JP4607716B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus for forming an image on a recording medium while conveying a long recording medium.

  Known is a thermal transfer type printer (image forming apparatus) that forms (prints) an image on a recording medium by pressing a thermal head (printing head) on the outer peripheral surface of the platen roller via a recording medium (printing medium) and an ink ribbon. It has been. Examples of the recording medium used in this thermal transfer type printer include a PVC tube, a heat shrinkable tube, a 4 mm ID strip, and a label tape. These various recording media are mounted on the main body of the image forming apparatus in a state of being stored in dedicated cassettes.

The above-mentioned label tape is composed of release paper (also called a separator) and a label coated with an adhesive, and is wound in a cassette with the label attached to the release paper in a long shape. . When an image is formed (printed) on a label, an image is formed on each label while a long label tape contained in a cassette is pulled out from one end and conveyed, and then the release paper is cut to a predetermined length. To do. The user peels off the label from the release paper and uses only the printed label (see Patent Document 1).
Japanese Patent Application Laid-Open No. 06-092336

  In the transport process in which the long label tape accommodated in the cassette is pulled out from one end and transported as described above, the label tape is transported while being pressurized by a transport roller or the like. In this case, there may be a deviation between the release paper and the label in the portion of the label tape immediately before being pressed by the conveyance roller (the portion slightly upstream of the conveyance roller in the conveyance and conveyance direction). May gradually become convex and the convexity may advance. In this way, when the projection proceeds, the label may break. Even if an image is formed on a broken label, this label cannot be used, so that wasteful image formation is performed.

  In view of the above circumstances, an object of the present invention is to provide an image forming apparatus that prevents useless image formation (useless printing).

In order to achieve the above object, an image forming apparatus according to the present invention forms an image on a conveying roller pair that conveys a recording medium having a label affixed to a long release sheet, and on the recording medium that is conveyed by the conveying roller pair. A print head that performs printing, a platen roller that sends a recording medium downstream from the print head, and a detection unit that is arranged on the upstream side of the pair of transport rollers and detects a defective portion of the recording medium from which a part of the label has been peeled off. The roller pair is provided with roller pressure releasing means for separating one roller from the other roller.
When the detection unit detects a defect in the recording medium, printing on the recording medium by the print head is stopped, and the conveyance roller pair is separated by the roller pressurization releasing unit so that the defective part of the recording medium is removed. Let it pass.

A cutting means for cutting the recording medium is provided on the downstream side of the print head, and the cutting means cuts the defective portion of the recording medium when the detecting means detects the defective recording medium .

The print head is provided with a head pressure release means that is separated from the platen roller, and the head pressure release means moves the print head when the detection means detects a defective portion of the recording medium. Separate from the platen roller.

The detection means is a reflective optical sensor having a light emitting element and a light receiving element, and detects a peeled portion of the recording medium from an output voltage value based on the amount of light received by the light receiving element.

  According to the present invention, since the defective portion of the recording medium is detected by the detecting means, it is possible to prevent an image from being formed on the defective portion. For this reason, an image is not formed wastefully on the recording medium, and wasteful image formation (waste printing) can be prevented.

  The present invention has been realized in a thermal transfer type label printer.

  With reference to FIGS. 1 and 2, a thermal transfer type label printing machine as an example of the image forming apparatus of the present invention will be described.

  FIG. 1 is a perspective view showing a schematic configuration of a thermal transfer type label printing machine. FIG. 2 is a schematic diagram illustrating an example of a type detection unit that detects the type of a recording medium.

  The label printer 10 is portable and is provided with a keyboard 12 for inputting characters and symbols to be printed. Characters and symbols input from the keyboard 12 are displayed on the display unit 14. In the label printer 10, an image is formed on a recording medium (printed object) T such as a label, a heat shrinkable tube, an ID strip, or a PVC tube.

  The label tape has a thin and constant thickness, and width dimensions are 6, 9, 12, 18, 25 mm, and the like. In addition, two types of colors, white and yellow, are prepared. The label printer 10 needs to print on a plurality of types of label tape, and each type is wound into a roll and stored (accommodated) in the medium cassette 16.

  Since the thickness of the material forming the tube is relatively thin, the heat-shrinkable tube or the PVC tube is flattened and wound into a roll and delivered to the medium cassette 16 like the label tape. There are several types of heat-shrinkable tubes and PVC tubes with different diameters. Since the diameters are different, when they are flattened, they become strip-like shapes with different width dimensions in the cassette. Stored.

