JP2006137075A - Image forming apparatus, and method and program for controlling it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constitution of an image forming apparatus, which enables a recording medium to be smoothly and stably fed through an AHS (automatic head shading) operation, and which enables AHS to be stably and properly corrected. <P>SOLUTION: In the AHS action, after a test pattern image is recorded on recording paper by using a recording head 2 while the recording paper is continuously fed in one direction by using a feed belt 31, the image is read by an image reader 50, and a driving condition of the recording head 2 is corrected according to the result of reading. Though an image reading speed of the reader 50 in a recording paper feed direction is lower than an ordinary recording speed of the recording head 2, in the recording of the test pattern, the recording speed of the recording head 2 is set to be a speed corresponding to the reading speed of the reader 50, or a speed nearest to the reading speed of the reader 50 within a possible range; and the recording paper feed speed is set to be a speed corresponding to the recording speed. After that, in the reading of the test pattern, the carrying speed is controlled to be the speed corresponding to the reading speed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus for forming an image on a recording medium, that is, recording an image, in particular, reading a test pattern image recorded after recording a test pattern image on a recording medium by a recording head, The present invention relates to an image forming apparatus that performs an operation of correcting a driving condition of a recording head based on the result, a control method thereof, and a control program thereof.

  In an image forming apparatus used as an image output apparatus such as a facsimile machine, a copier, a printer, and a multifunction machine having these functions, or a workstation, etc., a plurality of recording elements are integrated and arranged in order to improve the recording speed. In a recording head, for example, an ink jet recording head, a so-called multi-nozzle head in which a plurality of recording elements each having an ink discharge port and a liquid path are integrated and arranged is generally used.

  However, it is difficult to manufacture the recording elements of the multi-nozzle head with uniform characteristics due to variations in characteristics due to the manufacturing process, characteristics of the head constituent materials, and the like. Variation occurs. That is, in the multi-nozzle head, variations occur in the shapes of the discharge ports and liquid passages. Such non-uniformity of characteristics between the recording elements appears as non-uniformity in the size and density of dots recorded by the ink ejected by each recording element, resulting in uneven density in the recorded image. .

  To solve this problem, the drive signal given to each recording element is corrected, and the number of ink droplets ejected is adjusted according to the ink ejection amount of each recording element so as to obtain an image having a uniform density ( (Hereinafter referred to as head shading) is effective. In this head shading, an image of a test pattern for head shading is recorded on a recording medium by a recording head, and then the image of the recorded test pattern is read and the ink of each recording element is calculated based on the result of calculation processing of the read data. This is done by correcting the drive conditions such as the number of ink droplets discharged corresponding to the discharge amount to control the ink discharge amount. In the case of a conventional copying machine, an image of a test pattern is read using a reader unit (original reading device) arranged on the copying machine.

  However, in such a conventional configuration, first, in order to accurately grasp the state of the recording head from the test pattern, the recording medium on which the image of the test pattern is recorded must be accurately set on the reader unit. In addition, in order to perform head shading, it is necessary to operate a circuit unit that performs calculation and control for determining a head shading correction value on a reader unit that is separate from the printer unit. For this reason, a considerable amount of knowledge and skill is required for an operator to perform head shading, and there is a problem that an unaccustomed person cannot easily obtain an optimum image quality.

  Therefore, the present applicant has already proposed an automatic head shading configuration in which the head shading is automatically performed in the printer of the image forming apparatus according to Patent Documents 1 and 2 below. This is because an image reading device that reads an image recorded on a recording medium is provided on the downstream side of the image forming unit (recording unit) along the conveyance direction of the recording medium in the printer of the image forming apparatus. The test pattern image is recorded and read in a series of operations so that the head shading can be automatically corrected.

According to this configuration, it is possible to perform head shading in a short time and in a stable manner by providing the image reading device in the conveyance path of the recording medium. In addition, since the image reading device is built in the printer, it is not necessary to use an external image reading device such as a reader device of a copying machine for head shading. It became possible. In addition, since head shading can be performed automatically, maintenance related to head shading can be eliminated, and the number of head shading can be set freely, enabling more precise correction. .
JP-A-4-18358 JP-A-4-18356

  By the way, in the configuration of the automatic head shading of the image forming apparatus described above, the test recorded after the test pattern image is recorded on the recording medium by the recording head while continuously conveying the recording medium in one direction. The pattern image is read by the image reading means. Here, normally, as the image reading unit, if it is configured to be able to increase the reading speed for reading an image in the conveyance direction (sub-scanning direction) of the recording medium, it becomes expensive. Although it is inexpensive, a configuration in which the reading speed is slow and the recording speed of the recording head is much slower than the normal recording speed in the recording medium conveyance direction is used.

