JP2015009389A - Inkjet recording device and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording device and method capable of correcting a detection result in response to the characteristics of a detection part without needing the reading operation of an original in which an image being a comparison reference is recorded.SOLUTION: There is provided an inkjet recording device for recording an image on a recording medium using the recording head in which the discharge ports for discharging an ink are aligned. The device includes: a recording part for recording a reference pattern on a pattern recording face by an ink of the amount covering the pattern recording face of the recording medium; a detecting part for detecting the recording density of the reference pattern; and a calculating part for obtaining a correction value for the detection value of the detecting part, based on a detection value in the detection part and a target detection value corresponding to the reference pattern.

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method, and more particularly to an ink jet recording apparatus and an ink jet recording method capable of correcting a detection result in accordance with characteristics of a detection unit.

  In an ink jet recording type recording apparatus (ink jet recording apparatus), if the ejection amount differs for each ejection port for ejecting ink, the size of dots due to ink droplets applied to the recording medium will vary, resulting in an image being recorded The concentration of may differ from the desired concentration. In order to correct this, when detecting the recording density of the test pattern using a detection unit such as a sensor, if the characteristics of the sensor provided for each recording device vary, an error occurs in the detection result, and the recording density is set appropriately. There is a risk that it cannot be corrected.

  In addition, the color correction apparatus in the recording apparatus disclosed in Patent Document 1 reads a document of a preset reference color by a detection unit, hue data corresponding to the read data, preset reference hue data, Compare Based on the comparison result, the color shift caused by the spectral sensitivity characteristic of the filter provided in the detection unit is corrected.

Japanese Patent No. 3193591

  However, according to the color correction apparatus disclosed in Japanese Patent Application Laid-Open No. 2005-228561, a reference color original reading operation is required every time color correction is performed. It is also necessary to take into account variations in the reference color document and changes over time.

  The present invention has been made in view of the above problems. An object of the present invention is to provide an ink jet recording apparatus and an ink jet recording method capable of correcting a detection result according to the characteristics of a detection unit without requiring a reading operation of a document on which an image serving as a reference is recorded. It is in.

  In order to solve the above problems, an ink jet recording apparatus according to the present invention is an ink jet recording apparatus that records an image on a recording medium using a recording head in which ejection openings for ejecting ink are arranged. Corresponding to the reference pattern, a recording unit for recording a reference pattern on the pattern recording surface with an amount of ink covering the pattern recording surface, a detection unit for detecting the recording density of the reference pattern, a detection value in the detection unit, And a calculation unit that calculates a correction value for the detection value of the detection unit based on the target detection value to be detected.

  According to the above configuration, the detection result can be corrected according to the characteristics of the detection unit without requiring a reading operation of a document on which an image serving as a reference is recorded.

It is a schematic perspective view which shows the internal structure of an inkjet recording device. It is a schematic sectional drawing for demonstrating the structure of a sensor. It is a block diagram which shows the control structure of an inkjet recording device. It is a flowchart which shows the flow of a correction process. It is a figure which shows arrangement | positioning of a pattern. It is a graph which shows the relationship between the detection value of a sensor, and optical density. (A)-(d) is a figure which shows a recording medium and the ink provided to it. It is a graph which shows the relationship between the variation | change_quantity of the detected value of a sensor, and optical density. It is a graph which shows the relationship between the detection value of a sensor, and optical density.

Embodiments of the present invention will be described below in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic perspective view showing an internal configuration of an ink jet recording apparatus 10 (hereinafter referred to as “recording apparatus 10”) of the present embodiment. As shown in the figure, the recording apparatus 10 includes an upper housing 51, a lower housing 52, a transport roller 18, a transport roller support member 14, a platen 4, a carriage unit 1, a sensor 2, a main rail 8, a support member 7, A sub rail 6 and a mist suction port 50 are provided.

  The carriage unit 1 is mounted with a recording head (not shown), and reciprocates in the X direction, which is the main scanning direction, along the main rail 8 and the sub rail 6. The recording head is provided with a plurality of recording elements, and the recording element includes an ejection energy generating element and an ejection port. In the present embodiment, an electrothermal converter (heater) is used as the discharge energy generating element. In this case, the ink is foamed by the heat generated by the electrothermal transducer, and the ink is ejected from the ejection port using the foaming energy.

