JP2013022769A - Inkjet recorder, and inspecting method in the inkjet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recorder which detects malfunction of an encoder sensor in advance.SOLUTION: Driving current of a light emitting element of the encoder sensor is made different between a going time and a returning time in a predetermined section in a scanning direction, and a difference between the number of pulses output from the encoder sensor when going and the number of pulses output from the encoder sensor when returning is compared with a reference value. When the difference is larger than the reference value, it is determined as an error.

Description

  The present invention relates to an ink jet recording apparatus equipped with an encoder sensor and an inspection method in the ink jet recording apparatus.

  The ink jet recording apparatus has the following reasons: (1) it is easy to make a compact configuration, (2) it is possible to perform color and high image quality recording, and (3) it is a non-impact method, so it has excellent quietness. Widely used. In an ink jet recording apparatus, a serial method is known in which recording is performed while a recording head is mounted on a carriage and scanned in a scanning direction. Position / speed control of the moving carriage is detected using a linear scale and an encoder sensor. As the linear scale, an encoder pattern formed with a predetermined resolution on a transparent film is often used. As an encoder sensor, a photo interrupter with an encoder function using light is often used in terms of accuracy and cost. The linear scale and the encoder sensor provided for the carriage position control may be called a CR encoder film or a CR encoder sensor, respectively.

  In an ink jet recording apparatus, contamination inside and outside the apparatus due to ink mist, which is splash of ink droplets, is a problem. Ink mist refers to liquid ink ejected from a recording head that floats in a mist without reaching or being absorbed by the paper surface. These may adhere and be fixed inside the device body while floating. As a countermeasure, there is one having a fan that collects air in the ink jet recording apparatus including ink mist.

  However, even with such a fan, it is difficult to completely discharge the ink mist, and the accumulation of the remaining amount becomes a problem. Ink mist often occurs in applications where the printing duty of ink is high, such as printing of photographic images, and miniaturization of ink particles accompanying high resolution also contributes to the generation of floating fine mist. Therefore, it is considered that ink mist becomes a bigger problem as the resolution and speed of the ink jet recording apparatus are further increased.

  The above-described CR encoder sensor and CR encoder film are also affected by ink mist. When the surface of the optical sensor or the surface of the CR encoder film included in the CR encoder sensor is soiled, the light from the LED is blocked by the ink mist, so that the optical sensor light receiving unit cannot obtain a sufficient amount of light. In this case, the CR encoder sensor cannot detect a change in the encoder slit and cannot output a pulse result. As a result, an error occurs in the carriage position and speed control, which causes a serious problem in the operation of the ink jet recording apparatus.

  In order to reduce the light amount detection due to adhesion of ink mist, it is conceivable to increase the current value for driving the LED so that a sufficient amount of transmitted light is detected by the light receiving unit. However, when the current is increased, the deterioration of the LED is promoted and the amount of emitted light is reduced. Therefore, it is necessary from the viewpoint of usability and serviceability to detect the malfunction of the CR encoder sensor in advance.

JP 2003-316216 A

  Patent Document 1 describes a method of predicting the remaining life of an optical sensor for detecting the presence or absence of a medium by receiving a change in the adjusted light amount. However, the CR encoder sensor is an element that outputs a digitized pulse. In other words, since the conversion of the light amount level itself is not detected, the remaining life of the CR encoder sensor cannot be predicted by the method described in Patent Document 1. Therefore, even if the method of Patent Document 1 is used, it is only possible to detect a malfunction of the CR encoder sensor when the malfunction of the CR encoder sensor occurs.

  An object of the present invention is to solve such conventional problems. An object of the present invention is to provide an ink jet recording apparatus that detects in advance an operation failure of an encoder sensor and an inspection method in the ink jet recording apparatus.

In order to solve the above problems, an ink jet recording apparatus according to the present invention includes an encoder sensor that is mounted on a recording head, optically reads an encoder film provided in a scanning direction of the recording head, and outputs a pulse;
Changing means for making the drive current of the light emitting element of the encoder sensor different between the forward path and the backward path in the predetermined section in the scanning direction;
The difference between the number of pulses output from the encoder sensor during the forward pass and the number of pulses output from the encoder sensor during the return pass is compared with a reference value, and if the difference is greater than the reference value, it is determined as an error. And an error determination means.

  According to the present invention, malfunction of the encoder sensor can be detected in advance.

