JP4292741B2 - Printing apparatus, dot formation determination method, computer program, recording medium, and computer system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printing apparatus, a dot formation determination method, a computer program, a recording medium, and a computer system.
[0002]
[Background]
A color inkjet printer, which is a typical printing apparatus, is already well known. This color ink jet printer includes an ink jet print head that ejects ink from nozzles, and is configured to record images, characters, and the like by landing ink droplets on printing paper as an example of a printing medium. Yes.
[0003]
The print head is supported by the carriage with the nozzle surface on which the nozzles are formed facing the print paper, and moves (main scan) in the width direction of the print paper along the guide member. Ink droplets are ejected in synchronization with.
[0004]
By the way, there are cases where the nozzles formed on the print head are clogged and ink droplets cannot be ejected due to an increase in the viscosity of the ink or mixing of bubbles. When the nozzles are clogged, so-called dot dropout occurs in the image, causing deterioration in image quality.
[0005]
Therefore, a function for inspecting whether or not dots are formed normally by ejecting ink droplets is required.
[0006]
Several methods have been proposed to realize such a function. Printing is performed on printing paper, light emitted from a light emitting diode or the like is applied to the printing paper, and the reflected light reflected by the printing paper is applied to the photodiode. Whether or not dots are formed normally by comparing the output value of the light receiving sensor corresponding to the intensity of the reflected light received with a threshold value. There is a method to judge. In other words, even if the same intensity of light is applied, it is possible to utilize the fact that the intensity of the reflected light received is different between the location where the dot formation is normally performed on the printing paper and the location where the dot formation is not performed normally. It is determined whether or not dot formation has been performed normally.
[0007]
By the way, as an event to be noted in carrying out this method, there is a change (or fluctuation) in the intensity of reflected light received. Whether the change in the intensity of the reflected light is basically reflected light reflected from a place where dots are formed normally or reflected light from a place where dots are not formed normally. Regardless of whether they occur.
[0008]
There are several possible causes of the change in the intensity of the reflected light. First, there is a fluctuation in the intensity of emitted light. In accordance with such fluctuation, the intensity of the corresponding reflected light also fluctuates.
[0009]
Next, there is an error due to an error in the mounting position of a light emitting unit such as a light emitting diode or a light receiving unit such as a phototransistor. When the color inkjet printer is manufactured, it may not be installed as designed, or the mounting position may change over time.
[0010]
Next, there is a change in the type of printing paper. The color and the like differ slightly for each type of printing paper, and this changes the intensity of reflected light. Other factors include environmental changes and the generation of ambient light.
[0011]
The change in the intensity of the reflected light is such that the predetermined threshold value is the output value of the light receiving sensor corresponding to the intensity of the reflected light reflected by the place where the dot formation was normally performed, and the dot formation is normal. Since the output value of the light receiving sensor depending on the intensity of the reflected light reflected by the part that was not performed in the first step will not be between, it may interfere with the determination of missing dots. Generally, it is performed to absorb the change in the intensity of reflected light by adjusting the intensity of light emitted just before testing whether or not the light is emitted.
[0012]
However, in order to realize such an adjustment function, it is necessary to provide a circuit for controlling the intensity of emitted light, resulting in disadvantages such as a complicated circuit and a cost increase.
[0013]
[Problems to be solved by the invention]
The present invention has been made in view of such problems, and the object thereof is to more easily adjust the intensity of reflected light received by the light receiving sensor, a dot formation determination method, a computer program, and a recording. To realize a medium and a computer system.
[0014]
[Means for Solving the Problems]
  The main aspect of the present invention is that printing is performed by forming dots on a substrate by a print head, light is emitted toward the substrate, and reflected light of the emitted light by the substrate is received by a light receiving sensor. In a printing apparatus that receives light and determines whether or not the dot has been formed normally by comparing the output value of the light receiving sensor according to the intensity of the received reflected light with a threshold value,According to the thickness of the printing medium, it has means for changing the distance between the printing head and the printing medium,Change the distance between the light receiving sensor and the substrateLet meThe printing apparatus is characterized in that the intensity of reflected light received by the light receiving sensor is adjusted.
[0015]
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
=== Summary of disclosure ===
At least the following will be made clear by the description of the present specification and the accompanying drawings.
[0017]
  Printing is performed by forming dots on the printing medium with the print head, and light is emitted toward the printing medium. The light reflected by the printing medium is received by the light receiving sensor and received. In a printing apparatus that determines whether or not the dot has been formed normally by comparing the output value of the light receiving sensor according to the intensity of reflected light with a threshold value,According to the thickness of the printing medium, it has means for changing the distance between the printing head and the printing medium,The distance between the light receiving sensor and the substrate to be printed is changed.TheA printing apparatus that adjusts the intensity of reflected light received by the light receiving sensor.
[0018]
  By adjusting the intensity of the reflected light received by the light receiving sensor by changing the distance between the light receiving sensor and the printing material, it is not always necessary to control the intensity of the emitted light, and the light can be easily received. The intensity of the reflected light received by the sensor can be adjusted.In this way, a plurality of functions are realized with a single configuration, and effective use of resources held by the printing apparatus is achieved.
[0019]
  Further, the threshold value is an output value of the light receiving sensor according to the intensity of reflected light reflected by a place where the dot formation is normally performed on the printing medium, and the dot formation on the printing medium. To be between the output values of the light receiving sensor according to the intensity of the reflected light reflected by the location that was not normally performed,The intensity of the reflected light received by the light receiving sensor is adjusted by changing the distance between the light receiving sensor and the substrate.It is good as well.
[0020]
In this way, it is not always necessary to change the threshold value, and it is possible to reliably determine whether or not dot formation has been performed normally.
[0021]
  In addition, the threshold value includes a first output value of the light receiving sensor corresponding to the intensity of reflected light reflected by a portion where dot formation has been normally performed on the printing medium, and a dot with respect to the printing medium. Before the printing, the second output value that is between the second output values of the light receiving sensor according to the intensity of the reflected light reflected by the place where the formation of the light is not normally performed is previously set. The second output value stored in accordance with the intensity of the reflected light reflected by the portion of the light emitted toward the portion where the dot formation is not performed on the printing medium. Output value of the light receiving sensorThe intensity of the reflected light received by the light receiving sensor is adjusted by changing the distance between the light receiving sensor and the substrate to be equalized.It is good as well.
