BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a handheld printing apparatus for performing printing by having an operator manually scan its body.
Description of the Related Art
A handheld printing apparatus for performing printing by having a user manually scan its body has been known. Japanese Patent Laid-open No. 2019-162795 (hereinafter Document 1) discloses a handheld printing apparatus having a plurality of sensors that measure the amount of movement of the printing apparatus relative to a print medium. Document 1 also discloses that the plurality of sensors detect the moving amount of the printing apparatus during a scan for printing.
In a case where a plurality of sensors constantly contact a print medium to detect the moving amount of a printing apparatus as in the technique disclosed in Document 1, there is a possibility that the sensors are rubbed against a printed area of the print medium. In this case, if an ink yet to be fixed is remaining on the printed area, there is a possibility that the rubbing of the sensors causes scraping and detachment of the ink, transfer of the ink onto another area, thereby causing soiling, and so on, which deteriorate the printing quality.
SUMMARY OF THE INVENTION
A printing apparatus according to one aspect of the present invention is a printing apparatus including: a holding unit configured to be held by a user to move the printing apparatus; a printing unit configured to print an image onto a print medium according to a movement of the printing apparatus; a guide unit configured to guide the movement of the printing apparatus; a first detection unit configured to detect a relative moving amount between the printing apparatus and the print medium; a second detection unit provided at a position different from a position of the first detection unit; and a displacement unit configured to displace the first detection unit from a state where the first detection unit and the second detection unit are both in contact with the print medium into a state where the first detection unit is separated from the print medium.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B are perspective views illustrating a manually scanned handheld printing apparatus;
FIGS. 2A to 2D are views illustrating a printing operation of the printing apparatus on a print medium in a step-by-step manner;
FIG. 3 is a block diagram illustrating a configuration of a control unit in the printing apparatus;
FIGS. 4A to 4H are views illustrating a line break mechanism in the printing apparatus along the flow of a line break operation;
FIGS. 5A to 5D are views illustrating a positional relationship between a printed area and the printing apparatus, and operating states of sensors;
FIGS. 6A and 6B are views illustrating a downstream position detection sensor and components around it;
FIGS. 7A and 7C are views illustrating an upstream position detection sensor and components around it; and
FIG. 8 is a diagram describing an example of calculating a change in angle which occurred in a movement by a line break operation.
DESCRIPTION OF THE EMBODIMENTS
First Embodiment
A first embodiment of the present invention will be described below with reference to drawings.
Note that the term “print” herein is not limited to formation of information with a meaning such as characters or a figure, and includes formation of information with a meaning and also information without a meaning. Moreover, the term is not limited by whether what is to be “printed” is elicited so as to be visually perceptible to humans, and represents a wide range of meanings such as formation of an image, a design, a pattern, or the like on a print medium and processing a print medium.
Also, the term “ink” (also referred to as “liquid”) is to be widely interpreted as with the definitions of “print” mentioned above. Thus, the term represents a liquid to be used to form an image, a design, a pattern, or the like or process a print medium by being applied to a print medium, or to process an ink (e.g., solidification or insolubilization of a colorant in an ink to be applied to a print medium).
“Print medium” is mainly a medium such as a paper sheet or note, but is not particularly limited to these as long as it is a medium on which printing can be performed by attaching an ink. “Print medium” may be any material as long as it accepts an ink, such as fabric, plastic film, sheet metal, glass, ceramic, wood, or leather.
FIGS. 1A and 1B are perspective views illustrating a manually scanned handheld printing apparatus (hereinafter also referred to simply as “printing apparatus”) 1 in the present embodiment. FIG. 1A is a view illustrating the top side of the manually scanned handheld printing apparatus 1, while FIG. 1B is a view illustrating the bottom side of the manually scanned the handheld printing apparatus 1. The printing apparatus 1 includes an upper unit 3 mainly containing a control unit's components, a lower unit 2 including a print head 4 and guide rollers 10, and a line break handle 5 to be operated by an operator in a case of performing a line break operation. The print head 4 performs printing by ejecting an ink onto a print medium with movement of the printing apparatus 1.
A plurality of guide rollers 10 are provided. In the present embodiment, these are a paired right guide roller 10a and left guide roller 10b which guide movement of the printing apparatus 1 in ±X directions (first direction) while pressing a print medium P during a printing operation.
The lower unit 2 is provided with a downstream position detection sensor 11 and an upstream position detection sensor 12 with the print head 4 therebetween. The downstream position detection sensor 11 and the upstream position detection sensor 12 are provided to be capable of contacting the print medium. Relative to the print head 4, the downstream position detection sensor 11 is situated on a side in the traveling direction in a line break operation after printing a single line (i.e., in the moving direction for line break), and detects the relative moving amount between the printing apparatus 1 and the print medium. The upstream position detection sensor 12 is situated on the opposite side of the print head 4 in the traveling direction in a line break operation, and detects the moving amount of the printing apparatus body. In the present embodiment, as will be described later, a line break operation of the printing apparatus 1 is an operation of moving in a +Y direction (second direction). Thus, the +Y side will be referred to as the downstream side in the traveling direction for line break (new line side), while the −Y side will be referred to as the upstream side in the moving direction for line break (previous line side). The downstream position detection sensor 11 includes a downstream position detection sensor case 11a, sensor case sliders 11b, a sensor lens 11c, and a Y-direction sensor support shaft 11d (FIGS. 6A and 6B). The upstream position detection sensor 12 includes an upstream position detection sensor case 12a, sensor case sliders 12b, a sensor lens 12c, and a Y-direction sensor support shaft 12d (FIGS. 7A and 7B). The lower unit 2 is further provided with line break legs 13. The line break legs 13 are members that separate the guide rollers 10 from the print medium and move the printing apparatus body during a line break operation, and include a pair of right line break legs 13a and a pair of left line break legs 13b. During a line break operation, the two right line break legs 13a and the two left line break legs 13b contact the printing surface of the print medium.
