JP5171337B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that realizes an accurate image inspection by reducing the size of the apparatus.

  The inkjet image recording apparatus includes an inline inspection device (inline sensor) that inspects an output image to determine whether or not an abnormality has occurred in a printed image during normal image output (printing). There is something. Conventionally, there is an example in which an image is detected using a contact image sensor (CIS) in the inline sensor.

For example, an ink jet recording apparatus that inspects an ink jet head module so that the test pattern of the ink jet head module does not extend over two connected CIS inspection areas (see, for example, Patent Document 1), non-ejection detection in the test pattern Inkjet recording apparatus that reads a figure specifying a start position with a CCD (Charge Coupled Device) or CIS (see, for example, Patent Document 2), and an inkjet recording apparatus that prints non-ejection detection start positions with a plurality of heads and reads with a CCD or CIS (For example, refer to Patent Document 3).
JP 2006-240141 A JP 2006-240142 A JP 2006-240232 A

  However, when CIS is used for an in-line sensor, there is a problem because the optical system is an equal-magnification optical system using an equal-magnification lens generally called a GRIN lens (Gradient Index Lens), a self-focus lens, or a rod lens.

  Since a line sensor using a line CCD that is generally used is a reduction projection, the depth of the sheet surface can be deep (about ± 0.8 mm). On the other hand, a line sensor using CIS can only take a depth of focus of about ± 0.2 mm for equal magnification projection. Therefore, for example, when using paper having different thicknesses of 0.05 mm to 0.4 mm for the image recording apparatus, an image can be read by a reduction optical system in-line sensor using a line CCD, but it is out of depth by CSI using a 1 × optical system. Therefore, it cannot be read at a desired resolution. For this reason, only an inline sensor using a reduction optical system using a line CCD is used for both offset printing machines and inkjet printing machines. This is because in-line sensors using a reduction optical system require simultaneous observation with a small number of line sensors, and it is necessary to place a camera composed of line CCDs at a distance of 500 mm or more on the paper surface. For this reason, the line CCD camera protrudes from the printing apparatus main body, which is not preferable in terms of apparatus design.

  In order to solve this problem, it is possible to make the apparatus compact by using CIS as an in-line sensor of the inkjet image recording apparatus. However, even when CIS is used, there is a problem in that the read image quality is weak against displacement fluctuations and vibrations in the optical axis direction due to the equal magnification detection system, and it is easy to blur due to the shallow depth of focus.

  The present invention has been made in order to solve the above-described problems, and a reading image for inspection is not blurred due to the influence of the thickness of the paper or the vibration of the apparatus, and the outer shape of the apparatus can be kept small. It is an object of the present invention to provide an image forming apparatus that can be used.

In order to achieve the above object, an image forming apparatus according to claim 1 includes a thickness detecting unit that detects a thickness of a recording medium, a conveying unit that conveys the recording medium in a predetermined conveying direction, and the conveying unit. has image forming means for forming an image on a conveyed recording medium, a rotation means for rotating the recording medium on which an image is formed by winding on the surface by the image forming unit, a magnification optical system, both ends An image reading unit configured by a contact image sensor that is installed at a position facing the outer peripheral surface of the rotating unit in a state supported by a linear actuator and reads an image in the width direction formed on the recording medium at once. Position control means for controlling the distance between the image reading means and the recording medium based on the thickness of the recording medium detected by the thickness detecting means, and a frame side surface of the rotating means. A line is drawn in each of the recording medium conveyance direction and the width direction, the acceleration measurement means for measuring the acceleration in the three directions of the conveyance direction, the width direction and the normal direction of the recording medium conveyed by the conveyance means, In addition, by comparing the test image, which is a grid pattern provided on the entire output image, with the image read by the image reading unit, the amount of movement of the image read by the image reading unit in the three directions is determined. A movement amount detection means to be detected; a derivation means for deriving a relationship between the movement amount detected by the movement amount detection means and the acceleration in the three directions measured by the acceleration measurement means; and derived by the derivation means. Based on the storage means for storing the relation, the acceleration in the three directions measured by the acceleration measurement means, and the relation stored by the storage means. , And a, and correcting means for correcting the position of the image read by the image reading means.