  For this reason, assuming that the test pattern image is recorded by the recording head at the normal recording speed and then the test pattern image is continuously read by the image reading means, when the test pattern image is shifted from recording to reading. In addition, the recording medium conveyance speed is suddenly changed (decreased), and at that time, an unreasonable mechanical load is applied to the motor or conveyance member of the drive source of the recording medium conveyance mechanism, causing trouble. The recording medium conveyance speed becomes unstable, the test pattern image cannot be read stably and reliably, and shading correction may not be stably and properly performed.

  Accordingly, an object of the present invention is to improve the above-described problems in an image forming apparatus having an automatic head shading function, and to make it impossible to transport a recording medium for head shading to the transport mechanism with a configuration that can be realized at low cost. It is an object of the present invention to provide a configuration that can be performed smoothly and stably without applying a mechanical load, and that head shading correction can be performed stably and appropriately.

In order to solve the above-described problems, in the present invention, a conveying unit that conveys a recording medium in one direction, a recording head that can record an image at a recording speed that differs in the conveying direction with respect to the conveyed recording medium, and a recording medium Image reading means for reading the image recorded in the recording direction at a constant reading speed slower than the normal recording speed of the recording head in the conveying direction, while continuously conveying the recording medium in one direction, An image forming apparatus that performs an operation of reading a test pattern image recorded by a recording head after the test pattern image is read by an image reading unit and correcting a driving condition of the recording head based on the result, and a control method thereof, and In that control program,
When recording an image of the test pattern for the correction, the recording speed of the recording head in the transport direction is set to a speed that matches the reading speed of the image reading means, or the closest possible speed, and Employs a configuration in which the conveyance speed of the recording medium is set to a speed corresponding to the recording speed, and then the reading speed of the recording medium is controlled to the speed corresponding to the reading speed of the image reading means when reading the test pattern image. did.

  According to the configuration of the present invention, the recording medium conveyance speed when recording the head shading test pattern image coincides with the conveyance speed when the test pattern image is subsequently read, or within a possible range. Therefore, when the test pattern image is shifted from recording to reading, the conveyance speed of the recording medium is not rapidly changed (decreased). Therefore, no excessive mechanical load is applied to the recording medium conveyance mechanism at that time, the recording medium can be conveyed smoothly and stably, and the test pattern image can be read stably and reliably. Can be stably and properly performed. In addition, an inexpensive image reading unit having a low reading speed can be used as an image reading unit, and there is an excellent advantage that an automatic head shading function can be realized at a low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, an embodiment of an image forming apparatus of an ink jet recording system that forms an image on a recording medium by ejecting liquid ink from a recording head, that is, an image recording apparatus is shown. Of course, the present invention can also be applied to an image forming apparatus of this type. The image forming apparatus according to the embodiment is used, for example, as an image output apparatus of an information processing apparatus such as a computer, or as an image forming unit such as a copying machine or a facsimile apparatus.

  FIG. 1 shows a mechanical configuration of a main part related to the present invention of an image forming apparatus according to an embodiment of the present invention. In the figure, reference numeral 20 denotes a pre-registration roller, which temporarily stops a recording paper (which may be an OHP film or other medium) that is fed leftward in the drawing from a paper feeding device (not shown). Thus, the skew of the recording paper is corrected, and the recording paper is fed leftward in accordance with the timing of image formation. The recording paper is guided to the paper feeding side paper guides 21 and 22 and is guided onto the conveying belt 31 stretched between the pulleys 32A and 32B of the conveying belt device 30 that conveys the recording paper.