The right guide roller 10a and the left guide roller 10b are each formed as an integrated component with one shaft 10c and two rollers fixed to this shaft 10c. The two rollers are provided coaxially with each other. The shafts 10c of the right guide roller 10a and the left guide roller 10b are provided substantially parallel to each other, and are supported by the lower unit case 14 so as to allow the shafts 10c to turn while reducing their backlashes in the thrust direction. Each roller's cylindrical surface that contacts the print medium P is preferably subjected to a process such as sticking fine abrasive grains to increase the coefficient of friction with the print medium P, and the two rollers are preferably given substantially the same diameter to achieve good straightness of travel. For the straightness of travel, it is also preferable to support the right guide roller 10a and the left guide roller 10b in parallel to each other. During movement on the print medium P, configurations as above enable the guide rollers 10 to passively roll without slipping, and also improve the straightness of travel of the printing apparatus 1.
These mechanisms serve as a base of the lower unit 2 and housed in the lower unit case 14, in which the print head 4, the guide rollers 10, and so on are disposed.
FIGS. 2A to 2D are views illustrating a printing operation of the printing apparatus 1 on the print medium P in a step-by-step manner. In FIGS. 2A to 2D, areas PA represent printed areas where images are printed. A case of printing a first single line from the left side of the print medium P toward its right side will be described below. Note that it is also possible to perform the first printing from the right side of the print medium P toward its left side.
When starting the printing, the printing apparatus is positioned at an upper left portion of the print medium P, as illustrated in FIG. 2A. In this state, of the components of the printing apparatus 1, the four rollers 10a and 10b of the guide rollers 10 and the sensor case sliders 11b, which are part of the downstream position detection sensor 11, are in contact with the print medium P, whereas the upstream position detection sensor 12 is not in contact with the print medium P. The upstream position detection sensor 12 is not in contact with the print medium P during the printing operation in order to avoid rubbing the printed area after the later-described line break operation is performed. Specifically, as the printing apparatus 1 performs a line break operation, the position of the printed area and the contact position of the upstream position detection sensor 12 on the print medium P move relative to each other in the moving direction for line break. Thus, in the course of repeating line break operations, the contact position of the upstream position detection sensor 12 on the print medium P may overlap the printed area in the moving direction for line break in some cases. If the printing apparatus 1 is scanned for printing in this state, the sensor case sliders 12b of the upstream position detection sensor 12 will be rubbed against the printed area. An inkjet print head is used as the print head 4 in the present embodiment. If an ink yet to be fixed is remaining on the printed area, there is a possibility that the sensor case sliders 12b sliding over the ink scrape and detach the ink and transfer the ink onto another area, thereby causing soiling. Thus, in the present embodiment, the upstream position detection sensor 12 is controlled to be separated from (out of contact with) the print medium P during printing operations. Note that, as illustrated in FIG. 1B, the rollers 10a and 10b of the guide rollers 10 on the upstream side in the moving direction for line break (−Y side) are positioned closer to the print head 4 than the sensor case sliders 12b are. Nonetheless, since the rollers 10a and 10b make rotational motions on the print medium P, moving them on the printed area does not deteriorate the printing quality, as compared to the sliding movement of the sensor case sliders 12b.
Thereafter, in FIG. 2B, the operator places a hand on the printing apparatus 1 and moves the printing apparatus 1 in the moving direction for printing (the direction of the arrow DX). When the printing apparatus 1 starts moving, the downstream position detection sensor 11 detects the moving amount.
In the present embodiment, while the printing apparatus 1 is moved in the moving direction for printing by the operator's operation, the downstream position detection sensor 11 is used to detect the moving amount. Also, while the printing apparatus 1 is moved in a line break direction by a line break operation by the later-described line break mechanism, the downstream position detection sensor 11 and the upstream position detection sensor 12 are both used to detect the moving amount. The detected moving amount is more accurate with a detection result based on a plurality of detection sensors moving amount than with a detection result obtained from a single detection sensor. For this reason, the printing apparatus 1 in the present embodiment includes a plurality of detection sensors. As a rule, it is preferable to use a plurality of detection sensors to detect the moving amount. However, in the present embodiment, as mentioned above, the upstream position detection sensor 12 is configured to be separated from the print medium P in the case of moving the printing apparatus 1 in the moving direction for printing, in order to prevent the upstream position detection sensor 12 from being rubbed against the printed area. Specifically, the distance between the upstream position detection sensor 12 and the print medium P is a first distance during execution of line break operations. Moreover, the distance between the upstream position detection sensor 12 and the print medium P is a second distance longer than the first distance in periods other than during execution of line break operations.