[0022]
In this way, it is possible to easily adjust the intensity of the reflected light received by the light receiving sensor without being aware of the cause of the change in the intensity of the reflected light.
[0025]
Moreover, it is good also as ejecting ink from the said print head and forming a dot in the said to-be-printed body.
[0026]
In a so-called ink jet printing apparatus that performs printing by ejecting ink from a print head, a high image quality of the printing result is particularly required, so that the merit of the above means is further increased.
[0029]
  Printing is performed by forming dots on the printing medium with a print head, emitting light toward the printing medium, and light reflected by the printing medium is received by a light receiving sensor. And comparing the output value of the light receiving sensor according to the intensity of the received reflected light with a threshold value to determine whether the dot formation has been performed normally, In the dot formation determination method for determining whether or not it has been performed,By changing the distance between the print head and the printing body according to the thickness of the printing bodyChanging the distance between the light receiving sensor and the substrate to be printed;TheThe dot formation determination method may be characterized in that the intensity of reflected light received by the light receiving sensor is adjusted.
[0030]
By adjusting the intensity of the reflected light received by the light receiving sensor by changing the distance between the light receiving sensor and the printing material, it is not always necessary to control the intensity of the emitted light, and the light can be easily received. The intensity of the reflected light received by the sensor can be adjusted.
[0031]
It is also possible to realize a computer program for causing the printing apparatus to execute the above dot formation determination method.
[0032]
It is also possible to realize a computer-readable recording medium on which a computer program for causing the printing apparatus to execute the above dot formation determination method is recorded.
[0033]
It is also possible to realize a computer system having a computer apparatus and the above-described printing apparatus connectable to the computer apparatus main body.
[0034]
=== Example of Overall Configuration of Apparatus ===
FIG. 1 is a block diagram showing a configuration of a printing system as an example of the present invention. This printing system includes a computer 90 and a color inkjet printer 20 as an example of a printing apparatus. The printing system including the color inkjet printer 20 and the computer 90 can also be called a “printing apparatus” in a broad sense. Although not shown, from the computer 90, the color inkjet printer 20, a display device such as a CRT 21 or a liquid crystal display device, an input device such as a keyboard or a mouse, a drive device such as a flexible drive device or a CD-ROM drive device, or the like. A computer system has been built.
[0035]
In the computer 90, an application program 95 operates under a predetermined operating system. A video driver 91 and a printer driver 96 are incorporated in the operating system, and print data PD to be transferred to the color inkjet printer 20 is output from the application program 95 via these drivers. The application program 95 that performs image retouching or the like performs desired processing on the image to be processed, and displays an image on the CRT 21 via the video driver 91.
[0036]
When the application program 95 issues a print command, the printer driver 96 of the computer 90 receives the image data from the application program 95 and converts it into print data PD to be supplied to the color inkjet printer 20. The printer driver 96 includes a resolution conversion module 97, a color conversion module 98, a halftone module 99, a rasterizer 100, a user interface display module 101, a UI printer interface module 102, and a color conversion lookup table LUT. And are provided.
[0037]
The resolution conversion module 97 plays a role of converting the resolution of the color image data formed by the application program 95 into the print resolution. The image data thus converted in resolution is still image information composed of three color components of RGB. The color conversion module 98 converts RGB image data into multi-gradation data of a plurality of ink colors that can be used by the color inkjet printer 20 for each pixel while referring to the color conversion lookup table LUT.
[0038]
The color-converted multi-gradation data has, for example, 256 gradation values. The halftone module 99 performs so-called halftone processing to generate halftone image data. The halftone image data is rearranged in the order of data to be transferred to the color inkjet printer 20 by the rasterizer 100, and is output as final print data PD. The print data PD includes raster data indicating the dot formation state during each main scan and data indicating the sub-scan feed amount.
[0039]
The user interface display module 101 has a function of displaying various user interface windows related to printing, and a function of receiving user input in these windows.
[0040]
The UI printer interface module 102 has a function of interfacing between a user interface (UI) and a color inkjet printer. Interpret the command instructed by the user through the user interface and send various commands COM to the color inkjet printer, or conversely interpret the command COM received from the color inkjet printer and perform various displays on the user interface . Further, it has a function of reading a test pattern print signal TPS relating to a test pattern, which will be described later, from the hard disk 92 and supplying it to the color inkjet printer 20.
[0041]
The printer driver 96 realizes a function of transmitting / receiving various commands COM, a function of supplying the print data PD and the test pattern print signal TPS to the color inkjet printer 20, and the like. A program for realizing the function of the printer driver 96 is supplied in a form recorded on a computer-readable recording medium. Such recording media include flexible disks, CD-ROMs, magneto-optical disks, IC cards, ROM cartridges, punch cards, printed matter on which codes such as bar codes are printed, computer internal storage devices (such as RAM and ROM). A variety of computer-readable media such as a memory) and an external storage device can be used. It is also possible to download such a computer program to the computer 90 via the Internet.
[0042]
FIG. 2 is a schematic perspective view illustrating an example of a main configuration of the color inkjet printer 20. This color inkjet printer 20 includes a paper stacker 22, a paper feed roller 24 driven by a step motor (not shown), a platen 26, a carriage 28, a carriage motor 30, and a traction belt 32 driven by the carriage motor 30. And a guide rail 34 for the carriage 28. In addition, a print head 36 having a large number of nozzles and a reflective optical sensor 29 described in detail later are mounted on the carriage 28.
[0043]
The printing paper P is taken up by the paper feed roller 24 from the paper stacker 22 and fed on the surface of the platen 26 in the sub-scanning direction. The carriage 28 is pulled by a pulling belt 32 driven by a carriage motor 30 and moves in the main scanning direction along the guide rail 34. The main scanning direction is perpendicular to the sub-scanning direction. The paper feeding roller 24 also performs a paper feeding operation for supplying the printing paper P to the color ink jet printer 20 and a paper discharging operation for discharging the printing paper P from the color ink jet printer 20.