  The conveyance belt 31 travels counterclockwise in FIG. 1 by the rotation of the pulleys 32A and 32B, and conveys the recording paper in the left direction in FIG. A charging roller 35 attached to a roller housing 37 is pressed against the conveyance belt 31 by the bias of a spring 36, and the conveyance belt 31 is charged via a charging roller 35 from a high voltage device 61 connected to the charging roller 35. Is applied. The recording paper that has reached the conveying belt 31 is pressed by the pressing member 39 so as to be in close contact with the conveying belt 31. Then, the recording paper that has passed under the pressing member 39 is adsorbed onto the conveying belt 31 by the electric charges, and the recording paper is prevented from floating. A platen 33 is provided along the lower surface of the upper traveling portion where the recording paper of the conveyance belt 31 is adsorbed.

  Further, in the vicinity of the upper portion of the right side in FIG. 1, which is the upstream side of the conveyance belt 31 in the recording paper conveyance direction, an image forming unit 1 in which four recording heads 2 arranged along the recording paper conveyance direction are integrated. Are provided so as to be movable between a position during the recording operation shown in the drawing and a standby position during the non-recording operation above it. The four recording heads 2 correspond to, for example, four colors of cyan, magenta, yellow, and black, and form an image by ejecting liquid ink of each color onto the recording paper conveyed on the platen 33 by the conveying belt 31. That is, the maximum width of the recording paper that can be recorded by the image forming apparatus along one direction with a plurality of recording elements composed of electrothermal conversion elements and the like, which will be described later, and ink discharge ports, is used as an ink jet recording head for recording (recording of the image forming apparatus It is a so-called full-line type that is arranged with an arrangement length corresponding to the entire width of the region and arranged so that the arrangement direction is along one direction orthogonal to the recording paper conveyance direction. Each recording head 2 has a plurality of recording heads arranged in parallel along one direction orthogonal to the recording paper conveyance direction so that the length of the ejection port array of the plurality of heads is the full line length. May be.

  An ink connector 3 is installed on the top of each recording head 2 and connected to an ink supply device (not shown) via an ink tube. Further, a heat radiating plate 4 is installed at the end of each recording head 2 outside the range of the ejection opening array, and performs a heat radiating action so that each recording head 2 is in a required temperature range.

  Further, the image forming unit 1 is provided with a paper passage sensor 5 at the upstream (right side) end in the recording paper conveyance direction, and it is determined whether or not the recording paper has reached the site where the image forming unit 1 is disposed. Used to do.

  Further, an image reading device 50 is provided in the vicinity of the upper portion of the left side in FIG. 1, which is the downstream side of the conveyance belt 31 in the recording paper conveyance direction, and the recording paper conveyed by the conveyance belt 31 as described later. On the other hand, it is used for reading an image of a head shading test pattern recorded by each recording head 2 of the image forming unit 1.

  2A and 2B are a schematic plan view showing the configuration of the image reading apparatus 50 and a vertical sectional view taken along the line AA, respectively. Reference numeral 51 denotes a carriage on which optical components and electrical components constituting the image reading apparatus 50 are mounted. The carriage 51 is in one direction orthogonal to the recording paper conveyance direction (sub-scanning direction) by the conveyance belt 31, that is, the recording elements of each recording head 2. It is slidably supported by a rail 53 and a guide plate 54 installed in parallel to the outlet arrangement direction (main scanning direction), and can be moved along the discharge port arrangement direction of each recording head 2 by these guides. . A wire 52 stretched between a pair of pulleys (not shown) is coupled to the carriage 51, and a driving force of a carriage motor (not shown) coupled to one of the pulleys is transmitted to the carriage 51 so as to transmit it in the above direction. Slide to.

  In the carriage 51, a reading sensor (such as a visible light photodiode) 58 that reads an image recorded on the recording paper, a filter 57 that transmits light suitable for the sensor 58, and reflected light from the recording paper is collected on the sensor 58. A lens 56 to be moved and a diaphragm 55 for restricting the optical path area are mounted, and the optical axis passing through these centers is arranged to be perpendicular to the recording paper on the conveyance belt 31. The reading sensor 58 is mounted on a printed circuit board 59 fixed to the carriage 51. In addition, a lamp (such as a lens-equipped lamp) 60 that irradiates light onto the recording paper on the conveyance belt 31 is mounted on the carriage 51.

