Imaging apparatus

Abstract

To provide an imaging apparatus for suppressing an error between respective colors of outputted color component data, even when a conveyance speed of a printing medium is changed, in performing imaging, while conveying the printing medium.SOLUTION: In a printer 1, a first color reading element images a printing medium 9 in a first imaging position at imaging timing based on a drive signal SC and outputs a first color read signal S1 at a constant period. A second color reading element images the printing medium 9 in a second imaging position at the imaging timing and outputs a second color read signal S2 at a constant period. A first color averaging processing part 571 performs averaging processing of a plurality of stored first color read signals S1 with weight corresponding to a time lag between a first conveyance signal Rsub1 based on a pulse signal outputted by an encoder 30 according to a conveyance speed of the printing medium 9 and the drive signal SC. A second color averaging processing part 572 performs averaging processing of a plurality of stored second color read signals S2 on the basis of a second conveyance signal Rsub2 based on the pulse signal in the same way.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The subject matter disclosed herein relates to imaging devices.

[0002] Conventionally, while the print medium is transported in one direction, an image printed on the print medium is captured by a camera, and various inspections such as checking the print quality and nozzles are performed based on the obtained image data. For example, the camera uses a line sensor that captures an image of the print medium in one line, and captures images continuously while moving the print medium or the camera itself in a direction perpendicular to the line, thereby making it possible to obtain an image of the entire print medium in chronological order. For example, Patent Document 1 discloses a technology for reading an original using a contact image sensor (CIS), which is a type of line sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-170888 A Summary of the Invention [Problem to be solved by the invention]

[0004] The CIS (101) of the image reading device (100) of Patent Document 1 has an LED (201) as a light source, a light guide (202), a lens eye (203), and a line sensor (204). The LED (201) is composed of LED elements that emit R (red), G (green), and B (blue) light (paragraph 0016). When reading a color image, the CIS (101) is moved back and forth in the sub-scanning direction, and the LED (201) is turned on in a single color in the order of R, G, and B, and the diffused light from the original is received by the line sensor (204) (paragraph 0018). In addition, a shading correction circuit (309) performs filtering processing of the color shift value in the sub-scanning direction on the color component data of the pixel of interest output from the CIS (101) (abstract).

[0005] However, if the speed of movement of the CIS (101) in the sub-scanning direction changes, an error may occur in the correction results of the color component data between the colors, which may result in a decrease in quality when the color component data is subsequently combined to generate a single image.

[0006] The present invention has been developed in consideration of the above circumstances, and aims to provide a technology that can suppress errors between each color of color component data output from an imaging device when the printing medium is moved and imaged with an imaging device, even when the movement speed of the printing medium changes. [Means for solving the problem]

[0007] In order to solve the above problem, a first invention of the present application is an imaging device having a transport mechanism, an encoder, a first color reading element, a second color reading element, a buffer, a first color averaging processing unit, and a second color averaging processing unit. The transport mechanism transports a print medium along a transport path. The encoder outputs a pulse signal according to a transport speed of the print medium transported by the transport mechanism. The first color reading element captures an image of the print medium at a first imaging position on the transport path at a constant period of imaging timing based on a drive signal generated at a constant period of imaging timing, thereby outputting a first color reading signal that is a first color component at the constant period of imaging timing. The second color reading element captures an image of the print medium at a second imaging position downstream of the first imaging position on the transport path at the constant period of imaging timing, thereby outputting a second color reading signal that is a second color component at the constant period of imaging timing. The buffer is capable of storing a plurality of the first color read signals output by the first color read element and a plurality of the second color read signals output by the second color read element. The first color averaging processing unit averages the plurality of the first color read signals stored in the buffer with a weight according to a time lag between a first carrier signal based on the pulse signal and the drive signal. The second color averaging processing unit averages the plurality of the second color read signals stored in the buffer with a weight according to a time lag between a second carrier signal based on the pulse signal and the drive signal.

[0008] A second invention of the present application is the imaging device of the first invention, further comprising a third color reading element that outputs a third color reading signal, which is a third color component, at the constant period by imaging the print medium at a third imaging position downstream of the second imaging position on the transport path at the constant period imaging timing. The buffer is further capable of storing a plurality of the third color reading signals output by the third color reading element. The imaging device further comprises a third color averaging processing unit that averages the plurality of the third color reading signals stored in the buffer with a weight according to a time lag between a third transport signal based on the pulse signal and the drive signal.

