JP6384136B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an “image forming apparatus that forms an image as a toner image on a sheet-like recording medium”.

  An “image forming apparatus that forms an image as a toner image on a sheet-like recording medium” is widely known as an analog or digital electronic copying machine, a laser printer, or the like (Patent Documents 1 to 3, etc.).

  A “sheet-like recording medium formed as a toner image” is a sheet to which a toner image is transferred and fixed. A so-called “transfer paper” or a plastic sheet for an overhead projector (a so-called “OHP sheet”) is used. It is common.

  Such a sheet-like recording medium is nipped and conveyed by a rotating member such as an endless belt or a roller when a toner image is transferred or fixed.

  A rotating member that performs nipping and conveying of a sheet-like recording medium in this way is referred to as a “sheet conveying member”.

  The surface state of the sheet conveying member deteriorates with time as the sheet conveyance is repeated.

  That is, as the conveyance is repeated, the surface is roughened and roughened, “smoothness is impaired”, or the edge portion (sheet-like recording medium) of the cut portion of the sheet-like recording medium (the portion forming the thickness of the sheet end) “Streak-like scratches” may occur on the surface due to the surface and the edge of the cut end surface.

  This streak is referred to as a “sheet edge scratch”.

  The sheet edge damage gradually becomes deeper as the conveyance is repeated. When the depth of the sheet edge scratch exceeds the limit, the image formation is hindered.

  It is known from Patent Documents 1 and 2 that the surface state of the sheet conveying member is detected.

  An object of the present invention is to realize a novel image forming apparatus that can stably detect the surface state of a sheet conveying member that conveys a sheet-like recording medium.

The image forming apparatus according to the present invention is an image forming apparatus that forms an image as a toner image on a sheet-like recording medium, and detects a sheet conveying member that conveys the sheet-like recording medium and a surface state of the sheet conveying member. and two reflective sensors, the two sensors, distance from the surface of the sheet transport member: has a D, a sensor moving means for moving along a movement trajectory that intersects the movement direction of said surface, said and two calibration member for calibrating the two sensors, and a control means for controlling the detection of the surface conditions by the two sensors, the moving range of the two sensors, at least one side Includes a calibration area that protrudes outward in the width direction perpendicular to the movement direction of the surface of the sheet conveying member, and the calibration member is spaced from the movement trajectory of the two sensors in the calibration area. : D ' Disposed (≒ D) and septum and by the control means, wherein to perform calibration of the two sensors using two calibration member, said control means, the sensor of the surface condition of the sheet conveying members A storage function for storing the detection result together with information on the surface position; a comparison function for comparing the stored contents of the plurality of stored data; and a determination function for determining the surface state. Two sensors are moved in opposite directions, the surface state of the sheet conveying member is detected in opposite directions along the movement trajectory of the two sensors, and the detection results in opposite directions are stored, The stored detection results in opposite directions are compared, and the surface state is determined based on the comparison result .

  As described above, in the image forming apparatus of the present invention, the “reflective sensor for detecting the surface state of the sheet conveying member” is calibrated by the calibration member, so that the detection by the sensor can always be kept appropriate.

  Further, since the distance D ′ between the sensor and the calibration member is substantially equal to the distance D between the sensor and the surface of the sheet conveying member, the calibration can be appropriately performed in a state close to the detection of the surface state of the sheet conveying member. .

It is a figure for demonstrating the characterizing part of invention. It is a figure for demonstrating the embodiment of FIG. 1 further. It is a figure explaining the problem by a sheet | seat edge part damage | wound and a sheet | seat edge part damage | wound. It is a figure for demonstrating the detection of a sheet | seat edge part damage | wound. It is a figure for demonstrating another embodiment of invention. It is a figure for demonstrating another example of the detection of a sheet | seat edge part damage | wound. It is a figure for demonstrating one Embodiment which performs position calibration of a sensor. It is a figure for demonstrating embodiment which detects a surface state by reciprocation of a sensor. It is a figure for demonstrating the detection of a sheet | seat edge part damage | wound. It is a figure for demonstrating embodiment which detects a sheet | seat edge part damage | wound using two sensors. FIG. 6 is a diagram for explaining determination of deterioration over time of the surface of a sheet conveying member. It is a figure for demonstrating an example of the movement method of a sensor. It is a figure for demonstrating one Embodiment of an image forming apparatus.

Hereinafter, embodiments will be described.
For the sake of concreteness of description, the case where the sheet conveying member is a fixing member will be described.
First, with reference to FIG. 3, a fixing member, a sheet edge damage, and a “problem caused by a sheet edge damage” will be briefly described.

  FIG. 3A is a diagram for explaining the fixing member.

In this example, the fixing member is composed of two rollers R1 and R2.
In FIG. 3A, the symbol S indicates a sheet-like recording medium (transfer paper, OHP sheet, etc.).
In the following description, for the sake of concreteness of description, the sheet-like recording medium is assumed to be “transfer paper” and referred to as transfer paper S or the like.

  In FIG. 3A, the roller R1 and the roller R2 sandwich the transfer sheet S and rotate in the directions of the arrows, respectively, to “clamp and convey” the transfer sheet S upward in the drawing.

  At this time, the toner image to be fixed is formed on the “left side in the drawing” of the transfer paper S.

  Accordingly, when the transfer sheet S is conveyed under pressure as described above, the toner image contacts the roller R1 and the roller R2 contacts the back surface of the transfer sheet S.

  The roller R1 has a heater inside, and applies heat to the toner image on the transfer paper S when the transfer paper S is conveyed. At this time, the roller R2 applies pressure from the back side of the transfer paper S.

  The toner image on the transfer paper S is fixed on the transfer paper S by heat and pressure applied from the rollers R1 and R2.

  Hereinafter, the roller R1 is also referred to as a fixing roller R1, and the roller R2 is also referred to as a pressure roller R2.

  In FIG. 3B, reference numeral S1 indicates “small size transfer paper (for example, B5 size transfer paper)”.

  When the small-size transfer sheet S1 is nipped and conveyed by the fixing member, it is conveyed in the direction of the arrow (left side in the figure) while being pressed against the peripheral surface of the fixing roller R1, as shown in FIG. 3B.

  During this conveyance, the sheet end perpendicular to the conveyance direction of the transfer sheet S1 moves while being pressed against the position indicated by reference numeral BR in FIG.

  For this reason, when the fixing of the toner image to the small-size transfer paper S1 is repeated, a “sheet end scratch” is formed in the portion indicated by the symbol BR.

Hereinafter, this “sheet edge scratch” will be referred to as a sheet edge scratch BR.
The sheet edge scratch BR becomes “scratched deep” as the number of fixings increases, and when the depth of the scratch exceeds a limit, the “fixing function at the scratched portion” deteriorates.

  In FIG. 3C, reference numeral S2 indicates a transfer paper (for example, A4 size transfer paper) having a size larger than that of the transfer paper S1.