An example of the detection of the moving amount by the two detection sensors is described below. The downstream position detection sensor 11 and the upstream position detection sensor 12 optically read characteristics of the surface of the print medium P, detect the moving amount from the movement start position, and integrate this moving amount to thereby calculate the current position of the printing apparatus 1. In the present embodiment, sensors of types capable of accurately detecting moving amount are used, and the working distance between the sensors and the print medium P needs to be 2.4 mm with the distance tolerance range kept within ±0.3 mm. A printing operation is performed by detecting the relative moving amount between the printing apparatus 1 and the print medium P with sensors as above and ejecting the ink from the print head 4 according to the moving amount of the printing apparatus 1. Note that the detection method of the downstream position detection sensor 11 and the upstream position detection sensor 12 is not limited to the above method, and may be any method as long as it can detect the relative positions of the printing apparatus 1 and the print medium P.
Now, a configuration of a control unit 16 in the printing apparatus 1 will be described. FIG. 3 is a block diagram illustrating a configuration of the control unit 16 in the printing apparatus 1. The control unit 16 includes a CPU 200, a RAM 201, a ROM 202, a head driver 203, an external interface 205, and a wireless interface 206. Moreover, the control unit 16 is connected to an operation panel 204, the print head 4, the upstream position detection sensor 12, the downstream position detection sensor 11, a battery 207, and a line break leg sensor 208. The CPU 200 is responsible for performing data processing, obtaining sensor information, and controlling the driving of the print head. The RAM 201 is responsible for temporarily storing programs and image data to be printed and the like. The ROM 202 stores programs and various setting values. The head driver 203 is responsible for control for ejecting the ink from the nozzles in the print head 4.
The operation panel 204 is provided in the printing apparatus 1 and includes various switches, a display unit such as an LED display, a buzzer, and so on. The external interface 205 is responsible for data exchange with an external control apparatus and the like. The wireless interface 206 wirelessly controls the printing apparatus 1 in place of the external interface 205. The battery 207 is used to drive the printing apparatus 1 in a cordless manner. The line break leg sensor 208 detects the operation of the line break legs 13 to be described later. The ink ejection of the print head 4 is controlled by these components of the control unit 16. Specifically, before the start of a printing operation, at least print data necessary for printing a single line is received via the wireless interface 206 or the external interface 205, and this print data is stored in the RAM 201. After various print settings are determined and the printing operation becomes ready to be started, the operator is notified via the operation panel 204 that the printing operation can be started.
The print head 4 employs an inkjet method by which it ejects the ink from a plurality of minute nozzles arranged substantially straight in a direction crossing the moving direction for printing. Specifically, the print head 4 has a nozzle array being a plurality of nozzles arranged side by side, and the direction in which the nozzle array is arranged corresponds to the moving direction for line break. An image is formed by reading data out of the RAM 201 according to the result of the moving amount detection by the downstream position detection sensor 11 and causing the CPU 200 to determine the timing and the data to be printed at the corresponding position, and ejecting the ink from the print head 4 as appropriate. At this time, the printing apparatus 1 is manually scanned by the operator. The moving speed is therefore not guaranteed to be constant, and the speed is expected to vary. Control is performed such that the image will be printed as indicated by the original data on the print medium P even with such speed variation. By continuously performing this process, the operation of printing a single line is completed. After the completion of the single-line printing operation, the operator looks at the image or is notified of the completion of the single-line printing operation via the operation panel 204, and stops the scanning operation in the moving direction for printing DX.
In FIG. 2C, a line break operation is performed by the operator's operation. The line break operation is an operation performed for the purpose of applying an effect equivalent to a so-called line feed operation involving conveying a sheet by a predetermined distance after a single-line printing operation of the carriage in a general serial scan-type printer. Specifically, the line break operation is an operation of moving the print head 4 in the moving direction for line break (the direction of the arrow DY), which is substantially orthogonal to the moving direction for printing (the direction of the arrow DX), to a position from which to perform the next single-line printing operation according to the position, on the print medium P, of a printed area PA1 completed by the single-line printing operation.
While details of the line break operation will be described later, the operator's operation involves moving the line break handle 5 in a lever operating direction for line break (the direction of the arrow ML). In conjunction with the line break operation triggered by this operator's operation, the line break legs 13 act so as to move the printing apparatus 1 a predetermined distance in the moving direction for line break (the direction of the arrow DY). Note that the printing apparatus 1 includes a mechanism that brings not only the downstream position detection sensor 11 but also the upstream position detection sensor 12 into contact with the print medium P during a line break movement. The moving amount of the printing apparatus 1 may vary, and the printing apparatus 1 may rotate in the plane of the print medium P (in the direction of the arrow R in FIG. 2C) before or after the line break movement. In this case, by detecting the state of the line break movement of the printing apparatus 1 with the plurality of position detection sensors, it is possible to detect the amounts of the variation and the rotation. Note that the upstream position detection sensor 12 is configured to be separated from the print medium P again when the line break movement is finished. The line break operation is now completed.
Thereafter, in FIG. 2D, a printing operation is performed for the second line. The printing operation of the second line is prepared by preparing image data by a process similar to that for the printing operation of the first line and, if the moving amount varied during the line break operation, correcting the variation. The operator performs a basic operation similar to that for the first line. Here, by preparing print data during the line break operation, the printing operation will be basically ready to be performed after the line break operation. In this way, the operator can immediately start the second scan. Since the scanning direction for the second line is the reverse of the scanning direction for the first line, the operator moves the printing apparatus 1 in the direction of the arrow −DX.
