 76 is mostly dirty. It is very difficult to see and has a great effect on the printed image.

  Therefore, when the print surface Pa has the stain 83, the printability determination unit 55 compares the size of the stain 83 with the size of one image of the print data, and the size of the stain with respect to the size of one image. It is determined that printing is not possible when the ratio is greater than or equal to a predetermined ratio, and it is determined that printing is possible when it is less than the predetermined ratio.

  The comparison target of the print data with the size of the stain is not limited to the image, and may be anything such as a character. In the case of characters, if the size of the stain is greater than or equal to the specified size, the character will be crushed and become difficult to see. Since the character can be recognized even if it becomes a little difficult to see, it is determined that printing is possible.

  Further, the size of the stain determines the value of a certain area without comparing it with the size of the image or character, and the printability determination unit 55 determines that printing is not possible when the size of the stain is equal to or greater than that value. If it is less than that value, it may be determined that printing is possible. Regardless of the print data, if the dirt is large, the effect on the printed image or character will naturally increase, and if it is small, the effect on the printed image or character will decrease. What is necessary is just to determine the value suitably from brazing.

  3) As an example of judging from the shape of the stain on the print surface Pa, it is assumed that the stain analysis unit 54 has analyzed that the print surface Pa has a linear stain. At this time, even if the print data is printed on the printing surface Pa having linear stains, the images and characters are hardly made difficult to see only by the linear stains, and the influence on the printed images and characters is not so much. not big. However, it is assumed that the dirt analysis unit 54 has analyzed that the printing surface Pa has a blocky dirt. At this time, if the print data is printed on the printing surface Pa having the blocky stain, it is extremely difficult to see an image or a character that overlaps the blocky stain, and the influence on the printed image or the character is great. Therefore, the printability determination unit 55 determines that printing is not possible when the stain on the printing surface Pa is in a lump shape, and determines that printing is possible when the stain on the printing surface Pa is linear. When the thickness of the line increases, even if the stain is linear, it is difficult to see images and characters that overlap the linear stain. Therefore, the thickness of the line may be determined as appropriate according to the print data, and the line-shaped stain thicker than the thickness may be processed in the same manner as that for the block-like stain.

  Note that, as described above, not only the printability can be determined from any one of the shape, size, and position of the stain on the printing surface Pa, but also by combining the shape, size, and position of the stain on the printing surface Pa, Whether or not the data overlapping the dirt of the print data is an image or a character, and the size of the image or character may be taken into consideration to determine whether or not printing on the printing surface Pa is possible.

  According to the printer 1 described above, the printing surface Pa of the printing paper P is severely soiled so as to cause troubles such as difficulty in seeing printed images and characters even after printing, or the printing paper P It is possible to determine whether or not printing is possible on the printing surface Pa of the printing surface Pa so as not to cause troubles such as difficulty in seeing images or characters to be printed. it can. If it is determined that printing is possible, printing can be performed on the printing surface Pa of the printing paper P. In this way, even if the printing surface Pa is soiled, it is possible to perform printing on the printing surface Pa if there is little trouble after determining how much the stain affects the image or characters to be printed. This makes it possible to reduce the waste of the printing paper P.

  Further, when the printing surface Pa of a certain printing paper P conveyed by the paper feeding mechanism 4 is soiled and the printing availability determination unit 55 determines that printing is impossible, the printing paper P is discharged to the paper discharge tray 8. When a new printing paper P is fed from the paper feed tray 7, a stain is detected on the printing paper P, and whether or not printing is possible is determined by the printability determination unit 55 according to the information regarding the stain. Since the printing operation is performed, the printing operation does not stop even if the printing papers P that cannot be printed are mixed among the plurality of printing papers P to be fed, so that the user does not intervene. Printing can be continued automatically.

  Further, by analyzing the shape, size, and position as information about the stain on the printing surface Pa by the stain analysis unit 54, the printability determination unit 55 uses the analysis result to print images, characters, etc. It is possible to judge appropriately how much it affects.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, the same reference numerals are given to those having the same configuration as in the above embodiment, and the description thereof is omitted as appropriate.

  In the embodiment described above, the printability determination unit 55 determines whether or not to print on the printing surface Pa based on the shape, size, and position of the stain, and prints images and characters that are printed without correcting the print data. The effect of stains on the printed images and characters was corrected by correcting the print data when printing was judged to be possible because the effect of stains on the image was small. The printing may be performed with less.