  As the carriage unit 1 moves in the X direction, ink is ejected from the plurality of ejection ports of the recording head in the −Z direction shown in the figure, thereby forming an image on the recording medium conveyed inside the recording apparatus 10. Is done.

  The power of a motor 452 described later with reference to FIG. 3 is transmitted to the carriage unit 1 by a carriage belt (not shown). The main rail 8 is disposed along the X direction, maintains the posture of the carriage unit 1 and guides the movement of the carriage unit 1. The sub rail 6 is disposed along the X direction and in parallel with the main rail 8 and maintains the posture of the carriage unit 1. The support member 7 supports the main rail 8. As a result, the carriage unit 1 can move in the X direction.

  A sensor 2 is mounted on the carriage unit 1, and the sensor 2 detects various patterns recorded on the recording medium. In the present embodiment, the sensor 2 is a reflective optical sensor, and detects the density of an adjustment pattern formed by a plurality of gradation patterns described later. The sensor 2 may be used to detect the end of the recording medium.

  The conveyance roller 18 is a roller for conveying the recording medium in the conveyance direction (Y direction shown in FIG. 1). The conveyance roller support member 14 supports the conveyance roller 18.

  The mist suction port 50 is for collecting ink mist generated when ink is ejected from the ejection port of the recording head.

  The upper housing 51 is for attaching the main rail 8, the sub rail 6, a front cover (not shown), and the like. The lower housing 52 is for attaching the transport roller 18, the platen 4, and the like. In FIG. 1, an upper housing 51 and a lower housing 52 are combined.

  FIG. 2 is a schematic cross-sectional view for explaining the configuration of the sensor 2. As shown in the figure, the sensor 2 includes a light emitting unit 11, a light receiving unit 12, a storage area 53, and a control IC 54. The light 16 emitted from the light emitting unit 11 toward the recording medium 3 is reflected by the recording medium 3. In order to more accurately detect the recording density of the image formed on the recording medium 3, it is desirable to detect the irregularly reflected light 17. Therefore, the light receiving unit 12 is disposed at a position where the irregularly reflected light 17 is received. A signal detected by the light receiving unit 12 is transmitted to an electric board (not shown) of the recording apparatus 10. A storage area 53 is a storage area on the sensor 2. The control IC 54 controls the light emitting unit 11.

  In the present embodiment, the resist adjustment is performed for a plurality of recording heads that respectively discharge inks of a plurality of colors such as cyan (C), magenta (M), yellow (Y), and black (K). Therefore, a white LED or a three-color LED is used as the light emitting unit 11, and a photoelectric conversion element having sensitivity in the visible light region is used as the light receiving unit 12.

  However, when detecting the relationship between the relative recording position and the density when a plurality of different colors are overlaid, the light emitting unit 11 can select a color with high detection sensitivity when adjusting between different colors. It is preferable to use a three-color LED. In addition, the light receiving unit 12 can increase the detection sensitivity of high density by selecting an element with a small dark current.

  The sensor 2 only needs to have a detection resolution that can detect a relative density difference between a plurality of gradation patterns. The detection stability of the sensor 2 may be of a level that does not affect the detected density difference until the adjustment pattern is detected. The sensitivity adjustment is performed by moving the sensor 2 to a non-recording portion of the recording medium 3, for example. As an adjustment method, there is a method of adjusting the light emission intensity of the light emitting unit 11 so that the detection level becomes the upper limit value or adjusting the gain of the detection amplifier in the light receiving unit 12. Although sensitivity adjustment is not essential, it is suitable as a method for improving S / N and increasing detection accuracy.

  The spatial resolution of the sensor 2 is desirably a resolution that can detect an area smaller than the recording area of one adjustment pattern. In multi-pass printing, the two adjustment pattern groups can be printed so as to be adjacent to each other in the direction intersecting the main scanning direction (sub-scanning direction / conveyance direction). In this case, since the recording width in the sub-scanning direction becomes narrow according to the number of passes, the resolution of the sensor is limited by the number of recording passes. In order to avoid this limitation, for example, the number of passes (number of scans) for recording the adjustment pattern may be determined from the resolution of the sensor.

  As shown in FIG. 2, the sensor 2 of the present embodiment is configured by arranging the light emitting unit 11 on the upstream side in the Y direction and the light receiving unit 12 on the downstream side in the Y direction. However, the configuration of the sensor 2 is not limited to such a configuration, and the sensor 2 is configured by arranging the light emitting unit 11 on the downstream side in the Y direction and the light receiving unit 12 on the upstream side in the Y direction. May be.

