JP3852312B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine and a printer, and more particularly to an image forming apparatus having a function of correcting skew of a sheet being conveyed.
[0002]
[Prior art]
In general, in an image forming apparatus, skew (a phenomenon in which a sheet is sent obliquely with respect to the conveyance direction) may occur due to various factors during conveyance of the sheet. If the paper is fed while being skewed, the image is formed in an inclined state with respect to the paper. Therefore, many image forming apparatuses are provided with a skew correction mechanism.
[0003]
As an example of the skew correction mechanism, a side guide is provided along the conveyance direction on one side of the sheet conveyance path, and a skew roller is disposed in the vicinity of the side guide, and the sheet being conveyed is side-mounted by the skew roller. There is known a technique in which a skew is corrected by bringing a side edge (side edge) of a sheet into contact with a reference surface of a side guide by shifting the width toward the guide side.
[0004]
As another example of the skew correction mechanism, a plurality of conveyance rollers that apply conveyance force to the paper at different positions in the conveyance direction are provided to be movable in a direction orthogonal to the conveyance direction, and in the vicinity of the plurality of conveyance rollers. Detection sensors that detect the side edges of the paper are arranged, the side edges of the paper being conveyed are detected by these detection sensors, and the skew is corrected by controlling the movement of each conveyance roller based on the detection results. It has been known.
[0005]
By the way, an image forming apparatus provided with this type of skew correction mechanism employs a method in which the side edge of the paper being conveyed is aligned with a reference line along the reference surface of the side guide or a reference line connecting the detection points of each detection sensor. Therefore, if the reference line serving as the alignment reference for the paper side edge is inclined, the paper is also skewed according to this inclination.
[0006]
Therefore, conventionally, a certain kind of test chart is output to a sheet when adjusting registration of the sheet, and the inclination of the reference line in the skew correction mechanism is adjusted using the output result.
[0007]
[Problems to be solved by the invention]
However, the test chart used for registration adjustment is created based on the paper size or output by repeating a specific pattern (lattice pattern). It was not easy to figure out.
[0008]
More specifically, for example, when adjusting the inclination of the reference line along the reference surface of the side guide, the inclination amount of the image with respect to the sheet can be read from the test chart output to the sheet at the time of registration adjustment. When the test pattern is output as described above, the inclination amount of the actually read image and the inclination adjustment amount of the reference line do not correspond 1: 1. Therefore, at the time of registration adjustment, after using the ruler etc. to read the image tilt amount from the test chart output on the paper, the calculation for calculating the reference line tilt adjustment amount from the tilt amount is performed using a computer or the like. There was a need to do. Therefore, the work until the amount of inclination adjustment of the reference line is determined is troublesome and takes time. In addition, since the calculation is complicated, an erroneous operation of the computer is likely to be caused, and there is a possibility that an erroneous adjustment amount is calculated.
[0009]
Furthermore, even if the inclination adjustment amount of the reference line is accurately calculated, in actual adjustment work, fine adjustment of the side guide position and detection sensor position is repeatedly performed, and the adjustment result is confirmed with a test pattern each time. Needed to be troublesome.
[0010]
The present invention has been made to solve the above-described problems, and an object of the present invention is to form an image that can easily determine the amount of inclination adjustment of a reference line in a skew correction mechanism from a test chart output to a sheet. To provide an apparatus.
[0011]
[Means for Solving the Problems]
An image forming apparatus according to the present invention includes a skew correction unit that has a reference line that is substantially parallel to the sheet conveyance direction and corrects the skew of the sheet by aligning the side edge of the sheet with respect to the reference line. An inclination adjusting means having two adjustment operation points set at a first distance in the transport direction and adjusting the inclination of the reference line in the skew correction means with reference to the two adjustment operation points; and skew correction And a test chart output unit that outputs a test chart that can specify two measurement target points separated by a second distance in the transport direction with respect to the paper that has been skew-corrected by the unit. The first distance between the adjustment operation points and the second distance between two measurement target points in the test chart output means are set to be equal.
