Printing apparatus

Abstract

To reduce the time required for skew detection in the printing device. [Solution] A printing apparatus is used that comprises a transport unit for transporting a recording medium in the transport direction, a recording unit for recording an image on the recording medium transported by the transport unit, a first detection unit for detecting the amount of displacement of the surface image of the recording medium in the transport direction and the width direction intersecting the transport direction, and a notification unit for acquiring the amount of displacement with the first detection unit while the recording medium is moved by the transport unit, and notifying of transport errors based on the amount of displacement in the width direction.

Description

Technical Field

[0001] The present invention relates to a printing apparatus.

Background Art

[0002] [[ID=!!1]] A printing apparatus that records an image on a recording medium such as a loaded sheet has a conveyance unit for conveying the recording medium and feeding it to a recording unit. If the recording medium being conveyed by the conveyance unit skews, it may affect the printing accuracy, such as the image extending beyond the recording area.

[0003] In the printing apparatus described in Patent Document 1, a detection sensor for detecting the edge of the paper in the carriage movement direction (a direction intersecting the conveyance direction) is mounted on the carriage on which the recording head is mounted. By using this detection sensor to detect the edge of the paper at two positions in the conveyance direction, the skew of the paper can be detected.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, since the edge of the paper is detected using the detection sensor mounted on the carriage, it is necessary to drive the carriage to the position of the edge of the paper. Therefore, time is required to move the carriage to the position of the edge of the paper until the skew of the paper is determined.

[0006] The present invention has been made in view of the above problems, and an object thereof is to shorten the time required for skew detection of a printing apparatus.

Means for Solving the Problems

[0007] The present invention employs the following configuration. That is, A transport unit that transports the recording medium in the transport direction, A recording unit that records an image on a recording medium transported by the transport unit, A first detection unit for detecting the amount of displacement of the surface image of the recording medium in the transport direction and the width direction intersecting the transport direction, The printing apparatus is characterized by having a transport unit that moves the recording medium while the first detection unit acquires the amount of displacement, and a notification unit that notifies of transport errors based on the amount of displacement in the width direction. [Effects of the Invention]

[0008] According to the present invention, the time required for detecting skew in a printing device can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] Diagram showing the system configuration of the printing device. [Figure 2A] Perspective view showing the overall configuration of the printing apparatus. [Figure 2B] Perspective view showing the configuration of the printing device with the cover open. [Figure 3] Cross-sectional view showing the side configuration of the printing device. [Figure 4A] Flowchart explaining skew detection using a transport volume sensor [Figure 4B] A continuation of the flowchart explaining skew detection using a transport volume sensor. [Figure 5] A flowchart explaining the decision-making process of the sensor used for detecting skew. [Figure 6A] Flowchart explaining skew detection using edge detection sensors [Figure 6B] A continuation of the flowchart explaining skew detection using an edge detection sensor. [Figure 7] Example of a screen displayed on the control panel when the printing device detects skew. [Figure 8] Top view showing the relationship between carriage position and end detection. [Figure 9]A top view showing another form of the relationship between carriage position and end detection. [Modes for carrying out the invention]

[0010] Embodiments of this invention will be described below with reference to the drawings. Note that the components, control methods, dimensions, materials, shapes, and arrangements of the components described in these embodiments should be appropriately modified depending on the configuration and various conditions of the device to which the invention is applied. In other words, the scope of this invention is not intended to be limited to the following embodiments.

[0011] [Embodiment] Figure 1 is a block diagram showing the system configuration of the inkjet printing device 100 according to this embodiment. In this embodiment, the printing device 100 is shown as having only a printing function, but it is not limited to this. For example, the printing device 100 may be a multi-function device (MFP: Multi-Function Peripheral) that has a function to read images on a document, a function to copy the read images, and other functions. Also, the printing method is not limited to the inkjet method, and other methods such as the toner method may be used.

[0012] The printing device 100 can be connected to the host computer 190 via the network 191. The printing device 100 has an input / output interface 122, a ROM interface 125, a memory controller 126, a host interface 127, a CPU (Central Processing Unit) 128, and an image processing unit 130. These components are connected via the system bus 132. Furthermore, the printing device 100 has a Flash ROM 123 connected to the system bus 132 via the ROM interface 125, and a RAM 124 connected to the system bus 132 via the memory controller 126. In the diagram, "I / F" refers to an interface.