The image of the second line is formed in a similar manner to the scan for the first line by detecting the moving amount with the downstream position detection sensor 11 and ejecting the ink from the print head 4 according to the position. By performing appropriate correction, images can be formed in a unified manner in the printed area PA1 of the first line and a printed area PA2 of the second line with almost no misalignment. Note that description of the method of the correction is omitted since it is not the subject matter of the present embodiment. If necessary, the operator continuously performs a printing operation in a similar manner for the third line, the fourth line, and so on to complete forming the desired image.
FIGS. 4A to 4H are views illustrating the line break mechanism in the printing apparatus 1 along the flow of a line break operation. The line break mechanism in the printing apparatus 1 includes a line break lever 50, a line break mechanism drive gear train 51, a drive gear train reset lever 52, a drive gear train reset sub lever 53, and a drive gear train reset cam 54. The line break lever 50 operates in conjunction with the line break handle 5. The line break mechanism drive gear train 51 is driven in response to the operation of the line break lever 50, and causes the line break legs 13 to operate. The line break legs 13 are rotationally moved in the clockwise direction in FIGS. 4A to 4H by the line break mechanism drive gear train 51. When the line break legs 13 come into contact with the print medium P, the line break legs 13 serve as fixed base points on the print medium P, about which the printing apparatus 1 rotationally moves in the clockwise direction in FIGS. 4A to 4H.
The drive gear train reset lever 52 brings the line break mechanism drive gear train 51 back to its initial state. The drive gear train reset sub lever 53 operates in the last half of the operation of bringing the line break mechanism drive gear train 51 back to its initial state. The drive gear train reset cam 54 receives force from the drive gear train reset lever 52 and the drive gear train reset sub lever 53. The drive gear train reset cam 54, which is on the line break mechanism drive gear train 51, is provided integrally with one of the gears of the line break mechanism drive gear train 51, and rotates in the counterclockwise direction in FIGS. 4A to 4H in response to the operation on the line break lever 50. Also, gears coupled to both sides of both sides of a gear integrally provided to the drive gear train reset cam 54 rotate in the clockwise direction in FIGS. 4A to 4H in response to the operation of the line break lever 50. The line break legs 13 make the clockwise rotational movement in synchronization with this rotation.
FIG. 4A illustrates a normal standby state and a printing operation state before entering a line break operation. The line break handle 5 is stopped at its initial position in a state of being biased by a spring not illustrated. The guide rollers 10 are in contact with the print medium P and supported by bearings not illustrated which are provided in the lower unit case 14. Hence, the height to the printing apparatus 1 is determined by the guide rollers 10. The downstream position detection sensor 11 is constantly pressed in such a direction as to contact the print medium P, thereby being ready to measure the moving amount. The upstream position detection sensor 12 has retracted to a retracted position in conjunction with the line break mechanism drive gear train 51, thereby not being in contact with the print medium P. The line break legs 13 are in a standby state at their initial positions inside the printing apparatus 1, being not in contact with the print medium P.
FIG. 4B illustrates a state where the operator starts pulling the line break handle 5 in the +Y direction in FIG. 4B, thereby starting a line break operation. In response to the start of the line break operation, firstly, a lock member (arm drive lever A 63 in FIG. 7A) which has retracted the upstream position detection sensor 12 moves in a −Z direction. As a result, the upstream position detection sensor 12 becomes movable in the ±Z directions (up-down direction), and also pressed by a pressing spring not illustrated in the —Z direction into contact with the print medium P. Thereafter, in FIG. 4C, the operator moves the line break handle 5 farther in the +Y direction. This causes the line break mechanism drive gear train 51 to act so as to move the line break legs 13 in the −Z direction into contact with the print medium P.
Next, in FIG. 4D, the line break handle 5 is moved farther in the +Y direction by the operator's operation. As a result, the line break legs 13 project farther than the guide rollers 10 in the −Z direction. This causes the printing apparatus 1 to start moving in the +Z direction. The line break legs 13 themselves make a transitional movement having a rotational locus inside the printing apparatus 1 in conjunction with gears of the line break mechanism drive gear train 51. Since the tips of the line break legs 13, which are made of a slip resistance material, are in contact with the print medium P, the body of the printing apparatus 1 conversely starts moving in the +Z direction with a transitional movement having a rotational locus.
Specifically, the body of the printing apparatus 1 moves in the direction of the arrow A in FIG. 4D. FIG. 4D illustrates a state where the printing apparatus 1 has reached a half of the moving amount for the line break operation. This is a state where the printing apparatus 1 has moved a distance L1 in the moving direction for line break (+Y direction) from its position before the start of the line break (the white triangle mark in FIG. 4D). It can be observed that the height from the print medium P to the body of the printing apparatus 1 was H1 at the point of FIG. 4C but the height to the body of the printing apparatus 1 has increased to H2 in FIG. 4D. As the body of the printing apparatus 1 gets separated from the print medium P, the guide rollers 10 get separated from the print medium P as well. This enables the printing apparatus 1 to move forward in a direction other than the moving direction in the printing operation. As the line break mechanism drive gear train 51 further rotates from the state of FIG. 4D, the printing apparatus 1 starts moving in the −Z direction. During this time too, the upstream position detection sensor 12 keeps receiving a pressing force from the pressing spring. Thus, not only the downstream position detection sensor 11 but also the upstream position detection sensor 12 remains in contact with the print medium P.