[0012]
In the image forming apparatus having the above-described configuration, the first distance between the two adjustment operation points in the inclination adjustment unit and the second distance between the two measurement target points in the test chart output unit are set equal to each other. The difference value of the measurement dimension obtained by using the two measurement target points specified on the test chart output in (the value corresponding to the amount of inclination of the image with respect to the paper) and the amount of inclination adjustment of the reference line in the inclination adjusting means Correspond to each other in a 1: 1 relationship. For this reason, it is possible to easily determine the inclination adjustment amount of the reference line from the test chart output on the paper.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1 is a schematic diagram showing a configuration of a skew correction unit in the image forming apparatus according to the embodiment of the present invention. In FIG. 1, a plurality of (three in the illustrated example) skew rollers 1, 2, and 3 are provided in order from the upstream side to the downstream side in the sheet conveyance direction Y. These skew rollers 1, 2, and 3 are disposed so as to be inclined at a predetermined angle with respect to the paper transport direction Y, respectively. Further, each of the skew rollers 1, 2, 3 is constituted by a pair of rollers arranged so as to sandwich the sheet conveyance path from above and below.
[0015]
Further, in the vicinity of the skew rollers 1, 2, and 3, a long side guide 4 is disposed on one side of the sheet conveyance path. The side guide 4 serves as a reference guide for aligning the side edges of the paper 5 being conveyed, and is disposed substantially parallel to the paper conveyance direction Y. Further, the side guide 4 has a substantially U-shaped guide groove 6 when viewed from the transport direction Y, and the back end face of the guide groove is used as a reference surface 7 for abutting against the paper 5.
[0016]
Further, a rotation fulcrum 8 is provided on one end side of the side guide 4 by using a bracket 8, and the side guide 4 is rotatably supported around the rotation fulcrum 9. On the other hand, a tension coil spring 10 and an elliptical cam 11 are provided on the other end side of the side guide 4. The tension coil spring 10 is a member that urges the other end of the side guide 4 in one direction (left direction in the figure). The urging force of the tension coil spring 10 causes the side guide 4 to be in pressure contact with the outer peripheral surface of the elliptical cam 11. Is retained. The elliptic cam 11 is rotatably supported with its center as a rotation fulcrum 12. Further, the rotational operation of the elliptical cam 10 around the rotation fulcrum 12 is configured to be freely operated using an adjustment knob (not shown).
[0017]
In the skew correction unit having the above-described configuration, the sheet 5 conveyed from the upstream side in the conveyance direction Y is nipped by the skew rollers 1, 2, 3 in an oblique direction by the skew rollers 1, 2, 3. The width is gradually brought closer to the side guide 4 side by feeding to the side. As a result, one side edge 5A of the paper 5 is abutted against the reference surface 7 of the side guide 4, and the side edge 5A of the paper 5 is uniformly abutted against the reference surface 7 in the longitudinal direction of the side guide 4. It becomes a state. As a result, the side edge 5A of the sheet 5 being conveyed is aligned with a reference line K parallel to the reference surface 7 of the side guide 4. As a result, the skew of the sheet 5 can be corrected with the reference line K as a sight.
[0018]
When the elliptical cam 11 is rotated around the rotation fulcrum 12 using an adjustment knob (not shown), the side guide 4 is centered on the rotation fulcrum 8 according to the rotation direction and the rotation amount of the elliptical cam 10. Rotate. Then, the inclination of the side guide 4 with respect to the sheet conveyance direction Y changes, and the inclination of the reference line K in the side guide 4 also changes accordingly. From this, the rotation fulcrum 9 of the side guide 4 and the rotation fulcrum 12 of the elliptical cam 11 are set as the adjustment operation points, and the inclination of the reference line K in the side guide 4 can be adjusted based on these two adjustment operation points. It becomes possible. In this tilt adjustment mechanism, the rotation fulcrum 9 of the side guide 4 and the rotation fulcrum 12 of the elliptical cam 11 are set at a position separated by a first distance L1 in the sheet conveyance direction Y.
[0019]
FIG. 2 is a functional block diagram showing, in particular, the configuration of the test chart output means in the image forming apparatus according to the embodiment of the present invention. In FIG. 2, an operation mode selection unit 13 is for selecting an operation mode of the image forming apparatus, and is configured by, for example, a control panel. Various operation modes that can be selected by the operation mode selection unit 13 are conceivable. In this embodiment, as an example, a “normal image forming mode” that outputs an image on a sheet in accordance with an input image signal. And a “test mode” for outputting a test chart to a sheet in a pattern prepared in advance.
[0020]
The test pattern generation unit 14 stores and holds a test pattern (a kind of image signal) as a basis for outputting a test chart on a sheet, and generates a test pattern according to mode selection information from the operation mode selection unit 13. To do. The image output unit 15 outputs (prints) a test chart based on the test pattern generated by the test pattern generation unit 14 on a sheet as a visible image.