  When the transfer sheet S2 is nipped and conveyed by the fixing member, as shown in FIG. 2C, the transfer sheet S2 is conveyed in the arrow direction (left side in the figure) while being pressed against the peripheral surface of the fixing roller R2.

  Since the transfer sheet S2 is larger than the transfer sheet S1, the transfer sheet S2 overlaps the sheet edge scratch RR when being conveyed.

  At this time, if the depth of the sheet edge scratch BR exceeds the limit and the fixing function is deteriorated at the scratch, the fixing failure portion BRI is generated on the transfer sheet S2 corresponding to the sheet edge scratch BR. Resulting in.

  Therefore, in order to prevent the occurrence of such a fixing failure portion BRI, it is necessary to detect the presence / absence of a “sheet edge damage” by observing the surface state of the fixing roller R1.

  Although the sheet edge damage also occurs on the pressure roller R2, since the pressure roller R2 is softer than the fixing roller R1, a deep sheet edge damage is less likely to occur.

  In addition, the pressure roller R2 is pressed against the back surface on which the toner image is not formed when the sheet-like recording medium S is nipped and conveyed, so that there is little influence on the occurrence of fixing failure of the fixed image.

  Therefore, the detection of the surface state of the pressure roller R2 can be omitted.

FIG. 1 is a diagram for explaining surface state detection by one sensor .
It is assumed that the “sheet conveying member” whose surface state is to be detected is the fixing roller R1 described above with reference to FIG.

  In FIG. 1A, the fixing roller R1 rotates around an axis parallel to the horizontal direction of the drawing, and its front surface R1S is displaced from “the front side to the back side” in the drawing. Transport the transfer paper.

  In FIG. 1A, reference numerals 1A and 1B are "support plates", reference numeral 2 is a "feed screw" supported by the support plates 1A and 1B, and reference numeral M is a "motor" that drives the feed screw 2 to rotate forward and backward. Show.

  Reference numeral 3 indicates a “control unit”, reference numeral SNS indicates a “sensor”, and reference numeral AS indicates a “calibration member”.

  The sensor SNS is a “reflective sensor” and includes a sensor part SN and a holder HL, and is held by the holder HL with the sensor part SN facing the surface R1S of the fixing roller R2.

  The holder HL is screwed into the feed screw 2 and is moved in the left-right direction in the figure by forward and reverse rotation of the feed screw 2 by the motor M.

  Therefore, the sensor SNS is displaced in the left-right direction in FIG. 1A by driving the feed screw 2 by the motor M, and the sensor unit SN moves on a straight line indicated by a symbol TRS in FIG.

  The straight line TRS is called a “movement locus” of the sensor SNS.

  The control means 3 is composed of a microcomputer and a CPU, and controls the sensor SNS and the motor M.

The control means 3 has a function of controlling the detection operation by the sensor SNS and performing “various processes” according to the output of the sensor SNS.
This “various processing” includes processing for performing “sensor SNS calibration” to be described later.

  That is, the control means 3 controls “detection of the surface state by the sensor SNS”. Therefore, the control means 3 can have a “storage function”, a “comparison function”, and a “determination function” to be described later.

  As shown in FIG. 1A, the movement locus TRS of the sensor SNS is parallel to the generatrix direction of the surface R1S of the fixing roller R1, and is separated from the surface R1S by a distance D.

  At least one side of the movement range of the sensor SNS (left side in FIG. 1A) is a width direction (FIG. The calibration area ASD that protrudes outside (in the left-right direction) is included.

  The calibration member AS is arranged in this configuration area ASD.

  The calibration member AS is plate-shaped, and the upper surface in the drawing is a reflection surface, and is spaced from the movement locus TRS of the sensor SNS by a distance D ′.

  Interval: D and D ′ are “substantially equal to each other”, and in the embodiment being described, “D = D ′” is set.

  1A includes a fixing roller R1 that is a sheet conveying member that conveys a sheet-like recording medium, and a reflective sensor SNS that detects the state of the surface R1S.

  The sensor SNS is moved at a distance D from the surface R1S of the fixing roller R1, and sensor moving means 1A, 1B, 2, M for moving the sensor SNS along a movement trajectory TRS intersecting the moving direction of the surface are provided. Have.

  Furthermore, it has the calibration member AS which calibrates the sensor SNS, and the control means 3 which controls the detection of the surface state by the sensor SNS.

  At least one side of the movement range of the sensor SNS includes a calibration area ASD that protrudes outward in the width direction perpendicular to the movement direction of the surface R1S of the fixing roller R1.

  The calibration member AS is disposed in the calibration area ASD at a distance D ′ (= D) from the movement locus TRS of the sensor SNS.

The control means 3 performs “calibration of the sensor SNS” using the calibration member AS.
FIG. 1B shows a state in which the sensor SNS is moved to the calibration area ASD by the control means 3 to calibrate the sensor SNS, and the sensor portion SN of the sensor SNS is opposed to the surface of the calibration member AS. .

As described above, the sensor SNS is a “reflective sensor”.
Various types of reflective sensors including those described in Patent Document 1 are well known, and these known appropriate ones can be used in the practice of the present invention.

  Here, for the sake of concreteness of explanation, the example shown in FIG.

  FIG.1 (c-1) has shown explanatoryly sensor part SN of sensor SNS of the above description.

  The sensor unit SN is formed by combining a light emitting element LE and a light receiving element LR as illustrated.

  The surface R1S of the fixing roller is obliquely irradiated with the detection light DL from the light emitting element LE, and the regular reflection light RL from the surface R1S is received by the light receiving element LR.

  The surface of the fixing roller R1 is in a “mirror state” in a normal state, and the regular reflection light RL received by the light receiving element LR has a high light intensity.

  When detecting the surface state of the surface R1S, the sensor SNS is displaced at a constant speed in one of the left and right directions in FIG. 1A according to the control by the control means 3, and continuously irradiates the surface R1S with the detection light DR. To do.

  If the state of the surface R1S is normal, “high output (appropriately amplified when it is taken into the control means 3)” as shown in FIG. can get.

  The time on the horizontal axis corresponds to “the irradiation position of the detection light DR on the surface R1S”.

  That is, the control means 3 controls the blinking of the light emitting element LE, captures the output of the light receiving element LR when the light emitting element LE emits light, and the captured output is “predetermined reference value (hereinafter referred to as“ threshold ”)”. Compare.

  The threshold value is set to, for example, “0.8 × DNOR” with respect to the light reception intensity: DNOR of the regular reflection light RL specularly reflected in a normal state.

  When the output of the light receiving element LR is “greater than or equal to the threshold value”, the state of the surface R1S is determined to be “normal”.

  As described above, the surface of the sheet conveying member is roughened and roughened as the conveyance of the sheet-like recording medium is repeated, and the “smoothness” decreases.

  FIG. 1C-2 shows a state in which the surface state is detected with the surface R1S roughened.

  When the surface R1S is roughened, a part of the detection light DL is “diffusely reflected” on the surface R1S, so that the regular reflection light RL decreases in intensity and the output of the light receiving element LR decreases.