  By illuminating the recording paper on the conveying belt 31 by turning on the lamp 60, the reflected light from the recording paper is condensed on the reading sensor 58 through the diaphragm 55, the lens 56, and the filter 57, and recorded on the recording paper. One pixel of the recorded image can be read. Then, main scanning for reading an image for one line while moving the carriage 51 in one direction of the ejection port arrangement direction of each recording head 2, that is, one direction orthogonal to the ejection port arrangement direction, In other words, by repeating sub-scanning that conveys a predetermined minute amount corresponding to the pitch of one line in the sub-scanning direction, a recording area corresponding to the total length of the ejection openings of the recording heads 2 on the recording paper on the conveying belt 31. It is possible to read an image recorded within the range of the full width.

  In FIG. 1, a paper discharge side paper guide 23 is provided in the vicinity of the outside of the pulley 32B disposed at the downstream end of the conveyance belt device 30 in the conveyance direction, and is conveyed to the pulley 32B by the conveyance belt 31. The recording paper thus fed is guided by the paper guide 23, peeled off from the conveying belt 31, and discharged.

  A cleaner 40 including a wiper blade 41, a liquid absorbing material 42, and an ink receiver 43 is provided near the lower side of the pulley 32B, and removes unnecessary materials such as ink, paper dust, and dust adhered to the conveyor belt 31. It is designed to perform cleaning.

  In the above configuration, the recording speed of the image by the recording heads 2 of the image forming unit 1 with respect to the recording paper conveyed by the conveying belt 31, that is, the recording speed in the recording paper conveyance direction is controlled by the CPU of the apparatus described later. It is possible to set different recording speeds step by step or continuously. Further, the image reading speed in the recording sheet conveyance direction in which the image reading device 50 reads an image recorded on the recording sheet conveyed by the conveyance belt 31 is set in the recording sheet conveyance direction by each recording head Z of the image forming unit 1. It is assumed that the recording speed is slower than the normal constant recording speed, and is slower than the normal recording speed, but is set to the highest constant speed within a range where reading can be performed without hindrance. The recording paper conveyance speed can be arbitrarily variably set corresponding to the recording speed or reading speed in the recording paper conveyance direction.

  FIG. 3 shows the configuration of a control system related to the automatic head shading operation in the apparatus of this embodiment. In the figure, a CPU 70 executes a control program stored in a ROM 71 to control the entire apparatus. At that time, the RAM 72 is used as a work area for data processing or the like. Further, the CPU 70 controls the driving of a motor as a driving source of a paper feeding device (not shown) to feed recording paper, and drives the pre-registration rollers 20 and the conveying belt device 30 via a motor driver 73. The drive of the paper feed motor 79 is controlled to transport the recording paper. Further, the drive of each recording head 2 of the image forming unit 1 described above is controlled via the head driver 74 so that the image is recorded on the recording paper. Note that the CPU 70 can set the recording speed of the image in the recording paper conveyance direction stepwise or continuously to different recording speeds as described above by the drive control of the paper feed motor 79 and each recording head 2. The image data to be recorded is given from a host information processing device such as a computer (not shown) or from an image input means such as a scanner (not shown), and stored in the RAM 72 or an external storage device (not shown) for use. To do. The image data of the head shading test pattern is used by being stored in the ROM 71 or an external storage device (not shown).

  The CPU 70 controls the driving of a carriage motor 80 that is a driving source for moving the carriage 51 of the image reading device 50 via the motor driver 75, and the image reading sensor via a predetermined interface circuit 76 and the lamp driver 77. 58 and the driving of the lamp 60 are controlled to cause the image reading apparatus 50 to perform the above-described image reading operation on the recording paper. The read image data is temporarily stored in the RAM 72 and used. As described above, the image reading speed in the recording paper conveyance direction by the image reading device 50 is constant reading slower than the normal constant recording speed in the recording paper conveyance direction by each recording head 2 of the image forming unit 1. It shall be set to speed.

  Further, the CPU 70 controls the driving of the sensor group 81 that performs various detections including the paper passage sensor 5 described above via the interface circuit 78, performs various detections, takes in data of information of each detection result, and is necessary. Accordingly, the data is stored in the RAM 72 or the like for use.

  In the above configuration, the CPU 70 performs the automatic head shading operation at a predetermined timing, for example, immediately before starting an image forming job, in the following manner according to the control procedure shown in the flowchart of FIG. A control program corresponding to the control procedure is stored in the ROM 71 and executed by the CPU 70. The processes other than the following steps S1, S4 and S9 are the same as the head shading process described in Patent Documents 1 and 2.