  According to the first aspect of the present invention, it is possible to prevent the read image for inspection from being blurred due to the influence of the thickness of the paper.

According to the first aspect of the invention, the detection accuracy of the image sensor can be improved by correcting the deviation of the detected image due to the vibration of the apparatus.

  As described above, according to the present invention, it is possible to obtain an effect that the read image for inspection is not blurred by the influence of the thickness of the paper or the vibration of the apparatus and the outer shape of the apparatus can be kept small. .

  Embodiments of the present invention will be described below with reference to the drawings.

〔Device configuration〕
FIG. 1 is a schematic configuration diagram showing the overall configuration of an inkjet image recording apparatus according to an embodiment of the present invention. An ink jet image recording apparatus 10 shown in the present embodiment is an on-demand (no plate) image recording apparatus that forms a desired image on a recording medium 14 by ejecting ink according to image data.

  As shown in the figure, the inkjet image recording apparatus 10 wraps and fixes a recording medium 14 around the surfaces of a plurality of rotating drums 16 (16-1 to 16-7), and each rotating drum 16-1 to 16-. A drum transport system is used in which the recording medium 14 is transported while sequentially transferring between the seven sheets. Each of the rotating drums 16-1 to 16-7 has a width corresponding to the maximum width of the recording medium 14 used in the apparatus, and a predetermined rotational direction by a driving force applied from a driving source (motor) (not shown). The rotation direction of each of the rotating drums 16-1 to 16-7 is configured to rotate in the direction indicated by the arrow line. Further, the recording medium 14 is fixed to the outer peripheral surface of each rotary drum.

  The structure (method) for fixing the recording medium 14 includes an electrostatic adsorption method in which the outer peripheral surface of the rotary drum 16 is charged and the recording medium 14 is adsorbed by static electricity, or a suction port is provided in the outer peripheral surface of the rotary drum 16. For example, an air adsorption method in which the recording medium 14 is adsorbed by suction, and a nip method in which both ends of the recording medium 14 are nipped by a nip mechanism provided on the outer peripheral surface of the rotary drum 16. Note that the fixing method of the recording medium 14 is not limited to the method described above, and other methods can be applied.

  Further, at the transfer portion of the recording medium 14 between each of the rotating drums 16-1 to 16-7, a delivery mechanism such as a guide for calling the leading end of the recording medium 14 into the receiving rotating drum, or the presence or absence of the recording medium 14 is detected. A detection mechanism such as a sensor for detecting the rotational position of the rotary drum 16 is appropriately provided.

  A paper thickness measuring unit 32 that measures the thickness of the recording medium 14 to be loaded into the inkjet image recording apparatus 10 is disposed. The sheet thickness measuring unit 32 measures the thickness of the recording medium before the conveyance by the rotating drum 16 is started, and transmits the thickness information to a system control unit 72 configured by a central processing unit (CPU) or the like.

  When the recording medium 14 is set at the sheet feeding position of the sheet feeding drum 16-1, the sheet feeding drum 16-1 is rotated in the clockwise direction in FIG. Transport to 16-2. When the recording medium 14 is delivered to the processing liquid application processing drum 16-2, it is fixed to the outer peripheral surface of the processing liquid application processing drum 16-2. A processing liquid having a function of aggregating (thickening) ink on the recording medium 14 on the recording medium conveyance path of the processing liquid application processing drum 16-2 (a position facing the outer peripheral surface of the processing liquid application processing drum 16-2). And a heater 20 for drying the recording medium 14 to which the treatment liquid is applied. The recording medium 14 fixed to the outer peripheral surface of the treatment liquid application processing drum 16-2 is conveyed in a predetermined conveyance direction by rotating the treatment liquid application processing drum 16-2 counterclockwise in FIG. After the treatment liquid is ejected from the treatment liquid head 18 in the treatment liquid application region immediately below the liquid head 18, the treatment liquid head 18 is heated by the heater 20 provided on the downstream side in the recording medium conveyance direction. That is, the processing liquid application process and the processing liquid drying process are performed on the recording medium 14 conveyed by the processing liquid application processing drum 16-2.