[0009] A third invention of the present application is the imaging device of the second invention, further comprising an image data output unit that outputs an image obtained by superimposing a signal averaged by the first color averaging processing unit, a signal averaged by the second color averaging processing unit, and a signal averaged by the third color averaging processing unit to an external device that inspects the image. The first transport signal based on the pulse signal is a pulsed time series signal that rises every time the print medium is transported on the first imaging position by a distance equivalent to one pixel indicated by the resolution required for the inspection in the external device. The second transport signal based on the pulse signal is a pulsed time series signal that rises every time the print medium is transported on the second imaging position by a distance equivalent to one pixel indicated by the resolution required for the inspection in the external device. The third transport signal based on the pulse signal is a pulsed time series signal that rises every time the print medium is transported on the third imaging position by a distance equivalent to one pixel indicated by the resolution required for the inspection in the external device.

[0010] The fourth invention of the present application is an imaging device of the second or third invention, having a line sensor including a plurality of the first color reading elements arranged in the width direction of the printing medium, a plurality of the second color reading elements arranged in the width direction, and a plurality of the third color reading elements arranged in the width direction. Effect of the Invention

[0011] According to the first to fourth aspects of the present application, while conveying the print medium, a plurality of read signals obtained by capturing images with a plurality of reading elements at a plurality of image capturing positions can be appropriately averaged while referring to the pulse signal output from the encoder for each color. This makes it possible to suppress errors caused by shifts in the image capturing positions between the signals of each color after averaging, even if the conveying speed of the print medium changes. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram conceptually illustrating a configuration of a printing device. [Diagram 2] FIG. 4 is a view of the line sensor as viewed from below. [Diagram 3] 1 is a graph showing a first carrier signal, a second carrier signal, a third carrier signal, and a drive signal SC in time series, and arranged in parallel. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the components described in the embodiment are merely examples, and are not intended to limit the scope of the present invention. In addition, in the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary for ease of understanding.

[0014] <1. Printer configuration> FIG. 1 is a conceptual diagram showing the configuration of a printing device 1 according to an embodiment of the present invention. While conveying a print medium 9, the printing device 1 ejects ink droplets onto the print medium 9 using an inkjet method to record characters and images (hereinafter referred to as "image M1") on a print surface 91 of the print medium 9. In this example, the print medium 9 is in the form of a long strip (web). For example, printing paper, a resin film, or a metal foil is used as the print medium 9. As shown in FIG. 1, the printing device 1 has a conveying mechanism 10, a printing unit 20, an encoder 30, a print control unit 40, and an imaging device 50. It should be noted that the conveying mechanism 10 and the encoder 30 can also be interpreted as being included in the imaging device 50.

[0015] The transport mechanism 10 continuously transports the print medium 9 from the upstream side to the downstream side in a roll-to-roll manner along a specified transport path. The transport mechanism 10 has multiple rollers including an unwind roller 11, multiple transport rollers 12, and a take-up roller 13. The unwind roller 11, the multiple transport rollers 12, and the take-up roller 13 are each rotatable about an axis parallel to a width direction Y that is perpendicular and horizontal to a transport direction X of the print medium 9. The print medium 9 is stretched across these multiple rollers under tension. This prevents the print medium 9 from sagging or wrinkling during transport.

[0016] The transport mechanism 10 also has a motor (not shown) that rotates at least one roller (hereinafter referred to as a "drive roller") among the unwind roller 11, the multiple transport rollers 12, and the wind roller 13. By driving the motor, the rollers 11, 12, and 13, including the drive roller, rotate about an axis parallel to the width direction Y of the print medium 9. As a result, the unwind roller 11 continuously unwinds the print medium 9 wound in a roll on the outer circumferential surface of the unwind roller 11. The multiple transport rollers 12 are each located at a specified position on the transport path. Each transport roller 12 transports the print medium 9 unwound from the unwind roller 11 in the transport direction X while supporting the print medium 9 from the back surface 92 side opposite to the printing surface 91. The wind roller 13 winds up the print medium 9 hung on each transport roller 12 into a roll and collects it.