  Accordingly, the output of the light receiving element LR in this case is “output reduced from the normal surface state” as shown in FIG.

  FIG. 1 (c-3) shows a case where “sheet edge scratches” are present on the surface R <b> 1 </ b> S.

Since the detection light DL is “remarkably irregularly reflected” at the scratched portion of the sheet edge, the regular reflection light RL is “significantly reduced”.
Since the sheet edge scratch exists “locally” in the direction in which the sensor SNS moves, the output of the light receiving element LR is a portion of the sheet edge scratch, as shown in FIG. And changes in restoration.

  Accordingly, if it is detected that the change in the output of the light receiving element LR indicates “sudden decrease and restoration”, the presence of a sheet edge scratch is detected.

The sheet edge damage causes the detection light DR to be strongly diffusely reflected as the depth of the damage increases.
Therefore, the greater the depth of signal change in the “abrupt decrease and restoration” of the output signal in FIG.

  As described above, the control unit 3 controls blinking of the light emitting element LE, captures the output of the light receiving element LR when the light emitting element LE emits light, and compares the captured output with a “threshold value”.

  In the following description, the threshold value is “ST”, and the output of the light receiving element LR is “LRO”.

  Threshold value: When ST is “LRO ≧ ST”, the surface R1S can be set so that neither “roughening nor sheet edge damage” causes any trouble in image formation (“fixing of toner image” in the example being described). .

  When “LRO <ST” is set when the threshold value ST is set, it can be determined that the state of the surface R1S is “a state in which image formation is hindered due to sheet edge scratches or roughening”.

  In this case, when the state of “LRO <ST” continues for a certain period of time, it can be determined that “roughening” is in progress.

  Further, when there is a sudden change in the output of the light receiving element LR, it can be determined that “a sheet edge scratch exists”.

  Since the change in the output LRO due to the sheet edge scratch is much larger than the change due to the roughening, for example, if “sheet edge scratch detection threshold: ST1” is set such that ST >> ST1. Thus, it is possible to easily and reliably detect the sheet edge damage.

  FIG. 2A shows the detection state of the surface state of the surface R1S by the sensor SNS.

  At this time, if there is a sheet end flaw BR on the surface R1S, the output of the sensor SNS shows “abrupt decrease and restoration” in the time corresponding to the position of the sheet end flaw BR as described above.

  An output portion indicating such “abrupt decrease and restoration” in output will be referred to as a “scratch-corresponding output portion”.

  FIG. 2A-1 shows the output in such a case, and the scratch corresponding output portions SGR appear at two locations corresponding to the two sheet end scratches BR.

  The threshold value in FIG. 2A-1 is the above-described threshold value ST1, and even if the scratch-corresponding output portion SGR is present, if the output value is equal to or greater than the threshold value, the surface R1S is “problem to fix”. It is a surface state without any.

  Now, in an image forming apparatus that forms an image as a toner image on a sheet-like recording medium, the toner image before fixing is formed of “powder toner”.

  Accordingly, powder toner is somewhat floating in the image forming apparatus. In the case of the fixing member described above, powder toner is considerably floating near the sheet conveying member.

  Further, since sheet-like recording media are generally “paper quality”, the floating of paper dust cannot be ignored.

  When such floating toner or paper dust adheres to the reflective sensor SNS, the detection light DL and the amount of light received by the light receiving element are changed, making it difficult to properly detect the surface state of the sheet conveying member.

  When powder toner or paper dust adheres to the light emitting element LE, the detection light DL irradiated from the light emitting element LE to the surface R1S decreases, and the output of the light receiving element LR that receives the regular reflection light RL decreases.

  The output shown in FIG. 2A-1 is an example of the output in a state where the sensor SNS is “normally functioning”.

  If the output when the sensor SNS is functioning normally is as shown in FIG. 1 (a-1), the sheet end scratch BR is present on the surface R1S, but the level of the scratch is a level that can be “fixed without hindrance”. .

  FIG. 2A-2 shows an example of the output of the sensor SNS that has “degraded in function” due to adhesion of “toner powder or paper powder”.

  Due to the lowered function, the output of the sensor SNS decreases as a whole from the output level NL when the function is normal.

  For this reason, the flaw corresponding output portion SGR1 corresponding to the sheet end flaw BR is lower than the threshold value ST1.

  As a result, a “false detection” occurs in which a sheet end damage BR of “a level that does not hinder fixing” is actually detected as a “sheet edge damage at a level that hinders fixing”.

  Therefore, the present invention solves this problem as follows.

  As described above, the calibration area ASD that protrudes outside in the width direction orthogonal to the moving direction of the surface R1S is provided on one side of the moving range of the sensor SNS.

A calibration member AS is provided in the calibration area ASD.
The calibration member AS is disposed in the calibration area ASD at a distance D ′ (= D) from the movement trajectory TRS of the sensor SNS. The distance D ′ is equal to the movement trajectory TRS of the sensor SNS and the surface R1S. And distance: substantially equal to D.

  FIG. 2B shows a state where the sensor SNS is moved to the calibration area ASD and is opposed to the calibration member AS.

  The calibration member AS has a reflection surface on the side facing the sensor SNS, and when the detection light DL is irradiated from the light emitting element LE of the sensor SNS, the regular reflection light RL enters the light receiving element LR.

  The control means 3 previously irradiates the “surface R1S in the normal state” with the detection light DL from the light emitting element LE of the sensor SNS in the “state in which the normal function can be performed”.

  Then, the sensor SNS is adjusted and set so that the output of the light receiving element LR at this time (appropriately amplified in the state taken into the control means 3 as described above) becomes the reference output level: NL.

  On the other hand, the calibration member AS associates the output level: NA when the “regularly reflected light RL of the detection light DL” by the light receiving surface is received by the light receiving element LR with the output level: NL.

  That is, when the “normal surface R1S” is detected by the sensor SNS calibrated so that the output of the light receiving element LR becomes the output level: NA by the calibration member AS, the output of the light receiving element LR is a normal output. Level NL is realized.

  When “toner powder or paper powder” adheres to the sensor SNS, generally, the intensity of the detection light DL decreases, or the specularly reflected light RL is shielded by the toner powder or the like adhering to the light receiving element LR. The output value of decreases.

  As described above, the sensor SNS having a reduced output value cannot properly detect the surface state, which causes a problem of erroneous detection.

  Therefore, in the present invention, the sensor SNS is calibrated as needed by the control means 3 so that the function of the sensor SNS always works correctly.

  As the contents of the calibration, the state of the sensor SNS is adjusted so that the output value of the output of the light receiving element LR (the output taken into the control means 3) becomes the output level: NA.

  This adjustment can be performed by increasing the light emission amount of the light emitting element LE, increasing the amplification factor of the output taken in by the control means 3, or simultaneously adjusting the light emission amount and the amplification factor.

  If the sensor SNS calibrated in this way is used, an appropriate output can be obtained as shown in FIG.

  The timing for calibrating the sensor SNS may be determined by empirically examining changes over time in the function of the sensor SNS and setting the frequency of calibration.

  FIG. 4 shows a case in which the surface state of the surface R1S described above is detected to detect the presence / absence of “a sheet edge scratch at a level that causes trouble in fixing (hereinafter referred to as“ deep scratch ”)”. An example flow diagram is shown.

  In the example shown in this flowchart, the “state where the sensor SNS is facing the calibration member AS in the calibration area ASD” as shown in FIG. 2B is the home position (HP) of the sensor SNS.

  Then, “calibration of the sensor SNS” is performed when the sensor SNS moves toward the “detection region (width in the left-right direction of the surface R1S in FIG. 2)” for detecting the surface state.

  When starting at step: s1, “calibration” is executed at step: s2.

  Subsequently, the threshold value ST1 is set in step s3, the sensor moves to the detection region side, and the detection of the surface state is started. At this time, time: t is set to zero.

  Time: t increases with the movement of the sensor, and the output: LRO of the light receiving element LR at time: t is obtained. Output: LRO is a function of time: t and can be written as LRO (t).

In step: s6, output: LRO (t) and threshold value: ST1 are compared.
While “LRO (t)> ST1” holds, the comparison is continued until time: t becomes equal to time: T. Time: T is the time required for the sensor to move all over the detection area.

  In step: s7, if time: t is equal to or greater than T, that is, if “LRO (t)> ST1” is satisfied in the entire detection area, it is determined in step: s9 that “no deep damage”, Step: Proceeding to s11, the sensor is returned to the HP (home position) and the detection is terminated.

  On the other hand, if “LRO (t) ≦ ST1” is reached before time t reaches T, it is determined that “there is a deep wound” in step s8, and then “post-detection processing” is performed in step s10. In step: s11, the sensor is returned to HP and the detection ends.

  Step: “Post-detection process” performed in step s10 is a process of displaying a message such as “The fixing roller needs to be replaced” on the scanning panel of the image forming apparatus, for example.

  Alternatively, as the “polishing means for polishing the surface of the fixing roller R1” in the fixing device, for example, a polishing roller is provided to polish the surface of the fixing roller in which deep scratches have occurred and to expose the surface without scratches. The process of restoring the function can be included in the “post-detection process”.

In the example described above, the calibration of the sensor is performed “every time the surface state is detected”. However, the sensor calibration is not limited to this and is performed every time the surface state is detected a plurality of times (for example, five times). May be.

  A parameter n indicating the number of times the surface state is detected is prepared in the control means 3, and “n = 1” is set when the sensor is calibrated and the surface state is detected. Thereafter, only the surface state is detected. Each time, the value of n is incremented by one.

  Then, “sensor calibration” may be performed at the “next surface state detection” when “n = 5”.

Moreover, it is not always essential to return the sensor to HP after detecting the surface condition. Only when it is necessary to perform calibration, “the sensor may be set in the calibration area ASD”.
However, if the calibration area ASD is set to “Sensor HP” and the surface state is not detected, the sensor is always kept in the calibration area ASD to “reduce sensor contamination” by toner or paper dust from the fixing member. There is an effect.

  When executing the surface state detection according to the flowchart of FIG. 4, the presence of “deep wound” is detected in the state where “LRO ≦ ST1” in step s6.

Therefore, there is one “deep wound” detected in this case.
By the way, when the output of the light receiving element LR: LRO is “LRO ≦ ST1”, it is not always due to a scratch on the sheet edge.

  For example, when “dirt” due to a substance having high absorbability with respect to the detection light DR is attached to a part of the surface R1S, when this dirt portion is detected by the sensor, “scratch-corresponding output portion SGBR1” In the same manner as described above, an output indicating a rapid decrease and restoration of the output may occur.

  In FIG. 5A, the symbol DRT indicates “dirt adhering to the surface R1S”.

  When the dirt DRT is “highly absorbable with respect to the detection light DR,” “output change: FS below ST1: ST1” occurs as shown in FIG. there's a possibility that.

  In such a case, the “dirt DRT” may be misidentified as “deep wound” when the surface condition is detected according to the flowchart of FIG.

There are various ways to solve this problem.
One method is as follows. This method utilizes the following facts.

As described above, the “depth flaw” to be detected is the “sheet edge flaw”.
As described above with reference to FIG. 3, the sheet end scratch BR is formed on the sheet conveying member by “both ends in the direction orthogonal to the conveying direction” of the conveyed sheet-like recording medium.

  The “position in the direction perpendicular to the conveyance direction” at which the sheet-like recording medium is conveyed is determined, and therefore the “scratch occurrence position” at which a deep flaw occurs is substantially determined.

Therefore, as shown in FIG. 5B, flaw occurrence areas DM1 and DM2 are set in the periphery including the “flaw occurrence position” where the deep flaw BR occurs.
Then, "storage means" is provided in the control means 3, and these flaw occurrence areas DM1 and DM2 are stored as "flaw position information".

  That is, the control means 3 is provided with a “storage function”.

  Then, “position information of the sensor SNS” is acquired at the time of detection by the sensor SNS, and when the position information is within the “scratch occurrence area”, the output of the sensor SNS is compared with a threshold value ST1.

  In this way, whether or not there is a deep wound can be determined based on whether or not there is a “part where the output of the sensor SNS is equal to or less than the threshold value in the wound generation area”.

  As a result, “dirt generated outside the scratched area” is not erroneously determined as a scratch.

  The position of the sensor SNS when the surface state detection is performed corresponds to the time t described above.

  Accordingly, the flaw occurrence area DM1 in FIG. 5B corresponds to the time area t: t1 to t2 at the time of output, and the flaw occurrence area DM2 corresponds to the time areas t3 to t4.

  When the surface state is detected by the sensor SNS, the output: LRO (t) when the sensor SNS passes through the flaw occurrence region DM1 when t1 ≦ t ≦ t2 is compared with the threshold value ST1.

  Similarly, a time region where the sensor SNS passes through the flaw occurrence region DM2: an output when t3 ≦ t ≦ t4: LRO (t) is compared with a threshold value: ST1.

  In the surface state detection according to the flowchart of FIG. 4, either the case where the output LRO is “LRO ≦ ST1” in the scratch occurrence region DM1 or the case where “LRO ≦ ST1” is detected in the scratch generation region DM2 is detected. .

  In this case, if the dirt DRT is in “a position other than the scratch occurrence area DM1, DM2,” the dirt DRT is not “falsely detected as a deep wound”.

The surface state detection according to the flow diagram 4 is the most basic one, but only one “deep wound” is detected.

  Therefore, when the “surface state detection according to the flow diagram 4” is performed in the example shown in FIG. 5, if the dirt DRT is in one or both positions of the scratch generation areas DM1 and DM2, the dirt DRT is still deep. There remains a possibility of false detection as a flaw.

To avoid this, for example, the following method can be considered.
Since the sheet edge damage occurs at both ends of the sheet-like recording medium to be conveyed in the direction orthogonal to the conveyance direction, the sheet edge defect generally occurs at “two specific places”.

These two places are the flaw generating areas DM1 and DM2 in the above description.
Therefore, in this case, if the output LRO is compared with the threshold value ST1 in both of these two scratch generation regions, deeper damage can be detected more appropriately.

In such a case, the flow diagram 4 may be improved as shown in FIG.
When the process starts in step s61, first, “calibration of the sensor” is performed in step s62, the threshold value ST1 is set in step s63, and the value of parameter m is set to zero.

Parameter: m is a parameter indicating the number of deep wounds.
Step: At s64, time: t is set to 0, and "surface state detection" is started.

  In step: s65, output: LRO is collected. Step: s65 is executed during a period of time: t1 to t2 in which time: t corresponds to the scratch occurrence region DM1.

  This output: LRO is compared with the threshold value ST1 at step: s66, and when “LRO ≦ ST1”, the process proceeds to step: s67, and the value of parameter: m is increased by 1.

  Thereafter, when “t <T” in step s68, the process returns to step s65 to obtain output: LRO. The time t at this time is the time corresponding to the scratch occurrence region DM2: between t3 and t4.

  In step s68, if time t is equal to or greater than T, it is determined in step s69 whether the value of parameter m is 2.

  When m = 2, “the occurrence of deep flaws is detected in both of the flaw occurrence areas DM1 and DM2”, the process proceeds to step s70 to determine “there is a deep flaw”. Execute process ".

  Step: When “m ≠ 2” in s69, it is determined that “no deep flaw”, and in step: s73, the sensor is returned to HP and the detection operation is terminated.

  In this way, two deep scratches can be detected with a single surface state detection operation.

  In this way, if the presence or absence of a deep flaw is detected in the two flaw occurrence areas, not only the flaw DRT is not in the flaw occurrence area, but also the flaw DRT is in one flaw occurrence area, the sheet edge flaw ( Detection of deep wounds is possible.

  The case where time: t is used as the “position information” of the sensor SNS has been described above, but the position information of the sensor is not limited to this.

For example, an encoder is provided in the drive source of the sensor moving means (motor M in FIG. 1A), the rotation angle of the drive source is obtained, and the “relationship between the rotation angle and the sensor movement distance” specified in advance by measurement is used. It is also possible to acquire “position information” by a calculation method.
Alternatively, a stepping motor may be used as the driving source, and a method of calculating a moving distance by calculating a rotation angle from a PWM signal applied to the stepping motor may be used.

  Note that the rotation angle of the drive source and the movement distance of the sensor usually correspond “1: 1”, but errors may occur in the movement distance due to factors such as stepping motor step-out, gear slippage, and angle detection errors. Conceivable.

  In order to avoid such “error in the movement distance of the sensor”, it is preferable to calibrate the sensor position.

  The “calibration of the sensor position” can be performed by an appropriate method. However, since the present invention includes a calibration member that calibrates the sensor, it is conceivable to calibrate the sensor position using the calibration member.

7, Ru Oh a diagram for explaining this case.

  The output when the sensor SNS is moved at a constant speed to the right in the drawing with the position of the support plate 1A in the upper drawing in FIG. 7 as the “starting position” is as shown in the lower drawing in FIG.

  Therefore, at the moment when the output changes beyond the threshold value ST1, the position of the sensor SNS at the moment indicated by “a” or “b” in the figure can be used as the “reference position” to perform position calibration.

  For example, as described above, if the motor M that is a drive source is provided with an encoder and the rotation angle of the drive source is acquired, the rotation angle at the time point “a” or “b” is used as a reference angle. What is necessary is just to convert the motor rotation angle from this reference angle into the “movement distance of the sensor SNS”.

  In other words, in this example, the control means 3, the calibration member AS, and the drive source M constitute “sensor position calibration means for calibrating the sensor position”.

In each of the embodiments described above, the surface state of the surface R1S is detected when the sensor SNS moves in one direction (hereinafter referred to as “during forward movement”).
Also in the embodiment described above, the sensor SNS performs reciprocal displacement, so that the surface state can be detected not only during the forward movement but also during the “return movement”.

FIG. 8 is an explanatory diagram illustrating an example of the output of the sensor SNS at this time.
As shown in this figure, output fluctuations SG1, FS, DG2 that are equal to or less than the threshold value ST1 are obtained during the forward movement indicated as “outward”, and less than the threshold during the backward movement indicated as “return”. It is assumed that output fluctuations SG3 and SG4 are obtained.

  At this time, the output fluctuations SG1 and SG4 and SG2 and SG3 are generated when the sensor SNS is at the same position.

  On the other hand, the output fluctuation FS occurs only during the forward movement.

  The sheet edge damage “occurs continuously in parallel with the moving direction of the sheet-like recording medium”.

  In contrast, “dirt” occurs at a fixed position in the moving direction of the sheet-like recording medium.

  In the example of FIG. 8, a finite time has elapsed between when the sensor SNS moves on the forward path and when it moves on the return path, and the sheet-like recording medium moves continuously in the movement direction.

  From this, it is considered that the dirt adhering to the surface R1S caused the output fluctuation FS in the forward path, but separated from the detection position when the return path was detected and did not cause the output fluctuation.

  From this, when the signal at the time of forward movement and the signal at the time of backward movement are made to correspond to each other, and the "sensor SNS is at the same position on the forward path and the backward path", if the output change that is below the threshold value can be detected, this output change is It can be determined that it is a “deep wound at the end”.

  Further, it can be determined that the output change FS is caused by “causes other than deep wounds”.

FIG. 9 is a flowchart for explaining the detection of the surface state in this case.
Step: Start at s91, and execute "calibration of sensor SNS" at step: s92. Further, in step s93, the sensor sNS is “calibrated”.

  When the calibration of the sensor SNS and the calibration of the position are completed, “surface state detection” is started in step s94.

  In this embodiment, a storage unit such as a register is provided in the control unit 3 so that the control unit 3 has a “storage function”, and the output LRO (t) of the sensor SNS is recorded as it is.

  Step: When the “end of forward path detection” of s95 becomes yes (Y), the output LRO (t: forward path) of the forward path is stored.

  Step: When “end of forward path detection” is confirmed in s95, the moving direction of the sensor SNS is reversed, and the detection of the backward path is started. Then, when the “return path detection end” in step: s95 becomes YES, the return path output LRO (t: return path) is stored.

  In the subsequent step: s98, the stored output LRO (t: forward path) and LRO (t: return path) are compared to determine whether or not a flaw has been detected at the same position.

  Step: The “scratch” in s98 is an output change that is equal to or less than the threshold value ST1, and is generally “deep wound”.

  If “scratches are detected at the same position”, the process proceeds to step: s99, where it is determined that “there is a deep wound”, and the above-described “post-detection process” is performed at step: s100.

  On the other hand, if “no flaw is detected at the same position” in step s98, it is further determined in step s101 whether a flaw is detected in “only one” of the forward path and the return path.

  If the occurrence of a flaw is not detected in this step: s101, the surface R1S has no deep flaw of the sheet end flaw. Therefore, in step: s103, it is determined that there is no deep flaw and the surface state is detected. finish.

  Step: If “scratches only in one of the outward path and the return path” are detected in s101, it is determined that there is “an abnormality other than a sheet edge scratch (deep wound)” such as “dirt” on the surface R1S (step : S102), “notify the user (step: s104)” of the occurrence of the abnormality.

  And the detection of surface information is complete | finished (step: s105).

  Each “determination” above is executed by the “determination function” of the control means 3.

  In this example, since the sensor SNS is reciprocated, the sensor can be returned to HP by the movement of the sensor in the return path.

  Whether or not the reciprocation has been completed may be determined by determining that the sensor SNS has reached the position of the calibration member AS by detecting the reference position described with reference to FIG.

In the example described above, one sensor SNS is used.
The sensor SNS reciprocates and detects the surface state at least in the forward path.

The present invention uses two sensors and reciprocates them.

One embodiment of the present invention is shown in FIG .
In this embodiment, two sensors SNS1 and SNS2 are used.

  The support plates 1a and 1b support two guide bars 2A and 2B. The sensor SNS1 is provided on the guide bar 2A and the sensor SNS2 is provided on the guide bar 2B so as to be slidable.

  These sensors SNS1 and SNS2 are fixed to a wire W, and the wire W is wound around the drive shaft Ax of the motor M1 through rollers c1, c2, c3, and c4.

  By rotationally driving the motor M1 clockwise, the sensors SNS1 and SNS2 can be simultaneously displaced in the directions of the arrows.

  By rotationally driving the motor M1 counterclockwise, the sensors SNS1 and SNS2 can be simultaneously displaced in the opposite directions.

  The relationship between the movement locus, the calibration members AS1 and AS2, the surface of the sheet conveying member R2, and the movement locus of the sensor is the same as that of the sensors SNS1 and SNS2.

  With such a configuration, the surface information of the surface R1S can be acquired once for each of the “outward path and backward path” by the displacement of the two sensors SNS1 and SNS2 in one direction.

In addition, since the positions of the sensor SNS1 and the sensor SNS2 are separated in the “movement direction (indicated by a thick arrow)” of the surface RS1, the surface of the fixing roller R1 is moved when detecting the surface state. no, it is possible to detect the surface state of the two positions definitive in the moving direction.

  If this is used in place of the above-mentioned “outgoing path data, return path data”, the flaw detection is completed in one direction of operation, so that the detection time can be shortened.

  In the embodiment described above, when the “storage means” is provided in the control means 3 to have a storage function, the following determination can be made by the storage function.

  As described above, the surface of the sheet conveying member is not only deteriorated due to the “sheet end scratch”, but also deteriorated when the surface is roughened and roughened and “smoothness is impaired”.

Such general deterioration of the surface condition occurs “over time”.
On the other hand, since “calibration of the sensor” is executed in the present invention, an appropriate output can always be obtained from the sensor.

  “Initial” in FIG. 11 illustrates “output of sensor SNS when the surface of the sheet conveying member is in an initial state”.

  Reference numeral MN2 indicates an “average value of initial outputs”.

  Therefore, the average value: MN1 is stored in the storage means as an “initial value”.

  And the output of a sensor is acquired with a suitable period, and the average value is calculated | required.

  In FIG. 11, “after the time has elapsed” indicates the output of the sensor when the time has elapsed from the initial state, and the symbol MN2 indicates the average value thereof.

  At this time, the difference between the average value: MN1 and MN2 is due to the temporal change of the surface state, and the difference: Δ corresponds to “the degree of deterioration due to the temporal change”.

  Therefore, if “Δ” is obtained by obtaining MN2 at an appropriate period, the degree of deterioration of the surface of the sheet conveying member can be known.

  Therefore, for example, the control unit 3 can store the “threshold value for Δ: SΔ” and have a determination function for determining the life of the sheet conveying member when Δ is equal to or greater than SΔ.

Incidentally, In Fig. 1, etc., although at a site other than deep wounds the output of the sensor SNS are drawn in the "straight line", of course this is to simplify the drawing.

The output of the sensor SNS is actually to "fine variation" as shown in FIG. 11.

  A few supplements.

  In the above, the case where the sheet conveying member is the “fixing member” and the target whose surface state is to be detected is the fixing roller R1 has been described.

  Of course, the “surface state of the pressure roller R2” can be detected by the same method as described above.

  Although the roller-shaped fixing roller R1 is exemplified as the “member on the side in contact with the toner image” of the fixing member, the surface state of the “fixing belt” can be detected without being limited thereto.

  That is, the form of the sheet conveying member is not limited to a roller shape, but may be an “endless belt shape”.

  The sheet conveying member is not limited to the fixing roller, the fixing belt, the pressure roller, and the pressure belt listed above, but can be a direct transfer belt or an “intermediate transfer belt”. It can also be a photoreceptor.

FIG. 12 shows a case where a belt-like sheet conveying member BL (fixing belt or transfer belt) is used as the sheet conveying member .

  The sensor SNS is “slidable” on the guide rod 2A supported by the support plates 1a and 1b.

  The sensor SNS is fixed to the wire W, and the wire W is wound around the roller c5 and the drive shaft Ax of the motor M1.

  By rotating the motor M1 clockwise, the sensor SNS can be displaced in the direction of the arrow.

  The sensor SNS can be displaced in the reverse direction by rotationally driving the motor M1 counterclockwise.

  Needless to say, the embodiment described with reference to FIG. 10 can also be suitably applied to the belt-shaped sheet conveying member BL.

  The sensor moving means is not limited to the one described above, and any known appropriate moving means can be used.

  Hereinafter, an embodiment of the image forming apparatus will be described with reference to FIG.

  FIG. 13 is a diagram for explaining a “color printer” which is one type of image forming apparatus.

  Of course, the image forming apparatus of the present invention is not limited to the color printer shown in FIG. 13, but can also be implemented as a monochrome copying machine, a color copying machine, a facsimile apparatus, a plotter apparatus, or the like.

  Furthermore, it goes without saying that the present invention can be implemented as an MFP (multi-function printer) that combines the functions of these devices.

  FIG. 13A illustrates only the main part of the color printer 100 in an explanatory manner. The color printer 100 is a so-called “tandem printer”.

  The “transfer belt as an intermediate transfer member” denoted by reference numeral 11 is an endless belt, which is provided around a plurality of rollers (three in the figure) and is provided on a driving roller which is one of these rollers. It is driven to rotate counterclockwise.

  The lower portion of the transfer belt 11 in the drawing is stretched in a “planar” manner, and image forming units UY, UM, UC, UB are disposed in this portion.

  “Y, M, C, B” in the code represents each color of “yellow, magenta, cyan, black”.

  That is, the image forming unit UY forms a yellow image, the image forming unit UM forms a magenta image, the image forming unit UC forms a cyan image, and the image forming unit UB forms a black image. It is a unit to image.

  Below the image forming units UY to UB, an optical scanning device 13 which is an “image writing device” is provided, and a cassette 15 is further provided below the optical scanning device 13.

Since the image forming units UY to UB are structurally the same, the image forming unit UY is taken as an example and will be briefly described with reference to FIG.
The “image forming unit UY” shown in FIG. 13B has a photosensitive drum 20Y as a photoconductive photosensitive member, and around the photosensitive drum 20Y, a charger 30Y, a developing unit 40Y, a transfer roller 50Y, The cleaning unit 60Y is arranged.
The charger 30Y is a “contact type charging roller”.

  A space between the charger 30Y and the developing unit 40Y is set as an “image writing unit using the scanning light LY”. The transfer roller 50 </ b> Y is disposed on the side opposite to the photosensitive drum 20 </ b> Y via the transfer belt 11 and is in contact with the back surface of the transfer belt 11.

The image forming units UM to UB have the same configuration as the image forming unit UY.
When necessary, the photosensitive drums 20M to 20B, the chargers 30M to 30B, the developing units 40M to 40B, the transfer rollers 50M to 50B, and the cleaning units 60M to 60B are used.

  Such a “color image printing process” by the color printer 100 is well known, but will be briefly described below.

  Note that “rectangles indicated by broken lines” in FIG. 13B indicate the units of the image forming unit UY as “collection”, and do not necessarily indicate an entity such as a casing.

  When the color image forming process starts, the photosensitive drums 20Y to 20B and the transfer belt 11 start to rotate. The rotation of the photosensitive drums 20Y to 20B is clockwise, and the rotation of the transfer belt 11 is counterclockwise.

The photosensitive surfaces of the photosensitive drums 20Y to 20B are uniformly charged by the chargers 30Y to 30B, respectively. The optical scanning device 13 writes an image on each of the photosensitive drums 20Y to 20B by optical scanning with the scanning lights LY to LB.
Various types of optical scanning devices 13 for performing such image writing have been well known in the past, and these well-known devices are appropriately used as the optical scanning device 13.

  The photosensitive drum 20Y is optically scanned using a laser beam whose intensity is modulated according to the yellow image as the scanning light LY, and the yellow image is written to form an electrostatic latent image corresponding to the yellow image. .

  The formed electrostatic latent image is a so-called negative latent image, and is visualized as a “yellow toner image” by reversal development using yellow toner by the developing unit 40Y.

  The visualized yellow toner image is electrostatically primarily transferred onto the surface side of the transfer belt 11 by the transfer roller 50Y.

The photosensitive drum 20M is optically scanned using a laser beam whose intensity is modulated in accordance with the magenta image as the scanning light LM, and the magenta image is written, and an electrostatic latent image (negative latent image) corresponding to the magenta image is written. ) Is formed.
The formed electrostatic latent image is visualized as a “magenta toner image” by reversal development using magenta toner by the developing unit 40M.

The photosensitive drum 20C is optically scanned using a laser beam whose intensity is modulated according to the cyan image as the scanning light LC, and the cyan image is written, and an electrostatic latent image (negative latent image) corresponding to the cyan image is written. ) Is formed.
The formed electrostatic latent image is visualized as a “cyan toner image” by reversal development using cyan toner by the developing unit 40C.

The photosensitive drum 20B is optically scanned using a laser beam whose intensity is modulated in accordance with the black image as the scanning light LB, the black image is written, and an electrostatic latent image (negative latent image) corresponding to the black image is written. ) Is formed.
The formed electrostatic latent image is visualized as a “black toner image” by reversal development using black toner by the developing unit 40B.

The magenta toner image is electrostatically primarily transferred to the transfer belt 11 side by the transfer roller 50M. At this time, the magenta toner image is superimposed on the “yellow toner image previously transferred” on the transfer belt 11.
Similarly, the cyan toner image is primarily transferred onto the transfer belt 11 by the transfer roller 50C so as to be superimposed on the “yellow toner image and magenta toner image that have been previously superimposed and transferred”.

  The black toner image is primarily transferred to the yellow, magenta, and cyan color toner images on the transfer belt 11 by the transfer roller 50B.

  In this way, four color toner images of yellow, magenta, cyan, and black are superimposed on the transfer belt 11 to form a “color toner image”.

  The photosensitive drums 20Y to 20B are cleaned by the cleaning units 60Y to 60B, respectively, after the toner image is transferred, and residual toner and paper dust are removed.

  The color toner image formed on the transfer belt 11 in this way is electrostatically “secondarily transferred” from the transfer belt 11 onto the transfer sheet S as a “sheet-like recording medium” by the secondary transfer roller 17. Then, the toner image is fixed on the transfer paper S by the fixing device 19 and discharged outside the printer.

  The transfer paper S is stacked and accommodated in the cassette 15, and is fed by a well-known paper feeding mechanism (not shown).

  The fed transfer sheet S waits with its leading end held by a timing roller (not shown), and is fed to the secondary transfer unit in synchronization with the movement of the color toner image on the transfer belt 11.

  The secondary transfer portion is a contact portion between the transfer belt 11 and the secondary transfer roller 17 that rotates in contact with the transfer belt 11, and the timing at which the color toner image on the transfer belt 11 reaches the secondary transfer portion. And the transfer sheet S is sent to the secondary transfer portion by the timing roller.

  Thus, the color toner image and the transfer paper S are superimposed, and the color toner image is electrostatically transferred onto the transfer paper S.

  The transfer sheet S on which the color toner image is transferred by the secondary transfer is subsequently fixed on the color toner image when passing through the fixing device 19, and is then discharged onto the tray TR on the upper side of the color printer 100.

  The fixing device 19 fixes the color toner image on the transfer paper S by applying heat and pressure.

  The above is a schematic description of the “color image printing process” by the color printer 100.

  That is, the color printer 100 in FIG. 13 is an “image forming apparatus that forms an image as a toner image on a sheet-like recording medium”.

  In the embodiment described above, the case where the fixing device 19 includes the fixing roller R1 and the pressure roller R2 is taken as an example, and the case where the surface state of the fixing roller R1 is detected has been described.

  In the embodiment of FIG. 13, when the color toner image on the transfer belt 11 is secondarily transferred to the transfer paper S, the transfer paper S is conveyed while being sandwiched between the transfer belt 11 and the secondary transfer roller 17.

Therefore, “scratch on the sheet edge” and “roughening” can also occur in the transfer belt 11 and the secondary transfer roller 17 which are “transfer members”. Photoconductor, Transfer Member, Fixing Member The present invention can also be effectively applied to detection of the transfer member (transfer belt 11 and secondary transfer roller 17) and the surface shape of the photoconductor.

  As described above, according to the present invention, the following image forming apparatus can be realized.

[1]
An image forming apparatus that forms an image as a toner image on a sheet-like recording medium, the sheet-conveying member R1 that conveys the sheet-like recording medium, and two reflective sensors that detect the surface state of the sheet-conveying member Sensor moving means 2A, 2B, c1 to c4 that move the SNS1 and SNS2 and the two sensors along a movement trajectory that has a distance D from the surface of the sheet conveying member and intersects the moving direction of the surface. , and W, M1, and two sensors SNS1, two calibration member AS1, to calibrate the SNS2 AS2, comprising control means for controlling the detection of the surface state due to two sensors, a two of the moving range of the sensor, at least one side, includes a calibration region protrudes outward in the width direction orthogonal to the moving direction of the surface R1S in the sheet conveying members R1, calibration member AS1, a 2, the calibration region, apart from the movement locus of the sensor SNS1, SNS2: D '(≒ D) disposed septum, more to the control means, the calibration member two sensors using SNS1, SNS2 A storage function for storing the detection result of the surface state sensor of the sheet conveying member together with information on the surface position, and a comparison function for comparing the plurality of stored contents, A determination function for performing determination on the surface state, the two sensors are moved in opposite directions by the sensor moving means, and the surface state of the sheet conveying member R1 is moved by the two sensors SNS1 and SNS2. Detection is performed in opposite directions along the trajectory, the detection results in the opposite directions are stored, the stored detection results in the opposite directions are compared, and the surface state is detected based on the comparison result. That determination performs an image forming apparatus.

[2]
In [1] An image forming apparatus according the determination function of the control means, a case where the difference between the output value and the reference value of the sensor is constant or is intended to determine the deterioration of the sheet conveying member surface, two The detection area along the movement trajectory of the sensors SNS1 and SN2 includes two flaw occurrence areas DM1 and DM2 of flaws at the end of the sheet due to the edges on both sides in the width direction of the sheet-like recording medium S. In the detection results in the opposite directions by the sensor SNS, deterioration occurs only in one of the two flaw occurrence regions DM1 and DM2, and in the case where deterioration occurs in both the flaw occurrence regions. Forming apparatus that distinguishes and determines the type of the image forming apparatus.

[3]
In the image forming apparatus described in [2] , the determination function of the control means is that the deterioration is caused by the sheet edge scratch when the deterioration occurs in both of the two scratch generation areas DM1 and DM2 of the sheet edge scratch. An image forming apparatus that determines to be present.

[4]
The image forming apparatus according to any one of [1] to [3] , further comprising a sensor position calibration unit that calibrates the sensor positions of the two sensors SNS1 and SN2 .

[5]
The image forming apparatus according to any one of [1] to [4] , wherein the surface state is detected using one or more of a photoreceptor, a transfer member, and a fixing member as a sheet conveying member.

[6]
In the image forming apparatus according to any one of [1] to [5 ], one or more of a transfer member and a fixing member are used as a sheet conveying member to detect a surface state and detect a surface state. An image forming apparatus having a polishing means for polishing the surface.

[7]
In the image forming apparatus according to any one of [1] to [6] , the control unit that controls the detection of the surface state calculates an average value of the detection values over the detection regions of the two sensors SNS1 and SNS2 . is compared with a predetermined reference value, when said difference between the average value and the reference value exceeds a predetermined size, the image forming apparatus having a time change determination function to determine aging of the sheet conveying members.

In the image forming apparatus of the present invention, the distance between the calibration member and the sensor can be made substantially equal to the distance between the sheet conveying member and the sensor without providing a complicated mechanism.
As described above, since the distance between the calibration member and the sensor is substantially equal to the distance between the sheet conveyance member and the sensor, the calibration can be performed in the same state as the “detection of the surface state of the sheet conveyance member”.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments described above, and the invention described in the claims unless otherwise specified in the above description. Various modifications and changes are possible within the scope of the above.
The effects described in the embodiments of the present invention are merely a list of suitable effects resulting from the invention, and the effects of the present invention are not limited to those described in the embodiments.

R1 fixing roller (an example of a sheet conveying member)
R1S fixing roller surface
SNS sensor
2 Feed screw
M motor
AS calibration member
LE light emitting device
RL light receiving element

JP 2013-242398 A JP 2012-185475 A JP 2006-64895 A

Claims (7)

An image forming apparatus for forming an image as a toner image on a sheet-like recording medium,
A sheet conveying member for conveying a sheet-like recording medium;
Two reflective sensors for detecting the surface state of the sheet conveying member;
The two sensors, the distance from the surface of the sheet conveying members: has a D, a sensor moving means for moving along a movement trajectory that intersects the movement direction of said surface,
Two calibration members for calibrating the two sensors;
Control means for controlling the detection of the surface state by the two sensors,
At least one side of the movement range of the two sensors includes a calibration region that protrudes outside in the width direction perpendicular to the movement direction of the surface of the sheet conveying member,
The calibration member is disposed in the calibration area at a distance D ′ (≈D) from the movement trajectory of the two sensors.
By the control means performs a calibration of the two sensors using the two calibration member,
A storage function in which the control means stores a detection result of a surface state sensor of the sheet conveying member together with information on a surface position;
A comparison function for comparing the plurality of stored contents;
A determination function for performing determination on the surface state,
The two sensors are moved in opposite directions by the sensor moving means, and the surface state of the sheet conveying member is detected in the opposite directions along the movement trajectory of the two sensors,
Store the detection results in opposite directions,
Comparing the stored detection results in opposite directions,
A determination with respect to the surface state based on the result of the comparison, the image forming apparatus. The image forming apparatus according to claim 1.
The determination function of the control means determines that the difference between the output value of the sensor and the reference value is greater than or equal to a certain value as deterioration of the sheet conveying member surface,
The detection area along the movement trajectory of the two sensors includes two occurrence areas of the sheet edge scratches caused by the edges on both sides in the width direction of the sheet-like recording medium,
In the detection results of the two sensors in the opposite directions by the two sensors, the deterioration occurs in only one of the two generation regions, and the deterioration occurs in both of the two generation regions. An image forming apparatus that distinguishes and determines the type of deterioration . The image forming apparatus according to claim 2.
The determination function of the control unit is an image forming apparatus that determines that the deterioration is due to the sheet end flaw when the deterioration occurs in both of the two occurrence regions of the sheet end flaw . The image forming apparatus according to any one of claims 1 to 3 ,
An image forming apparatus having sensor position calibration means for calibrating sensor positions of two sensors . The image forming apparatus according to any one of claims 1 to 4 ,
An image forming apparatus that detects a surface state using one or more of a photoreceptor, a transfer member, and a fixing member as a sheet conveying member . The image forming apparatus according to any one of claims 1 to 5,
One or more of the transfer member and the fixing member are used as a sheet conveying member to detect the surface state,
An image forming apparatus having a polishing means for polishing a surface of a sheet conveying member for detecting a surface state . The image forming apparatus according to any one of claims 1 to 6,
The control means for controlling the detection of the surface state compares the average value of the detection values over the detection area of one or more sensors with a predetermined reference value, and the difference between the average value and the reference value is a predetermined value. An image forming apparatus having a temporal change determination function of determining deterioration with time of a sheet conveying member when the size is exceeded .

Images