[0044]
=== Configuration Example of Reflective Optical Sensor ===
FIG. 3 is a schematic diagram for explaining an example of the reflective optical sensor 29. The reflective optical sensor 29 is attached to the carriage 28, and includes a light emitting unit 38 made of, for example, a light emitting diode and a light receiving unit 40 made of, for example, a phototransistor. Light emitted from the light emitting unit 38, that is, incident light is reflected by the printing paper P, and the reflected light is received by the light receiving unit 40 and converted into an electrical signal. And the magnitude | size of an electrical signal is measured as an output value of the light receiving sensor according to the intensity of the received reflected light.
[0045]
In the above description, as shown in the drawing, the light emitting unit 38 and the light receiving unit 40 are integrated to form a device called the reflective optical sensor 29. However, like the light emitting device and the light receiving device, respectively. A separate device may be configured.
[0046]
In the above, in order to obtain the intensity of the received reflected light, the magnitude of the electric signal is measured after converting the reflected light into an electric signal. However, the present invention is not limited to this. It is only necessary to measure the output value of the light receiving sensor according to the intensity of the reflected light.
[0047]
=== Configuration Example of Paper Gap Adjustment Mechanism ===
FIG. 4 is a schematic diagram for explaining an example of a paper gap adjusting mechanism for adjusting the paper gap. In the present specification, the “paper gap” means a gap between a print sheet as an example of a printing medium and a print head, or a gap between the print sheet and a reflective optical sensor.
[0048]
The paper gap adjusting mechanism shown in FIG. 4 includes two guide rails 34 mounted in parallel, a support block 42 that supports the guide rail 34, and an instruction block guide 43 that guides the vertical movement of the support block 42. The eccentric cam 44 that moves the support block 42 up and down by rotating to change the paper gap amount, the paper gap adjusting motor 46 that rotates the eccentric cam 44, and the eccentric cam 44 is rotated by the paper gap adjusting motor 46. In order to achieve this, a gear 48 is provided for connecting the two. The paper gap adjusting motor 46 rotates forward or reverse to rotate the eccentric cam 44, and moves the support block 42 up and down, so that the print head 36 or the reflective optical sensor 29 mounted on the carriage 28 and the printing paper P The gap amount, that is, the paper gap is adjusted.
[0049]
In the above description, the position of the reflection type optical sensor 29 mounted on the carriage 28 is changed by changing the position of the carriage 28. However, the reflection type optical sensor 29 is independent of the position of the carriage 28. The position of the sensor 29 may be changed.
[0050]
=== Example of an electrical configuration of a color inkjet printer ===
FIG. 5 is a block diagram illustrating an example of an electrical configuration of the color inkjet printer 20. The color inkjet printer 20 includes a buffer memory 50 that receives a signal supplied from a computer 90, an image buffer 52 that stores print data, a system controller 54 that controls the overall operation of the color inkjet printer 20, and a main memory 56. And an EEPROM 58. The system controller 54 further includes a main scanning drive circuit 61 that drives the carriage motor 30, a sub-scanning drive circuit 62 that drives the paper feed motor 31, and a paper gap adjustment motor drive that drives the paper gap adjustment motor 46. A circuit 64, a head driving circuit 63 that drives the print head 36, and a reflective optical sensor control circuit 65 that controls the light emitting unit 38 and the light receiving unit 40 of the reflective optical sensor 29 are connected. The reflection type optical sensor control circuit 65 includes an electric signal measurement unit 66 for measuring an electric signal converted from the reflected light received by the light receiving unit 40.
[0051]
The print data transferred from the computer 90 is temporarily stored in the buffer memory 50. In the color ink jet printer 20, the system controller 54 reads necessary information from the print data from the buffer memory 50, and based on this, the main scanning drive circuit 61, the sub-scanning drive circuit 62, and the head drive circuit 63 are read. Send a control signal.
[0052]
The image buffer 52 stores print data of a plurality of color components received by the buffer memory 50. The head drive circuit 63 reads the print data of each color component from the image buffer 52 in accordance with a control signal from the system controller 54 and drives the nozzle array of each color provided in the print head 36 in response to this.
[0053]
=== Example of print head nozzle arrangement ===
FIG. 6 is an explanatory diagram showing the nozzle arrangement on the lower surface of the print head 36. First, paying attention to FIG. 6A, the print head 36 has a black nozzle row and a color nozzle row respectively arranged on a straight line along the sub-scanning direction SS. In this specification, the “nozzle row” is also referred to as “nozzle group”.
[0054]
The black nozzle row (indicated by white circles) has 180 nozzles # 1 to # 180. These nozzles # 1 to # 180 are arranged at a constant nozzle pitch k · D along the sub-scanning direction. Here, D is the dot pitch in the sub-scanning direction SS, and k is an integer. The dot pitch D in the sub-scanning direction is equal to the pitch of the main scanning line (raster line). Hereinafter, the integer k representing the nozzle pitch k · D is simply referred to as “nozzle pitch k”. The unit of the nozzle pitch k is “dot”, which means the dot pitch in the sub-scanning direction.
[0055]
In the example of FIG. 6, the nozzle pitch k is 4 dots. However, the nozzle pitch k can be set to an arbitrary integer.
[0056]
The color nozzle array includes a yellow nozzle group Y (indicated by white triangles), a magenta nozzle group M (indicated by white squares), and a cyan nozzle group C (indicated by white rhombuses). In this specification, the nozzle group for chromatic ink is also referred to as a “chromatic nozzle group”. Each chromatic nozzle group has 60 nozzles # 1 to # 60. Further, the nozzle pitch of the chromatic nozzle group is the same as the nozzle pitch k of the black nozzle row. The nozzles of the chromatic color nozzle group are arranged at the same sub-scanning position as the nozzles of the black nozzle row.
[0057]
During printing, ink droplets are ejected from each nozzle while the print head 36 is moving in the main scanning direction together with the carriage 28. However, depending on the printing method, not all nozzles are always used, and only some nozzles may be used.