[0013] The CPU 128 is a central processing unit that controls the operation of the entire printing apparatus 100 by executing programs and starting up the hardware, and functions as a control unit. The Flash ROM 123 stores programs for the CPU 128 to execute and various data necessary for various operations of the printing apparatus 100. The RAM 124 is used as a work area for the CPU 128, as a temporary storage area for various received data, and to store various setting data.

[0014] The image processing unit 130 performs various image processes. For example, it performs a process of expanding (converting) print data (for example, data represented in a page description language) handled by the printing apparatus 100 into image data (bitmap image data). Further, the image processing unit 130 converts the color space (for example, YCbCr) of the image data included in the input print data into a standard RGB color space (for example, sRGB). Also, the image processing unit 130 performs image processes such as syntax analysis, resolution conversion to the number of pixels that the printing apparatus 100 can print, image analysis, and image correction on the image data as necessary. The image data obtained by the image processing is stored in the RAM 124.

[0015] The printing apparatus 100 includes a recording head 151, a cutter motor 162, a conveyance motor 163, a maintenance motor 164, a carriage motor 165, various sensors 171, an edge detection sensor 172 (second detection unit), a paper type estimation sensor 173 (discrimination unit), and a conveyance amount sensor 174 (first detection unit).

[0016] The edge detection sensor 172 is a type of optical sensor and detects the edge position of the paper from the amount of change in density detected by the sensor. Also, the edge detection sensor 172 includes a specular reflection sensor and can detect the edge position of transparent paper. The edge detection sensor 172 may be any method that can detect the paper edge and is not limited to the above sensor method.

[0017] The paper type estimation sensor 173 is a sensor that combines an ultrasonic sensor and a CIS (Contact Image Sensor). It estimates the paper type from the basis weight of the paper detected by the ultrasonic sensor and the image of the paper surface detected by the CIS. The paper type estimation sensor 173 can use any method that can distinguish paper types and is not limited to the sensor method described above.

[0018] The transport amount sensor 174 is a type of CMOS image sensor that detects the amount of displacement incurred during paper transport based on a surface image acquired by imaging the surface of the paper. Therefore, the transport amount sensor 174 is positioned in the transport path so as to face the area through which the paper passes. The transport amount sensor 174 can be any method capable of detecting the amount of paper transported, and is not limited to the sensor method described above. For example, the transport amount sensor 174 may be configured to emit red light and detect the reflected light. In that case, the CPU 128 performs optical flow processing on the digital signal based on the reflected light to detect the amount of movement in the XY direction.

[0019] The recording head 151 is connected to the system bus 132 via the head interface 152. The cutter motor 162, transport motor 163, maintenance motor 164, carriage motor 165, and paper feed motor 166 are connected to the system bus 132 via the motor driver 161. Various sensors 171, edge detection sensor 172, paper type estimation sensor 173, and transport amount sensor 174 are connected to the system bus 132 via the sensor interface 170.

[0020] The CPU 128 prints an image based on image data onto the paper, which serves as the recording medium, by controlling the recording head 151 via the head interface 152. The recording head 151 ejects ink from its nozzles in synchronization with the transport of the paper 206 and the movement of the recording head 151's carriage to form the image.

[0021] The cutter motor 162 is a motor that drives a cutter that cuts roll paper used as a recording medium. The CPU 128 controls the drive of the cutter motor 162 via the motor driver 161 to cut the roll paper after image printing to a predetermined length.

[0022] The transport motor 163 is a motor that drives the transport rollers that transport the roll of paper. The CPU 128 controls the transport motor 163 via the motor driver 161. The transport rollers and the transport motor 163 together can also be considered as the transport unit.

[0023] The maintenance motor 164 is driven during maintenance operations of the recording head 151. The carriage motor 165 is a motor that drives the carriage of the recording head 151. The CPU 128 controls the carriage motor 165 via the motor driver 161.

[0024] The paper feed motor 166 rotates the roll paper core and transports the roll paper in cooperation with the transport motor 163. The CPU 128 controls the paper feed motor 166 via the motor driver 161. By driving the paper feed motor 166 to rotate the roll paper core in reverse, the roll paper on the transport roller can also be wound towards the roll paper core. Various sensors 171 are sensors that detect, for example, the transport status of the roll paper and the carriage position of the recording head. The CPU 128 acquires sensor signals via the sensor interface 170.