  First, in step S1, the image recording speed of each recording head 2 in the recording paper conveyance direction must be set to a speed that matches the image reading speed of the image reading device 50 in the recording paper conveyance direction, or it cannot be done. If possible, the speed close to the reading speed is set within a possible range, and the recording paper transport speed is set to a transport speed corresponding to the set recording speed. Of course, the recording speed set here is slower than the normal recording speed.

  Next, in step S2, a paper feeding device (not shown) is driven and a paper feed motor 79 is driven to feed and transport the recording paper.

  Next, in step S3, when the recording paper transported by the transport belt 31 passes through the recording position immediately below the respective ejection port arrays of the four recording heads 2, all the recording elements of each recording head 2 are moved. Drive the test pattern image for head shading for each of the four colors of cyan, magenta, yellow, and black in different areas in the recording paper transport direction to the full length of the array of recording elements and ejection openings of each recording head 2 Record across the width.

  Next, in step S4, when the leading edge of the recording paper being conveyed reaches the reading position directly below the lens 56 of the image reading device 50, the recording paper conveyance speed at that time is the recording paper conveyance direction of the image reading device 50. It is checked whether or not the conveyance speed corresponds to the image reading speed, and if the conveyance speed does not correspond to the reading speed, the setting is changed to the corresponding conveyance speed.

  Next, in step S5, among the images of the four color test patterns recorded on the recording paper in step S3, the image of the first one color, for example, the cyan test pattern in the order of the conveyance direction is displayed on the image reading device 50. When the reading position is reached, the carriage motor 80 is driven and the reading sensor 58 and the lamp 60 are driven to scan and read the image of the one-color test pattern.

  When the reading of the one-color test pattern image is completed, in step S6, based on the read one-color image data, the driving condition of the recording head 2 that records the one-color image, for example, one for each ejection port. Data processing for obtaining correction data for correcting the number of ink droplet ejection corresponding to the ink ejection amount for recording dots is performed. The obtained correction data is fed back to the head driver 74, whereby the drive conditions of the corresponding recording head 2 are corrected. Note that if it is predicted that the ink discharge amount of each discharge port of the recording head 2 will change due to the fact that the recording speed at which the test pattern image is recorded is lower than the normal recording speed, the recording speed is recorded in advance. It is also possible to prepare the change data of the discharge amount by preparing the correction data by data conversion based on the prepared data.

  When the data processing for obtaining the correction data for the one color recording head 2 is completed, it is determined in step S7 whether or not the data processing for obtaining the correction data for all the four color recording heads 2 is completed. If not, the processes in steps S5 and S6 are repeated, and data processing for sequentially reading the test pattern image of the next color and obtaining correction data for correcting the drive condition of the recording head 2 of that color is performed.

  When the data processing for obtaining the correction data for all the four color recording heads 2 is completed in this manner, the recording paper is discharged in step S8, and then the recording speed of each recording head 2 in the recording paper conveyance direction is set to normal in step S9. In addition to setting the recording speed, the recording paper conveyance speed is set to a speed corresponding to the normal recording speed, and the process ends.

  According to this embodiment as described above, the conveyance speed of the recording paper when recording the test pattern image for head shading coincides with the conveyance speed when the image of the test pattern is read thereafter, or possible. Therefore, when the test pattern image is shifted from recording to reading, the conveyance speed of the recording paper is not rapidly changed (decreased). Accordingly, an excessive mechanical load is not applied to the mechanism of the paper feed motor 79 and the transport belt device 30 at that time, and the recording paper can be transported smoothly and stably, and the test pattern image can be read stably. The head shading correction can be performed stably and properly. Further, the image reading apparatus 50 may be configured to have a low reading speed, can be configured with an inexpensive configuration, and an automatic head shading function can be realized at a low cost.

  In the embodiment described above, the image reading apparatus 50 moves in the main scanning direction orthogonal to the recording paper conveyance direction to read the image. However, the full width of the head shading test pattern in the main scanning direction (implementation) In the example, it is assumed that the image for one line over the discharge port array of each recording head 2 is composed of a line sensor having a length that can be read at one time, and the image is not moved in the main scanning direction. It is good also as what reads. In this way, the reading speed in the recording paper conveyance direction of the image reading apparatus can be increased, and the normal recording speed in the recording paper conveyance direction of the recording head 2 can be brought close to improve the throughput of the entire head shading operation.