[0058]
Note that FIG. 6B will be described later.
[0059]
=== First Embodiment ===
Next, a first embodiment of the present invention will be described with reference to FIG. FIG. 7 is a flowchart for explaining the first embodiment.
[0060]
First, when the user senses an abnormality in missing dots, an instruction is given from the UI window to perform a missing dot inspection to determine whether or not dot formation has been performed normally (step S2). .
[0061]
FIG. 8 is a schematic diagram illustrating an example of a UI window for a user to instruct a dot dropout inspection. A screen for instructing such inspection exists in the printer property utility, etc., and the user clicks a button corresponding to dot missing inspection (the square button shown in the upper left of the figure) with the mouse to perform dot missing inspection. Let it begin.
[0062]
A user's instruction for dot dropout inspection is received by the user interface display module 101 and sent to the UI printer interface module 102. The UI printer interface module 102 interprets the instructed command and transmits a command COM to the color inkjet printer 20. The color inkjet printer 20 receives the command COM by the buffer memory 50 and then transmits it to the system controller 54.
[0063]
Based on the command transmitted to the system controller 54, the color inkjet printer 20 feeds the printing paper by driving the paper feed motor 31 by the sub-scanning drive circuit 62 (step S4).
[0064]
Further, the color inkjet printer 20 uses the main scanning drive circuit 61, the sub-scanning drive circuit 62, and the head drive circuit 63 based on the command transmitted to the system controller 54, so that the carriage motor 30, the paper feed motor 31, and the print head 36. And a predetermined test pattern is printed on the fed printing paper (step S6).
[0065]
Here, an example of the test pattern will be described with reference to FIGS. 6B and 9.
[0066]
FIG. 6B shows a simplified arrangement of the nozzles of the print head 36 shown in FIG. 6A described above in order to explain the test pattern and the procedure for creating the test pattern. In other words, this simplified nozzle arrangement maintains the relationship between the arrangement of the black nozzle arrays and the arrangement of the color nozzle arrays shown in FIG. Each of the 60 color nozzle rows is reduced to 1 each.
[0067]
FIG. 9 is a diagram showing an example of the test pattern and a procedure for creating the test pattern.
[0068]
The test pattern is printed as follows by the print head 36 having the nozzle arrangement shown in FIG. First, ink is ejected from three black nozzles to form three dots arranged in the sub-scanning direction. This is repeated four times while moving the carriage in the main scanning direction. Subsequently, while moving the carriage in the main scanning direction, ink is ejected from each color nozzle to form three dots arranged in the sub-scanning direction. This is repeated four times in the same manner as above (the upper left diagram in FIG. 9).
[0069]
Next, 1-dot paper feeding is performed, and the same procedure is repeated (the upper right diagram in FIG. 9). In the example of FIG. 6, the nozzle pitch k is 4 dots. Therefore, by repeating this procedure two more times, the pattern shown in the lower right diagram of FIG. 9 is completed.
[0070]
In FIG. 9, the dots indicated by white circles, white triangles, white squares, and white rhombuses are formed by the black nozzle, yellow nozzle, magenta nozzle, and cyan nozzle shown in FIG. 6B, respectively. The dot is shown. In FIG. 6B, the numbers 1 to 3 shown in the white circles, white triangles, white squares, and white rhombuses indicating the nozzles of the print head 36 are the white circles, white dots indicating the dots formed in FIG. It corresponds to the numbers 1 to 3 represented in triangles, white squares, and white rhombuses.
[0071]
When attention is paid to the completed pattern shown in the lower right diagram of FIG. 9, 16 dots (4 (4)) divided by a one-dot chain line in each of the six nozzles (three black nozzles and three color nozzles) are shown. × 4 dots) is formed. Then, light is applied to each section, the reflected light reflected is received by the light receiving sensor, and the output value of the light receiving sensor corresponding to the intensity of the received reflected light is compared with a threshold value, so that each nozzle In addition, it is possible to determine whether or not dot formation has been performed normally.
[0072]
Here, for the sake of convenience, the simplified nozzle arrangement of the print head 36 shown in FIG. 6B has been described as an example, but the same applies to the more complicated nozzle arrangement shown in FIG. 6A. Test patterns can be created with the idea.
[0073]
In this example, one section is formed by 16 dots, but the size of one section is completely arbitrary, and one dot may be used if the accuracy of the reflective optical sensor is good.
[0074]
Returning again to the flowchart shown in FIG. After the printing of the test pattern is completed, the color inkjet printer 20 drives the paper feed motor 31 by the sub-scanning drive circuit 62 based on the command transmitted from the computer 90 to the system controller 54, and the like. The paper is discharged (step S8).
[0075]
Next, in order to display a message prompting the user to set again the printing paper on which the test pattern is printed, the system controller 54 transmits a command to that effect to the buffer memory 50, and the buffer memory 50 (Command COM) is transmitted to the computer 90. The computer 90 receives the command by the UI printer interface module 102, and causes the user interface display module 101 to display a message for prompting the user to set again the printing paper on which the test pattern is printed (step S10).
[0076]
The user who sees the message prints the test pattern and sets the discharged printing paper on the color inkjet printer again (step S12). This printing paper is fed by the same method as described above (step S14).
[0077]
Next, an operation performed in parallel with the above-described operations from Step S4 to Step S14 will be described below. As described in the background section, it is necessary to make an adjustment to absorb the change in the intensity of the reflected light immediately before inspecting whether the dot formation is performed normally. In this embodiment, this adjustment is performed as follows. In the present embodiment, a case will be described in which the change in the type of printing paper described in the background section is a dominant factor in the change in the intensity of reflected light.
[0078]
The user designates the type of printing paper in the UI window when or after giving an instruction to perform dot dropout inspection from the UI window (step S2) (step S20). Then, the adjustment is performed based on the information on the type of printing paper.
[0079]
This will be specifically described with reference to FIGS. FIG. 10 is an example of experimental data showing the relationship between the type of printing paper and the intensity of reflected light received. FIG. 11 is an example of experimental data showing the relationship between the distance between the reflective optical sensor and the printing paper and the intensity of the reflected light received.