  FIG. 3 is a block diagram showing a control configuration of the recording apparatus 10. The recording apparatus 10 includes a controller 400, an interface (I / F) 412, an operation unit 420, a sensor group 430, a head driver 440, a motor driver 450, a motor driver 460, a recording head 201, a motor 452, and a motor 462.

  As shown in FIG. 3, the recording device 10 is connected to a host device 410. The host apparatus 410 is a supply source of image data recorded by the recording apparatus 10. The host device 410 may be in the form of a reader unit for image reading, in addition to a computer that creates and processes image data. Image data, other commands, status signals, and the like are transmitted and received from the host device 410 to the controller 400 via the interface 412.

  The controller 400 (calculation unit / setting unit / adjustment unit) includes a CPU 401, a ROM 403, and a RAM 405. The CPU 401 is a central processing unit and comprehensively controls the operation of each component of the recording apparatus 10. In addition, the CPU 401 reads various programs and various data from the ROM 403 and performs calculations. The ROM 403 stores various programs, tables, and other fixed data. The RAM 405 is used as a working area of the CPU 401 or a buffer area for storing various data input from the host device 410 or the like.

  In the controller 400, image processing is performed on the image data input from the host device 410, and recording data to be recorded by the recording device 10 is generated.

  The head driver 440 is a driver that drives the discharge heater 402 of the recording head 201 according to the recording data. Although not shown, the head driver 440 includes a shift register, a latch circuit, a logic circuit element, a timing setting unit, and the like.

  The shift register arranges print data corresponding to the position of the discharge heater 402. The latch circuit latches the recording data output from the shift register at an appropriate timing. The logic circuit element operates the discharge heater in synchronization with the drive timing signal output from the latch circuit. The timing setting unit appropriately sets drive timing (discharge timing) for dot formation position alignment.

  As shown in FIG. 3, the recording head 201 is also provided with a sub-heater 442. The sub-heater 442 performs temperature adjustment for stabilizing the ink ejection characteristics. The sub heater 442 may be formed on the substrate of the recording head 201 together with the discharge heater 402 and / or attached to the main body or head cartridge of the recording head 201.

  The motor driver 450 is a driver for driving the motor 452 for the carriage unit 1. The motor driver 460 is a driver for driving the motor 462 for the transport roller 18. A control signal from the controller 400 is input to these drivers. In accordance with this control signal, the head driver 440 drives the discharge heater 402 and the sub-heater 442 of the recording head 201, the motor driver 450 drives the motor 452, and the motor driver 460 drives the motor 462.

  The operation unit 420 is a switch group that receives an instruction input from the user. As shown in FIG. 3, the operation unit 420 includes a power switch 422, a recovery switch 426, a registration activation switch 427, a registration adjustment value input unit 429, and the like.

  The power switch 422 is a switch for switching on / off the power of the recording apparatus 10. The recovery switch 426 is a switch for instructing the start of suction recovery for the surface of the recording head 201 on which the ejection port is provided. The registration activation switch 427 is a switch for manually performing registration adjustment. The registration adjustment value input unit 429 is for inputting a registration adjustment value manually.

  The sensor group 430 is a sensor group for detecting the state of the recording apparatus 10. The sensor group 430 includes a photocoupler 109, a temperature sensor 434, a sensor 2, and the like. The photocoupler 109 detects the home position of the carriage unit 1. The temperature sensor 434 is provided at an appropriate location for detecting the environmental temperature. As described above, the sensor 2 detects various patterns recorded on the recording medium.

  Here, an outline of the present embodiment will be described. In the present embodiment, a gradation pattern for each ink color is recorded on the recording medium 3, and the recording density of the gradation pattern is detected using the sensor 2 mounted on the carriage unit 1. From this detection result, the input value at the time of recording and the recorded density are determined. Then, a correction value for correcting an error in the detection result of the sensor 2 is calculated, and thereby the detection error is corrected. In the subsequent recording, the ink ejection amount (number of dots) is adjusted so that the input value is recorded with a predetermined reference density.

  FIG. 4 is a flowchart showing the flow of correction processing in the present embodiment. The correction process is started by the user's instruction or the setting timing of the recording apparatus 10. Then, the gradation pattern constituting the adjustment pattern is recorded on the recording medium 3 (S41). An example of the arrangement of gradation patterns recorded at this time will be described with reference to FIG.

  FIG. 5 is a diagram showing the arrangement of gradation patterns. The gradation pattern 20 indicates a gradation pattern with a relatively high input value, and the gradation pattern 21 indicates a gradation pattern with a relatively low input value. When the input value is high, the amount of liquid droplets ejected from the ejection port of the head 201 increases.

  When the amount of droplets increases, the recording medium to which the droplets are applied may expand and deformation such as undulation may occur in that portion. When such deformation occurs, the pattern cannot be detected accurately, and the detection accuracy may be reduced. For this reason, it is more preferable to arrange gradation patterns having different densities in consideration of the ink amount so as to relatively reduce the droplet amount (ink amount) per unit area on the recording medium.

  In the present embodiment, a plurality of gradation patterns are arranged at equal intervals in the X direction and in a staggered pattern in the Y direction. More specifically, in the region 22 where the pattern group is recorded along the moving direction (X direction) of the carriage unit 1, the gradation patterns are arranged so that the gradation patterns having different densities are adjacent to each other. In the region 23 where the pattern group is recorded along the conveyance direction (Y direction) of the recording medium 3, patterns having different densities are arranged in a staggered pattern. Thus, in this embodiment, a plurality of gradation patterns are recorded so that the total droplet amount in a predetermined area is relatively small.

  Next, the gradation pattern recorded on the recording medium 3 is detected using the sensor 2 (S42). In the present embodiment, the detection result when the pattern recording surface of the recording medium 3 on which no image or the like is recorded is used as a white level reference. The white level and the gradation pattern are desirably detected under the same conditions in order to reduce the detection error of the sensor 2. For example, if the positions in the X direction are different and the distance between the sensor 2 and the recording medium 3 may change and affect the detection result, these are detected at the same position in the X direction. Is desirable.

  It is desirable to calibrate the output of the sensor 2 at the white level. In order to widen the dynamic range, the width of the hardware AD detection range is set to the maximum on the basis of the white level. The gradation pattern recorded on the recording medium 3 is detected using the sensor 2 set in this way.

  Here, the relationship between the detection value of the sensor and the optical density (number of recording dots) will be described. FIG. 6 is a graph showing the relationship between the detection value of the sensor and the optical density. In the figure, the vertical axis represents the detection value of the sensor, and the horizontal axis represents the optical density (number of recording dots). In addition, a solid line 24 shown in FIG. 6 indicates a detection result by the sensor a having a reference spectral sensitivity characteristic, and a dotted line 25 indicates a detection result by the sensor b having a spectral sensitivity characteristic different from the reference. A region 26 surrounded by a broken line is a region where the recording density is saturated.

  Although the reflected light from the gradation pattern decreases as the number of recording dots increases, in FIG. 6, for the sake of explanation, the detection result is expressed so that the detection value of the sensor increases as the number of recording dots increases. As shown in FIG. 6, as the number of recording dots increases and the optical density increases in both the solid line 24 and the dotted line 25, the detection value of the sensor also changes, but the change amount of the detection value differs. Thus, if the spectral sensitivity characteristics of the sensors are different, the detection results will be different even if the same gradation pattern is detected.

Let A be the ink spectral sensitivity characteristic of a certain gradation pattern. Let B be the spectral sensitivity characteristic of the light emitting part of the sensor a. Let C be the spectral sensitivity characteristic of the light receiving portion of sensor a. Let D be the spectral sensitivity characteristic of the light emitting part of the sensor b. Let E be the spectral sensitivity characteristic of the light receiving portion of the sensor b. At this time, the assumed detection value of the sensor a having the reference spectral characteristic can be expressed by the following formula 1.
U1 = ∫A × B × C (Formula 1)
When the light emission characteristic of the sensor is limited to visible light, the integration range may be visible light.

Further, the assumed detection value of the sensor b having a spectral sensitivity characteristic different from the reference can be expressed by the following equation 2.
U2 = ∫A × D × E (Formula 2)
Thus, the output value detected by the difference in the spectral sensitivity characteristics of the sensor also changes, so that the error in the detection result by the sensor is corrected.