[0017] The printing unit 20 prints an image M1 on a printing surface 91 of the printing medium 9 transported by the transport mechanism 10. The printing unit 20 has a plurality of print heads 21 that eject ink droplets. In this example, a print head 21 that ejects black (K) ink droplets, a print head 21 that ejects cyan (C) ink droplets, a print head 21 that ejects M (magenta) ink droplets, and a print head 21 that ejects yellow (Y) ink droplets are arranged at intervals from each other along the transport direction X. The four print heads 21 have the same structure. The printing medium 9 moves below the four print heads 21, approximately parallel to the arrangement direction of the four print heads 21. At this time, the printing surface 91 of the printing medium 9 faces the print head 21 side. That is, the printing surface 91 of the printing medium 9 faces upward.

[0018] The color of ink ejected by each print head 21 can be changed as desired. Furthermore, the printing unit 20 may have a print head 21 that ejects ink droplets of a color other than K, C, M, and Y. Furthermore, the number of print heads 21 that the printing unit 20 has may be one.

[0019] A plurality of ejection nozzles (not shown) that eject ink droplets are arranged on the surface of the print head 21 that faces the printing surface 91 of the print medium 9. The multiple ejection nozzles are arranged in a width direction Y that is perpendicular to the transport direction X. The range in which the print head 21 can eject ink droplets (printable range) covers the entire width direction Y of the print medium 9. The printing device 1 is a so-called single-pass type printing device that ejects ink droplets from each print head 21 to print an image M1 on the print medium 9 while the print medium 9 passes under the multiple print heads 21 only once.

[0020] The encoder 30 is a sensor for detecting the transport speed of the print medium 9. The encoder 30 is attached to the axis of one of the multiple transport rollers 12 (the transport roller 121 in FIG. 1). The encoder 30 outputs a pulse signal En once every time the transport roller 121 rotates a predetermined angle. That is, the encoder 30 outputs a pulse signal En according to the transport speed of the print medium 9 transported by the transport mechanism 10. Therefore, the pulse signal En becomes data reflecting the change over time in the transport speed of the print medium 9 transported by the multiple transport rollers 12 including the transport roller 121.

[0021] The pulse signal En is input from the encoder 30 to the print control unit 40 and a timing signal generating unit 55 (described later) of the imaging device 50. However, the encoder 30 only needs to be directly or indirectly connected to at least one of the multiple conveying rollers 12, and the connection destination is not limited to the conveying roller 121.

[0022] The print control unit 40 controls the print unit 20. The print control unit 40 is, for example, a computer equipped with a processor such as a CPU, a memory such as a RAM, and an auxiliary storage device such as a hard disk drive. The print control unit 40 may be configured with a dedicated electronic circuit such as an application specific integrated circuit (ASIC).

[0023] When the pulse signal En is input from the encoder 30, the print control unit 40 specifies the position on the print medium 9 where the image M1 is to be printed based on the pulse signal En. Then, the print control unit 40 controls the ejection of ink droplets from each nozzle of each print head 21 based on information related to the image M1 and information related to the position on the print medium 9 where the image M1 is to be printed.

[0024] As a result, each of the four print heads 21 ejects droplets of each color of ink onto an appropriate position in the transport direction X of the print medium 9. As a result, each of the four print heads 21 records a single-color image onto an appropriate location on the print surface 91 of the print medium 9. Then, a high-quality multi-color image is formed on the print surface 91 of the print medium 9 by superimposing the four single-color images.

[0025] The imaging device 50 captures an image M1 printed on a print medium 9 and outputs image data DM to an inspection device 8, which is an external device. The imaging device 50 has a computer equipped with, for example, a processor such as a CPU, a memory such as a RAM, and an auxiliary storage device such as a hard disk drive. The imaging device 50 reads out computer programs and data stored in the auxiliary storage device into the memory, and operates the processor in accordance with the computer programs and data. This allows the imaging device 50 to proceed with the processing steps.

[0026] The inspection device 8 is a device that inspects whether the image M1 has been printed correctly by, for example, comparing the image data DM output from the imaging device 50 with a reference image. The inspection device 8 may also be a device that checks the presence or absence of density unevenness and the color of the image M1. In other words, the inspection device 8 may be an external device that inspects the image M1.