[0080]
In FIG. 10, the vertical axis indicates “intensity of reflected light received”, and the horizontal axis indicates three types of printing paper “paper X”, “paper Y”, and “paper Z” as “printing paper type”. taking it. Two broken lines are shown in the figure, but the broken line shown at the top of the white circles shows the intensity of the reflected light reflected from the point where no dots are formed on the printing paper. It is shown in Further, the broken line shown in the upper part connecting the black circles represents the intensity of the reflected light reflected from the position where the dots are formed on the printing paper for each type of printing paper. The symbols “a1”, “b1”, “c1”, “A1”, “B1”, and “C1” shown in the figure represent the light intensity at each point. Note that the data of each point is acquired in a state where the intensity of emitted light is constant.
[0081]
In FIG. 11, the vertical axis represents “the intensity of reflected light received”, and the horizontal axis represents “4 mm”, “5 mm”, and “6 mm” as “distance between the reflective optical sensor and printing paper”. Two polygonal lines are shown on the figure, but the polygonal line shown at the top connecting the white circles shows the intensity of the reflected light reflected from the area where no dots are formed on the printing paper for each distance. It is a thing. In addition, the broken line shown in the upper part connecting the black circles represents the intensity of the reflected light reflected from the portion where the dots are formed on the printing paper for each distance. The symbols “a2”, “b2”, “c2”, “A2”, “B2”, “C2”, and the intensity of emitted light are as described above.
[0082]
In the present embodiment, it is assumed that a threshold value serving as a reference for determining whether or not dot formation has been normally performed is appropriately set in advance under the conditions of “paper Y” and “5 mm”. At this time, when the type of printing paper designated in the UI window is “paper Z”, as shown in FIG. 10, the reflected light is received more than when the type of printing paper is “paper Y”. This will need to be adjusted because the strength of the is weakened. Such adjustment is performed by increasing the intensity of the reflected light received by changing the distance between the reflective optical sensor and the printing paper.
[0083]
More specifically, first, the difference between the intensity of reflected light in the case of “paper Y” and the intensity of reflected light in the case of “paper Z” is taken. As shown in the figure, even in a broken line connecting white circles indicating the intensity of the reflected light reflected from the place where the dots are not formed on the printing paper, the reflected light reflected from the place where the dots are formed Even in the broken line connecting the black circles representing the strength, the difference is almost equal, so either may be taken. Here, a difference is taken in the broken line connecting the white circles, and the difference is b1-c1.
[0084]
Next, in FIG. 11, a point where the intensity of the reflected light is increased by b1-c1 from the point where the distance between the reflective optical sensor and the printing paper is “5 mm” is found. Also here, a broken line connecting white circles indicating the intensity of reflected light reflected from a place where dots are not formed on the printing paper and the intensity of reflected light reflected from a place where dots are formed are shown. Either of the broken lines connecting the black circles may be used. Here, a point is found in a broken line connecting white circles. That is, in the broken line connecting the white circles, the point where the intensity of the reflected light is b2 + (b1-c1) is the point, and the distance between the reflective optical sensor corresponding to the point and the printing paper changes from “5 mm”. This is the distance between the reflective optical sensor to be printed and the printing paper (indicated by symbol “G” in FIG. 11). Based on this result, the position of the reflective optical sensor is adjusted (step S22).
[0085]
In the above description, in order to find the distance G between the reflective optical sensor to be changed and the printing paper, linear interpolation is performed based on the data of each point, but interpolation by a curve may be performed.
[0086]
Further, the distance between the reflective optical sensor and the printing paper is changed in a state where light is applied to the printing paper, and when the intensity of the reflected light becomes the intensity corresponding to “paper Y”, that is, b1, the reflection is performed. The position adjustment of the mold optical sensor may be completed.
[0087]
The designation of the printing paper type by the user (step S20) is received by the user interface display module 101 and sent to the UI printer interface module 102. The UI printer interface module 102 obtains the distance between the above-described reflective optical sensor to be changed and the printing paper, and transmits the result as a command COM to the color inkjet printer 20. The color inkjet printer 20 receives the command COM by the buffer memory 50 and then transmits it to the system controller 54. The color inkjet printer 20 adjusts the position of the reflective optical sensor by driving the paper gap adjusting motor 46 by the paper gap adjusting motor driving circuit 64 based on the command transmitted to the system controller 54. (Step S22).
[0088]
Note that the distance between the reflective optical sensor and the printing paper may be obtained in the color inkjet printer 20 such as the system controller 54.
[0089]
When the printing paper on which the test pattern is printed is fed (step S14) and the position of the reflective optical sensor is adjusted (step S22), light is applied to the test pattern on the printing paper and the intensity of the reflected light is increased. By measuring the thickness (step S16), it is determined whether or not dot formation has been performed normally (step S24).
[0090]
This procedure is shown below. First, the color inkjet printer 20 emits light toward the test pattern on the printing paper, for example, by controlling the light emitting unit 38 by the reflective optical sensor control circuit 65 based on a command from the system controller 54. The light reflected by the test pattern of the emitted light is received by the light receiving unit 40 and converted into an electrical signal by the reflective optical sensor control circuit 65. Then, as the output value of the light receiving sensor corresponding to the intensity of the received reflected light, the magnitude of the electric signal is measured by the electric signal measuring unit 66 provided in the reflective optical sensor control circuit 65.
[0091]
The measurement result is sent to the UI printer interface module 102 provided in the printer driver 96 via the system controller 54 and the buffer memory 50. In the UI printer interface module 102, the measurement result is compared with a preset threshold value, and it is determined whether or not dot formation has been performed normally. Then, the result of the determination is sent to the user interface display module 101, and the result of the missing dot inspection is displayed in the UI interface window (step S24). The determination may be performed in the color inkjet printer 20 such as the system controller 54.
[0092]
In parallel with step S24, discharge of the printing paper on which the test pattern is printed (step S18) and scanning for returning the position of the reflective optical sensor to the original (step S23) are performed. Note that when an abnormality in dot formation is recognized, the print head may be cleaned, or a dot dropout inspection may be performed once again for reconfirmation.
[0093]
Thus, if the intensity of the reflected light received by the light receiving sensor is adjusted by changing the distance between the reflective optical sensor and the printing paper, it is not always necessary to control the intensity of the emitted light. The intensity of reflected light received by the light receiving sensor can be easily adjusted.
[0094]
In addition, the threshold value used as a reference for determining whether or not the dot formation has been normally performed is the electric signal measurement unit that reflects the intensity of the reflected light reflected by the location where the dot formation has been normally performed in the test pattern. The light receiving sensor receives the light so that the measured value measured at 66 and the intensity of the reflected light reflected by the portion where the dot formation is not normally performed are between the measured values measured at the electric signal measuring unit 66. It is also possible to adjust the intensity of reflected light.
[0095]
For example, the above embodiment will be described as an example. The intensity of reflected light reflected by a spot where dot formation is normally performed under the conditions of “paper Y” and “5 mm” and dot formation are normally performed. What is necessary is just to set a threshold value so that it may become between the intensity | strengths of the reflected light reflected by the location which did not exist, and to adjust the intensity | strength of the reflected light which a light reception sensor light-receives by the already described procedure.
[0096]
In this way, it is not always necessary to change the threshold value, and it is possible to reliably determine whether or not dot formation has been performed normally.
[0097]
In the above description, the intensity of the reflected light received by the light receiving sensor is always adjusted before the missing dot inspection. However, the threshold value is a reflection reflected by a location where dots are normally formed in the test pattern. The intensity of the reflected light may be adjusted only when it does not fall between the intensity of the light and the intensity of the reflected light reflected by the portion where the dot formation is not normally performed. Further, a predetermined amount of light is reflected between the intensity of the reflected light reflected from the place where the dot formation is normally performed in the test pattern and the intensity of the reflected light reflected from the place where the dot formation is not normally performed. A range may be provided and the intensity of the reflected light may be adjusted only when the threshold value does not fall within this range.
[0098]
Next, with reference to FIGS. 12 and 13, the relationship between the attachment position of the reflective optical sensor and the intensity of the reflected light received, and the relationship between the intensity of the emitted light and the intensity of the reflected light received will be described. To do. FIG. 12 is an example of experimental data showing the relationship between the attachment position of the reflective optical sensor and the intensity of the reflected light received. FIG. 13 is an example of experimental data showing the relationship between the intensity of emitted light and the intensity of reflected light received.
[0099]
In FIG. 12, “+ 5 °”, “+ 2.5 °”, “0 °”, “−2” is shown as “intensity of reflected light received” on the vertical axis and “mounting angle of the reflective optical sensor” on the horizontal axis. .5 ° ”and“ −5 ° ”. In FIG. 13, “20 mA” and “10 mA” are taken with “the intensity of the reflected light received” on the vertical axis and “the value obtained by converting the intensity of the emitted light into a current value” on the horizontal axis. ing. In each figure, two broken lines are shown, but the broken line shown at the top of the white circle represents the intensity of the reflected light reflected from the point where no dots are formed on the printing paper. It is. Further, the broken line shown at the upper part connecting the black circles represents the intensity of the reflected light reflected from the portion where the dots are formed on the printing paper.
[0100]
As in the case of FIGS. 10 and 11 already shown, the broken line connecting the white circles and the broken line connecting the black circles shown in FIGS. 12 and 13 are constant with each other according to the change in the mounting angle and the conversion value. It is changing while keeping the interval. Therefore, even when the mounting position of the reflective optical sensor or the change in the intensity of the emitted light is a dominant factor in the change in the intensity of the reflected light, the mounting angle of the reflective optical sensor or the light emitted It is possible to adjust the intensity of reflected light received by the method described in this embodiment by detecting a value obtained by converting the intensity of the current into a current value.
[0101]
=== Second Embodiment ===
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 14 is a flowchart for explaining the second embodiment.
[0102]
The procedure from step S2 in which the user gives an instruction to perform dot dropout inspection from the UI window to step S14 in which the printing paper on which the test pattern is printed is fed is the same as that described in the first embodiment. It is.
[0103]
Further, in order to make an adjustment for absorbing a change in the intensity of the reflected light immediately before inspecting whether or not the dot formation is normally performed, the procedure according to steps S20 and S22 in the first embodiment. Instead, the following procedure is performed.
[0104]
After the printing paper on which the test pattern is printed is fed (step S14), the dots are formed normally by applying light onto the test pattern on the printing paper and measuring the intensity of the reflected light. Before determining whether the test pattern has been printed (step S16), light is applied to a portion of the printing paper where the test pattern is not printed, such as a portion where the dot is not formed, and the intensity of the reflected light is measured. (Step S26). Then, adjustment for absorbing the change in the intensity of the reflected light is performed based on the measured value.
[0105]
This will be specifically described with reference to FIG. FIG. 15 is an explanatory diagram for explaining the second embodiment.
[0106]
In FIG. 15, the vertical axis represents “the intensity of reflected light received”, and the horizontal axis represents “reference value” and “measured value”. The white circles in the figure represent the intensity of the reflected light reflected from the portions where dots are not formed on the printing paper. The black circle represents the intensity of the reflected light reflected from the place where dots are formed on the printing paper.
[0107]
A white circle and a black circle on the drawing indicated as “reference value” indicate predetermined conditions, for example, the type of printing paper “paper Y”, the distance “5 mm” between the reflective optical sensor and the printing paper, and the attachment of the reflective optical sensor. Reflected by a spot where dots are normally formed on the printing paper, measured or calculated in advance under the condition of an angle “0 °” and a value “15 mA” obtained by converting the intensity of emitted light into a current value. The intensity of the reflected light and the intensity of the reflected light reflected by the location where the dots were not formed normally. Further, the threshold value is set in advance so as to be between the two reference values.
[0108]
A white circle on the figure indicated as “measured value” represents the light intensity measured in step S26. As shown in the figure, the intensity of the reflected light is different between the white circle corresponding to the “reference value” and the white circle corresponding to the “measured value”. This difference is due to the change factor of the intensity of the reflected light described in the background art section.