  Reference is again made to FIG. If a gradation pattern is detected (S42), then a saturation point is specified (S43). In this step, in order to correct the detection result according to the characteristics of the sensor, a saturation point is specified using a region where the detection value of the sensor is saturated with respect to the number of dots ejected to the recording medium 3. In the present embodiment, the number of dots at which the recording density is saturated in the area 26 shown in FIG. 6 is specified.

  When the recording density of the gradation pattern having the maximum number of recording dots is saturated, the number of recording dots of the gradation pattern may be determined as the recording density is saturated. However, for light color inks, the recording density may not be saturated even if the number of recording dots is increased. If the number of recording dots is increased too much, ink may not be fixed on the recording medium 3 and a stable detection result may not be obtained. For this reason, it is more desirable to use a method for determining a saturation point from a plurality of patterns in which the number of recording dots is changed. In this embodiment, the saturation point is determined from a plurality of gradation patterns having different numbers of recording dots.

  7A to 7D are views showing the recording medium 3 and ink droplets 29 applied thereto. The droplets 29 shown in FIGS. 4A to 4D are ink droplets applied to the recording medium 3 from the ejection openings of the recording head 201. 7A to 7D show a state where the amount of ink applied to the recording medium 3 is increasing.

  In FIG. 7A, the region where the droplets 29 are not applied is wider than the region where the droplets 29 are applied on the recording medium 3. In FIG. 7B, the area where the droplet 29 is applied and the area where the droplet 29 is not applied have substantially the same size. In FIG. 7C, droplets 29 are applied over substantially the entire recording surface of the recording medium 3. In FIG. 7D, another droplet 29 is applied on the droplet 29 applied to the recording medium 3.

  For example, the droplet 29 is a droplet of black ink. The state in which the droplets 29 are applied over almost the entire unit area of the recording medium 3 (FIG. 7C) from the state in which the few droplets 29 are applied to the recording medium 3 (FIG. 7A). ) Until the white area of the recording medium 3 decreases and the black area increases. Therefore, the amount of change in the detection value by the sensor 2 becomes relatively large with respect to the amount of increase in the number of dots.

  However, the state in which the liquid droplet 29 is further applied (FIG. 7C) to the state in which the liquid droplet 29 is applied over substantially the entire unit area of the recording medium 3 (FIG. 7C). However, the white area of the recording medium 3 is not reduced. Therefore, the change amount of the detection value by the sensor 2 becomes relatively small with respect to the increase amount of the number of dots.

  FIG. 8 is a graph showing the relationship between the change amount of the detection value of the sensor 2 and the optical density. As shown in the figure, the region in which the optical density goes from 0% to 100% (a state in which dots are applied to the entire recording surface of the recording medium 3 from a state in which no dots are applied to the recording surface of the recording medium 3) The amount of change in the detection value of the sensor 2 is relatively large.

  Then, in an area where the optical density is from 100% to 200% (at a time when a dot is applied to the entire recording surface of the recording medium 3 and a dot is further applied on the dot). The amount of change in the detection value of the sensor 2 becomes smaller. In the region where the optical density goes from 200% to 400%, the amount of change in the detection value of the sensor 2 changes only slightly.

  The number of dots with which the amount of change in the detection value of the sensor 2 is small is specified, and it is determined that the optical density is saturated in the gradation pattern based on the number of dots greater than the number of dots. In this embodiment, the amount of change between the detection value of the gradation pattern with an optical density of 25% and the detection value of the gradation pattern with an optical density of 50% is used as a reference. Then, with respect to the change amount serving as the reference, the number of recording dots in which the change amount of the detection value of the gradation pattern in which the number of dots is increased is 1/20 or less is the number of dots in which the optical density is saturated. Judge.

  Here, it is determined that the optical density is saturated when the optical density shown in FIG. That is, in this embodiment, the amount of change between the detection value of the gradation patch with an optical density of 175% and the detection value of the gradation patch with an optical density of 200% is about 1/20 or less of the reference change amount. It becomes.

  Note that the reference change amount may be calculated from other than the above-described optical density gradation pattern. In the above-described case, a case has been described in which it is determined that the number of dots in which the detection value that is a change amount of 1/20 or less with respect to the reference change amount is the dot number in which the optical density is saturated. However, 1/20 or less is merely an example. The saturation point can be appropriately changed depending on various conditions such as the type of ink color and the material of the recording medium 3.