  In the embodiment, the recording head 2 is of a full line type. However, it goes without saying that the present invention can also be applied to a so-called serial type in which recording is performed by moving the recording head in the main scanning direction. . Even if it is a serial type, it is integrated with the replaceable chip type recording head or the recording head itself, which can be connected to the main body of the device and supplied with ink from the main body of the device. Of course, the present invention can also be applied to the case where a cartridge type recording head provided with an ink tank is used.

  Further, the present invention is suitable when the recording head is of the ink jet recording system as in the embodiment, but in particular, the means for generating thermal energy as the energy for causing ink ejection in the ink jet recording system. (For example, an electrothermal conversion element, a laser beam element, and the like), and an excellent effect is achieved in a recording head of a system that causes a change in the state of ink by the thermal energy. This is because this method can achieve higher recording density and higher definition. As the typical configuration and principle, for example, those disclosed in US Pat. Nos. 4,723,129 and 4,740,796 are preferably used. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying a drive signal that corresponds to the recorded information and gives a rapid temperature rise exceeding the film boiling to the electrothermal conversion element, heat energy is generated, and film boiling occurs on the heat acting surface of the recording head. As a result, bubbles corresponding to the drive signals on a one-to-one basis can be formed in the liquid (ink), which is effective. By the growth and contraction of the bubbles, liquid (ink) is ejected from the ejection port to form at least one droplet. It is more preferable that the driving signal has a pulse shape, since bubbles are grown and contracted immediately and appropriately, and liquid (ink) discharge with particularly excellent responsiveness can be achieved. As this pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further excellent recording can be performed by employing the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface.

  As the configuration of the recording head, in addition to the combination configuration (straight liquid flow path or right-angle liquid flow path) of the discharge port, the liquid path, and the electrothermal conversion element as disclosed in each of the above specifications, the thermal action A configuration (US Pat. No. 4,558,333, US Pat. No. 4,459,600) may be adopted in which the portion is disposed in the bent region. In addition, for a plurality of electrothermal conversion elements, a configuration in which a common slit is used as a discharge portion of the electrothermal conversion element (Japanese Patent Application Laid-Open No. 59-123670) and an opening for absorbing a pressure wave of thermal energy are provided. You may employ | adopt the structure (Unexamined-Japanese-Patent No. 59-138461) corresponding to a discharge part.

  The image forming apparatus according to the present invention includes a discharge recovery means including a capping means, a cleaning means, a pressurizing or suction means for recovering the normal ink discharge state of the recording head, and a reserve of ink for the recording head. It is preferable to add a preheating means for heating or a predischarge means for preliminarily discharging ink different from recording because head shading can be performed more easily and stably.

  The image forming apparatus according to the embodiment performs four color recording with four recording heads. However, the number of recording heads and the number of ink colors or densities are of course not limited thereto. .

  In the embodiments, the ink is described as a liquid. However, an ink that is solidified at room temperature or lower and that softens or liquefies at room temperature may be used. In addition, in the ink jet system, the temperature of the ink itself is generally adjusted within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. It is also possible to use a liquid in which the ink is liquid at the time of application. In order to prevent the temperature rise by heat energy by using the heat energy as the energy for changing the state of the ink from the solid state to the liquid state, or to prevent the ink from evaporating, it is solidified in the state of being left. Ink that is liquefied by heating may be used. In any case, by applying thermal energy according to the recording signal, the ink is liquefied and the liquid ink is ejected, or when it reaches the recording medium, it starts to solidify. The present invention can also be applied to the case where ink having a property of being liquefied for the first time is used. In such a case, the ink is in a state of being held as a liquid or a solid in a recess or a through hole of the porous sheet as described in JP-A-54-56847 or JP-A-60-71260. Thus, the electrothermal conversion element may be opposed to the electrothermal conversion element. The present invention is most effective in the case of an apparatus using each of these inks for an apparatus for recording an image by the film boiling method described above.