  The recording medium 14 that has been subjected to the treatment liquid application process and the treatment liquid drying process is transferred to the printing drum 16-4 via the intermediate conveyance drum 16-3 that rotates in the clockwise direction in FIG. 4 is fixed to the outer peripheral surface. Corresponding to K (black), C (cyan), M (magenta), and Y (yellow) on the recording medium conveyance path of the printing drum 16-4 (position facing the outer peripheral surface of the printing drum 16-4). Then, the printing unit 22 including the recording heads 22K, 22C, 22M, and 22Y arranged in the order of KCMY from the upstream side in the transport direction along the transport direction of the recording medium 14, and ink of each color of KCMY was applied by the printing unit 22 A solvent drying unit 24 for drying excess solvent on the recording medium 14 is provided.

  The recording medium 14 fixed to the outer peripheral surface of the printing drum 16-4 is conveyed in a predetermined conveying direction by rotating the printing drum 16-4 counterclockwise in FIG. 1, and image formation immediately below the printing unit 22 is performed. Ink is ejected from the printing unit 22 in the region to form a desired image. Further, the recording medium 14 after printing is subjected to an excess solvent removing process by a solvent drying unit 24 provided on the downstream side of the printing unit 22 in the recording medium conveyance direction. Thereafter, the recording medium 14 is transferred to the inspection drum 16-6 via the intermediate conveyance drum 16-5 that rotates in the clockwise direction in FIG.

  An inline detection unit 26 is provided on the recording medium conveyance path of the inspection drum 16-6 (a position facing the outer peripheral surface of the inspection drum 16-6). The recording medium 14 fixed to the outer peripheral surface of the inspection drum 16-6 is transported in a predetermined transport direction by rotating the inspection drum 16-6 counterclockwise in FIG. An image is read in the area by the inline detection unit.

  Both ends of the inline detection unit 26 are supported by the linear actuator 34, and the central axis of the linear actuator 34 itself is arranged to coincide with the radial direction of the inspection drum 16-6.

  An acceleration measuring unit 36 is disposed on the side surface of the inspection drum 16-6. The acceleration measuring unit 36 measures the acceleration in the three axes of the conveyance direction, the width direction, and the normal direction of the recording medium 14, and therefore the inspection drum on which the recording medium 14 to which the image read by the inline detection unit 26 is output is fixedly rotated. Placed on the side of 16-6.

  After the image reading by the in-line detection unit 26 and the acceleration measurement by the acceleration measurement unit 36 are completed, the recording medium 14 is discharged to the outside of the apparatus via a paper discharge drum 16-7 that rotates in the clockwise direction in FIG.

  In the inkjet image recording apparatus 10 shown in the present embodiment, the moving speed of the recording medium 14 is controlled to be constant in a normal image forming process (normal image output mode). Further, the conveyance speed of the recording medium 14 (that is, the rotation speed of each of the rotating drums 16-1 to 16-7) can be appropriately changed according to the operation mode of the apparatus.

  In FIG. 1, the drum conveyance method is illustrated as an aspect of the conveyance mechanism of the recording medium 14, but other conveyance methods such as a belt conveyance method are also applicable. In addition, although an ink jet method is exemplified as one mode of applying the treatment liquid to the recording medium 14, other application methods such as application using an application roller or application by a spray method are also applicable.

[Explanation of control system]
FIG. 2 is a block diagram illustrating a system configuration of the inkjet image recording apparatus 10. The inkjet image recording apparatus 10 includes a communication interface 70, a system control unit 72, an image memory 74, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory (not shown), a head driver 84, an image processing unit 94, A ROM 60, an inline detection unit 26, an acceleration measurement unit 36, and the like are provided.