  In FIG. 4, when the saturation point is not specified (NO in S43), that is, the change amount of the detected value is equal to or less than a predetermined value (in this embodiment, 1/20 with respect to the reference change amount). If not, the number of recording dots is further increased and the gradation pattern is recorded again (S44). And it goes through the above-mentioned process (S42-S43) again.

  On the other hand, when the saturation point is specified (YES in S43), the correction value of the sensor 2 is determined (S45). The detection value detected in a gradation pattern (reference pattern) having a larger number of recording dots than the saturation point depends on the spectral sensitivity characteristic of the sensor 2 rather than the amount of liquid droplets ejected from the ejection opening of the recording head 201. Will increase. Therefore, the detection error due to the spectral sensitivity characteristic of the sensor 2 is corrected using the detection value of the gradation pattern. In the present embodiment, the detection value of one gradation pattern having a larger number of recording dots than the saturation point is used, but the detection values of a plurality of gradation patterns having the number of recording dots larger than the saturation point may be used. Good.

  Then, a coefficient (correction value) is calculated so as to be a predetermined target value (target detection value). By applying the obtained coefficient to each of the detection results detected from the gradation pattern groups with different numbers of recording dots, the detection result can be corrected according to the characteristics of the sensor 2.

  This target value is stored in advance in the ROM 403 of the recording apparatus 10, and is a detection value when a gradation pattern having the same number of recording dots is detected using a reference sensor. Further, the target value for correcting the detection error may be a detection value in another recording apparatus. When there is a target device that matches the color of the recording apparatus 10, a more stable detection result can be obtained by matching the color of the device. Therefore, a detection value obtained by detecting a gradation pattern having more dots than the saturation point acquired by the same processing as the above-described processing in another recording apparatus may be set as the target value.

  Next, the case of an error in the amount of ink ejected from the recording head will be described. FIG. 9 is a graph showing the relationship between the detection value of the sensor 2 and the optical density. A solid line 27 shown in the figure indicates a case where the discharge amount is small, a broken line 28 indicates a case where the discharge amount is large, and a one-dot broken line 29 indicates a case where the discharge amount is standard.

  An example will be described in which an input value from the host device 410 is developed to an ink discharge amount from the recording head 201 and 100 dots are recorded. It is assumed that the detection result of a gradation pattern recorded with 100 dots in a recording apparatus with a standard discharge amount is 1.

  When the ejection amount is a standard recording head (one-dot broken line 29 in FIG. 9), as shown in FIG. 9, the detected value of the gradation pattern recorded with the number of recording dots of 100 dots is 1, so the ejection amount ( The number of recorded dots is not corrected.

  In the case of a recording head having a large ejection amount (broken line 28 in FIG. 9), the detection value of the 100-dot gradation pattern is larger than 1 as shown in FIG. In this recording head, the detection value of the sensor 2 becomes 1 when a gradation pattern having 95 recording dots is detected. In a recording head having a larger discharge amount than the standard with respect to the input value from the host device 410, the discharge amount is recorded by recording a gradation pattern with a dot number smaller than 100 dots (95 dots in the above case). Produces the same recording results as a standard recording head.

  In the case of a recording head with a small ejection amount (solid line 27 in FIG. 9), the detected value of the 100-dot gradation pattern is smaller than 1 as shown in FIG. In this recording head, the detection value of the sensor 2 becomes 1 when a gradation pattern having 105 recording dots is detected. In a recording head that discharges less than the standard value relative to the input value from the host device 410, the gradation pattern is recorded with a recording dot number larger than 100 dots (105 dots in the above case), thereby discharging The same recording result as the recording head whose quantity is standard is obtained.

  As described above, since the discharge amount may be different for each print head with respect to the same input value, the ink discharge amount is adjusted.

  Reference is again made to FIG. Based on the detection result of the recording density with respect to the input value, the ink ejection amount is corrected (S46). This detection result is a detection result after correcting the detection error of the sensor 2. Image data input from the host apparatus 410 to the recording apparatus 10 is developed into binary output data corresponding to the ink color mounted on the recording apparatus 10. The output data to be generated for a specific input value is created with reference to a recording head having a standard droplet size discharged from the discharge port of the recording head.