  The 4 mm ID strip is inserted into a strip holder previously attached to an electric wire or the like, and the thickness is relatively thick (about 1 mm) and the width dimension is 4, 6, 9, 12, 18, 25 mm. ing. This 4 mm ID strip is also wound into a roll like the label, heat shrinkable tube, and polyvinyl chloride tube, and stored in the medium cassette 16. As described above, when the type of most of the print target T is replaced, the medium cassette 16 is replaced.

  Since the label printer 10 can print on a plurality of types of recording media T as described above, a type detector (push switch sensor) 20 that detects the type of recording media contained in the media cassette 16 is provided. At the bottom of the medium cassette 16, recesses (a different number of recesses depending on the type) corresponding to the type of the recording medium T are formed. The type detector 20 is provided with a plurality of rod-like push switches 22 that fit into the recesses. When the medium cassette 16 is mounted at a predetermined position of the label printing machine 10, a plurality of push switches 22 are selectively fitted in the recesses corresponding to the type of the recording medium T, and an electric signal generated thereby is generated by the label printing machine 10. The type of recording medium T is detected (determined).

  When printing on the recording medium T, first, the medium cassette 16 is mounted (set) on the label printer 10. With this attachment, the recording medium T is sandwiched between a pair of feed rollers 18a and 18b (which is an example of a transport unit according to the present invention) and sent out (transported) toward the thermal head 22. The recording medium T that has passed through the thermal head 22 is conveyed to the cutter 28 through between the platen roller 24 (see FIG. 5) and the pinch roller 26 facing the platen roller 24. The recording medium T is cut (or half-cut) by the cutter 28 every predetermined length.

  As described above, a defective portion may occur in the recording medium T being conveyed. This defective portion will be described with reference to FIG.

  FIG. 3 is a schematic diagram illustrating an example of a defective portion of the recording medium.

  A case where the label tape 40 is used as the recording medium T will be described. The label tape 40 includes a release paper (also referred to as a separator) 42 and a label 44 coated with an adhesive material. The label tape 40 has a long shape with a plurality of labels 44 attached to the release paper 42 side by side. It is wound around the medium cassette 16 as it is. While the label tape 40 is being transported, a shift occurs in the portion of the label tape 40 that is sandwiched between the feed rollers 18a and 18b, and this shift is gradually accumulated so that a part of the label 44 is part of the release paper 42. In some cases, a defective portion (a portion indicated by X) that floats away from the head is generated. The defective portion X is a portion where the label 44 is raised in a convex shape, and is finally transported in a state in which the label 44 is folded or transported in a state in which the release paper 42 and the label 44 are displaced in the vertical direction. . For this reason, the defective portion X cannot be printed normally.

  In view of this, the label printing machine 10 is provided with a reflective sensor 30 (which is an example of the detecting means in the present invention) that detects the defective portion X of the recording medium T being conveyed. In the label printer 10, printing control is executed based on information detected by the reflective sensor 30 as described later. The reflective sensor 30 includes a light emitting element 30a and a light receiving element 30b. Light emitted from the light emitting element 30a toward the recording medium T is received by the light receiving element 30b. Therefore, as shown in FIG. 3, when the floating (problem portion X) occurs in the recording medium T and the distance from the reflective sensor 30 to the recording medium T becomes shorter than normal, the focal length shifts. Therefore, the light receiving element 30b receives only a small amount of energy. In this case, the reflection type sensor 30 detects a medium detection voltage lower than that when the distance is normal.

  The medium detection voltage will be described. The reflective sensor 30 can also detect the presence or absence of the recording medium T.

  As shown in Table 1, the presence or absence of a recording medium and the presence or absence of a defective portion X are determined according to the detection voltage detected by the reflective sensor 30. Further, as described above, the push switch sensor 20 detects the type of the recording medium T. In the label printer 10, the type of the recording medium T is detected by the push switch sensor 20, and the detected type of the recording medium T (PVC tube, heat shrinkable tube, 4 mm ID strip, label tape 40) is supported. The presence or absence of the recording medium T is determined based on the medium detection voltage.

The focal length of the reflective sensor 30 is arranged so as to be the position of the thickness of the thinnest label tape 40, and the detection voltage when there is no abnormality is set to 4.1 to 4.5V. In the label tape 40, when the label 44 rises in a convex shape and the float occurs, the detection value (medium detection voltage) decreases from the above focal length, and the detection voltage in this case is 2.0 to 4. It is set to 0V. Note that the detection voltage when determining that there is no recording medium T is set to 0.2 V or less for all types of recording media T. In addition, since the PVC tube or the like is relatively thick and the distance to the reflective sensor 30 is different between the thin outer diameter and the thick outer diameter, the detection voltage value is set to 1.5 to 3.0 V. .