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. The image data sent from the host computer 86 is taken into the inkjet image recording apparatus 10 via the communication interface 70 and temporarily stored in the image memory 74.

  The image memory 74 temporarily stores image data input via the communication interface 70, read data of an image read by the inline detection unit 26, an image (data) after image processing by the image processing unit 94, and the like. Data is read and written through the system control unit 72. The image memory 74 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system control unit 72 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet image recording apparatus 10 according to a predetermined program, and as an arithmetic device that performs various calculations. Function. That is, the system control unit 72 controls each unit such as the communication interface 70, the image memory 74, the motor driver 76, the heater driver 78, etc., and performs communication control with the host computer 86, read / write control of the image memory 74 and the ROM 60, and the like. At the same time, a control signal for controlling the motor 88, the heater 89, the linear actuator 34, etc. of the transport system is generated. In addition to the control signal, image information stored in the image memory 74 is transmitted to the print control unit 80.

  The ROM 60 stores programs executed by the CPU of the system control unit 72 and various data necessary for control. The ROM 60 also stores formulas, tables, and the like that indicate the relationship between the acceleration in the triaxial direction of the image and the amount of movement. Furthermore, it is also used as a program development area and a CPU calculation work area. The ROM 60 may be a non-rewritable storage means. However, when data at various places is updated as necessary, it is preferable to use a rewritable storage means such as an EEPROM.

  The motor driver 76 is a driver (drive circuit) that drives the motor 88 of the conveyance system in accordance with an instruction from the system control unit 72. The motor 88 shown in FIG. 2 includes a motor that drives the rotating drums 16-1 to 16-7 in FIG.

  The heater driver 78 is a driver (drive circuit) that drives the heater 89 in accordance with an instruction from the system control unit 72. In FIG. 2, a plurality of heaters provided in the inkjet image recording apparatus 10 are represented by reference numeral 89. For example, the heater 89 shown in FIG. 2 includes the heater 20 of FIG. 1 and the heater of the solvent drying unit 24.

  The linear actuator 34 moves the in-line detection unit 26 so as to be an appropriate distance from the image surface of the recording medium 14 in accordance with an instruction from the system control unit 72.

  The print control unit 80 has a signal processing function for performing various processes such as processing and correction for generating a print control signal from the image data in the image memory 74 in accordance with an instruction from the system control unit. It is a control unit that supplies data (dot data) to the head driver 84 and the treatment liquid head driver 85. Necessary signal processing is performed in the print controller 80, and the ejection amount and ejection timing of the ink droplets of the head 50 are controlled via the head driver 84 based on the various image data. Thereby, a desired dot size and dot arrangement are realized. Further, the processing liquid discharge amount and the discharge timing of the processing liquid head 18 are controlled via the processing liquid head driver 85 based on the image data.

  The print control unit 80 includes an image buffer memory (not shown), and image data, parameters, and other data are temporarily stored in the image buffer memory when the print control unit 80 processes image data. Also possible is a mode in which the print control unit 80 and the system control unit 72 are integrated to form a single processor.

  The head driver 84 generates a drive signal to be applied to a piezoelectric element (not shown) of the head 50 based on the image data given from the print control unit 80, and applies the drive signal to the piezoelectric element to apply the piezoelectric element. A drive circuit for driving is included. The head driver 84 shown in FIG. 2 may include a feedback control system for keeping the driving condition of the head 50 constant. Further, the same configuration as that of the head driver 84 is applied to the treatment liquid head driver 85. Since the dots of the processing liquid do not require the same resolution as the dots, the dot resolution of the processing liquid can be made coarser than the dot resolution of the ink.

  That is, the nozzle diameter of the treatment liquid head 18 is larger than the nozzle diameters of the ink heads 22K, 22C, 22M, and 22Y, and the nozzle density of the treatment liquid head 18 is greater than the nozzle density of the ink heads 22K, 22C, 22M, and 22Y. Can also be roughened.

  Data of an image to be printed is input from the outside via the communication interface 70 and stored in the image memory 74.