Next, in FIG. 4E, the line break handle 5 is moved farther in the +Y direction by the operator's operation and reaches a predetermined position. As a result, the guide rollers 10 contact the print medium P, and the line break legs 13 are contained in the printing apparatus 1. With the guide rollers 10 contacting the print medium P, the guide rollers 10 act such that the printing apparatus 1 stops moving in the line break direction (+Y direction). The printing apparatus 1 has now completed moving a moving amount L2 determined in advance by the configuration of the line break mechanism drive gear train 51. Thereafter, in FIG. 4F, the line break handle 5 is returned to its initial position illustrated in FIG. 4A by the action of the spring not illustrated. Note that the above does not apply if the operator keeps holding the line break handle 5. Incidentally, the line break lever 50 and the line break mechanism drive gear train 51 are coupled via a one-way clutch not illustrated. Thus, the line break mechanism drive gear train 51 shifts to the next operation regardless of the position of the line break lever 50.
The drive gear train reset cam 54 on the line break mechanism drive gear train 51 is at such an angular phase as to receive a force from the drive gear train reset lever 52 and the drive gear train reset sub lever 53, which are spring-biased. Thus, due to the force from the drive gear train reset lever 52 and the drive gear train reset sub lever 53, the drive gear train reset cam 54 is subjected to a rotational force in the counterclockwise direction in FIGS. 4A to 4H. The line break mechanism drive gear train 51 keeps operating for as long as this rotational force acts on the drive gear train cam 54. Also, immediately after reaching the state of FIG. 4F, the lock member not illustrated in FIGS. 4A to 4H (the arm drive lever A 63 in FIG. 7A) rises, so that the upstream position detection sensor 12 starts moving in the +Z direction toward the retracted position.
FIG. 4G illustrates a next state where the line break legs 13 have moved to the farthest position from the print medium P in the course of the resetting operation of the line break mechanism drive gear train 51. In this state, the upstream position detection sensor 12 has moved to the retracted position and is completely separated from the print medium P. FIG. 4H illustrates a subsequent state where the force from the drive gear train reset lever 52 and the drive gear train reset sub lever 53 no longer acts on the drive gear train reset cam 54 and the line break mechanism drive gear train 51 has stopped rotating, so that components have returned to their initial positions. Specifically, the upstream position detection sensor 12 and the line break legs 13 have returned to the same states as their states in FIG. 4A.
Line break is performed by such a series of operations. It can be observed that the printing apparatus 1 is actually moved in the period from FIG. 4C to FIG. 4E, as described above. In this period, the height from the print medium P to the body of the printing apparatus 1 increases from the height H1 to the height H2 but the downstream position detection sensor 11 and the upstream position detection sensor 12 remain in contact with the print medium P. Thus, during a line break operation, the moving amount of the printing apparatus 1 is detected by the two sensors, the downstream position detection sensor 11 and the upstream position detection sensor 12.
FIGS. 5A to 5D are views schematically illustrating the positional relationship between a printed area PA and the printing apparatus 1 and the operating state of each sensor in printing operations including line break operations. In FIGS. 5A to 5D, each black rectangle represents a state where the upstream position detection sensor 12 or the downstream position detection sensor 11 is in contact with the print medium P, while each white rectangle represents a state where the upstream position detection sensor 12 or the downstream position detection sensor 11 is not in contact with the print medium P. FIG. 5A illustrates a state where a line break operation has been performed after an operation of printing the first line from the right side of FIG. 5A to its left side, and an operation of printing the second line is being performed from the left side toward the right side. In this state, the downstream position detection sensor 11 is in contact with the print medium P while the upstream position detection sensor 12 is not in contact with the print medium P.
FIG. 5B illustrates a state where the printing operation of the second line has been finished, and a line break operation has started. Basically, the line break operation is performed from a position separated from the printed area PA. Specifically, after completing the printing of the second line, the operator continues moving the printing apparatus 1 farther and performs the line break operation from a position separated from the printed area PA. During the line break operation, the downstream position detection sensor 11 is in contact with the print medium P and the upstream position detection sensor 12 is also in contact with the print medium P. By performing the line break operation from a position separated from the printed area PA as described above, the line break operation can be performed without the upstream position detection sensor 12 rubbed on the printed area PA.
FIG. 5C illustrates a state where the line break operation has been finished. In this state, the downstream position detection sensor 11 is in contact with the print medium P while the upstream position detection sensor 12 is not in contact with the print medium P. FIG. 5D illustrates a state where an operation of printing the third line is being performed from the right side toward the left side. In this state, the downstream position detection sensor 11 is in contact with the print medium P while the upstream position detection sensor 12 is not in contact with the print medium P. Since the upstream position detection sensor 12 is not in contact with the print medium P, the upstream position detection sensor 12 is not rubbed on the printed area PA during the printing operation.