  An example of print control executed by the label printer 10 based on information (detection voltage) detected by the reflective sensor 30 will be described with reference to FIG.

  FIG. 4 is a flowchart illustrating an example of print control.

  This flow is activated when the print start button of the label printer 10 (see FIG. 1) is pressed. First, the type of the recording medium T is detected by the push switch sensor 20 (S401). As described above, since this detection is determined by the concave portion of the medium cassette 16, it cannot be determined whether or not the recording medium T is actually contained (remaining) in the medium cassette 16. Therefore, if it is determined by this detection that it is other than the label tape 40 (see FIG. 3), the reflection type sensor 30 (see FIG. 1) determines the presence or absence of the recording medium T (S402). If it is determined that there is the recording medium T, the recording medium T is conveyed to a predetermined position by a conveyance motor (not shown) and printing is started (S403). During printing, the presence / absence of the recording medium T is constantly monitored (S404), and printing is continued until there is no print data (S405) (S406). If it is determined in S405 that there is no print data, the printing operation is terminated (S417), and this flow is terminated. When it is determined that there is no recording medium T in S404, “no medium” is displayed on the display unit 14 (see FIG. 1), printing is interrupted (S407), and this flow is ended. Similarly, when it is determined that there is no recording medium T in S402, “no medium” is displayed on the display unit 14, printing is interrupted (S407), and this flow is ended.

  When it is determined in S401 that the medium cassette 16 contains the label tape 40, the presence or absence of the recording medium T is determined by the reflective sensor 30 in the same manner as described above (S408). Here, when it is determined that the recording medium T is present, it is subsequently determined whether or not the detection voltage detected by the reflective sensor 30 is within the range of “peeling detection voltage (see Table 1)” (S409). . If it is determined that the voltage is not the “peeling detection voltage”, the recording medium T is transported to a predetermined position by a transport motor (not shown) and printing is started (S410). During printing, the level of peeling (S411) and the presence / absence of the recording medium T are constantly monitored (S412), and printing is continued until there is no print data (S413) (S414). If it is determined in S413 that there is no print data, the printing operation is terminated (S418), and this flow is terminated.

  When it is determined in S411 that the level is peeled off (the detection voltage is within the range of 2.0 V to 4.0 V shown in Table 1), the printing operation is stopped and the part peeled off (floating part, The cutting operation (which will be described later with reference to FIG. 5) is executed (S415), and this flow ends. When it is determined in S408 that there is no recording medium T, “no medium” is displayed on the display unit 14 (see FIG. 1), printing is interrupted (S416), and this flow is ended.

  The above-described “floating portion” cutting operation (removal) will be described with reference to FIG.

  FIG. 5A is a flowchart showing the procedure of the cutting operation for cutting and removing the “floating portion”, and FIG. 5B is a schematic diagram corresponding to the flow of FIG. In FIG. 5, it is assumed that a defective portion X (floating portion 40a) as shown in FIG. 3 has occurred.

  In the “floating portion” cutting operation, first, the rotation of the feed roller 18a (drive roller) and the platen roller 24 is stopped, and at the same time, the energization to the thermal head 22 is stopped to stop printing (S501). Subsequently, in order to pass the defective portion 40a, the feed roller 18b is separated (separated) from the feed roller 18a by a pressure release mechanism (not shown) (S502). Subsequently, the platen roller 24 is rotated by a motor (not shown) by a predetermined number of pulses in the direction of arrow A until the defective portion 40a passes the nip portion of the feed rollers 18a and 18b (S503). As a result, the defective portion 40 a is located between the feed rollers 18 a and 18 b and the platen roller 24. Subsequently, the thermal head 22 is separated from the platen roller 24 by a pressure release mechanism (not shown), and the label tape 40 is clamped by the feed rollers 18a and 18b (S504).

  In this clamped state, a transport motor (not shown) is driven to rotate the feed roller 18a by a predetermined number of pulses to transport the label tape 40. When the defective portion 40a passes the cutter 28, the transport motor is turned on. Stop (S505). A portion of the label tape 40 that is slightly upstream of the defective portion 40a in the transport direction is cut by the cutter 28 (S506). According to the above operation, an image is not formed on the defective portion 40a, so that useless image formation (waste printing) can be prevented. In order to print again on the label tape 40 from which the defective portion 40a has been removed, the feed roller 18a sandwiching the label tape 40 is rotated by a predetermined number of pulses in the direction of arrow C (the direction opposite to the direction of arrow B). Then, the label tape 40 is conveyed in the reverse direction (S507).