[0027] 2. Detailed configuration and processing steps of the imaging device Next, a detailed configuration of the imaging device 50 and a processing step performed by the imaging device 50 will be described. As shown in FIG. 1, the imaging device 50 of this embodiment has a drive signal generating section 51, a line sensor 52, a buffer 53, an image data output section 54, a timing signal generating section 55, an average number generating section 56, a first color averaging processing section 571, a second color averaging processing section 572, and a third color averaging processing section 573. The drive signal generating section 51, the image data output section 54, the timing signal generating section 55, the average number generating section 56, the first color averaging processing section 571, the second color averaging processing section 572, and the third color averaging processing section 573 are part of the functions of the imaging device 50, and are configured by hardware (FPGA, etc.) configured by logic circuits such as dedicated circuits. The functions of the above-mentioned sections may be realized by software by a general-purpose processor such as a CPU executing a program.

[0028] The drive signal generating unit 51 generates a pulsed drive signal SC at a constant period T1. The drive signal SC is a signal for driving the line sensor 52 to capture an image M1 printed on the print medium 9. As shown in Fig. 1, the drive signal SC is input to both the line sensor 52 and the average number generating unit 56 at the constant period T1.

[0029] The line sensor 52 is a device for capturing an image M1 printed on the print medium 9. The range that the line sensor 52 can capture covers the entire width direction Y of the print medium 9. A contact image sensor (CIS) is used for the line sensor 52 in this embodiment. FIG. 2 is a view of the line sensor 52 as viewed from below. In FIG. 2, the print medium 9 is shown by a virtual line (two-dot chain line). As shown in FIG. 2, a plurality of first color reading elements 521, a plurality of second color reading elements 522, and a plurality of third color reading elements 523 are arranged on the lower surface of the line sensor 52.

[0030] The multiple first color reading elements 521 are each arranged in a line in the width direction Y of the print medium 9 at a first imaging position P1 on the transport path. The multiple second color reading elements 522 are each arranged in a line in the width direction Y of the print medium 9 at a second imaging position P2 downstream of the first imaging position P1 on the transport path. The multiple third color reading elements 523 are each arranged in a line in the width direction Y of the print medium 9 at a third imaging position P3 downstream of the second imaging position P2 on the transport path.

[0031] That is, the line sensor 52 includes a plurality of first color reading elements 521 arranged in the width direction Y of the printing medium 9, a plurality of second color reading elements 522 arranged in the width direction Y of the printing medium 9, and a plurality of third color reading elements 523 arranged in the width direction Y of the printing medium 9. The plurality of first color reading elements 521, the plurality of second color reading elements 522, and the plurality of third color reading elements 523 are arranged at intervals from one another in the transport direction X. Each of the first color reading elements 521, each of the second color reading elements 522, and each of the third color reading elements 523 is a CCD or a CMOS.

[0032] Each first color reading element 521 can read red (R) light, which is a first color component of visible light. When a drive signal SC is input from the drive signal generating unit 51, each first color reading element 521 captures an image of the print medium 9 at a first imaging position P1 on the transport path at an imaging timing of a fixed period T2. As a result, each first color reading element 521 optically reads red (R), which is a first color component, of the image M1 on the print medium 9, and outputs a first color reading signal S1 relating to the read red (R) to the buffer 53 at the fixed period T2.

[0033] That is, each first color reading element 521 captures an image of the print medium 9 at a first imaging position P1 on the transport path at an imaging timing of a fixed period T2 based on a drive signal SC generated at the fixed period T1, thereby outputting a first color reading signal S1, which is a first color component, at the fixed period T2. Note that the first color reading signal S1 is data indicating the luminance value of the red (R) component of the image M1 on the print medium 9 at the first imaging position P1.

[0034] Each second color reading element 522 is capable of reading green (G) light, which is a second color component of visible light. When a drive signal SC is input from the drive signal generating unit 51, each second color reading element 522 captures an image of the print medium 9 at a second imaging position P2 on the transport path at an imaging timing of a constant period T2. As a result, each second color reading element 522 optically reads green (G), which is a second color component, of the image M1 on the print medium 9, and outputs a second color reading signal S2 relating to the read green (G) to the buffer 53 at the constant period T2.