As has been described above, the upstream position detection sensor 12 switches back and forth between a contact state and a non-contact state. Hence, a trigger for determining the timing to start a position detecting operation is needed. For this reason, in the present embodiment, the line break leg sensor 208 (see FIG. 3) is used. The line break leg sensor 208 is a sensor that detects the position of the line break legs 13. In the present embodiment, the upstream position detection sensor 12 is displaced in conjunction with the line break legs 13. Thus, by using the line break leg sensor 208, it is possible to detect whether the upstream position detection sensor 12 is in the raised position or the lowered position. The upstream position detection sensor 12 is caused to start a reading operation in a case where the line break leg sensor 208 detects that the upstream position detection sensor 12 is lowered, and is caused to finish the reading operation in a case where the line break leg sensor 208 detects that the upstream position detection sensor 12 is raised.
FIGS. 6A and 6B are views illustrating the downstream position detection sensor 11 and components around it. FIGS. 6A and 6B are views of the downstream position detection sensor 11 as seen from the position indicated by the line VI-VI of FIG. 4A. FIG. 6A illustrates a normal standby state and a printing operation state before the printing apparatus 1 enters a line break operation. The downstream position detection sensor 11 is constantly biased toward the print medium P. In the state of FIG. 6A, the downstream position detection sensor 11 and the print medium P are in contact with each other. The guide rollers 10 are also in contact with the print medium P. FIG. 6B is a cross-sectional view illustrating the operating state illustrated in FIG. 4D, which is a state in the middle of a line break operation. In FIGS. 6A and 6B, only the lower unit 2 is illustrated, and a cross section of the upper unit 3 is omitted.
The Y-direction sensor support shaft 11d is formed integrally with the downstream position detection sensor case 11a and extends in the Y direction. A downstream sensor case support arm 60 is rotatably engaged with the Y-direction sensor support shaft 11d and is rotatably supported as a link that rotates about a support arm shaft 61 fixed to the lower unit case 14. In the state of FIG. 6A, the guide rollers 10 are in contact with the print medium P and at the same time the downstream position detection sensor 11 is in contact with the print medium P, as mentioned above. The downstream position detection sensor 11 is brought into contact with the print medium P as a result of the downstream sensor case support arm 60 being biased by a spring not illustrated with a moment in the clockwise direction in FIG. 6A about the support arm shaft 61.
The downstream sensor case support arm 60 presses the Y-direction sensor support shaft lid in the −Z direction, and the two sensor case sliders 11b, which are disposed bilaterally symmetrically about the Y-direction sensor support shaft 11d, are brought into contact with the print medium P. As a result, the downstream position detection sensor case 11a is equalized along the print medium P and brought into stable contact with it. For the sensor case sliders 11b, it is preferable to use a material with a low coefficient of friction with the print medium P. Doing so can reduce the sliding friction between the print medium P and the sensor case sliders 11b during printing operations and line break operations.
Also, the bearing portion of the support arm shaft 61 and the downstream sensor case support arm 60 and the bearing portion of the downstream sensor case support arm 60 and the Y-direction sensor support shaft lid are each preferably configured with as small play as possible. Configurations with small play can prevent a change in the relative positions of the lower unit case 14 and the downstream position detection sensor case 11a and vibration of the downstream position detection sensor case 11a when the sensor case sliders 11b receive a frictional force. Moreover, the downstream position detection sensor case 11a and the downstream sensor case support arm 60 have a spring installed on one side of a support portion of the downstream position detection sensor case 11a so as to bias the downstream position detection sensor case 11a in one of the ±Y directions. This configuration can prevent a change in the relative position of the downstream position detection sensor case 11a in the line break direction and vibration of the downstream position detection sensor case 11a.
Owing to such a support configuration of the downstream position detection sensor 11, the downstream position detection sensor case 11a is stably pressed against the print medium P. Accordingly, the distance between the sensor lens 11c and the downstream position detection sensor 11, which are fixed inside the downstream position detection sensor case 11a, and the print medium P can be maintained constant. Moreover, the distance between the downstream position detection sensor 11 and the print medium P can be accurately maintained since the accuracy of the distance is determined by the dimensional accuracy of a single component, the downstream position detection sensor case 11a.
The downstream position detection sensor case 11a is usually a part produced by resin molding with a mold. Accordingly, the part's dimensional reproducibility is high. This makes it possible to significantly reduce variation between products. Further, as illustrated in FIG. 1B, the sensor case sliders 11b are positioned very close to the sensor lens 11c. Thus, even if the print medium P is deformed, the sensor case sliders 11b hold down the deformed portion. Hence, the downstream position detection sensor 11 is hardly affected by the deformation of the print medium P and can stably detect the moving amount.
During a line break operation, as illustrated in FIG. 6B, the line break legs 13 project from a lower portion of the lower unit case 14 and come into contact with the print medium P, so that the body of the printing apparatus 1 moves in the +Z direction. At this time, the downstream sensor case support arm 60, which is biased in the −Z direction by the spring not illustrated, rotates clockwise and keeps biasing the downstream position detection sensor case 11a toward the print medium P. This makes it possible to continue detecting the moving amount of the printing apparatus 1 even during the line break operation.
In the present embodiment, the movement of the downstream position detection sensor 11 involves a rotational movement via a swinging movement of the downstream sensor case support arm 60. This means that the downstream position detection sensor 11 is slightly displaced in the ±X directions as viewed from the lower unit case 14. Nonetheless, the slight displacement in the ±X directions is not problematic since it is only necessary to compare the position in the Y direction in the state of FIG. 4C and that in the state of FIG. 4E in order to determine the moving distances and moving directions before and after a line break operation.