  The image data stored in the image memory 74 is sent to the print control unit 80 via the system control unit 72, and is converted into dot data for each ink color by the print control unit 80. In other words, the print control unit 80 performs RIP processing for converting the input RGB raster data into dot data of four colors of KCMY. The dot data generated by the print controller 80 is stored in an image buffer memory (not shown). Further, the dot data of the treatment liquid can be formed in the same manner. The processing liquid dot data may be formed as dedicated dot data different from the ink dot data.

  The system control unit 72 appropriately changes the distance of the in-line detection unit 26 from the recording medium 14 through the linear actuator 34 according to the thickness of the recording medium 14 measured by the paper thickness measurement unit 32. That is, the inline detection unit 26 changes the distance from the recording medium 14 in accordance with a command signal sent from the system control unit 72.

  The read image data read by the inline detection unit 26 is subjected to predetermined signal processing such as noise removal, amplification, and waveform shaping, and then sent to the image processing unit 94 via the system control unit 72. The image processing unit 94 performs predetermined image processing on the read image data and position correction of the image data based on the acceleration in each direction measured by the acceleration measuring unit 36, and then the processed data is stored in the image memory. The data is stored in a predetermined area in 74.

[Description of image correction]
In the inkjet image recording apparatus 10, the paper thickness measuring unit 32 measures the thickness of the recording medium 14 when the recording medium 14 to be loaded into the apparatus is conveyed from a paper stacker (not shown) to the paper supply drum 16-1. . As the paper thickness measuring unit 32, a device that measures the thickness by mechanical contact, such as a minute displacement sensor, is particularly suitable for the purpose of measuring the thickness of the paper. In addition, the thickness of the recording medium 14 can be measured using a contact displacement sensor or a laser displacement sensor. The sheet thickness measuring unit 32 measures the thickness of the recording medium before the conveyance by the rotating drum 16 is started, and transmits the thickness information to a system control unit 72 configured by a central processing unit (CPU) or the like. In addition, the thickness of the recording medium 14 is measured only for the first sheet, and thereafter, every time the recording medium 14 is changed.

  The system control unit 72 obtains a relational expression that gives a necessary displacement with respect to the thickness of the recording medium 14 and stores it in the ROM 60 in advance, and the thickness information transmitted from the relational expression and the sheet thickness measurement unit 32. Is used to determine the required command pulse signal and transmit this signal to the linear actuator 34. The linear actuator 34 moves the in-line detection unit 26 so as to be an appropriate distance from the image surface of the recording medium 14 based on a command pulse signal from the system control unit.

  As described above, the inline detection unit 26 is arranged at a suitable distance from the recording medium 14 immediately before the recording medium 14 reaches the inspection drum 16-6 based on the thickness information from the sheet thickness measuring unit 32. The

  The inline detection unit 26 is configured by CIS. FIG. 3 is a schematic configuration diagram of the CIS used in the present embodiment. As shown in FIG. 3, the CIS includes a cover glass 42, an illumination unit 44, a 1 × optical system 46, and a sensor unit 48. The illumination unit 44 is a light source (fluorescent lamp, LED array, or the like) that irradiates light on the image surface 40 of the recording medium 14 when reading an image. Light reflected from the illumination unit 44 and reflected by the image on the image plane 40 is guided to the equal magnification optical system 46 and read by the sensor unit 48.

  For example, the focal depth position of the CIS is +0.2 mm on the cover glass 42 surface, the focal depth is ± 0.2 mm, and 600 dpi. In this case, in the inkjet image recording apparatus 10, if the thickness of the recording medium 14 to be used is 0.05 to 0.4 mm, if the operation area of the above-described sheet thickness measuring unit 32 is 0 to 200 μm, two pieces are used. A range of 0 to 400 μm can be measured by shifting the height at which the sheet thickness measuring unit is arranged.

  In addition, since the CIS has a shallow depth of focus and does not require a large distance from the recording medium 14, an effect that the outer shape of the inkjet image recording apparatus 10 can be reduced can be obtained.