  Another example of print control executed by the label printer 10 based on information (detection voltage) detected by the reflective sensor 30 will be described with reference to FIG.

  FIG. 6 is a flowchart illustrating another example of print control.

  The main difference between the print control shown in the flow of FIG. 6 and the print control shown in the flow of FIG. 5 is that the type of the recording medium T is not detected. That is, the control is not based on the type of the recording medium T detected by the push switch sensor 20.

  This flow is activated when the print start button of the label printer 10 (see FIG. 1) is pressed. First, the presence or absence of the recording medium T is detected by detecting the medium detection voltage by the reflective sensor 30 (S601). In this case, when the medium detection voltage shown in Table 1 is 4.7 V or more, it is determined that there is no recording medium T of all types, and “no medium” is displayed on the display unit 14 (see FIG. 1) ( S602), this flow is finished. When the medium detection voltage detected in S601 is less than 4.7 V, the medium detection voltage is stored as an initial value (S603), and then printing is started at a predetermined position (S604).

  During printing, the presence / absence of the recording medium T is always determined (S605). If it is determined in S605 that there is no recording medium T, the process proceeds to S602. If it is determined in S605 that the recording medium T is present, it is determined whether or not the medium detection voltage measured by the reflective sensor 30 for this determination is the same as the medium detection voltage stored in S603. (S606). If it is determined in S606 that the medium detection voltage has changed, there is a possibility that a defective part has occurred, so printing is stopped and “is there any peeling (failed part)?” Is displayed on the display unit 14 ( 1) (S607), and this flow is finished. If it is determined in S606 that the medium detection voltage has not changed, it is determined whether there is print data (S608). If there is print data, printing is continued (S609). If it is determined in S608 that there is no print data, printing is terminated (S610), and this flow is terminated. The voltage change in S606 is determined as “changed” when there is a change of 0.3 V or more.

  As described above, according to the printing control shown in FIG. 6, a defective portion (peeling) can be detected without detecting the type of the recording medium T by the push switch sensor 20. As a result, it is possible to prevent wasteful printing because the printing operation is stopped before a defective image is generated while the apparatus is kept at a low cost.

It is a perspective view which shows schematic structure of a thermal transfer type label printing machine. It is a schematic diagram which shows an example of the kind detection means which detects the kind of recording medium. It is a schematic diagram which shows an example of the malfunctioning part of a recording medium. It is a flowchart which shows an example of printing control. (A) is a flowchart which shows the procedure of the cutting operation | movement which cuts and removes a "floating part", (b) is a schematic diagram corresponding to the flow of (a). It is a flowchart which shows the other example of printing control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Label printer 16 Media cassette 18a, 18b A pair of feed roller 20 Push switch sensor 28 Cutter 30 Reflective sensor 40 Label tape 42 Release paper 44 Label

Claims (4)

A pair of transport rollers for transporting a recording medium having a label attached to a long release paper ;
A print head for forming an image on a recording medium conveyed by the conveyance roller pair;
A platen roller that sends a recording medium downstream from the print head;
A detecting means that is arranged on the upstream side of the conveying roller pair and detects a defective portion of the recording medium from which a part of the label is peeled off;
With
The conveying roller pair is provided with roller pressure release means for separating one roller from the other roller,
When the detection means detects a malfunction of the recording medium,
While stopping printing on the recording medium by the print head,
An image forming apparatus, wherein the roller pressure release means separates the pair of conveying rollers to pass a defective portion of the recording medium .
A cutting means for cutting the recording medium is provided on the downstream side of the print head,
This cutting means is when the detecting means detects a malfunction of the recording medium,
The image forming apparatus according to claim 1, wherein a defective portion of the recording medium is cut .
The print head is provided with a head pressure release means that is separated from the platen roller,
This head pressure release means
When the detecting means detects a defective part of the recording medium,
The image forming apparatus according to claim 1 or 2, characterized in that to separate the print head from the platen roller.
The detection means is a reflective optical sensor having a light emitting element and a light receiving element, and detects a peeled portion of the recording medium from an output voltage value based on the amount of light received by the light receiving element. The image forming apparatus according to any one of 1 to 3 .

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