[0035] That is, each second color reading element 522 captures an image of the print medium 9 at a second imaging position P2 downstream of the first imaging position P1 on the transport path at an imaging timing of a constant period T2 based on a drive signal SC generated at the constant period T1, thereby outputting a second color reading signal S2, which is a second color component, at the constant period T2. Note that the second color reading signal S2 is data indicating the luminance value of the green (G) component of the image M1 on the print medium 9 at the second imaging position P2.

[0036] Each third color reading element 523 is capable of reading blue (B) light, which is a third color component of visible light. When a drive signal SC is input from the drive signal generating unit 51, each third color reading element 523 captures an image of the print medium 9 at a third imaging position P3 on the transport path at an imaging timing of a constant period T2. As a result, each third color reading element 523 optically reads blue (B), which is a third color component, of the image M1 on the print medium 9, and outputs a third color reading signal S3 relating to the read blue (B) to the buffer 53 at the constant period T2.

[0037] That is, each third color reading element 523 captures an image of the print medium 9 at a third imaging position P3 downstream of the second imaging position P2 on the transport path at an imaging timing of a constant period T2 based on a drive signal SC generated at the constant period T1, thereby outputting a third color reading signal S3, which is a third color component, at the constant period T2. Note that the third color reading signal S3 is data indicating the luminance value of the blue (B) component of the image M1 on the print medium 9 at the third imaging position P3.

[0038] That is, the multiple first color reading elements 521, the multiple second color reading elements 522, and the multiple third color reading elements 523 capture images of the print medium 9 simultaneously and at a constant period T2, and output the first color reading signal S1, the second color reading signal S2, and the third color reading signal S3 to the buffer 53. Note that the constant period T2 can also be considered to be substantially simultaneous with the constant period T1 at which the drive signal generation unit 51 generates the drive signal SC.

[0039] For example, a semiconductor memory is used for the buffer 53. The buffer 53 can temporarily store the first color reading signals S1 output by the first color reading elements 521, the second color reading signals S2 output by the second color reading elements 522, and the third color reading signals S3 output by the third color reading elements 523.

[0040] The image data output unit 54 outputs the image data DM to an external device, that is, an inspection device 8. As will be described in detail later, the image data DM is image data obtained by averaging a plurality of first color read signals S1, a plurality of second color read signals S2, and a plurality of third color read signals S3, and then superimposing the averaged signals.

[0041] Here, the inspection resolution of the inspection device 8 of this embodiment is, for example, 600 dpi. That is, the length of one pixel indicated by the inspection resolution is 42.3 μm (= 25.4 mm / 600 dpi). Therefore, to inspect an image in the inspection device 8, imaging data relating to an image for each length of (1 pixel =) 42.3 μm is required.

[0042] Therefore, the timing signal generating unit 55 first identifies the position of the print medium 9 based on the pulse signal En input from the encoder 30. Then, the timing signal generating unit 55 generates a pulse-like signal (see "signal Rmain" in FIG. 3) every time the print medium 9 is transported a distance of (1 pixel =) 42.3 μm in the transport direction X below the line sensor 52. However, in the present invention, the timing signal generating unit 55 generates a different pulse-like signal each time the print medium 9 is transported a distance of (1 pixel =) 42.3 μm in the transport direction X through each of the multiple imaging positions P1 to P3. A specific description will be given below.

[0043] First, the timing signal generating unit 55 generates a pulsed first conveying signal Rsub1 every time the print medium 9 is conveyed a distance of (1 pixel =) 42.3 μm in the conveying direction X above the first imaging position P1 based on the pulse signal En input from the encoder 30, and outputs the signal to the average number generating unit 56 (see FIG. 3). That is, the first conveying signal Rsub1 based on the pulse signal En is a pulsed time series signal that rises every time the print medium 9 is conveyed a distance equivalent to 1 pixel indicated by the resolution required for inspection in the inspection device 8 above the first imaging position P1.

[0044] Furthermore, the timing signal generating unit 55 generates a pulsed second conveying signal Rsub2 each time the print medium 9 is conveyed a distance of (1 pixel =) 42.3 μm in the conveying direction X above the second imaging position P2 based on the pulse signal En input from the encoder 30, and outputs the generated signal to the average number generating unit 56 (see FIG. 3). That is, the second conveying signal Rsub2 based on the pulse signal En is a pulsed time series signal that rises each time the print medium 9 is conveyed a distance equivalent to 1 pixel indicated by the resolution required for inspection in the inspection device 8 above the second imaging position P2.

[0045] Furthermore, the timing signal generating unit 55 generates a pulsed third transport signal Rsub3 every time the print medium 9 is transported a distance of (1 pixel =) 42.3 μm in the transport direction X above the third imaging position P3 based on the pulse signal En input from the encoder 30, and outputs the generated signal to the average number generating unit 56 (see FIG. 3). That is, the third transport signal Rsub3 based on the pulse signal En is a pulsed time series signal that rises every time the print medium 9 is transported a distance equivalent to 1 pixel indicated by the resolution required for inspection in the inspection device 8 above the third imaging position P3.

[0046] 3 is a graph showing in time series the first carrier signal Rsub1, the second carrier signal Rsub2, and the third carrier signal Rsub3 output from the timing signal generating unit 55, and the drive signal SC output from the drive signal generating unit 51, and arranging them in parallel. Note that in FIG. 3, the above-mentioned signal Rmain is also shown for comparison.

[0047] As described above, in order to inspect an image using the inspection device 8, imaging data relating to an image for each length of 42.3 μm (1 pixel) is required. For this reason, it is conceivable to image the image M1 at the rising timing of each pulse of the first carrier signal Rsub1, the second carrier signal Rsub2, and the third carrier signal Rsub3, and output each read signal S1 to S3. However, in reality, the first color reading elements 521, the second color reading elements 522, and the third color reading elements 523 image the print medium 9 simultaneously and at a constant period T2 different from the inspection resolution based on the drive signal SC, and output the first color reading signal S1, the second color reading signal S2, and the third color reading signal S3.

[0048] Therefore, the average number generation unit 56 counts the number of times n1(t) that the drive signal SC is input from the drive signal generation unit 51 between a certain pulse Rsub1(p) and the next pulse Rsub1(p+1) in the first carrier signal Rsub1, and outputs the result as time-series data to the first color averaging processing unit 571. The average number generation unit 56 sequentially outputs the count result of the number of times n1(t) to the first color averaging processing unit 571 every time the first carrier signal Rsub1 is input. In the example of FIG. 3, the drive signal SC is input three times, 1 to 3, between the pulse Rsub1(p) and the next pulse Rsub1(p+1), so the number of times n1(t)=3.

[0049] Furthermore, the average number generation unit 56 counts the number of times n2(t) that the drive signal SC is input from the drive signal generation unit 51 between a certain pulse Rsub2(q) and the next pulse Rsub2(q+1) in the second carrier signal Rsub2, and outputs the result as time-series data to the second color averaging processing unit 572. The average number generation unit 56 sequentially outputs the count result of the number of times n2(t) to the second color averaging processing unit 572 every time the second carrier signal Rsub2 is input. In the example of FIG. 3, the drive signal SC is input 2 to 5 times, four times between the pulse Rsub2(q) and the next pulse Rsub2(q+1), so the number of times n2(t)=4.

[0050] The average number generation unit 56 also counts the number of times n3(t) that the drive signal SC is input from the drive signal generation unit 51 between a certain pulse Rsub3(r) and the next pulse Rsub3(r+1) (not shown) in the third carrier signal Rsub3, and outputs the result as time-series data to the third color averaging processing unit 573. The average number generation unit 56 sequentially outputs the count result of the number of times n3(t) to the third color averaging processing unit 573 every time the third carrier signal Rsub3 is input.

[0051] Next, when the first color averaging processing unit 571 receives the number of times n1(t) from the average number generating unit 56, it reads out from the buffer 53 a plurality of first color read signals S1 accumulated in the period between the pulse Rsub1(p) and the next pulse Rsub1(p+1), adds them together, and divides the sum by the number of times n1(t). In the example of FIG. 3, the first color averaging processing unit 571 divides the sum of the plurality of first color read signals S1 accumulated in the period between the pulse Rsub1(p) and the next pulse Rsub1(p+1) by (number of times n1(t)=)3. Then, it outputs the first color average signal S1m, which is the result of the division, to the image data output unit 54.