[0021]
Here, as shown in FIG. 3, the test chart output to the paper by the test chart output means can specify two measurement target points P1 and P2 separated by a second distance L2 in the paper transport direction Y. The first linear pattern SL1 parallel to the transport direction Y, and the second and third linear patterns SL2 and SL3 orthogonal to the first linear pattern SL1 on the front side and the rear side of the paper 5 with respect to the transport direction Y It is comprised by. Further, the second distance L2 between the two measurement target points P1 and P2 that can be specified by these linear patterns SL1, SL2, and SL3 is the first distance between the two adjustment operation points 9 and 12 in the tilt adjustment mechanism. Is set equal to the distance L1.
[0022]
In the image forming apparatus having the above-described configuration, when the “test mode” is selected by the operation mode selection unit 13 and the image forming operation is executed, the sheet 5 is transported in the same manner as in the “normal image forming mode” and is being transported. As described above, the side edge 5A of the sheet 5 is aligned with the reference line K by the skew rollers 1, 2, 3 and the side guide 4. On the other hand, the test pattern generation unit 14 generates a test pattern in response to the mode selection information from the operation mode selection unit 13, and the image output unit 15 performs image output processing based on the test pattern. As a result, a test chart is output by the image output unit 15 to the paper 5 aligned by the skew rollers 1, 2, 3 and the side guide 4.
[0023]
When the inclination of the reference line K is adjusted using the test chart output in this way, first, as shown in FIG. 3, two measurement target points P1, which are specified on the test chart output to the paper 5 are used. For P2, the dimensions X1 and X2 are measured up to the sheet side end 5A which is the abutting side to the side guide 4 respectively. Each of the measurement dimensions X1 and X2 is defined by the length in a direction orthogonal to the paper transport direction X (a direction along the leading edge or the rear edge of the paper 5).
[0024]
Next, the difference between the dimensions X1 and X2 obtained as a measurement result is obtained. Here, the difference value between the dimensions X1 and X2 corresponds to the second distance L2 between the two measurement target points P1 and P2 in the test chart, and the second distance L2 corresponds to the two distances in the tilt adjustment mechanism. Since it is set equal to the first distance L1 between the adjustment operation points 9 and 12, the difference between the dimensions X1 and X2 and the inclination adjustment amount of the inclination adjustment mechanism (reference line K) have a relationship of 1: 1. It comes to correspond. Therefore, the tilt adjustment amount of the tilt adjustment mechanism can be easily calculated from the difference value between the dimensions X1 and X2.
[0025]
That is, as shown in FIG. 4, when the difference value between the measurement dimensions X1 and X2 obtained from the test chart using the three linear patterns SL1, SL2, and SL3 is ΔX, this ΔX corresponds to the inclination adjustment amount of the inclination adjustment mechanism. To be. Therefore, when adjusting the inclination of the reference line K, the elliptical cam 11 is rotated so that the position of the side guide 4 is displaced by the ΔX dimension on the axis passing through the rotation fulcrum 12 in the direction orthogonal to the conveyance direction Y. . As a result, the test charts SL1, SL2, and SL3 that are output with the test charts SL1, SL2, and SL3 tilted with respect to the sheet 5 as shown in FIG. 5A before adjustment are shown in FIG. 5B after adjustment. Thus, the test charts SL1, SL2, and SL3 are output to the paper 5 without inclination.
[0026]
As described above, in the image forming apparatus according to the embodiment of the present invention, the first distance L1 between the two adjustment operation points 9 and 12 in the tilt adjustment mechanism and the two measurement target points P1 and P2 in the test chart output unit. By configuring so that the second distance L2 between them is equal, the inclination adjustment amount of the inclination adjustment mechanism can be easily determined from the test charts SL1, SL2, SL3 output to the paper 5. This makes it possible to simplify the tilt adjustment work for skew correction and shorten the work time.
[0027]
As an output form of the test chart output means, as shown in FIG. 6A, the second and third linear patterns SL2 and SL3 intersecting the first linear pattern SL1 at two measurement target points P1 and P2. By outputting the test chart with the scales M1 and M2 attached thereto, the dimension measurement can be accurately performed without using a ruler or the like. Further, by outputting the calculation column 16 for deriving the tilt adjustment amount from the measurement dimensions X1 and X2 simultaneously with the test chart, the tilt adjustment amount of the tilt adjustment mechanism can be calculated without error. In addition to this, as shown in FIG. 6B, the correspondence table 17 of the inclination adjustment amount derived from the calculation column 16 and the adjustment method (rotation direction and rotation angle of the elliptical cam 11 and the like) adapted thereto is tested. By outputting simultaneously with the chart, it is possible to reduce adjustment errors in the adjustment work. The scales M1 and M2, the calculation column 16 and the correspondence table 17 mentioned here may all be output simultaneously with the test chart, or any two may be output simultaneously with the test chart.
[0028]
FIG. 7 is a schematic diagram showing a configuration of a skew correction unit of an image forming apparatus according to another embodiment of the present invention. In FIG. 7, in the paper transport direction Y, two transport rollers 21 and 22 are provided on the upstream side and the downstream side thereof. The transport roller 21 is attached to the rotary shaft 23 and is driven to rotate integrally with the rotary shaft 23. The rotating shaft 23 is supported so as to be movable in a direction (arrow direction) perpendicular to the transport direction Y by a moving mechanism (not shown). The transport roller 22 is attached to a rotation shaft 24 and is driven to rotate integrally with the rotation shaft 24. The rotating shaft 24 is supported by a moving mechanism (not shown) so as to be movable in a direction (arrow direction) perpendicular to the transport direction Y. Further, the rotation shafts 23 and 24 corresponding to the transport rollers 21 and 22 are configured to be able to move independently in a direction orthogonal to the transport direction Y.
[0029]
A detection sensor 25 is disposed in the vicinity of the conveyance roller 21, and a detection sensor 26 is disposed in the vicinity of the conveyance roller 22. These two detection sensors 25 and 26 detect the side edge 27A of the paper 27 conveyed by the conveyance rollers 21 and 22. The detection points S1 and S2 of the detection sensors 25 and 26 are set at a first distance L1 in the paper transport direction Y, and the axis passing through the detection points S1 and S2 positions the side edge 27A of the paper 27. This is a reference line K for matching.
[0030]
In addition, the inclination of the reference line K passing through the detection points S1 and S2 of the detection sensors 25 and 26 can be adjusted by moving at least one of the detection points S1 and S2 in a direction orthogonal to the transport direction Y. It has become.
[0031]
As a specific tilt adjustment mechanism, for example, when a photo sensor that turns on and off depending on the presence or absence of paper at the detection points S1 and S2 is used as the detection sensors 25 and 26, at least one of the detection sensors 25 and 26 is orthogonal to the transport direction Y The structure supported so that it can move to the direction to do is considered. When this tilt adjustment mechanism is employed, the detection points S1 and S2 of the detection sensors 25 and 26 are used as adjustment operation points, respectively, and the reference by the two detection sensors 25 and 26 is used with these two adjustment operation points S1 and S2 as a reference. The inclination of the line K can be adjusted.
[0032]
When CCD line sensors are used as the detection sensors 25 and 26, the sensor detection value when the side edge 27A of the paper 27 is recognized as being on the reference line K is changed, thereby changing each sensor in the transport direction Y. The inclination of the reference line K can be adjusted using the detection point of the CCD line sensor as the adjustment operation point.
[0033]
In the skew correction unit configured as described above, the sheet 27 conveyed from the upstream side in the conveyance direction Y is sequentially nipped by the conveyance rollers 21 and 22 and conveyed to the downstream side. At this time, when the leading edge of the paper 27 passes through the conveyance roller 22, the movement of the conveyance rollers 21 and 22 (movement in a direction perpendicular to the conveyance direction Y) is controlled based on the detection results from the detection sensors 25 and 26. The At this time, when a photo sensor or the like is used for the detection sensors 25 and 26, skew correction of the paper 27 is performed by the following control method.
[0034]
That is, when the detection sensor 25 does not detect the paper 27, the transport roller 21 is moved to the right side of the figure, and when the detection sensor 25 is detecting the paper 27, the transport roller 21 is moved to the left side of the figure. Let Similarly, when the detection sensor 26 does not detect the paper 27, the conveyance roller 21 is moved to the right side of the figure, and when the detection sensor 26 detects the paper 27, the conveyance roller 22 is Move to the left. Further, the movement operation of the transport rollers 21 and 22 is repeated until the rear side of the paper 27 passes the transport roller 21. By controlling the movement of the transport rollers 21 and 22 in this way, the side edge 27A of the paper 27 is aligned with the reference line K. As a result, the skew of the paper 27 can be corrected with the reference line K as a sight.
[0035]
On the other hand, a test chart output unit of an image forming apparatus according to another embodiment of the present invention has the same configuration as that shown in FIG. As shown in FIG. 8, the test chart output to the paper by the test chart output means is conveyed so that two measurement target points P1 and P2 separated by the second distance L2 in the paper conveyance direction Y can be specified. The first linear pattern SL1 parallel to the direction Y and the second and third linear patterns SL2 and SL3 orthogonal to the first linear pattern SL1 on the front side and the rear side of the paper 5 with respect to the transport direction Y Composed. Further, the second distance L2 between the two measurement target points P1 and P2 that can be specified by these linear patterns SL1, SL2, and SL3 is the first distance between the two adjustment operation points S1 and S2 in the tilt adjustment mechanism described above. Is set equal to the distance L1.
[0036]
As described above, also in the image forming apparatus according to another embodiment of the present invention, the first distance L1 between the two adjustment operation points S1 and S2 in the tilt adjustment mechanism and the two measurement target points P1 in the test chart output unit. , P2 is set equal to the second distance L2, the inclination adjustment amount of the inclination adjustment mechanism can be easily calculated from the test charts SL1, SL2, SL3 output to the paper 27. Therefore, as in the previous embodiment, it is possible to simplify the tilt adjustment work for skew correction and shorten the work time.
[0037]
In the above embodiment, a test chart composed of three linear patterns SL1, SL2, and SL3 is output to the paper. However, for this test chart, two measurements separated by a distance in the paper transport direction Y are performed. Any pattern may be output as long as the target point can be specified. For example, a test chart in which two measurement target points are indicated by x marks or black dots may be output. Various modifications can be made to the skew correction mechanism and the tilt adjustment mechanism.
[0038]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, the first distance between the two adjustment operation points in the inclination adjustment unit and the second distance between the two measurement target points in the test chart output unit are obtained. By setting them equal, it is possible to easily determine the reference line inclination adjustment amount from the test chart output on the paper. This makes it possible to simplify the tilt adjustment work for skew correction and shorten the work time.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of a skew correction unit of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a functional block diagram illustrating a configuration of a test chart output unit of the image forming apparatus according to the embodiment of the present invention.
FIG. 3 is a diagram showing an output state of a test chart according to the embodiment of the present invention.
FIG. 4 is a diagram illustrating a specific example of tilt adjustment.
FIG. 5 is a diagram comparing the output of a test chart before and after tilt adjustment.
FIG. 6 is a diagram showing an example of output form of test chart output means.
FIG. 7 is a schematic diagram illustrating a configuration of a skew correction unit of an image forming apparatus according to another embodiment of the present invention.
FIG. 8 is a diagram showing an output state of a test chart according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2, 3 ... Skew roller, 4 ... Side guide, 5, 27 ... Paper, 7 ... Reference plane, 8 ... Bracket, 9 ... Turning fulcrum (adjustment operation point), 10 ... Tension coil spring, 11 ... Elliptical cam , 12 ... Rotation fulcrum (adjustment operation point), 13 ... Operation mode selection part, 14 ... Test pattern generation part, 15 ... Image output part, 16 ... Calculation column, 17 ... Correspondence table, 21, 22 ... Conveyance roller, 23, 24: Rotating shaft, 25, 26: Detection sensor, K: Reference line, L1: First distance, L2: Second distance, P1, P2: Measurement target point, S1, S2: Sensor detection point (adjustment operation point) ), Y ... Transport direction

Claims (4)

A skew correction unit that has a reference line substantially parallel to the conveyance direction of the paper and corrects the skew of the paper by aligning the side edge of the paper with respect to the reference line;
Inclination adjusting means having two adjustment operation points separated by a first distance in the transport direction and adjusting the inclination of the reference line in the skew correction means with reference to the two adjustment operation points;
A test chart output means for outputting a test chart capable of specifying two measurement target points separated by a second distance in the transport direction with respect to the paper whose skew has been corrected by the skew correction means;
An image obtained by setting the first distance between the two adjustment operation points in the inclination adjusting means equal to the second distance between the two measurement target points in the test chart output means Forming equipment. The image forming apparatus according to claim 1, wherein the test chart output unit outputs a scale for dimension measurement using the two measurement target points simultaneously with the test chart. The image forming apparatus according to claim 1, wherein the test chart output unit outputs a calculation column for deriving an inclination adjustment amount of the inclination adjustment mechanism simultaneously with the test chart. The image forming apparatus according to claim 1, wherein the test chart output unit outputs a correspondence table of an inclination adjustment amount of the inclination adjustment mechanism and an adjustment method suitable for the same simultaneously with the test chart.

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