  When correcting the print data in this way, as shown in FIG. 8, the control device 50 of the printer 1 includes a head control unit 51, a carriage control unit 52, a paper feed control unit 53, a stain analysis unit 54, and printability. In addition to the determination unit 55, a print data correction unit 56 is provided.

  The print data correction unit 56 corrects the print data input from the PC 70 so that the influence of dirt on the image or characters to be printed is reduced, and sends the corrected print data to the head control unit 51. .

  The operation of the printer 1 from the start of printing to the end of printing at this time is a step of correcting print data after it is determined that printing is possible by the printability determination unit 55 in the flowchart shown in FIG. 4 (S6: Yes). The printing operation is performed based on the corrected print data (S4).

  In the following, an example of correcting print data that reduces the influence of dirt on printed images and characters will be described.

  a) For example, as shown in FIG. 9, when it is analyzed by the stain analysis unit 54 that there is a linear stain 84 in the print area 77 where the print data of the printing surface Pa is printed, the print propriety determination unit 55 is a print including information indicating that printing is possible when the print data to be printed in the area overlapping the linear stain 84 is a character, and that the character overlapping the stain 84 is thickened (the density is increased). An enable signal is sent to the print data correction unit 56. Then, the print data correction unit 56 corrects the print data based on this information, and sends the corrected print data to the head control unit 51. Then, the head control unit 51 prints a desired character on the printing surface Pa by thickening the character that overlaps the stain 84 (increasing the density) based on the corrected print data. As a result, even if characters are printed over the area with the dirt on the printing surface Pa, since the letters are thickened, the difference between the dirt and the letters that overlap with the dirt when printed is clarified, and printing is performed. Printing can be performed with less influence of smudges on the printed characters.

  b) Also, as shown in FIG. 10, when it is analyzed by the stain analysis unit 54 that there is a stain 85 in the print region 78 where the print data of the printing surface Pa is printed, the print availability determination unit 55 By comparing the size of the print area Pa with no dirt 85 and the size of the print data print area 78, it is determined that printing is possible when the area of the print face Pa without the dirt 85 is larger. Then, a printable signal including information indicating that the position of the print area 78 for printing the print data on the print surface Pa is shifted is sent to the print data correction unit 56. Then, the print data correction unit 56 corrects the print data based on this information, and sends the corrected print data to the head control unit 51. Then, the head control unit 51 shifts the position of the print area 78 based on the corrected print data, and prints a desired image or character on the print surface Pa. As a result, there is no area where the stain on the printing surface Pa overlaps with the image or characters to be printed, so even if printing is performed on the printing surface Pa with this stain, the image or characters on which the stain is printed are directly affected. There is nothing.

  Further, when the size of the empty area without the stain 85 on the printing surface Pa is smaller than the print area 78 of the print data, for example, a highly important one is arranged in the central area of the image, and the periphery of the central area is In the case where an object having a lower importance than the central area is arranged, the position may be shifted with respect to the print area 78 so that the stain 85 is at the end, and printing may be performed on the printing surface Pa. Good. As a result, the stain on the printing surface Pa is shifted from a position that greatly affects the image to be printed, and printing can be performed with less influence of the stain on the printed image.

  c) Further, when it is analyzed by the stain analysis unit 54 that there is a stain 85 in or near the end within the print region 78 where the print data of the printing surface Pa is printed, the printability determination unit 55 Determines that printing is possible, thins out dot information of the print data at predetermined intervals in the scanning direction and the paper feed direction, and corrects the printable signal including information indicating that printing is performed in a clean area on the printing surface Pa. Send to part 56. Then, the print data correction unit 56 corrects the print data based on this information, and sends the corrected print data to the head control unit 51. Then, the head control unit 51 prints a desired image, character, or the like that is reduced on the printing surface Pa avoiding the position of the stain, based on the corrected print data. As a result, there is no area where the stain on the printing surface Pa overlaps with the image or characters to be printed, so even if printing is performed on the printing surface Pa with this stain, the image or characters on which the stain is printed are directly affected. There is nothing.

  In this embodiment, the media sensor 5 detects the presence / absence of a stain on the entire printing surface Pa, and the stain analysis unit 54 analyzes the shape, size, or position of the stain as information on the stain on the printing surface Pa. However, it is also possible to detect the color of the stain, analyze the information about the stain including the color by the stain analysis unit 54, and determine whether the print is possible or not by the print availability determination unit 55. At this time, since it is difficult for the media sensor 5 to detect even the stain color, an image sensor capable of separately detecting the color such as a scanner is required. Then, instead of providing the media sensor 5 and the image sensor, only the image sensor may be provided, and this image sensor may detect information on all the stains.

  In the following, an example of printability determination according to the stain color will be described.

  A) For example, it is assumed that the stain analysis unit 54 has analyzed that the print surface Pa has yellow stains. At this time, the printability determination unit 55 uses data that overlaps dirt on the print data printed on the printing surface Pa as characters, and has a color that has a strong contrast with yellow and has no problem with character recognition. In some cases, it is determined that printing is possible, and when the color of the character is a color whose contrast is weaker than that of yellow and the character is difficult to recognize, it is determined that printing is not possible.

  B) Further, as shown in FIG. 11, when the stain analyzing unit 54 analyzes that the black stain 86 exists in the print area 79 where the print data of the printing surface Pa is printed, the print propriety judging unit 55 Includes information indicating that printing is possible when the data overlapping the stain 86 of the print data printed on the printing surface Pa is a character, and that the character has a strong contrast with the color of the stain 86. A printable signal is sent to the print data correction unit 56. Then, the print data correction unit 56 corrects the print data based on this information, and sends the corrected print data to the head control unit 51. Then, based on the corrected print data, the head control unit 51 prints a desired character on the printing surface Pa so that the character that overlaps the stain 86 becomes a color with a strong contrast with black (for example, white). As a result, even if a character is printed in an overlapping area on the printing surface Pa, the character has a strong contrast with the color of the stain, and the character that overlaps with the stain when printed with the stain Thus, printing can be performed with less influence of smudges on printed characters.

  Further, in the present embodiment, the determination of whether or not printing is possible based on the information about one stain on the printing surface Pa has been described. However, as information about the stain, the number of stains on the printing surface Pa is analyzed, and the printability determination unit 55 performs the analysis. It may be determined whether printing is possible. For example, the printability determination unit 55 determines that printing is possible when the number of stains is less than a predetermined number, and determines that printing is not possible when the number is greater than the predetermined number. At this time, whether or not printing is possible may be determined not by the number of stains in the entire printing surface Pa but by the number of stains in a specific region that greatly affects printed images or characters if there is a stain in the central region or the like.

  Further, in the present embodiment, the media sensor 5 that detects the stain on only one point of the printing surface Pa is used. However, the media sensor 5 extends in the scanning direction upstream of the first feeding roller 12 in the paper feeding direction, and the printing surface Pa. A line sensor capable of reading the entire scanning direction may be used.

  Further, in the present embodiment, the information regarding the stain on the printing surface Pa of the printing paper P is always analyzed before the printing operation. However, the printing surface Pa is surely blank with no stain, or is dirty. If it is acceptable to print on the printing surface Pa, the analysis is not performed. The information on the stain is analyzed only when the user needs it, and the information on the stain is analyzed at other times. You may print without performing. As a result, printing can be performed quickly.

  Further, in order to quickly detect dirt, the conveyance amount of the printing paper P by the paper feeding mechanism 4 is increased, and the media sensor 5 detects the dirt at discrete intervals in the paper feeding direction of the printing paper P. It is also possible to detect the dirt at short intervals in the paper feed direction by reducing the conveyance amount from the time when the media sensor 5 finds the dirt.

  In the present embodiment, the printability determination unit 55 determines whether or not printing is possible, and if printing is possible, printing is automatically performed on the printing surface Pa of the printing paper P. After that, without automatically printing, the display (not shown) of the PC 70 or the printer 1 displays the shape, size and position of the stain and the fact that the printer 1 has determined that printing is possible, and based on this information The user may determine whether or not to perform printing. At this time, on the display (not shown) of the PC 70 or the printer 1, a preview of the printing surface Pa including the stain may be displayed so that the shape, size and position of the stain can be understood. May be displayed as a message such as text.

  Further, when printing is continuously performed on a plurality of printing papers P, after the printing on all the printing papers P is completed, the number of the printing papers P on which printing has been performed although there is dirt, or Alternatively, information on the number of print sheets P that are judged to be unusable due to severe stains and discharged without being printed may be accumulated and displayed on a display (not shown). If necessary, the printer may be configured to perform reprinting only on print data printed on the printing paper P on which printing has been performed, if necessary.