  Further, as described above, in order to read an image on the recording medium 14, light is emitted from a light source and reflected light is detected by a sensor. In the case of a reduction optical system, only a small amount of irradiated light reaches the sensor. On the other hand, in the CIS that is an equal magnification optical system, the sensor position is close to the paper surface, and the efficiency with which the irradiated light reaches the sensor is high. In general, the distance between the sensor and the sheet surface is 9 to 20 mm. In addition, in the case of CIS, the area per pixel of the sensor that receives light is also equal, so the sensitivity is high. Therefore, it is possible to reduce the amount of light that irradiates the paper surface. For example, while an in-line sensor using a reduction optical system requires three light sources of 50,000 Lx, CIS also has an advantage that it can be illuminated with LEDs arranged in the vicinity of the sensor. In this case, the light source power may be about 1/50.

  In this way, until the recording medium 14 moves to the inspection drum 16-6 according to the measurement value of the paper thickness measurement unit 32 provided in the paper transport unit before being loaded into the paper supply drum 16-1. In addition, by changing the distance of the inline detection unit 26 from the recording medium 14, an image on the recording medium 14 can be read at a desired resolution even when a different type of recording medium 14 is used in the inkjet image recording apparatus 10. It becomes possible. That is, the read image for inspection is not blurred by the influence of the thickness of the recording medium 14.

  Further, in order to cope with the problem that the read image is easily blurred because the depth is shallow because the CIS is an equal-magnification optical system, the conveyance direction of the recording medium 14 is measured by the acceleration measuring unit 36 installed on the side surface of the inspection drum 16-6. The acceleration in the three-axis directions in the width direction and the normal direction is measured.

  The acceleration measuring unit 36 is based on a small MEMS (Micro Electro Mechanical System) technology depending on a detection mechanism. The acceleration measurement unit 36 includes 1) a piezoresistive type, 2) a capacitance type, 3) a heat detection type, and (0 to several kHz). In addition, it is classified into electrodynamic type (0 to about 100 Hz), strain gauge type (0 to several kHz), and piezoelectric type (several k to several tens kHz). Among these, in the present embodiment, the three-axis acceleration sensor based on the MEMS technology is arranged on the frame side surface of the inspection drum 16-6 on which the recording medium 14 detected by the in-line detection unit 26 is fixedly rotated.

  Further, since the vibration accompanying the conveyance of the recording medium 14 has periodicity and regularity, a lattice-shaped test pattern image in which a pattern to be formed is determined is conveyed, how the image fluctuates, Whether it is detected as being shifted can be determined in correspondence with the measurement value of the acceleration measuring unit 36. FIG. 4 is a test pattern image used in the present embodiment, in which straight lines are drawn in a lattice pattern in the conveyance direction and the width direction of the recording medium 14. Since the output data is simple and known in advance in the lattice pattern provided on the entire output image in this way, it is easy to determine how much the image is detected to be shifted due to the vibration of the recording medium 14. it can. FIG. 5 is a graph showing the relationship between the acceleration in the triaxial direction and the amount of movement of the detected image point. In actual image creation, the correction amount of the image position can be increased or decreased depending on the magnitude of the measurement value of the acceleration measuring unit 36. It is also possible to obtain a correction amount that can intentionally give vibration and can cope with image fluctuation caused by unexpected vibration.

  In the present embodiment, with respect to the conveyance direction and the width direction of the recording medium 14, the amount and acceleration of the movement in the conveyance direction and the width direction are compared by comparing the grid-like test pattern image and the output image as shown in FIG. 4. Then, a relational expression or a table showing the relation is created and stored in the ROM 60. By accumulating vibration tendencies in this way, it is possible to correct image data in advance for repeated vibrations. At the time of image creation, the movement amount of the image in each direction can be predicted from the measurement value of the acceleration measuring unit 36 and the above-described relational expression or table. Therefore, by performing correction for moving the image in the direction opposite to the predicted movement amount, it is possible to prevent image fluctuations and deviations.