1 is an external perspective view showing an outline of a configuration of an ink jet recording apparatus. It is a block diagram which shows the control structure of an inkjet recording device. It is a figure which shows the structure of CR encoder sensor. It is a figure which shows the structure of a carriage periphery. It is a figure which shows the structure of a multipurpose sensor. It is a figure which shows the electrical structure regarding CR encoder sensor. It is a flowchart which shows the procedure of the inspection process of CR encoder sensor. It is a flowchart which shows the procedure of an error process. It is a figure which shows an example of an encoder count value and a drive current value. It is a figure which shows a response | compatibility with a drive current value and the identification number which identifies each drive current.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the present invention according to the claims, and all combinations of features described in the present embodiments are not necessarily essential to the solution means of the present invention. . The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.

<Description of inkjet recording apparatus>
FIG. 1 is an external perspective view showing an outline of the configuration of an ink jet recording apparatus which is a typical embodiment of the present invention.

  As shown in FIG. 1, an ink jet recording apparatus 100 transmits a driving force generated by a carriage motor M1 from a transmission mechanism 104 to a carriage 102 on which a recording head 103 that performs recording by discharging ink according to an ink jet method is transmitted. Is moved back and forth in the direction of arrow A, and for example, a recording medium P such as recording paper is fed through the paper feeding mechanism 105 and conveyed to the recording position, and ink is transferred from the recording head 103 to the recording medium P at the recording position. Recording is performed by discharging the.

  Further, in order to maintain the state of the recording head 103 satisfactorily, the carriage 102 is moved to the position of the recovery device 110, and the ejection recovery process of the recording head 103 is performed intermittently.

  In addition to mounting the recording head 103 on the carriage 102 of the inkjet recording apparatus 100, an ink cartridge 106 for storing ink to be supplied to the recording head 103 is mounted. The ink cartridge 106 is detachable from the carriage 102.

  The ink jet recording apparatus 100 shown in FIG. 1 is capable of color recording. For this reason, the carriage 102 contains magenta (M), cyan (C), yellow (Y), and black (K) inks 4, respectively. Equipped with two ink cartridges. These four ink cartridges are detachable independently.

  The carriage 102 and the recording head 103 can achieve and maintain a required electrical connection by properly contacting the joint surfaces of both members. The recording head 103 selectively discharges ink from a plurality of discharge ports and records by applying energy according to a recording signal. In particular, the recording head 103 in this embodiment employs an ink jet system that ejects ink using thermal energy, and includes an electrothermal transducer to generate thermal energy, and is applied to the electrothermal transducer. The generated electrical energy is converted into thermal energy, and ink is ejected from the ejection port by utilizing pressure changes caused by bubble growth and contraction caused by film boiling caused by applying the thermal energy to the ink. The electrothermal transducer is provided corresponding to each of the ejection ports, and ink is ejected from the corresponding ejection port by applying a pulse voltage to the corresponding electrothermal transducer in accordance with the recording signal.

  As shown in FIG. 1, the carriage 102 is connected to a part of the driving belt 107 of the transmission mechanism 104 that transmits the driving force of the carriage motor M <b> 1, and slides in the direction of arrow A along the guide shaft 113. It is guided and supported freely. Accordingly, the carriage 102 reciprocates along the guide shaft 113 by forward rotation and reverse rotation of the carriage motor M1. In addition, a scale 108 (CR encoder film) is provided for indicating the absolute position of the carriage 102 along the movement direction (arrow A direction) of the carriage 102. In this embodiment, the scale 108 uses a transparent PET film with black bars printed at the required pitch, one of which is fixed to the chassis 109 and the other is supported by a leaf spring (not shown). Yes.

  Further, the inkjet recording apparatus 100 is provided with a platen (not shown) facing the discharge port surface where the discharge port (not shown) of the recording head 103 is formed, and the recording head is driven by the driving force of the carriage motor M1. Simultaneously with the reciprocating movement of the carriage 102 on which the recording medium 103 is mounted, recording is performed over the entire width of the recording medium P conveyed on the platen by giving a recording signal to the recording head 103 and ejecting ink.

  Further, the transport roller 114 in FIG. 1 is driven by a transport motor M2 to transport the recording medium P. The pinch roller 115 abuts the recording medium P against the transport roller 114 by a spring (not shown). Further, the pinch roller holder 116 supports the pinch roller 115 rotatably. Further, the transport roller gear 117 is fixed to one end of the transport roller 114. The transport roller 114 is driven by the rotation of the transport motor M2 transmitted to the transport roller gear 117 via an intermediate gear (not shown).

  The discharge roller 120 discharges the recording medium P on which an image is formed by the recording head 103 to the outside of the ink jet recording apparatus. The discharge roller 120 is driven by the rotation of the transport motor M2. The discharge roller 120 abuts on a spur roller (not shown) that presses the recording medium P by a spring (not shown). The spur holder 122 rotatably supports the spur roller.

  In addition, as shown in FIG. 1, the inkjet recording apparatus 100 includes a desired position (for example, a home position) outside the range of reciprocating motion (outside the recording area) for the recording operation of the carriage 102 on which the recording head 103 is mounted. A recovery device 110 for recovering the ejection failure of the recording head 103 is disposed at a position corresponding to the position).

  The recovery device 110 includes a capping mechanism 111 for capping the ejection port surface of the recording head 103 and a wiping mechanism 112 for cleaning the ejection port surface of the recording head 103, and interlocks with the capping of the ejection port surface by the capping mechanism 111. Ink recovery such as forcibly discharging ink from the discharge port by a suction configuration (suction pump or the like) in the recovery device, thereby removing ink or bubbles having increased viscosity in the ink flow path of the recording head 103 Process.

  Further, at the time of non-recording operation, etc., the ejection port surface of the recording head 103 is capped by the capping mechanism 111, whereby the recording head 103 can be protected and ink evaporation and drying can be prevented. On the other hand, the wiping mechanism 112 is disposed in the vicinity of the capping mechanism 111 and wipes ink droplets adhering to the discharge port surface of the recording head 103.

  The capping mechanism 111 and the wiping mechanism 112 can keep the ink ejection state of the recording head 103 normal.

<Control configuration of inkjet recording apparatus>
FIG. 2 is a block diagram showing a control configuration of the inkjet recording apparatus 100 shown in FIG.

  As shown in FIG. 2, the control unit 210 includes an MPU 211, a ROM 212 storing a program corresponding to a control sequence to be described later, a required table, and other fixed data, control of the carriage motor M1 and the conveyance motor M2, and Each block is interconnected with a special purpose integrated circuit (ASIC) 213 that generates a control signal for controlling the recording head 103, a RAM 214 having a development area for image data, a work area for program execution, and the like. And a system bus 215 for transmitting and receiving data, and an A / D converter 216 for inputting analog signals from the sensor group described below to perform A / D conversion and supplying digital signals to the MPU 211. Is done.

  In FIG. 2, a host apparatus 200 is a computer (or a reader for image reading, a digital camera, or the like) serving as a supply source of image data. Image data, commands, status signals, and the like are transmitted and received between the host apparatus 200 and the inkjet recording apparatus 100 via an interface (I / F) 201.

  Further, the switch group 220 instructs the activation of the power switch 221, the print switch 222 for instructing the start of printing, and the processing (recovery processing) for maintaining the ink ejection performance of the recording head 103 in a good state. The recovery switch 223 and the like are configured to receive a command input from the operator. The sensor group 230 includes an ink jet recording apparatus including a position sensor 231 such as a photocoupler for detecting a home position, a temperature sensor 232 provided at an appropriate position of the ink jet recording apparatus 100 for detecting an environmental temperature, and the like. A sensor group for detecting 100 states.

  Further, the carriage motor driver 240 drives a carriage motor M1 for reciprocally scanning the carriage 102 in the direction of arrow A shown in FIG. Further, the transport motor driver 250 drives a transport motor M2 for transporting the recording medium P.

  The ASIC 213 transfers drive data of the printing element (discharge heater) to the print head while directly accessing the storage area of the ROM 212 during print scanning by the print head 103.

  The configuration shown in FIG. 1 is a configuration in which the ink cartridge 106 and the recording head 103 can be separated, but a replaceable head cartridge may be configured by integrally forming them.

  Furthermore, in the following embodiments, the liquid droplets ejected from the recording head are described as ink, and the liquid stored in the ink tank is described as ink. However, the storage is limited to ink. It is not a thing. For example, a treatment liquid discharged to the recording medium may be accommodated in the ink tank in order to improve the fixability and water resistance of the recorded image or to improve the image quality.

  The following embodiments are provided with a configuration (for example, an electrothermal converter, a laser beam, etc.) that generates thermal energy as energy used to perform ink ejection, particularly in an ink jet recording system, and the ink is heated by thermal energy. By using a system that causes a state change, it is possible to achieve high density and high definition of recording.

  Furthermore, as a full-line type recording head having a length corresponding to the maximum width of the recording medium that can be recorded by the inkjet recording apparatus 100, the length is obtained by combining a plurality of recording heads as disclosed in the above-mentioned specification. Either a configuration satisfying the above or a configuration as a single recording head formed integrally may be used.

  In addition to the cartridge-type recording head in which the ink tank is integrally provided in the recording head itself described above, it is mounted on the apparatus main body so that it can be electrically connected to the apparatus main body and from the apparatus main body. Alternatively, a replaceable chip type recording head that can supply the ink may be used.

  In addition, as the form of the ink jet recording apparatus 100 in the present embodiment, in addition to an image output terminal of an information processing apparatus such as a computer that is provided integrally or separately, a copying apparatus combined with a reading apparatus or the like, It may take the form of a facsimile machine having a transmission / reception function.

  FIG. 3 is a diagram illustrating a configuration of the CR encoder sensor 300 mounted on the inkjet recording apparatus 100. As the CR encoder sensor 300 in this embodiment, a photo interrupter with an encoder function is used. The photo interrupter with an encoder function is an optical device having a configuration in which an LED serving as a light emitting unit and a light receiving unit are paired. As shown in FIG. 3, the light receiving unit 302 includes four light receiving units A, A ′, B, and B ′. They are arranged so as to receive light from positions whose phases are shifted by 90 degrees with respect to the encoder film 303 provided oppositely. The output voltages from these four light receiving units are compared in the comparison units 304 and 305 by a combination of the light receiving units A and A ′ and the light receiving units B and B ′. The comparison units 304 and 305 output the comparison result as an H level or L level digital signal. Further, the drive current of the LED 301 is supplied from the outside. The CR encoder sensor 300 optically reads an encoder pattern on the CR encoder film 303 as the carriage 102 moves, and outputs an A phase / B phase or A ′ phase / B ′ phase pulse signal. Output at the same interval as the resolution on the encoder film 303. The position / velocity of the carriage 102 can be detected by the output pulse signal.

  A recording head 103, a CR encoder sensor 300, and a multi-purpose sensor 401 are mounted on the carriage 102, and can be reciprocated in the main scanning direction (the direction of arrow A in FIG. 1) by a conveyor belt. The recording medium P is transported to the platen by transport rollers (not shown). The platen holds the recording medium 203 flat in the printing area. The recovery device 110 performs a recovery operation by wiping the surface of the recording head 103 and sucking ink. The recovery device 110 is configured to cap the surface of the recording head 103, and discharges ink while being capped during the recovery operation. Ink droplets are ejected from the recording head 103 one dot at a time according to the ejection signal from the control unit 210. The total number of ejected ink droplets is stored as a dot count value in the RAM 214 or the like.

  FIG. 4 is a diagram showing a configuration around the carriage 102. A CR encoder sensor 300 and a multipurpose sensor 401 are mounted on the carriage 102. The CR encoder sensor 300 is composed of an increment type photo interrupter with an encoder function. The carriage home position sensor 402 is configured such that the LED and the photo sensor face each other. A flag 403 is provided on the carriage 102. When the carriage 102 moves to the home position, the flag 403 blocks the optical axis of the carriage home position sensor 402. As a result, the carriage home position sensor 402 can detect that the carriage 102 has moved to the home position.

  FIG. 5 is a diagram illustrating a configuration of the multipurpose sensor 401. Photodiodes 501 and 502 are light receiving elements in the multipurpose sensor 401. The visible LEDs 503, 504, and 505 and the infrared LED 506 are light emitting elements in the multipurpose sensor 401. The multi-purpose sensor 401 is configured to irradiate light from each LED onto a paper surface or an object and receive the reflected light. The multipurpose sensor 401 can operate in a multifunctional manner as a density sensor, a distance sensor, an edge sensor, or the like, depending on the combination of driving of each LED and each photodiode described above. For example, the recording parameter in the recording operation of the inkjet recording apparatus 100 Used for automatic adjustment.

  FIG. 6 is a diagram showing an electrical configuration related to the CR encoder sensor 300. The power supplied to the LED of the CR encoder sensor 300 and the LED of the multi-purpose sensor 401 is controlled by the power control unit 602 on the carriage board (CR board) 601. Further, the power control unit 602 is supplied with a power source 603 and a control signal 604 from a main board (not shown). The power control unit 602 can variably control the power supplied to the CR encoder sensor 300 and the multipurpose sensor 401 by a control signal 604 from the MPU 211.

  Normally, when switching the drive current of each LED, a configuration using a switch is conceivable. However, if a plurality of drive current sources for switching are provided, the number of circuits / control lines increases accordingly. . In that respect, the configuration shown in the present embodiment makes it possible to set a flexible drive current value while suppressing an increase in circuit / control lines.

  Hereinafter, an inspection method of the CR encoder sensor 300 in the present embodiment will be described. In this embodiment, the encoder count values at the time of the forward pass and the return pass in a predetermined test section are compared with each other based on the position detected by the carriage home position sensor 402. Further, the LED of the CR encoder sensor 300 is driven with a normal drive current value in the forward path, and the drive current value is changed to be lower than the normal drive current value by the control signal 604 in the return path.

  When the CR encoder film 303 or the CR encoder sensor 300 cannot be read normally due to dirt such as ink mist, the encoder count value (that is, the number of pulses) is missed, so the count tends to decrease. In the present embodiment, further, it is utilized that the encoder count value is easily missed when the LED drive current value is decreased to reduce the light amount. For this reason, in this embodiment, the degree of contamination is confirmed by comparing the encoder count value when driving with a normal driving current value and when driving with a lower driving current value. It is also possible.

  FIG. 7 is a flowchart showing the procedure of the inspection process of the CR encoder sensor 300 in the present embodiment. 7 is executed by the MPU 211 of the inkjet recording apparatus 100, for example. When the inspection process is started, the MPU 211 starts moving the carriage 102 in the forward direction with the position detected by the carriage home position sensor 402 as a base point (S701). Then, the MPU 211 moves the carriage 102 to the predetermined inspection position by the encoder servo mechanism (S702). At that time, for example, the encoder count value C1 is stored in a storage area such as the RAM 214. When the carriage 102 reaches a predetermined inspection position, the MPU 211 stops the carriage 102 at that position, and sets the drive current value supplied to the LED 301 of the CR encoder sensor 300 to the inspection drive current value (S703). . Here, the test drive current value is set to a value smaller than the normal drive current value.

  After that, the MPU 211 starts the backward movement of the carriage 102 from that position (S704), and moves to a position detected by the carriage home position sensor 402 (S705). At this time, the MPU 211 stores the encoder count value C2 in a storage area such as the RAM 214 as in the forward direction. The moving speed of the carriage 102 in the backward direction is set to be slower than the speed in the forward path in order to prevent the carriage 102 from colliding with the side surface of the main body of the inkjet recording apparatus 100. In the region near the recovery device 110 provided in the vicinity of the carriage home position sensor 402, ink droplets are not ejected and therefore there is little contamination due to ink mist, so that a normal encoder pulse is output from the CR encoder sensor 300.

  When the carriage 102 reaches the position detected by the carriage home position sensor 402, the MPU 211 compares the encoder count values C1 and C2, and compares the difference with a threshold value (S706). Here, when it is determined that the difference between C1 and C2 is smaller than the threshold value, the MPU 211 determines that there is no problem (no dirt) in the state of the CR encoder sensor 300 (S707: No), and ends this processing. . On the other hand, when it is determined that the value is equal to or greater than the reference value, the MPU 211 determines that there is a problem (dirty) in the state of the CR encoder sensor 300 and executes error processing described later (S707: Yes, S708). .

  FIG. 8 is a flowchart showing the error processing procedure in S708 of FIG. When it is determined in S707 that the error processing is performed, the MPU 211 stores the encoder counter value and the drive current value at the time of the error determination in a storage area such as the RAM 214 (S801). FIG. 9 is a diagram showing an example of the stored encoder count value and drive current value. In this embodiment, an identification number for identifying each drive current is given in advance corresponding to each drive current value as shown in FIG. In this embodiment, according to FIG. 10, the identification number and the dot count value are stored in association with each other.

  After S801, the MPU 211 increases the drive current value by one step according to the table shown in FIG. 10 (S802). Here, the MPU 211 indicates that the drive current corresponding to the increased drive current value is the drive current No. It is determined whether or not the number is 4 or more (S803). Drive current No. Whether or not it is 4 or more means that in this embodiment, the drive current value is 10 mA or more. In step S803, the drive current No. If it is determined that the number is not 4 or more, the process proceeds to S804. On the other hand, the drive current No. If it is determined that the value is 4 or more, in S805, the MPU 211 further increases the drive current value by one step. The purpose of the determination in S803 is to determine whether or not the driving current value at the time of inspection is close to the normal driving current value. That is, this is for confirming the concern that the dot count may be lost due to dirt even in the normal drive current value.

  In step S804, the MPU 211 further determines that the drive current is a drive current No. It is determined whether it is 8 or more. Drive current No. Whether or not it is 8 or more means that in this embodiment, the drive current value is 35 mA or more. In S804, the drive current No. If it is determined that the number is not 8 or more, the MPU 211 executes the inspection process shown in FIG. 7 again with the drive current value increased in S802 or S805 (S806). On the other hand, the drive current No. If it is determined that the number is 8 or more, an error is displayed to request a response such as part replacement by the service, and the process ends (S807). For example, the error display may be performed by a warning LED. The determination in S804 is performed to confirm that the drive current value at the time of inspection is driven to near the limit of the specifications of the CR encoder sensor 300. When a large current is passed through the LEDs in the CR encoder sensor 300, deterioration of the element is accelerated even if it is within the electrical maximum rating. Therefore, it is necessary to set an upper limit value for determining safety within the maximum rating. If it is determined in S804 that the drive current value has reached or exceeded the upper limit value, it is determined that the corresponding limit is due to the change in the current value in S805 because the stain progresses too much due to the ink mist. Request for parts replacement by service.

  Even if the drive current value is increased by one step in S805, the drive current No. In some cases, it is determined that the number is not 8 or more, and as a result, the error process is not determined by the inspection process illustrated in FIG. In such a case, even if it is determined as error processing in the first inspection process shown in FIG. 7 (determined as dirt due to ink mist), if the amount of light is further increased in S805, it is determined as error processing in the second inspection process. That was not done. In other words, if the LED drive current value is smaller than the above upper limit value, a certain amount of ink mist contamination is allowed by increasing the drive current value one step further to increase the amount of light. As a result, the number of parts replacement can be suppressed. On the other hand, when the drive current value reaches the upper limit value, the contamination is progressing to the extent that the drive current value must be increased to the upper limit value (the light amount must be increased). In this embodiment, in this case, a response such as replacement of parts is requested.

  The present invention is also realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (5)

An encoder sensor mounted on a recording head, optically reading an encoder film provided in the scanning direction of the recording head, and outputting a pulse;
Changing means for making the drive current of the light emitting element of the encoder sensor different between the forward path and the backward path in the predetermined section in the scanning direction;
The difference between the number of pulses output from the encoder sensor during the forward pass and the number of pulses output from the encoder sensor during the return pass is compared with a reference value, and if the difference is greater than the reference value, it is determined as an error. An ink jet recording apparatus, comprising: An adjusting means for adjusting the drive current at the time of the forward path or the return path when the error determination means determines an error;
The inkjet recording apparatus according to claim 1, further comprising: a control unit that controls the error determination unit to perform the determination based on the drive current adjusted by the adjustment unit.   The inkjet recording apparatus according to claim 2, wherein the adjustment unit adjusts the drive current so that a difference between the drive currents during the forward pass and the return pass is small.   When the drive current adjusted by the adjustment means becomes equal to or higher than a predetermined upper limit value, warning means is further provided to warn to replace at least one of the encoder film and the encoder sensor. The ink jet recording apparatus according to claim 3. An inspection method that is mounted on a recording head and optically reads an encoder film provided in the scanning direction of the recording head and is executed in an ink jet recording apparatus that includes an encoder sensor that outputs a pulse,
A changing step of changing the drive current of the light emitting element of the encoder sensor between the forward pass and the return pass in a predetermined section in the scanning direction,
The error determination means of the inkjet recording apparatus compares a difference between the number of pulses output from the encoder sensor during the forward pass and the number of pulses output from the encoder sensor during the return pass with a reference value, and the difference is An inspection method comprising: an error determination step of determining an error when larger than a reference value.

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