  On the other hand, when the droplet size is smaller than the standard, that is, as a result of the density detection, the density is detected to be thinner than the standard, the binary output data is changed to increase the input data. On the other hand, when the droplet size is larger than the standard, that is, as a result of the density detection, it is detected that the density is higher than the standard, the binary output data for the input data is changed so as to be reduced. In this way, by changing the number of dots with respect to the input data input from the host device 410 according to the density detection result, it is possible to suppress variations in recording density.

  The change in the number of dots in the present embodiment may be performed when the recording apparatus 10 converts the data into binary data. Alternatively, the image data supply source such as the host device 410 may convert the data into binary data and input the binary data to the recording device 10. The ejection amount is corrected by changing the number of recording dots (the number of ink ejections) as described above, and by changing the droplet size by changing the amount of ink ejected at one time. It may be broken.

  As described above, in this embodiment, the detection result can be corrected according to the characteristics of the detection unit without requiring a reading operation of a document on which an image serving as a comparison reference is recorded. In the subsequent recording, the ink ejection amount is adjusted so that the image is recorded at a predetermined reference density with respect to the input value. As a result, an image having a stable recording density can be formed.

(Other embodiments)
In the above embodiment, the case where the electrothermal conversion element is used as the ejection energy generating element has been described, but a piezo element or the like can be used. In the above embodiment, the ink jet recording type recording apparatus has been described. However, the recording apparatus may be configured by a recording method other than the ink jet recording method. For example, various recording systems such as a thermal transfer system, a thermal system, a wire dot system, and a laser beam system can be employed.

  In the above-described embodiment, the case where the recording apparatus has the function of calculating the correction value of the sensor and the function of adjusting the ink discharge amount has been described as an example. However, some of these functions may be performed by an external device such as a host device.

2 Sensor (detection unit)
3 Recording medium 10 Inkjet recording apparatus 201 Recording head (recording unit)
400 Controller (Calculation unit / Setting unit / Adjustment unit)

Claims (10)

An inkjet recording apparatus that records an image on a recording medium using a recording head in which ejection openings for ejecting ink are arranged,
A recording unit for recording a reference pattern on the pattern recording surface with an amount of ink covering the pattern recording surface of the recording medium;
A detection unit for detecting a recording density of the reference pattern;
A calculation unit for obtaining a correction value for the detection value of the detection unit based on a detection value in the detection unit and a target detection value corresponding to the reference pattern;
An ink jet recording apparatus comprising: A setting unit for setting the reference pattern;
The recording unit records a plurality of patterns having different recording densities on the pattern recording surface,
2. The inkjet recording apparatus according to claim 1, wherein the setting unit sets, as the reference pattern, a pattern having a darker recording density than a pattern in which a change amount of detection values of the plurality of patterns becomes a predetermined value. .   The inkjet recording apparatus according to claim 1, wherein the calculation unit uses a detection value of the reference pattern in another apparatus as the target detection value.   The inkjet recording apparatus according to claim 2, wherein the plurality of patterns are arranged in consideration of an ink amount per unit area in the recording medium. The recording head is movable in a direction intersecting with a conveyance direction of the recording medium;
The plurality of patterns are arranged at equal intervals in the moving direction of the recording head, and are arranged in a staggered pattern in the conveying direction of the recording medium that intersects the moving direction. The ink jet recording apparatus according to any one of claims 2 to 4. The recording unit includes the recording head and a carriage on which the recording head is mounted,
The inkjet recording apparatus according to claim 1, wherein the detection unit is provided in the carriage.   The ink jet recording apparatus according to claim 1, wherein the number of scans of the recording head when the pattern is recorded is determined from the resolution of the detection unit. An adjustment unit for adjusting the amount of ink discharged from the discharge port of the recording head;
8. The inkjet according to claim 1, wherein the adjustment unit adjusts the amount of ink ejected from the ejection port using a detection value corrected by the correction value. 9. Recording device.   The inkjet recording apparatus according to claim 8, wherein the adjustment unit adjusts the ink amount by changing the number of ink ejections and / or the amount of ink ejected at one time. An inkjet recording method for recording an image on a recording medium using a recording head in which ejection openings for ejecting ink are arranged,
Recording a reference pattern on the pattern recording surface with an amount of ink covering the pattern recording surface of the recording medium;
Detecting the recording density of the reference pattern;
Calculating a correction value for the detection value in the detecting step based on the detection value in the detecting step and a target detection value corresponding to the reference pattern;
An ink jet recording method comprising:

Images