  In addition, the recording head 3 can print white of the same color as the printing surface Pa of the printing paper P. If the dirt is severe, white is printed on the dirt of the printing paper P to reduce the dirt. It may be configured as follows.

  Further, when the printer has a configuration capable of duplex printing, when one side of the printing paper P is conveyed so as to be the printing surface Pa, and the stain on the printing surface Pa is severely unprintable, A configuration may be adopted in which the printing paper P is reversed by a double-sided path (not shown) and conveyed so that the other surface becomes the printing surface Pa, and the printing surface Pa is also determined. Thus, for example, when a misprint is printed only on one side, and the opposite side is stored in the paper feed tray 7 so that the blank printing paper is mistakenly printed and the side on which the misprint is printed becomes the printing surface Pa In addition, printing can be performed on the blank printing surface Pa without any user intervention.

  In the present embodiment, the print operation is performed when the printability determination unit 55 determines that printing is possible without correcting the print data. However, when it is determined that printing is not possible, the print data is stored. Whether or not the influence of the stain on the image or characters to be printed can be reduced by the correction, the printability determination unit 55 again determines whether or not the print data can be printed. If it is determined, printing may be performed.

  Furthermore, in the present embodiment, as shown in FIG. 4, when the printability determination unit 55 determines whether or not the printing surface Pa is dirty, and when it is determined that there is dirt (S3: Yes). In this case, it is determined whether or not printing is possible (S6). However, as information on the stain, S3 and S6 may be collectively determined by the printability determination unit 55 including the case where there is no stain.

  Further, as the information regarding the stain, the position, size, and color of the stain are detected, and the printability determination unit 55 ranks each of these three pieces of information according to the degree, Whether or not printing is possible may be determined based on whether or not the total value of the ranks is greater than a predetermined value. As an example of ranking, regarding the position of the stain, the center of the printing surface Pa is set to the highest rank, and the rank is reduced toward the end. As for the size of the dirt, the rank is increased as the dirt becomes larger. Further, for the stain color, the rank increases as the color having the contrast increases from the color closest to the color of the print surface Pa (for example, if the print surface Pa is white, the light color has a low rank, black, etc. Has a high rank). Further, the importance may be changed by the position, the size, and the color of the dirt by multiplying each rank by a coefficient according to the user setting. For example, if the dirt position and size are very strict criteria, but the dirt color is a loose criterion, multiply the dirt position and size rank by a large factor of one or more. Multiply the stain color rank by a small factor less than one. Then, the print propriety determination unit 55 may determine whether or not print is possible depending on whether or not the total value is larger than a predetermined value.

  In the above-described embodiment and its modifications, the present invention is applied to a so-called serial printer. However, the present invention is not limited to this, and the present invention may be applied to a printing apparatus such as a printer having a so-called line head. Is possible.

DESCRIPTION OF SYMBOLS 1 Printer 2 Carriage 3 Recording head 5 Media sensor 11 Position detection sensor 12 1st feed roller 13 2nd feed roller 50 Control apparatus 54 Dirt analysis part 55 Printability judgment part 56 Print data correction part

Claims (8)

Printing means for printing on the printing surface of the printing medium;
Before the printing is performed by the printing unit, a stain detection unit that detects information about the stain on the printing surface;
A printing apparatus comprising: a printing availability determination unit that determines whether printing on the printing surface is possible based on information on the printing surface that is detected by the contamination detection unit. A printing control unit for controlling the printing unit;
The printing apparatus according to claim 1, wherein the printing control unit causes the printing unit to perform printing on the printing surface when the printing availability determination unit determines that printing is possible.   The printing apparatus according to claim 1, wherein the stain detection unit detects a stain position on the printing surface.   The printing apparatus according to claim 3, wherein the printing propriety determining unit determines that printing is possible when a stain position on the printing surface is outside a predetermined region.   The printing apparatus according to claim 4, wherein the predetermined area is a printing area printed by the printing unit.   The printing apparatus according to claim 1, wherein the stain detection unit detects a size of stain on the printing surface.   The printing apparatus according to claim 6, wherein the printing availability determination unit determines that printing is possible when the size of the stain on the printing surface is less than a predetermined size. The print control means detects that the stain position of the printing surface is within the print area of the print data printed by the printing means by the stain detection means, and allows printing by the print availability determination means. If determined, the printing unit is controlled to correct the input print data according to the stain on the print surface, and printing is performed on the print surface based on the corrected print data. The printing apparatus according to claim 2, wherein the printing apparatus is a printer.

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