[0109]
The adjustment procedure for absorbing the change in the intensity of the reflected light is the same as that already described in the first embodiment. That is, the intensity of the reflected light is the difference between the intensity of the reflected light between the white circle corresponding to the “reference value” and the white circle corresponding to the “measured value” from the point where the distance between the reflective optical sensor and the printing paper is “5 mm”. The distance between the reflective optical sensor and the printing paper such that changes is found, and the position of the reflective optical sensor is adjusted based on this distance (step S28).
[0110]
Note that the position adjustment of the reflective optical sensor is completed when the distance between the reflective optical sensor and the print paper is changed while the light is applied to the print paper and the intensity of the reflected light becomes equal to the reference value. It is good as well.
[0111]
After such adjustment, light is applied to the test pattern on the printing paper, and the intensity of the reflected light is measured (step S16). The subsequent steps are the same as those already described in the first embodiment.
[0112]
If the intensity of the reflected light is adjusted as described above, the adjustment can be easily performed without being aware of the factor of the change in the intensity of the reflected light. That is, even if the cause of the difference in the intensity of the reflected light corresponding to the white circle corresponding to the “reference value” and the white circle corresponding to the “measured value” in FIG. It is possible to adjust the intensity of reflected light by changing the position of the sensor.
[0113]
=== Adjustment of gap between print paper and print head according to print paper thickness ===
Next, means for adjusting the gap between the print paper and the print head according to the thickness of the print paper will be described.
[0114]
First, the color inkjet printer 20 emits light toward the printing paper by controlling the light emitting unit 38 by the reflection type optical sensor control circuit 65 based on a command from the system controller 54. The light reflected by the test pattern of the emitted light is received by the light receiving unit 40 and converted into an electrical signal by the reflective optical sensor control circuit 65. Then, the electrical signal measuring unit 66 measures the magnitude of the electrical signal as the output value of the light receiving sensor corresponding to the intensity of the received reflected light.
[0115]
This measurement result is converted by the system controller 54 into a gap amount between the corresponding printing paper and the print head. The converted gap amount is compared with a reference gap amount stored in the EEPROM 58 as an appropriate cap amount. Based on the difference, the color inkjet printer 20 uses the paper gap adjustment motor drive circuit 64 to adjust the paper gap. For example, by driving the motor 46, the position of the print head is adjusted so that the distance between the print paper and the print head is always constant.
[0116]
2 and 4, since both the print head 36 and the reflective optical sensor 29 are mounted on the carriage 36, the carriage 36 can be moved up and down by driving the paper gap adjusting motor 46. In addition to the adjustment of the gap amount between the print head 36 and the print paper P, the gap amount between the reflective optical sensor 29 and the print paper P can also be adjusted.
[0117]
As described above, most of the configurations and methods for adjusting the gap amount between the print head 36 and the printing paper P and the configurations and methods for adjusting the gap amount between the reflective optical sensor 29 and the printing paper P are almost all. Duplicate in part. Therefore, if the color inkjet printer has a function to adjust the gap between the print paper and the print head according to the thickness of the print paper, the reflected light intensity is adjusted to absorb the change in the reflected light intensity. There is no need to prepare a new mechanism for this, and the merit that the manufacturing cost of the color inkjet printer is reduced can be enjoyed.
[0118]
=== Modification ===
As described above, the printing apparatus and the like according to the present invention have been described based on one embodiment. However, the above-described embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. Absent. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof.
[0119]
Moreover, although the printing paper has been described as an example of the printing material, a film, a cloth, a thin metal plate, or the like may be used as the printing material.
[0120]
Further, a computer main body, a display device connected to the computer main body, a printer according to the above-described embodiment connected to the computer main body, an input device such as a mouse and a keyboard provided as necessary, a flexible disk drive A computer system having a device and a CD-ROM drive device can also be realized, and the computer system realized in this way is an overall system superior to the conventional system.
[0121]
The printer according to the above-described embodiment may have a part of functions or mechanisms respectively included in the computer main body, the display device, the input device, the flexible disk drive device, and the CD-ROM drive device. For example, the printer includes an image processing unit that performs image processing, a display unit that performs various displays, and a recording medium attachment / detachment unit for attaching / detaching a recording medium that records image data captured by a digital camera or the like. Also good.
[0122]
In the above embodiment, a color ink jet printer has been described. However, the present invention can be applied to a monochrome ink jet printer, and can also be applied to printers other than the ink jet system. The present invention is generally applicable to a printing apparatus that prints on a printing medium, and can also be applied to, for example, a facsimile machine and a copier. However, in a so-called ink jet type printing apparatus that performs printing by discharging ink from the print head, a high image quality of the printing result is particularly required, so that the merit of the above-described means is further increased.
[0123]
In the above description, the dot dropout inspection is performed according to the user's instruction, but may be automatically performed without the user's instruction. Further, the inspection may be performed before the printing apparatus reaches the user's hand, for example, at the time of shipment.
[0124]
In the above, the test pattern is printed on the printing paper (step S6), the printing paper is discharged (step S8), and the printing paper is set again on the color inkjet printer by the user (step S12). The printing paper is fed (step S14) and light is applied to the test pattern of the printing paper and the intensity of the reflected light is measured (step S16). It is also possible to omit steps S8, S12, and S14 by continuously performing the measurement.
[0125]
【The invention's effect】
According to the present invention, it is possible to realize a printing apparatus, a dot formation determination method, a computer program, a recording medium, and a computer system that adjust the intensity of reflected light received by a light receiving sensor more easily.
[0126]
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a printing system as an example of the present invention.
FIG. 2 is a schematic perspective view illustrating an example of a main configuration of the color inkjet printer 20;
FIG. 3 is a schematic diagram for explaining an example of a reflective optical sensor 29;
FIG. 4 is a schematic diagram for explaining an example of a paper gap adjusting mechanism for adjusting a paper gap.
5 is a block diagram illustrating an example of an electrical configuration of the color inkjet printer 20. FIG.
6 is an explanatory diagram showing a nozzle arrangement on the lower surface of the print head 36. FIG.