1 is a side view showing a mechanical configuration of a main part related to the present invention of an image forming apparatus according to an embodiment of the present invention. (A) is a top view which shows the mechanical structure of the image reading apparatus provided in the image forming apparatus of the Example, (b) is a vertical sectional view along the AA line in (a). 2 is a block diagram illustrating a configuration of a control system of the image forming apparatus according to the exemplary embodiment. FIG. FIG. 6 is a flowchart illustrating a control procedure of automatic head shading processing in the image forming apparatus of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming unit 2 Recording head 30 Conveying belt apparatus 31 Conveying belt 50 Image reading apparatus 51 Carriage 58 Reading sensor 60 Lamp 70 CPU
71 ROM
72 RAM
79 Paper feed motor 80 Carriage motor

Claims (8)

Conveying means for conveying the recording medium in one direction, a recording head capable of recording an image at different recording speeds in the conveying direction with respect to the conveyed recording medium, and a recording head for recording an image recorded on the recording medium in the conveying direction Having an image reading means for reading at a constant reading speed slower than the normal recording speed, and recording the test pattern image on the recording medium by the recording head while continuously conveying the recording medium in one direction. An image forming apparatus that performs an operation of reading an image of a test pattern that has been read by an image reading unit and correcting a driving condition of a recording head based on the result,
When recording an image of the test pattern for the correction, the recording speed of the recording head in the transport direction is set to a speed that matches the reading speed of the image reading means, or the closest possible speed, and Control means for controlling the conveyance speed of the recording medium to a speed corresponding to the recording speed and then controlling the conveyance speed of the recording medium to a speed corresponding to the reading speed of the image reading means when reading the image of the test pattern. An image forming apparatus provided.   The image forming apparatus according to claim 1, wherein the recording head records an image by a plurality of recording elements arranged along one direction orthogonal to the recording medium conveyance direction.   3. The image forming apparatus according to claim 2, wherein the recording head is a full-line type recording head in which the length of the array of the recording elements extends over the entire width of the recording area of the image forming apparatus. .   4. The image forming apparatus according to claim 1, wherein the image reading unit reads an image by moving in a direction orthogonal to a recording medium conveyance direction. 5.   2. The image reading unit includes a line sensor having a length capable of reading an image for one line over the entire width of the test pattern in a direction orthogonal to a recording medium conveyance direction at a time. 4. The image forming apparatus according to any one of items 1 to 3.   6. The ink jet recording head according to claim 1, wherein the recording head is an ink jet recording head that discharges ink by causing film boiling in the ink by heat generated by an electrothermal conversion element as a recording element. The image forming apparatus described in the item. A recording head capable of recording an image at a recording speed different in the conveyance direction with respect to a recording medium conveyed in one direction, and a constant image slower than the normal recording speed of the recording head in the conveyance direction. It has an image reading means that reads at a reading speed, and reads the test pattern image recorded after recording the test pattern image on the recording medium while continuously conveying the recording medium in one direction. A control method of an image forming apparatus that performs an operation of correcting a driving condition of a recording head based on
When recording an image of the test pattern for the correction, the recording speed of the recording head in the transport direction is set to a speed that matches the reading speed of the image reading means, or the closest possible speed, and The conveyance speed of the recording medium is set to a speed corresponding to the recording speed, and thereafter, when reading the test pattern image, the conveyance speed of the recording medium is controlled to be a speed corresponding to the reading speed of the image reading means. And a control method of the image forming apparatus. A recording head capable of recording an image at a recording speed different in the conveyance direction with respect to a recording medium conveyed in one direction, and a constant image slower than the normal recording speed of the recording head in the conveyance direction. It has an image reading means that reads at a reading speed, and reads the test pattern image recorded after recording the test pattern image on the recording medium while continuously conveying the recording medium in one direction. A control program for an image forming apparatus that performs an operation of correcting a drive condition of a recording head based on
When recording an image of the test pattern for the correction, the recording speed of the recording head in the transport direction is set to a speed that matches the reading speed of the image reading means, or the closest possible speed, and A control procedure for controlling the conveyance speed of the recording medium to a speed corresponding to the recording speed and then controlling the conveyance speed of the recording medium to a speed corresponding to the reading speed of the image reading means when reading the image of the test pattern. A control program for an image forming apparatus, comprising: