JP2007055050A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording device capable of compensating the performance degradation of an encoder due to the adhesion of ink mist to prolong the life of the main body. <P>SOLUTION: The inkjet recording device, which makes a recording head scan relative to a print medium and ejects ink for recording comprises a scanning means for making the recording head scan, an encoder means for detecting the position where the recording head scans, and a control means for controlling the scanning means based on the signal from the encoder means, wherein a plurality of color LEDs are provided to the light emitting section of the sensor means of the encoder means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mechanism for maintaining the performance of encoder means in an ink jet recording apparatus.

  Among the ink jet recording apparatuses, a so-called serial type ink jet recording apparatus that scans a print head in a direction perpendicular to the feeding direction of a print medium and records an image for each line is detachably mounted with a print head, A carriage operated along the surface of the print medium is provided.

  In order to perform such printing, it is necessary to detect and control the position and movement amount of the carriage and the conveyance amount of the print medium. There is a method using an encoder as one method for detecting the movement amount of the carriage and the conveyance amount of the print medium.

  There are encoders that display a position by a magnetic method, and those that display a position by an optical method. The optical method is a method of providing a scale at a predetermined interval on a film affixed to the surface of the encoder scale, optically reading the scale with an encoder sensor, and counting the scale to recognize the position and movement amount. .

  The encoder sensor includes a light emitting unit that emits light and a light receiving unit that receives light. The scale is a scale in which a portion that transmits light and a portion that does not transmit light arranged on the encoder scale are arranged at a predetermined interval. In most general encoder sensors, an infrared LED is used for the light emitting part and a photodiode is used for the light receiving part.

  In an ink jet recording apparatus, when ink is ejected from a discharge port toward a print medium, or when ink lands on a print medium, fine mist ink mist may float in the air. The floated ink mist adheres to each part of the print medium and the ink jet recording apparatus and unnecessarily soils them. Naturally, the ink mist may adhere to the light emitting part and the light receiving part of the encoder scale and the encoder sensor, and the encoder may not work normally. In such a case, the ink jet recording apparatus may not be able to perform a normal recording operation.

  A possible cause of the deterioration of the encoder performance due to the ink mist is that the scale cannot be recognized correctly because the light emitted from the light emitting portion of the encoder sensor is absorbed by the ink mist on the encoder scale.

As a countermeasure against ink mist, a method of preventing ink mist from adhering to the encoder (Patent Document 1), cleaning the encoder, or cleaning the encoder scale (Patent Document 2) can be considered.
JP 2004-188701 A (JP-A-9-189574)

  However, in the above method, inconvenience occurs because the size of the apparatus is increased due to extra parts.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording apparatus that can compensate for performance degradation due to deterioration in sensitivity of an encoder caused by ink mist by paying attention to absorption spectrum characteristics of ink light and optical characteristics of a light emitting portion of an encoder sensor. It is in.

  In order to achieve the above object, an inkjet recording apparatus of the present invention is an inkjet recording apparatus that performs recording by causing a recording head to scan a print medium and ejecting ink, and scanning means for scanning the recording head; Encoder means for detecting the scanning position of the recording head; and control means for controlling the scanning means based on a signal from the encoder means; and a plurality of color LEDs in a light emitting portion of sensor means of the encoder means. It is characterized by that.

  Further, another ink jet recording apparatus of the present invention is an ink jet recording apparatus that performs recording by causing a recording head to scan a print medium and ejecting ink, the transport means for transporting the print medium, and the transport Encoder means for detecting the operation amount of the means, and control means for controlling the transport means based on a signal from the encoder means, and a light emitting portion of the sensor means of the encoder means is provided with a plurality of color LEDs. And

  According to the present invention, by using the dot count value, the LED of the light emitting unit of the encoder sensor is switched according to the user's ink usage situation, and the encoder performance deterioration is compensated for by compensating for the deterioration of the encoder performance due to ink mist adhesion. Therefore, it is possible to avoid and eliminate the control malfunction of the apparatus, and to extend the life of the main body.

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

[Embodiment 1]
<Structure of mechanism part>
FIG. 1 is a schematic view of a printing unit used in the present invention.

  Reference numeral 301 denotes an auto-feeder unit, which separates sheets stacked on the sheet one by one and performs a conveying operation by a conveying mechanism such as an LF motor 305 and an LF gear 304. At this time, the sheet conveyance amount is controlled using the LF encoder scale 314 and the LF encoder sensor 315. The encoder is provided on the transport roller, but may be provided on another mechanism.

  The carriage 307 scans and moves in a direction perpendicular to the paper feeding direction by moving the belt 311 connected to the carriage 307 by the carriage drive motor 310 while the paper is fed. An ink jet head 302 is mounted on the carriage 307 and is mounted by a head attaching / detaching lever 308. The carriage 307 is connected to a shaft fixed to the chassis 303 by a bearing 306. An optical sensor 312 is mounted on the side surface of the carriage 307. The position detection that the carriage 307 has moved is performed by a carriage encoder scale 313 and a carriage encoder sensor mounted on the rear part of the carriage 307. Reference numeral 309 denotes a recovery unit, which is a unit for performing maintenance of the inkjet head 302.

  This apparatus is a recording apparatus that inputs data from the outside such as a host and performs recording on a recording medium such as a recording sheet. In addition, the data may be input from a storage medium such as a memory card.

<Multi-color LED>
Most commercially available encoder sensors have an infrared LED in the light emitting section. In particular, most of the near infrared light has a wavelength of about 800 nm to 900 nm. Infrared light has the property of being easily absorbed by organic compounds. Since the ink used in the ink jet recording apparatus is an organic solvent, it has a property of easily absorbing infrared light regardless of the color of the ink.

  Therefore, when ink mist adheres to the encoder scale or encoder sensor, the light emitted from the light emitting part of the encoder sensor is absorbed by the ink mist, and the scale on the encoder scale may not be read correctly. Infrared LED light has a characteristic of being absorbed regardless of the color of the ink. On the other hand, as shown in FIG. 2, the transmittance of visible light LED light varies depending on the color of the ink.

  For example, the emission characteristic 403 of the red LED transmits 65% or more of yellow ink 405 and magenta ink 406, but absorbs 100% of cyan ink 404. In the light emission characteristic 401 of the blue LED, the cyan ink 404 transmits about 65%, but the yellow ink 405 and the magenta ink 406 transmit only about 15%.

  The control means (for example, CPU) that controls the ink jet recording apparatus according to the present invention using the above characteristics includes a plurality of visible light LEDs in the light emitting portion of the encoder sensor, and switches the light emission color of the LEDs to thereby change the ink mist. The performance deterioration of the encoder due to the adhesion of can be compensated.

<LED switching by dot count>
The amount of ink mist generated for each color depends on the user who uses the ink jet recording apparatus. By using the dot count value that counts the number of ink droplets, it is possible to switch the light emission color of the LED of the encoder sensor light emitting unit according to the ink usage status for each user.

  FIG. 3 is a flowchart showing the LED switching timing for an example in which green and red LEDs are used for the encoder sensor light emitting unit in the present embodiment.

  In Step 101, a green LED is set in the light emitting unit of the encoder sensor as an initial setting. Next, in Step 102, it is determined whether or not the magenta dot count value out of the dot count for counting the number of ink droplets ejected from the print head for each ink color exceeds a predetermined threshold. If YES in step 104, the process proceeds to step 104, and the LED is switched from red to green. If not, step 103 continues to count the dots.

  FIG. 4 is a flowchart showing the LED switching timing in an example in which blue, green, and red LEDs are used for the encoder sensor light emitting unit in the present embodiment.

  In Step 201, a blue LED is set in the light emitting unit of the encoder sensor as an initial setting.

  Next, in Step 202, it is determined whether or not the yellow dot count value has exceeded a predetermined threshold value. If it has exceeded, the process proceeds to Step 204. If the LED has not exceeded, the LED is switched from blue to red. Dot count continues. If the process proceeds to Step 204, it is next determined in Step 205 whether or not the cyan dot count value has exceeded the threshold value. If it has exceeded, the process proceeds to Step 207 and the LED is switched from red to green. In step 206, the dot count is continued.

  Depending on the configuration of the apparatus, the threshold for switching the LED of the carriage encoder may be different from the threshold for switching the LED of the LF encoder.

[Embodiment 2]
Next, a second embodiment of the present invention will be described. Note that the dot count method is different between the present embodiment and the above-described first embodiment, and other configurations and operations are the same as those of the first embodiment, and redundant description is omitted.

<LED switching by borderless dot count>
In an ink jet recording apparatus, borderless printing is a print mode in which ink mist is likely to occur. Borderless printing is a printing means that prints on the entire surface of a print medium without providing a margin in the print medium when printing an image such as a photograph. Borderless printing is realized by performing printing that protrudes a predetermined amount. When performing borderless printing, the ink droplets ejected as a protruding part land on the ink absorber, but the distance from the ejection port of the print head to the ink absorber is greater than the distance from the ejection port to the print medium. Therefore, it is known that the probability of separation, diffusion and floating in the air is high, and ink mist is likely to occur.

  Therefore, in the present embodiment, the dot count for counting the number of ink droplets used for the protrusion at the time of marginless printing for each color, that is, the dotless dot count is performed, and the encoder sensor is used by using the marginless dot count value. Switch the emission color of the LED of the light emitting unit.

  FIG. 5 is a flowchart showing the LED switching timing for an example in which green and red LEDs are used for the encoder sensor light-emitting unit in the present embodiment, and FIG. 6 is an encoder sensor in the present embodiment. It is a flowchart showing LED switching timing about the example at the time of using LED of three colors, blue, green, and red, for a light emission part. 5 and 6 are obtained by replacing the dot counts in FIGS. 3 and 4 of the first embodiment with borderless dot counts, respectively, and thus detailed description thereof will be omitted.

It is the perspective view which looked at the internal mechanism of the printing apparatus applied by this invention from the upper left part. It is the model showing the light transmittance with respect to the range of the wavelength of the light irradiated from LED of each color tone, and the wavelength of each ink. It is a flowchart which shows the schematic process of an example in Embodiment 1 of this invention. It is a flowchart which shows the schematic process of the example different from FIG. 3 in Embodiment 1 of this invention. It is a flowchart which shows the schematic process of an example in Embodiment 2 of this invention. It is a flowchart which shows the schematic process of the example different from FIG. 5 in Embodiment 2 of this invention.

Explanation of symbols

301 Auto Sheet Feeder Unit 302 Inkjet Head 303 Chassis 304 LF Gear 305 LF Motor 306 Bearing 307 Carriage 308 Head Removable Lever 309 Recovery Unit 310 Carriage Drive Motor 311 Belt 312 Optical Sensor 313 Carriage Encoder Scale 314 LF Encoder Scale 315 LF Encoder Sensor 401 Blue LED emission characteristics 402 Green LED emission characteristics 403 Red LED emission characteristics 404 Cyan ink transmittance 405 Yellow ink transmittance 406 Magenta ink transmittance

Claims (5)

An inkjet recording apparatus that performs recording by scanning a recording medium with respect to a print medium and discharging ink,
Scanning means for scanning the recording head, encoder means for detecting a scanning position of the recording head, and control means for controlling the scanning means based on a signal from the encoder means, and a sensor means of the encoder means. An ink jet recording apparatus comprising: a light emitting unit including a plurality of colors of LEDs. An inkjet recording apparatus that performs recording by scanning a recording medium with respect to a print medium and discharging ink,
A transport unit that transports the print medium; an encoder unit that detects an operation amount of the transport unit; and a control unit that controls the transport unit based on a signal from the encoder unit. An ink jet recording apparatus comprising: a light emitting unit including a plurality of colors of LEDs.   3. The ink jet recording apparatus according to claim 1, wherein the LED is switched according to an instruction from the control means.   The inkjet recording apparatus according to claim 1, further comprising a dot count unit that counts the number of ink droplets ejected from the recording head for each ink color.   The inkjet recording apparatus according to claim 1, wherein the LEDs are switched based on a value counted by the dot counting means.

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