The configuration of the downstream position detection sensor 11 described above is the same as the upstream position detection sensor 12. Thus, the above statement also applies to the upstream position detection sensor 12.
Next, a reason for retracting the upstream position detection sensor 12 to separate it from the print medium P during periods other than while line break operations are performed in the present embodiment will be described. As has been described above, detecting the position of the printing apparatus 1 requires the sensor case sliders 11b and 12b (see FIG. 1B) and the print medium P to be rubbed against each other. As can be analogized from the explanatory views of FIGS. 2C and 2D, if the upstream position detection sensor 12 is brought into contact with the print medium P during the printing of the second line in FIG. 2D or of a subsequent line, the sensor case sliders 12b get rubbed on the printed area PA. If there is an ink yet to be fixed in the rubbed region, the sensor case sliders 12b spread this ink over the print medium P, which results in unintended soiling. This deteriorates the image quality and must be avoided.
For this reason, in the present embodiment, the upstream position detection sensor 12 is separated from the print medium P during printing operations. During line break operations, which are performed outside the printed area PA, rubbing the upstream position detection sensor 12 does not cause soiling. The upstream position detection sensor 12 is therefore brought into contact with the print medium P, and the position of the printing apparatus 1 is detected with the two sensors, the downstream position detection sensor 11 and the upstream position detection sensor 12. This enables accurate measurement of the moving amount of the printing apparatus 1.
FIGS. 7A to 7C are views illustrating the upstream position detection sensor 12 and components around it. FIGS. 7A to 7C are views of the upstream position detection sensor 12 as seen from the position indicated by the line VII-VII of FIG. 4A. FIG. 7A illustrates a normal standby state and a printing operation state before the printing apparatus 1 enters a line break operation. The upstream position detection sensor 12 in the present embodiment is configured to be movable relative to the guide rollers 10 in the ±Z directions, like the downstream position detection sensor 11.
The upstream position detection sensor 12 is configured to be capable of being moved by a moving mechanism between the retracted position and the contact position in conjunction with the line break mechanism drive gear train 51. The moving mechanism includes an upstream sensor case support arm 62, the arm drive lever A 63, and an arm drive lever B 64. Like the downstream sensor case support arm 60 (see FIGS. 6A and 6B), the upstream sensor case support arm 62 supports the upstream position detection sensor case 12a. The arm drive lever A 63 is used to drive the upstream sensor case support arm 62. The arm drive lever B 64 is a member linking the arm drive lever A 63 and the upstream sensor case support arm 62.
In the state of FIG. 7A, the upstream position detection sensor 12 has retracted to the retracted position in conjunction with the line break mechanism drive gear train 51 and is not in contact with the print medium P. The upstream position detection sensor 12 is basically configured to be moved in the ±Z directions by the moving mechanism in conjunction with the line break mechanism drive gear train 51. The upstream position detection sensor 12 is brought into contact with the print medium P only during line break operations. During other periods, the upstream position detection sensor 12 is separated from the print medium P and retracted to the retracted position inside the body of the printing apparatus 1.
During printing operations, during which the upstream position detection sensor 12 is located at the retracted position, and in a state immediately before starting a line break operation (the state of FIG. 7A), a spring not illustrated acts on the arm drive lever A 63 such that the arm drive lever A 63 is biased in the +Z direction and brought into contact with and stopped by a stopper not illustrated. The arm drive lever A 63 includes a protrusion 63a. The arm drive lever A 63 is engaged with the upstream sensor case support arm 62 via the arm drive lever B 64 fitted to the protrusion 63a through a hole therein. The upstream sensor case support arm 62 includes a support arm protrusion 62a, which is pulled up in the +Z direction by the arm drive lever B 64, thereby retracting the upstream position detection sensor 12 to the retracted position inside the printing apparatus 1.
As the line break handle 5 is moved by the operator's operation and a line break operation starts, the cam on the line break mechanism drive gear train 51 acts so as to press the arm drive lever A 63 such that the state of FIG. 7B is reached from the state of FIG. 7A. Specifically, the protrusion 63a of the arm drive lever A 63 moves in the −Z direction, so that the arm drive lever B 64 moves in the −Z direction as well. This releases the support arm protrusion 62a from a constrained state, so that the upstream sensor case support arm 62 rotates about the support arm shaft 61 in the clockwise direction in FIGS. 7A to 7C. Thus, the upstream position detection sensor 12 also contacts the print medium P, as illustrated in FIG. 7B. The protrusion 63a of the arm drive lever A 63 and the hole of the arm drive lever B 64 are fitted to each other with a large backlash therebetween. Accordingly, in the state where the arm drive lever A 63 is lowered, the upstream position detection sensor 12 is freely movable in the up-down direction within a predetermined range. The movement in this state is similar to that of the downstream position detection sensor 11 described with reference to FIGS. 6A and 6B. FIG. 7C is a view of a state corresponding to FIG. 4D. The rollers 10a and 10b have been separated from the print medium P but the upstream position detection sensor 12 remains in contact with the print medium P.
As described above, according to the present embodiment, the position detection sensor is configured to be separatable from the print medium P. Specifically, the upstream position detection sensor 12 situated at a position where it may slide on a printed area of the print medium P is separated from the print medium P. Performing a printing operation in this state can prevent the upstream position detection sensor 12 from scraping and detaching an ink yet to be fixed and transferring the ink onto another area, and thus suppress deterioration in printing quality.
Second Embodiment
In the first embodiment, a description has been given of an example in which the downstream position detection sensor 11 and the upstream position detection sensor 12 are used to measure the moving amount of the printing apparatus 1 during a line break operation. In the present embodiment, a description will be given of an example in which the downstream position detection sensor 11 and the upstream position detection sensor 12 are used to calculate a change in angle which occurred in a movement by a line break operation. The basic configuration is similar to the example described in the first embodiment, and the difference will therefore be described below.
FIG. 8 is a diagram describing an example of calculating a change in angle which occurred in a movement by a line break operation in the present embodiment. In FIG. 8, a position 801 is the position of the printing apparatus 1 before executing a line break operation. A position 802 is the position after executing a line break operation in the direction of the arrow DY from the position 801. FIG. 8 schematically illustrates the posture of the printing apparatus 1 in the course of performing this line break operation from the position 801 to the position 802. Note that the actual amount of movement by the line break operation is not as large as illustrated in FIG. 8. However, if the two positions overlap, it will be difficult to visually recognize them, and the moving amount is therefore illustrated in an exaggerated fashion to facilitate understanding.
In FIG. 8, the printing apparatus 1 is assumed to be placed on the X-Y plane. An X coordinate and a Y coordinate obtained as a result of the position measurement by the downstream position detection sensor 11 before the line break operation are defined as X1A and Y1A, respectively. An X coordinate and a Y coordinate obtained as a result of the position measurement by the upstream position detection sensor 12 are defined as X2A and Y2A, respectively. Also, the X coordinate and the Y coordinate of the midpoint between the above two sets of coordinates are defined as XA and YA, respectively. Similarly, an X coordinate and a Y coordinate obtained as a result of the position measurement by the downstream position detection sensor 11 after the line break operation are defined as X1B and Y1B, respectively. An X coordinate and a Y coordinate obtained as a result of the position measurement by the upstream position detection sensor 12 are defined as X2B and Y2B, respectively. Also, the X coordinate and the Y coordinate of the midpoint between the above two sets of coordinates are defined as XB and YB, respectively.
In the present embodiment, a moving amount L of the sensor midpoint from the position 801 to the position 802 in FIG. 8 is calculated. Moreover, an angle θ of rotation of a line connecting the downstream position detection sensor 11 and the upstream position detection sensor 12 from before to after the line break operation is calculated. In this way, the change in the posture of the printing apparatus 1 (the tilt in the X-Y plane) which occurred in the movement by the line break operation can be calculated.
Specifically, the moving amount L and the tilt θ can be represented as below via geometric calculations using the coordinates X1A, Y1A, X2A, Y2A, X1B, Y1B, X2B, and Y2B from the sensors' position information.
L=½*((X1B+X2B−X1A−X2A)**2+(Y1B+Y2B−Y1A−Y2A)**2)**(½) (1)
θ=ARCTAN((Y2B−Y1B)/(X2B−X1B))−ARCTAN((Y2A−Y1A)/(X2A−X1A)) (2)
Note that “**” in Equation 1 denotes exponentiation, and “ARCTAN” in Equation 2 denotes arctangent. The moving amount L and the tilt θ are calculated from the above equations. Thus, in a case of performing a printing operation after a line break, the print data is corrected by applying the moving amount L and the tilt θ to the printed area PA before the line break. This can reduce misalignment between the printed area PA and the area to be printed after the line break. The control unit 16 in the printing apparatus 1 performs the above calculations. Alternatively, the sensors' position information may be sent to an external control apparatus, which may in turn perform calculations as shown in Equations 1 and 2. Also, one of the moving amount L or the tilt θ may be calculated.
As described above, according to the present embodiment, it is possible to calculate a change in the posture of the printing apparatus 1 from before to after a line break operation. Accordingly, it is possible to suppress misalignment between the printed area before the line break and the area to be printed after the line break.
Other Embodiments
In the above embodiments, an example has been described in which, in a line break operation, the user presses down the line break handle 5 in the moving direction for line break to thereby cause the line break lever 50 to operate in conjunction with the line break handle 5, and the line break mechanism drive gear train 51 is driven according to the operation of the line break lever 50 to thereby cause the line break legs 13 to operate. However, the line break operation is not limited to this example. For instance, a motor, a solenoid, or the like that drives a chain of drives may be used as an actuator. Moreover, the line break handle 5 may be replaced with a line break button or the like that drives the actuator.
Also, the upstream position detection sensor 12 and the line break mechanism may be configured as separate components from the body of the printing apparatus 1. Specifically, in a use situation that requires accuracy during a line break movement, a line break device including the upstream position detection sensor 12 and the line break mechanism may be mounted to the body, and an operation as described in the above embodiments may be performed.
Also, in the above embodiments, an example has been described in which a single position detection sensor is provided on the upstream side and the downstream side in the moving direction for line break. However, a plurality of position detection sensors may be provided on at least one of the upstream side or the downstream side.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
According to the present disclosure, it is possible to suppress deterioration in printing quality.
This application claims the benefit of Japanese Patent Application No. 2021-125319, filed Jul. 30, 2021, which is hereby incorporated by reference wherein in its entirety.
Patent Grant
11833845