[0052] That is, the first color averaging processor 571 averages the multiple first color read signals S1 stored in the buffer 53 with a weight according to the time lag between the first conveyance signal Rsub1 based on the pulse signal En and the drive signal SC. The first color average signal S1m is the average value of the first color read signals S1 indicating the luminance value of the red (R) component in the image M1 read by the multiple first color reading elements 521 while the print medium 9 is conveyed a distance equivalent to one pixel on the first imaging position P1.

[0053] Furthermore, when the second color averaging processing unit 572 receives the number of times n2(t) from the average number generating unit 56, it reads out from the buffer 53 a plurality of second color read signals S2 accumulated in the period between the pulse Rsub2(q) and the next pulse Rsub2(q+1), adds them together, and divides them by the number of times n2(t). In the example of FIG. 3, the second color averaging processing unit 572 divides the plurality of second color read signals S2 accumulated in the period between the pulse Rsub2(q) and the next pulse Rsub2(q+1) by (number of times n2(t)=)4. Then, it outputs the second color average signal S2m, which is the result of the division, to the image data output unit 54.

[0054] That is, the second color averaging processor 572 averages the multiple second color read signals S2 stored in the buffer 53 with a weight according to the time lag between the second carry signal Rsub2 based on the pulse signal En and the drive signal SC. The second color average signal S2m is the average value of the second color read signals S2 indicating the luminance value of the green (G) component in the image M1 read by the multiple second color reading elements 522 while the print medium 9 is carried a distance equivalent to one pixel on the second imaging position P2.

[0055] Furthermore, when the third color averaging processing unit 573 receives the number of times n3(t) from the average number generating unit 56, it reads out from the buffer 53 a plurality of third color read signals S3 accumulated in the period between the pulse Rsub3(r) and the next pulse Rsub3(r+1), adds them together, and divides the sum by the number of times n3(t).Then, it outputs the third color average signal S3m, which is the result of the division, to the image data output unit 54.

[0056] That is, the third color averaging processor 573 averages the multiple third color read signals S3 stored in the buffer 53 with a weight according to the time lag between the third conveyance signal Rsub3 based on the pulse signal En and the drive signal SC. The third color average signal S3m is the average value of the third color read signals S3 indicating the luminance value of the blue (B) component in the image M1 read by the multiple third color reading elements 523 while the print medium 9 is conveyed a distance equivalent to one pixel on the third imaging position P3.

[0057] The image data output unit 54 generates image data DM by adding together the first color average signal S1m input from the first color averaging processing unit 571, the second color average signal S2m input from the second color averaging processing unit 572, and the third color average signal S3m input from the third color averaging processing unit 573. Then, the image data output unit 54 outputs the generated image data DM to the inspection device 8, which is an external device. That is, the image data output unit 54 outputs image data DM relating to an image obtained by superimposing the first color average signal S1m, which is a signal averaged by the first color averaging processing unit 571, the second color average signal S2m, which is a signal averaged by the second color averaging processing unit 572, and the third color average signal S3m, which is a signal averaged by the third color averaging processing unit 573, to the inspection device 8, which is an external device that inspects the image M1.

[0058] As described above, the image according to the image data DM is generated by adding together the average value of the first color read signal S1 read while the image M1 printed on the printing medium 9 is transported a distance equivalent to one pixel on the first imaging position P1, the average value of the second color read signal S2 read while the image M1 is transported a distance equivalent to one pixel on the second imaging position P2, and the average value of the third color read signal S3 read while the image M1 is transported a distance equivalent to one pixel on the third imaging position P3. That is, in the printing device 1 of this embodiment, while transporting the printing medium 9, the printing medium 9 can be appropriately averaged by referring to the pulse signal En output from the encoder 30 for each color by capturing images of the multiple read signals S1 to S3 at the multiple imaging positions P1 to P3.

[0059] Therefore, even if the transport speed of the print medium 9 on which the image M1 is printed changes while it is transported between the imaging positions P1 to P3, the effect of this on the multiple read signals S1 to S3 can be suppressed. As a result, it is possible to suppress the occurrence of errors caused by the shifting of the imaging positions P1 to P3 among the signals S1m to S3m of each color after the averaging process. Therefore, a high-quality image can be obtained by superimposing the signals S1m to S3m of each color after the averaging process.