FIG. 7 is a flowchart for explaining the first embodiment;
FIG. 8 is a schematic diagram showing an example of a UI window for a user to instruct dot drop inspection.
FIG. 9 is a diagram illustrating an example of a test pattern and a procedure for creating the test pattern.
FIG. 10 is an example of experimental data showing the relationship between the type of printing paper and the intensity of reflected light received.
FIG. 11 is an example of experimental data showing the relationship between the distance between the reflective optical sensor and the printing paper and the intensity of the reflected light received.
FIG. 12 is an example of experimental data showing the relationship between the attachment position of the reflective optical sensor and the intensity of reflected light received.
FIG. 13 is an example of experimental data showing the relationship between the intensity of emitted light and the intensity of reflected light received.
FIG. 14 is a flowchart for explaining a second embodiment;
FIG. 15 is an explanatory diagram for explaining a second embodiment;
[Explanation of symbols]
20 ... Color inkjet printer
21 ... CRT
22: Paper stacker
24 ... paper feed roller
26 ... Platen
28 ... Carriage
29 ... Reflective optical sensor
30 ... Carriage motor
31 ... Paper feed motor
32 ... Traction belt
34 ... Guide rail
36... Print head
38: Light emitting section 38
40: Light receiving part
42 ... Support block
43 ... Support block guide
44 ... Eccentric cam
46 ... Motor for paper gap adjustment
48 ... Gear
50 ... Buffer memory
52 ... Image buffer
54 ... System controller
56 ... Main memory
58 ・ ・ ・ EEPROM
61 ... Main scanning drive circuit
62... Sub-scanning drive circuit
63... Head drive circuit
64... Motor drive circuit for paper gap adjustment
65... Reflective optical sensor control circuit
66 ... Electric signal measuring unit
90 ... Computer
91 ... Video driver
92 ... Hard disk
95 ... Application program
96 ... Printer driver
97 ... Resolution conversion module
98 ... color conversion module
99 ・ ・ ・ Halftone module
100 ... Rasterizer
101 ... User interface display module
102: UI printer interface module

Claims (8)

Printing is performed by forming dots on the printing medium with the print head, and light is emitted toward the printing medium. The light reflected by the printing medium is received by the light receiving sensor and received. In a printing apparatus that determines whether or not the dot has been formed normally by comparing the output value of the light receiving sensor according to the intensity of reflected light with a threshold value,
Wherein in accordance with the thickness of the printing material, and means for varying the distance between the medium to be printed and the print head, by the means, by changing the distance between the printing substrate and the light receiving sensor wherein A printing apparatus that adjusts the intensity of reflected light received by a light receiving sensor. The printing apparatus according to claim 1,
The threshold value is an output value of the light receiving sensor corresponding to the intensity of reflected light reflected by a place where dot formation has been normally performed on the printing medium, and dot formation is normal on the printing medium. The light receiving sensor receives light by changing the distance between the light receiving sensor and the printing medium so that it is between the output values of the light receiving sensor according to the intensity of the reflected light reflected by the part that has not been performed. A printing apparatus characterized by adjusting the intensity of reflected light . The printing apparatus according to claim 2,
The threshold value is a first output value of the light receiving sensor corresponding to the intensity of reflected light reflected by a place where dot formation is normally performed on the printing medium, and dot formation on the printing medium. The second output value that is between the second output values of the light receiving sensor according to the intensity of the reflected light reflected by the location where the normal operation has not been performed is stored in advance before the printing. In addition, the received light according to the intensity of the reflected light reflected by the portion where the light emitted toward the portion where the dot formation is not performed on the printed material is applied to the stored second output value. A printing apparatus, wherein the intensity of reflected light received by the light receiving sensor is adjusted by changing a distance between the light receiving sensor and the printing medium so that the output values of the sensors become equal . The printing apparatus according to any one of claims 1 to 3,
A printing apparatus that discharges ink from the print head to form dots on the substrate. Printing is performed by forming dots on the printing medium with a print head, emitting light toward the printing medium, and light reflected by the printing medium is received by a light receiving sensor. And comparing the output value of the light receiving sensor according to the intensity of the received reflected light with a threshold value to determine whether the dot formation has been performed normally, In the dot formation determination method for determining whether or not it has been performed,
Wherein in accordance with the thickness of the printing substrate, the print head and the reflected light which the light receiving sensor by changing the distance between the printing substrate and the light receiving sensor by changing the distance between printing material is received The dot formation determination method, wherein the strength of the dot is adjusted. Printing is performed by forming dots on the printing medium with the print head, and light is emitted toward the printing medium. The light reflected by the printing medium is received by the light receiving sensor and received. According to the thickness of the substrate to be printed , a printing apparatus that determines whether the dot formation has been normally performed by comparing the output value of the light receiving sensor according to the intensity of reflected light with a threshold value , computer program for adjusting the intensity of the reflected light which the light receiving sensor by changing the distance between the printing substrate and the light receiving sensor by changing the distance between the medium to be printed and the print head is received. Printing is performed by forming dots on the printing medium with the print head, and light is emitted toward the printing medium. The light reflected by the printing medium is received by the light receiving sensor and received. According to the thickness of the substrate to be printed , a printing apparatus that determines whether the dot formation has been normally performed by comparing the output value of the light receiving sensor according to the intensity of reflected light with a threshold value , the computer program for adjusting the intensity of the reflected light which the light receiving sensor by changing the distance between the printing substrate and the light receiving sensor by changing the distance between the medium to be printed and the print head is received A recorded computer-readable recording medium. A computer apparatus main body, connectable to the computer apparatus main body, performing printing by forming dots on the printing medium with a print head, emitting light toward the printing medium, and the target of the emitted light The reflected light from the printing body is received by a light receiving sensor, and the output value of the light receiving sensor corresponding to the intensity of the received reflected light is compared with a threshold value to determine whether or not the dot has been formed normally. In the printing apparatus, the distance between the light receiving sensor and the printing body is changed by changing a distance between the printing head and the printing body according to a thickness of the printing body, and the light reception is performed. And a printing apparatus that adjusts the intensity of reflected light received by the sensor.

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