  On the other hand, with respect to the normal direction of the recording medium 14, since the image is detected by being shifted from the focal position, the image of the lattice line is blurred. Also in this case, since the original image is known in advance, it is possible to adjust the sharpness to be corrected and the degree of sharpening processing to the obtained image.

  The target in-line detection unit 26 in the inkjet image recording apparatus 10 detects non-ejection of inkjet droplet ejection and unevenness due to variation in droplet ejection amount using a test pattern and a chart. Therefore, it is important to detect the occurrence of non-ejection and the occurrence of unevenness without error for blur caused by vibration in the normal direction.

  As described above, it is possible to improve the accuracy of specifying the non-ejection nozzles by correcting the image. In addition, the image detection data by the in-line detection unit 26 is used when the non-ejection is detected to identify the nozzle, the ejection amount from the nozzles on both sides of the nozzle is increased, and the deterioration of the image quality due to the generation of the stripe is corrected. Can also be used.

  In addition, this invention is not limited to embodiment mentioned above, It can apply also to what changed the design within the range described in the claim.

  In addition, this invention is not limited to the above-mentioned embodiment, It is applicable also to what changed the design within the range described in the claim.

  For example, the sheet thickness measuring unit 32 is not provided at a position before the recording medium 14 is carried into the paper supply drum 16-1, but the laser displacement sensor 33 is integrated with the in-line detecting unit 26 as shown in FIG. Thus, an autofocus system by the autofocus control unit 38 may be used.

  Further, instead of detecting the entire width of the recording medium 14 with one CIS sensor, small CIS sensors may be connected and arranged. In that case, the distance from each CIS sheet is changed or one fixed stage is moved.

1 is a schematic configuration diagram illustrating an overall configuration of an inkjet image recording apparatus according to an embodiment of the present invention. 1 is a block diagram showing a system configuration of an inkjet image recording apparatus according to an embodiment of the present invention. It is a schematic block diagram of CIS used by this Embodiment. It is a figure which shows the test pattern image used in this Embodiment. It is a graph showing the relationship between the acceleration of a 3 axis direction of a recording medium, and the moving amount | distance of a detection image point. It is a figure which shows the case where a laser displacement sensor and a CIS sensor are integrated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet image recording apparatus 26 In-line detection part 32 Paper thickness measurement part 34 Linear actuator 36 Acceleration measurement part 60 ROM
70 Communication Interface 72 System Control Unit 74 Image Memory 76 Motor Driver 78 Heater Driver 80 Print Control Unit 84 Head Driver 85 Treatment Liquid Driver 86 Host Computer 88 Motor 89 Heater 94 Image Processing Unit

Claims (1)

A thickness detecting means for detecting the thickness of the recording medium;
Conveying means for conveying the recording medium in a predetermined conveying direction;
Image forming means for forming an image on a recording medium conveyed by the conveying means;
A rotating means for rotating the recording medium on which an image has been formed by the image forming means, on a surface;
A contact image sensor having an equal-magnification optical system and installed at a position facing the outer peripheral surface of the rotating means in a state where both ends are supported by a linear actuator, and reads an image in the width direction formed on the recording medium at a time. An image reading means constituted by :
Position control means for controlling the distance between the image reading means and the recording medium based on the thickness of the recording medium detected by the thickness detecting means;
An acceleration measuring means that is installed on a frame side surface of the rotating means and measures acceleration in three directions of a recording medium conveyed in the conveying direction, a width direction, and a normal direction of the recording medium;
By comparing the test image, which is a lattice pattern provided on the entire surface of the output image, with lines drawn in the conveyance direction and the width direction of the recording medium, and the image read by the image reading unit, the image A movement amount detection means for detecting a movement amount in the three directions of the image read by the reading means;
Derivation means for deriving a relationship between the movement amount detected by the movement amount detection means and the acceleration in the three directions measured by the acceleration measurement means;
Storage means for storing the relationship derived by the derivation means;
Correction means for correcting the position of the image read by the image reading means based on the acceleration in the three directions measured by the acceleration measuring means and the relationship stored by the storage means;
An image forming apparatus.

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