[0060] <3. Modifications> Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0061] In the above embodiment, the encoder 30 is used as a sensor for detecting the transport speed and transport amount of the print medium 9. However, instead of using the encoder 30, for example, marks recorded at predetermined intervals on the print medium 9 may be read by a camera or the like, and the transport speed and transport amount per unit time of the print medium 9 may be calculated based on the reading time.

[0062] Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate to the extent that no contradiction arises. [Explanation of symbols]

[0063] 1 Printing device 8. Inspection Equipment 9 Print media 10. Conveyor mechanism 12 Transport roller 20 Printing Department 30 Encoder 40 Printing control unit 50 Imaging device 51 Drive signal generator 52 Line sensor 53 Buffer 54 Image data output section 55 Timing signal generator 56 Average number generation unit 91 (printed media) printed surface 121 Transport roller 521 First color reading element 522 Second color reading element 523 Third color reading element 571 First color averaging processing section 572 Second color averaging processing section 573 Third color averaging processing section DM (image data output to external device) En Pulse signal M1 (printed on print media) image P1 First imaging position P2 Second imaging position P3 3rd imaging position Rmain (reference) signal Rsub1 1st carrier signal Rsub2 Second carrier signal Rsub3 3rd carrier signal S1 1st color reading signal S1m 1st color average signal S2 Second color reading signal S2m 2nd color average signal S3 3rd color reading signal S3m 3rd color average signal SC drive signal T1 (generates the drive signal) T2 (image of print media) fixed period X (print media) transport direction Y (width of print media) n1~n3 (number of times the drive signal is input)

Claims

1. 1. An imaging device, comprising: a transport mechanism that transports the print medium along a transport path; an encoder that outputs a pulse signal corresponding to a transport speed of the print medium transported by the transport mechanism; a first color reading element that captures an image of the print medium at a first imaging position on the transport path at a constant imaging timing based on a drive signal generated at the constant period, and outputs a first color reading signal that is a first color component at the constant period; a second color reading element that captures an image of the print medium at a second imaging position downstream of the first imaging position on the transport path during the constant period of imaging timing, thereby outputting a second color reading signal that is a second color component at the constant period of imaging timing; a buffer capable of storing a plurality of the first color reading signals output by the first color reading element and a plurality of the second color reading signals output by the second color reading element; a first color averaging processing unit that averages the plurality of first color read signals stored in the buffer with a weight according to a time difference between a first carrier signal based on the pulse signal and the drive signal; a second color averaging processing unit that averages the plurality of second color read signals stored in the buffer with a weight according to a time difference between a second carrier signal based on the pulse signal and the drive signal; An imaging device comprising:

2. 2. The imaging device according to claim 1, a third color reading element that captures an image of the print medium at a third imaging position downstream of the second imaging position on the transport path during the constant period of imaging timing, thereby outputting a third color reading signal that is a third color component at the constant period of imaging timing. and the buffer is further capable of storing a plurality of the third color reading signals outputted by the third color reading element; a third color averaging processing unit that averages the third color read signals stored in the buffer with a weight according to a time difference between a third carrier signal based on the pulse signal and the drive signal; The imaging device further comprises:

3. 3. The imaging device according to claim 2, an image data output unit that outputs an image obtained by superimposing the signal averaged by the first color averaging processing unit, the signal averaged by the second color averaging processing unit, and the signal averaged by the third color averaging processing unit to an external device that inspects the image; and the first transport signal based on the pulse signal is a pulsed time series signal that rises each time the print medium is transported over the first imaging position by a distance equivalent to one pixel indicated by a resolution required for the inspection in the external device, the second transport signal based on the pulse signal is a pulsed time series signal that rises each time the print medium is transported over the second imaging position by a distance equivalent to one pixel indicated by a resolution required for the inspection in the external device, An imaging device, wherein the third transport signal based on the pulse signal is a pulsed time series signal that rises each time the printing medium is transported over the third imaging position a distance equivalent to one pixel indicated by the resolution required for the inspection in the external device.

4. 4. The imaging device according to claim 2, An imaging device having a line sensor including a plurality of the first color reading elements arranged in a width direction of the printing medium, a plurality of the second color reading elements arranged in the width direction, and a plurality of the third color reading elements arranged in the width direction.

Images