[0025] The input / output unit 121 has hard keys and touches for the user to perform various operations such as print settings. The input / output unit 121 includes a display unit for displaying (notifying) various information to the user. The input / output unit 121 is controlled by the CPU 128 via the input / output unit interface 122. The input / output unit 121 may also notify the user of information audibly (buzzer, voice, etc.). The input / output unit 121 may be located outside the printing device 100. For example, the input / output unit 121 may be configured as an external unit via the network 191. Alternatively, the host computer 190 may also function as the input / output unit 121. In addition to the input / output unit 121, the printing device 100 may be further connected to other input / output units via the network 191, etc. The input / output unit 121 can also be considered as a notification unit that notifies the user of information (e.g., the occurrence of an error related to transport) and an input unit where the user inputs information.

[0026] The host computer 190 is an external device that serves as a source of print data, and a printer driver is installed on it. Alternatively, a data supply device may be provided on the printing device 100 instead of the host computer 190. Examples of data supply devices include image readers, digital cameras, and smartphones.

[0027] The host interface 127 receives print data from the host computer 190 via stream communication. The received print data is stored in the RAM 124 via the memory controller 126. The connection method between each device and the printing device 100 is not limited to via the network 191; for example, they may be directly connected via wireless communication.

[0028] Figure 2A is a perspective view showing the overall appearance of the printing device 100. Figure 2B is a perspective view showing the internal structure of the printing device 100 with the top cover 201 opened.

[0029] As shown in Figure 2A, the printing device 100 includes a fuser 202 for fixing ink after image recording and a cutter 203 for cutting paper after image recording. If the front of the device in the figure is considered the front and the back is considered the rear, the input / output unit 121 described above is located at the front of the device for easy user operation.

[0030] Figure 2B shows the printing device 100 with a roll of paper 206, which is a roll of paper wound into a sheet, attached as the recording medium. The recording medium may also be cut paper. Furthermore, the recording medium is not limited to paper; it may also be film, cloth, plastic, etc. Various types of paper can also be used, such as glossy paper or coated paper. When paper 206 is roll paper, if multiple jobs are printed by the image recording operation, multiple images corresponding to each job are printed consecutively on the roll paper. Therefore, printing and drying are repeated continuously. On the other hand, when paper 206 is cut paper, one job is printed per sheet of cut paper. Therefore, printing and drying are performed only once per sheet of cut paper.

[0031] The carriage 208 is equipped with a recording head 151 that ejects ink supplied from the ink tank 204. The carriage 208 is configured to reciprocate in the Y direction along the shaft 210 via a carriage belt 209, driven by a carriage motor 165.

[0032] As shown in the schematic side cross-sectional view in Figure 3, the paper 206 is held between the upper transport roller 302 and the lower transport roller 303. The upper transport roller 302 and the lower transport roller 303 can also be collectively referred to as the transport roller 301.

[0033] The paper 206 is transported along the transport path in the transport direction F (X direction, sub-scanning direction) by the rotation of the transport roller 301. The transport path includes the platen 207 corresponding to the recording unit. Of the transport path, the side on which the paper 206 is mounted is called the upstream side, and the side on which the paper 206 is ejected is called the downstream side. In conjunction with this, the carriage 208 moves in a direction (Y) that intersects the transport direction F. As the recording head 151 moves (in the main scanning direction and width direction), ink droplets are ejected from its nozzles. This records an image on the paper. When the carriage 208 moves to the edge of the recording area on the paper 206, the transport rollers 301 transport a fixed amount of paper 206, moving the area to be scanned for the next recording to a position where the recording head 151 can record. The image is recorded by repeating the above operations.

[0034] Furthermore, "recording" includes not only cases where meaningful information such as text and figures is formed, but also cases where images, patterns, etc. are formed on a recording medium, or where the medium is processed, regardless of whether it is meaningful or not, and does not depend on whether or not it is manifested in a way that can be perceived visually by humans.

[0035] As described above, the recording operation is performed by the ejection of ink from the nozzles of the recording head 151 mounted on the carriage 208. Of the nozzles on the recording head 151, the one furthest upstream is called the upstream nozzle 305, and the one furthest downstream is called the downstream nozzle 306.

[0036] After image recording, the paper 206 is transported to the fuser 202 where it undergoes heat treatment and the ink is fixed onto the paper. After fixing, the paper 206 is wound onto the winding device 304. If cutting is required, the cutter 203 cuts the paper.

[0037] An edge detection sensor 172 is mounted on the side of the carriage 208 to detect the edges of the paper 206 in the main scanning direction. The edge detection sensor 172 detects the edges of the paper 206 in conjunction with the movement of the carriage 208. That is, after detecting one edge of the paper 206, the edge detection sensor 172 moves with the scanning of the carriage 208 and detects the other edge.

[0038] Furthermore, a paper type estimation sensor 173 is mounted on the back of the printing device 100 to estimate the type of paper 206 that has been fed into the device.

[0039] A transport amount sensor 174 is mounted near or on the platen 207. When the transport amount sensor 174 is powered on by a signal from the CPU 128, it transitions to a detectable state. When the transport amount sensor 174 receives a read command, it acquires the displacement amount, including positive and negative values, based on the surface information of the paper 206 detected during the previous read. It then notifies the printing device 100 of the displacement amount of the transported paper 206 as the transport amount. The resolution is, for example, 17904 CPI (Counts Per Inch). However, the resolution of the value acquired by the transport amount sensor 174 is not limited to this. The surface information of the paper 206 is typically an image recorded on its surface. The surface image may be, for example, an image recorded by a recording unit, or an image pre-recorded on the paper 206.

[0040] The transport amount sensor 174 has the function of detecting the amount of paper 206 transported in the XY direction, assuming that the drive direction of the carriage 208 is the Y direction and the paper transport direction is the X direction. In this way, the transport amount sensor 174 can obtain the amount of transported paper 206 in the XY direction. However, since the transport amount sensor 174 in this embodiment calculates the displacement amount from the surface image, it is difficult to detect the transport of recording media that have smooth or transparent surfaces, such as film.

[0041] [Example 1] Figures 4A to 4B show flowcharts of the skew detection process using the transport amount sensor 174. Figures 8(a) to 8(d) are schematic top views of the carriage area of ​​the printing device 100 viewed from above (Z-axis positive side), showing the changes in the positional relationship between the paper 206, carriage 208, and transport amount sensor 174 during paper feeding. Note that the transport amount in the following explanation refers to... The specific values ​​are merely examples and do not limit the amount of material transported during the detection process.

[0042] The flow in Figures 4A to 4B starts from the point when the user loads paper 206 into the printer 100 and then instructs image recording to begin, as shown in step S400. At this point, the printer 100 is in the paper feeding state, with paper 206 on the platen 207. Each of the following steps is executed by the CPU 128, which functions as a control unit, controlling each component of the printer 100.

[0043] Next, in step S401, the CPU 128 drives the transport motor 163 to rotate the transport roller 301, thereby transporting a fixed amount (450 mm in this case) of paper 206 in the transport direction F, which is the paper discharge direction. Next, in step S402, the CPU 128 sends a power-on command to the transport amount sensor 174, causing the transport amount sensor 174 to perform its initialization operation and become ready to acquire the transport amount. Next, in step S403, the CPU 128 executes the sensor reading start process for the edge detection sensor 172 mounted on the side of the carriage 208.

[0044] Next, in step S404, the CPU 128 issues a read command to the transport amount sensor 174 to acquire the transport amount in the main scanning direction (Y direction) in which the carriage 208 moves, and temporarily stores the acquired value in the RAM 124. The acquired value of the transport amount in the main scanning direction that is stored at this time is called ΔY0. Here, for example, the acquired value of the transport amount ΔY0 is set to 705 (equivalent to 1 mm) in 17904 CPI units.

[0045] Next, in step S405, the CPU 128 drives the carriage motor 165. This step corresponds to the state shown in Figure 8(a). In Figure 8(a), the symbol E1 indicates the end detection location on the reference end side. The carriage 208 (also referred to as CR in the figure) moves in the carriage movement direction G due to the driving of the carriage motor 165.

[0046] Next, in step S406, the CPU 128 determines whether the edge detection sensor 172 detected the edge of the paper 206 while the carriage 208 was moving. If it did not detect the edge (S406=No), the process proceeds to step S407. In step S407, the CPU 128 determines whether the carriage 208 has moved a certain amount. If it has not moved (S407=No), the process returns to step S406. On the other hand, if the carriage 208 has moved a certain amount but no edge detection signal is sent to the CPU 128 (S407=Yes), the process proceeds to step S408 and terminates the paper feeding process as a failure to detect the reference edge.

[0047] If an end detection signal is sent to the CPU 128 while the carriage 208 is moving (S406=Yes), the process proceeds to step S409. In step S409, the CPU 128 stores the encoder value of the carriage motor 165 at the reference end detection point in the RAM 124. The encoder value stored at this time corresponds to the symbol E1 in Figure 8(a).

[0048] After step S409, the carriage 208 continues to move in the direction G. Next, in step S410, the CPU 128 determines whether the non-reference side paper edge has been detected by the edge detection sensor 172. If it has not been detected (S410=No), the process proceeds to step S411. In step S41, the CPU 128 determines whether the carriage 208 has moved a certain amount. If it has not moved (S411=No), the process returns to step S410. On the other hand, if the carriage 208 has moved a certain amount but the non-reference side edge detection signal has not been notified to the CPU 128 (S411=Yes), the process proceeds to step S412, and the paper feeding process ends as a failure to detect the non-reference side edge.

[0049] If a non-reference end detection signal is sent to the CPU 128 while the carriage 208 is moving (S410=Yes), the process proceeds to step S413. In step S413, C PU128 stores the encoder value of the carriage motor 165 at the non-reference end detection point in RAM124. At this time, the encoder value corresponds to NE in Figure 8(b).

[0050] After step S413, once the carriage 208 has moved a certain distance, in step S414, the CPU 128 issues a command to stop the carriage motor 165, thereby stopping the movement of the carriage 208. This state corresponds to Figure 8(b).

[0051] Next, in step S415, the CPU 128 drives the carriage motor 165 to move the carriage 208 to the standby position. This state corresponds to Figure 8(c), and the carriage 208 moves in the direction of movement (-G).

[0052] The process then moves to step S416, shown in Figure 4B. After the carriage 208 has finished moving, the CPU 128 drives the transport motor 163 to rotate the transport roller 301 and transports a certain amount of paper 206 upstream (300 mm in this case).

[0053] Next, in step S417, the CPU 128 stores the cumulative stored value of the transport amount sensor in the RAM 124. Here, the cumulative stored value of the transport amount sensor in the main scanning direction (Y direction), which is the carriage movement direction, is referred to as ΔY. The cumulative stored value of the transport amount sensor ΔY stores the value of the transport amount sensor reading ΔY0 obtained in step S404. In this example, the reading ΔY0 in step S404 is 705, so ΔY = ΔY0, and 705 is stored in ΔY.

[0054] With the paper 206 still being transported, in step S418, the CPU 128 determines whether the time set in advance in RAM 124 has expired. RAM 124 stores in advance the polling period for reading the transport amount sensor 174, which is used to periodically acquire the displacement amount of the paper 206 in the Y direction during transport (here, the reading period is 100 msec). Note that the reading period is not limited to this time. If the set time has not elapsed (S418=No), the process is repeated periodically.

[0055] On the other hand, if the set time has elapsed (S418=Yes), the process proceeds to step S419. In step S419, the CPU 128 again obtains the transport amount in the Y direction using the transport amount sensor 174. The transport amount in the Y direction obtained here is called ΔYn. Here, we assume that the obtained transport amount ΔYn was 70 in 17904 CPI units (corresponding to 0.1 mm).

[0056] Next, in S420, the CPU 128 adds the transport amount sensor cumulative stored value ΔY to the transport amount ΔYn obtained in step S419, and stores the sum in the transport amount sensor cumulative stored value ΔY. Applying the above assumed values, ΔY=705 and ΔYn=70, and since ΔY=ΔY+ΔYn, ΔY=705+70, which equals ΔY=775. Therefore, 775 is stored in ΔY.

[0057] Next, in step S421, the CPU 128 compares the absolute value |ΔY| of the cumulative stored value ΔY from the transport amount sensor with the skew judgment threshold, which is a threshold value set in RAM 124 to determine whether or not there is skew. Here, ΔY = 775, so the absolute value |Yn| is 775. The skew judgment threshold here is 3524 (equivalent to 5 mm) in 17904 CPI units. However, the threshold is not limited to this value. Since the absolute value |ΔY| of the cumulative stored value ΔY from the transport amount sensor, which is 775, is smaller than the threshold value of 3524 (S421 = No), the process proceeds to step S424.

[0058] Next, in step S424, CPU128 moves a certain distance (300 in this case) of paper 206. The system determines whether the transport of the paper (mm) is complete. Movement in the sub-scanning direction intersecting the carriage movement direction is also referred to as LF (Line Feed) in the diagram. If the transport of a certain distance is not complete (S424=No), the process from steps S418 to S421 is repeated until the transport is complete. On the other hand, if the transport of a certain distance is complete (S424=Yes), the system proceeds to step S425. In step S425, the CPU 128 stops the drive of the transport motor 163, ends the transport of the paper 206, and ends the paper feed flow.

[0059] On the other hand, in step S421, if the absolute value |ΔY| of the cumulative stored value of the transport amount sensor is greater than or equal to the skew judgment threshold (S421=Yes), it is determined that the paper 206 is skewed by a certain amount, and the process proceeds to step S422. In step S422, the CPU 128 stops the drive of the transport motor 163. For example, in the processing from steps S418 to S424, the first cumulative stored value ΔY of the transport amount sensor is 775.

[0060] Next, let's assume that the value ΔYn obtained from the sensor reading in the second step S419 is 352 (equivalent to 0.5 mm) while the transport of 300 mm of paper is still continuing. At this point, in step S420, ΔY = 775 + 352, or ΔY = 1127. Steps S418 to S424 are repeated in this manner to obtain the cumulative value of the transport amount sensor acquired at a 100 ms cycle. For example, if the cumulative stored value becomes ΔY = 3525, then |ΔY| has exceeded the skew judgment threshold of 3524, so the CPU 128 determines that skew has been detected and proceeds to step S422 to stop the paper transport.

[0061] Next, in step S423, the CPU 128 determines that the printer 100 is in a skew detection error state and terminates the paper feeding process. If the printer 100 is in a skew detection error state, it is advisable to output the message 700 shown in Figure 7 to the input / output unit 121. This notifies the user that the paper 206 is skewed and prompts them to remove the paper 206 or re-feed it.

[0062] As described above, this embodiment enables skew detection using a transport amount sensor 174 capable of detecting displacement in the XY direction. As a result, it becomes possible to detect skew while the paper 206 is being transported upstream, and the time required for skew detection can be reduced.

[0063] [Example 2] Next, we will describe Example 2. We will omit explanations of the basic configuration and functions of the printing device 100, which are the same as in Example 1.

[0064] Figure 5 shows a flowchart of the paper skew detection process using the edge detection sensor 172, assuming that the transport amount sensor 174 of the printing device 100 may be unavailable, as well as the subsequent recording and paper ejection processes.

[0065] This flow starts from the point in step S500 when the user loads paper 206 into the printer 100 and then image recording is instructed and paper feeding begins. In step S501, the CPU 128 estimates the type of paper 206 being fed based on the detection result of the paper type estimation sensor 173. As mentioned above, the transport amount sensor 174 has difficulty detecting smooth-surfaced paper such as film or transparent paper. Therefore, in step S502, the CPU 128 determines whether the estimated type of paper 206 is suitable or unsuitable for detection by the transport amount sensor 174.

[0066] Then, if the paper 206 is unsuitable for detection by the transport amount sensor 174 (S502=Yes), the process proceeds to step S503. In step S503, the CPU 128 turns OFF the transport amount sensor usage flag held in RAM 124. Meanwhile, if the paper 206 If the transport amount sensor 174 is suitable for detection (S502=No), the process proceeds to step S504. In step S504, the CPU 128 turns on the transport amount sensor usage flag held in RAM 124.

[0067] After the transport amount sensor usage flag is set, in step S505, the CPU 128 drives the transport motor 163 to rotate the transport roller 301 and transport the paper 206 in the transport direction F to the position of the edge detection sensor 172 (see Figure 3).

[0068] Once the transport of the paper 206 in step S505 is complete, the CPU 128 determines in step S506 whether the transport amount sensor usage flag is ON. If the transport amount sensor usage flag is ON (S506=Yes), the process proceeds to step S507, where the skew detection process using the transport amount sensor 174, as explained using Figure 4, is executed. On the other hand, if the transport amount sensor usage flag is OFF (S506=No), the paper 206 is a type of recording medium that cannot be used with the transport amount sensor 174. In that case, the process transitions to the flowcharts shown in Figures 6A and 6B, which will be described later.

[0069] Figures 6A and 6B are flowcharts illustrating the skew detection process when the transport amount sensor 174 cannot be used. In this flowchart, skew detection is performed using the edge detection sensor 172 of the printing device 100. Figure 9 is a schematic diagram of the printing device 100 viewed from above, showing the positional relationship between the paper 206, carriage 208, and edge detection sensor 172 during the paper feeding operation.

[0070] In step S600, the paper feeding process begins if the transport amount sensor usage flag is OFF. This step starts from the intermediate state shown in Figure 5. Steps S601 to S614 are the same processes as steps S401, S403, and S405-S416 in Figure 4, so their explanation is omitted. Steps S402 and S404 in Figure 4 are processes using the transport amount sensor 174, and are therefore not executed in the flow shown in Figure 6.

[0071] Furthermore, the relationship between Figures 9(a) to 9(d) and the processes in the flowchart of Figure 6 is the same as the relationship between Figures 8(a) to 8(d) and the processes in the flowchart of Figure 4, as mentioned above. In step S614 of Figure 6B, the state after the upstream transport of the paper 206 is completed is shown in Figure 9(e).

[0072] Next, in step S615, reading is started again with the end detection sensor 172, similar to step S602. Then, in step S616, the CPU 128 starts driving the carriage motor 165. This corresponds to the state shown in Figure 9(f), and the CPU 128 moves the carriage 208 by a certain amount in the carriage movement direction G shown in Figure 9(f).

[0073] Next, in step S617, the CPU 128 monitors whether an edge detection signal from the edge detection sensor 172 is notified to the CPU 128 while the carriage 208 is moving. If there is no notification (S617=No), the process proceeds to step S618. In step S618, the CPU 128 determines whether the carriage 208 has moved a certain amount. If step S618 is Yes, that is, if the carriage 208 has moved a certain amount but no edge detection signal is notified to the CPU 128, the process proceeds to step S619 and terminates the paper feeding process as a failure of reference-side edge detection. On the other hand, if step S618 is No, the process returns to step S617 and continues monitoring.

[0074] Furthermore, if an end detection signal is notified to the CPU 128 while the carriage 208 is moving (S617=Yes), the process proceeds to step S620. In step S620, the CPU 128 receives the encoder value of the carriage motor 165 at the reference end detection point from RAM1 The value is held at 24. The encoder value of the carriage motor 165 held in RAM 124 corresponds to E2 in Figure 9(f). In this flow, the presence or absence of skew is determined based on the position of the edge detected at the first timing and the position of the edge detected at the second timing after the paper 206 has been transported following the first timing.

[0075] Next, in step S621, the CPU 128 calculates the difference between the encoder values ​​E1 and E2 of the reference edge detection, which have been acquired twice. The CPU 128 then compares the absolute value of the calculated difference with the threshold value for skew judgment that has been set in advance in RAM 124. If the absolute value of the calculated difference is smaller than the skew judgment threshold (S621=No), the paper feeding process is terminated. If the threshold value for the measured amount of the transport amount sensor 174 used in step S421 is called the first threshold, then the threshold value for the measured amount of the edge detection used in this step can be called the second threshold.

[0076] On the other hand, if the absolute value of the calculated difference is greater than or equal to the skew detection threshold (S621=Yes), the paper 206 is skewed. In this case, the process proceeds to step S622, the printer 100 enters a skew detection error state, and the paper feeding process ends. Here, if the printer 100 enters a skew detection error state, the text shown in Figure 7 may be output to the input / output unit 121, as in Example 1. This makes it possible to notify the user of the skewed state of the paper and prompt them to refeed the paper 206 or remove the paper.

[0077] Returning to the flow chart in Figure 5, the explanation continues. Once the processing in step S507 or step S508 is complete, the process proceeds to step S509, and the paper feeding is completed. Next, if the printer 100 has received a print job, the process proceeds to step S510 to start recording on the paper 206. Then, once recording is complete in step S511, the process proceeds to step S512, where the CPU 128 drives the cutter motor 162 to cut and eject the paper 206.

[0078] As described above, if the paper type estimation sensor 173 determines that detection by the transport amount sensor 174 is not possible based on the estimation result, the skew detection process using the edge detection sensor 172 is executed.

[0079] According to this embodiment, skew detection can be performed by combining the end detection sensor 172 and the transport volume sensor 174. In particular, when detection is possible by the transport volume sensor 174, the time required for skew detection can be shortened by detecting skew during transport in the upstream direction. Furthermore, even when detection is not possible by the transport volume sensor 174, detection can be reliably performed by using the end detection sensor 172.

[0080] As described above, conventionally, when detecting the paper edge using the edge detection sensor 172 mounted on the carriage 208, it was necessary to drive the carriage 208 to the paper edge position. Therefore, there was a problem that the time required to determine if the paper 206 was skewed was prolonged by the movement time of the carriage 208. However, with the method disclosed herein, it is possible to detect skew using a transport amount sensor 174 that can detect the amount of movement in the XY direction, thereby shortening the required time.

[0081] [Configuration 1] A transport unit that transports the recording medium in the transport direction, A recording unit that records an image on a recording medium transported by the transport unit, A first detection unit for detecting the amount of displacement of the surface image of the recording medium in the transport direction and the width direction intersecting the transport direction, A printing apparatus characterized by comprising a transport unit that moves a recording medium while the transport unit acquires the displacement amount with the first detection unit, and a notification unit that notifies of transport errors based on the displacement amount in the width direction. [Configuration 2] The system further includes a control unit that determines whether the recording medium being transported by the transport unit is tilted based on the displacement amount acquired by the first detection unit, The printing apparatus according to configuration 1, characterized in that the notification unit notifies the error when the control unit determines that there is skew. [Configuration 3] The printing apparatus according to configuration 2, characterized in that the control unit determines that the error is due to the recording medium being obliquely oriented when the amount of displacement in the width direction while the transport unit moves the recording medium by a certain distance exceeds a threshold. [Structure 4] The printing apparatus according to any one of configurations 1 to 3, characterized in that the first detection unit is a sensor arranged on the transport path of the recording medium and captures an image of the recording medium to acquire the surface image. [Composition 5] The printing apparatus according to any one of configurations 1 to 3, characterized in that the first detection unit is a sensor arranged on the transport path of the recording medium and detects reflected light by irradiating the recording medium with light. [Composition 6] A second detection unit for detecting the position of the edge of the recording medium in the width direction, The system further includes a determination unit that determines whether the recording medium is of a type that can be detected by the first detection unit, The printing apparatus according to configuration 2, characterized in that the control unit determines whether or not there is skewness using the second detection unit if the recording medium is not of a type that can be detected by the first detection unit. [Composition 7] The printing apparatus according to configuration 6, characterized in that, when determining whether or not there is skew using the second detection unit, the control unit transports the recording medium by the transport unit between the first timing and the second timing, and determines whether or not there is skew based on the difference between the position of the end at the first timing and the position of the end at the second timing. [Structure 8] The recording medium is wound in a roll shape. A printing apparatus according to any one of configurations 1 to 7, characterized by the above. [Explanation of Symbols]

[0082] 100: Printing device, 128: CPU, 151: Recording head, 163: Transport motor, 174: Transport volume sensor, 301: Transport roller

Claims

1. A transport unit that transports the recording medium in the transport direction, A recording unit that records an image onto a recording medium transported by the transport unit, A first detection unit for detecting the amount of displacement of the surface image of the recording medium in the transport direction and the width direction intersecting the transport direction, A printing apparatus characterized by comprising a transport unit that moves a recording medium while the transport unit acquires the displacement amount with the first detection unit, and a notification unit that notifies of transport errors based on the displacement amount in the width direction.

2. The system further includes a control unit that determines whether the recording medium being transported by the transport unit is tilted based on the displacement amount acquired by the first detection unit, The printing apparatus according to claim 1, characterized in that the notification unit notifies the error when the control unit determines that there is skew.

3. The printing apparatus according to claim 2, characterized in that the control unit determines that the error is due to the recording medium being obliquely oriented when the amount of displacement in the width direction while the transport unit moves the recording medium by a certain distance exceeds a threshold.

4. The printing apparatus according to any one of claims 1 to 3, characterized in that the first detection unit is a sensor arranged on the transport path of the recording medium and captures an image of the recording medium to acquire the surface image.

5. The printing apparatus according to any one of claims 1 to 3, characterized in that the first detection unit is a sensor arranged on the transport path of the recording medium and detects reflected light by irradiating the recording medium with light.

6. A second detection unit for detecting the position of the edge of the recording medium in the width direction, The system further includes a determination unit that determines whether the recording medium is of a type that can be detected by the first detection unit, The printing apparatus according to claim 2, characterized in that the control unit determines whether or not there is skewness using the second detection unit if the recording medium is not of a type that can be detected by the first detection unit.

7. The printing apparatus according to claim 6, characterized in that, when determining whether or not there is skew using the second detection unit, the control unit transports the recording medium by the transport unit between the first timing and the second timing, and determines whether or not there is skew based on the difference between the position of the end at the first timing and the position of the end at the second timing.

8. The recording medium is wound in a roll shape. The printing apparatus according to any one of claims 1 to 3.

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