JP2003252476A - Sheet conveying method, sheet conveying device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveying method enabling measurement of sheet conveying speed with little labor and low cost. <P>SOLUTION: This sheet conveying method sends out a sheet in a conveyance direction by rotating a conveying roller 1 abutting on a sheet 2 or a pair of conveying rollers 1 abutting on the front and rear sides of the sheet. Sheet conveying speed V is derived from a formula: V=ΔL/ΔT where ΔT is a prescribed time which an ink jet head 10 disposed at either the front part or rear part of a conveying roller 1 ejects ink droplets, and ΔL is the distance between an initiation droplet and a termination droplet in the conveyance direction of the ink droplets ejected on the sheet. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sheet conveying method,
The present invention relates to a sheet conveying device and an image forming apparatus such as a copying machine, a facsimile, and a printer that uses the sheet conveying device.

[0002]

2. Description of the Related Art As a method of transporting a sheet that is in contact with the transport roller by rotating the transport roller and measuring the sheet transport speed, for example, a photo sensor fixed in the transport path is used to measure the sheet at a specified distance. There is a method of measuring the passing time and dividing the specified distance by the time. As the specified distance, for example, in the technique described in Japanese Patent Laid-Open No. 6-263283, the distance between the paper feed roller and the paper passing sensor is used.
The transport speed is measured by dividing this specified distance by the time required for the leading edge of the paper to pass. Further, in the technique described in Japanese Patent Laid-Open No. 6-297786, the time required to convey one recording sheet (conveyance is determined by sequentially detecting the page head marks corresponding to the folds in the folded recording sheet by a reflective photosensor. Speed) is being measured.

[0003]

When the transport roller is rotated,
When a sheet that is in contact with the transport roller is transported, the transport roller rotation speed and the sheet transport speed do not match, and the latter is usually slightly delayed, and if another load is applied to the sheet, for example, The delay becomes more significant when the rear side is bitten by the upstream conveying roller. In order to perform sheet conveyance control with high accuracy, it is important to know the sheet conveyance speed.Therefore, as a method of measuring the sheet conveyance speed, for example, a sheet detection device is conventionally used to measure the time taken for the sheet to pass a specified distance. Was measured, and the specified distance was divided by the time. Hereinafter, the problems to be solved by the present invention will be described with reference to FIGS.
This will be described using 8. The numbers after each name in the following description correspond to the numbers in the figure. FIG. 15 shows an outline of a method obtained by measuring the time required for a sheet to pass a specified distance and dividing the specified distance by the time. In FIG. 15, one sheet detection device 4 is installed downstream of the transport rollers 1, 1 ′, and a sheet 2 downstream of the transport rollers 1, 1 ′ is installed.
Measure the transport speed of. That is, the sheet detecting device (sensor) 4 conveys the sheet 2 conveyed by the conveying rollers 1, 1 '.
When the leading edge of the sheet passes, the sheet detection device 4 detects the sheet 2
If the time at this time is T1 and the rear end of the sheet 2 further passes the sensor 4, the sensor 4 regards the sheet 2 as non-detection, and if the time at this time is T2, If the dimension of the sheet 2 in the transport directions 3 and 3 ′ is L, the transport speed V of the sheet 2 is calculated by the following formula. V = L / (T2-T1) On the other hand, as another method for measuring the sheet conveying speed, as shown in FIG. 16, two sheet detecting devices 5a and 5b are provided downstream of the conveying rollers 1 and 1 ′ by a distance L1. Others are installed separately and measure the sheet transport speed downstream of the transport rollers. That is, the sheet detection device 5a is connected to the transport rollers 1, 1 '.
When the leading edge of the sheet 2 conveyed by means of the sheet detector 5a detects the sheet, and the time at this time is T1, the leading edge of the sheet 2 then passes the sheet detector 5b. If the detection device 5b detects and the time at this time is T2, the transport speed V of the sheet 2 can be calculated by the following formula. V = L1 / (T2-T1) ... Alternatively, as shown in FIG.
There is also a case where the sheet is installed downstream of the conveying rollers 1 and 1 ', and the conveying speed of the print sheet 7 in which the print pattern 8 is applied in advance in the sheet conveying direction 9 on the surface of the sheet as shown in FIG. 18 is measured. In this case, the print detection device 6 measures the time required for the distance L2, which is the pattern interval of the print pattern 8 of the print sheet 7 transported by the transport rollers 1 and 1 ′, to pass as T ′. The transport speed V of the print sheet 7 is calculated from the equation. V = L2 / T '... The sheet conveying speed can be obtained by the above conventional method, but with the sheet conveying speed V calculated by the formula, only the average speed for one sheet is calculated. If there is a fluctuation component of the sheet conveying speed within the time when one sheet passes, it cannot be measured. Also, with the formula, it is possible to measure even if there is a fluctuation component of the sheet conveyance speed within the time when one sheet passes, but in order to achieve this, in other words, to increase the spatial resolution of the speed. In addition, it is necessary to increase the number of sets of the two sheet detection devices and to install them densely, which requires complicated installation and control and is expensive. Furthermore, with the formula, it is possible to measure even if there is a fluctuation component of the sheet conveyance speed within the time when one sheet passes, but it is necessary to prepare a printing sheet on which the printing pattern is printed beforehand, It required high printing accuracy and effort to create patterns. In view of the above problems, the present invention includes an inkjet drive device and an inkjet head upstream or downstream of a transport roller, and ejects ink droplets onto a sheet surface being transported by the inkjet drive device for a sufficiently short predetermined time ΔT. The distance ΔL between the start position and the end position of the ink droplet ejected within the time ΔT is
For example, by measuring with a scale or the like, and calculating ΔL / ΔT, it has a high spatial resolution, and by not using a sheet detection device, a print detection device, etc. An object of the present invention is to provide a sheet conveyance method, a sheet conveyance device, and an image forming apparatus that enable measurement.

[0004]

In order to achieve the above object, the invention according to claim 1 rotates one conveying roller that abuts against a sheet or a pair of conveying rollers that abut on the front and back of the sheet, In the sheet conveying method of sending the ink droplets in the conveying direction, the predetermined time for the ink jet heads arranged at either the front portion or the rear portion of the conveying roller to eject the ink droplets is ΔT, from the start droplet in the conveying direction of the ink droplets ejected to the sheet. ΔL is the distance to the end drop
In this case, the sheet conveying method that derives the sheet conveying speed V from the equation of V = ΔL / ΔT is the most main feature.
According to the second aspect of the present invention, in the sheet conveying method according to the first aspect, when the conveyance roller rotation speed is V0, a relative comparison between the sheet conveyance speed V and the conveyance roller rotation speed V0 is performed.
The main feature is the sheet conveying method performed by the equation of the slip ratio S represented by = (V0-V) / V0 × 100 [%].
A third aspect of the present invention is mainly characterized in that, in the sheet conveying method according to the second aspect, when the slip ratio S is larger than a predetermined threshold value, it is determined that it is time to replace the conveying roller. According to a fourth aspect of the invention, there is provided the sheet transport method according to any one of the first to third aspects, wherein the ON signal of the sheet detection device downstream of the inkjet head is used as a trigger for starting the ejection of ink droplets. The main feature. A fifth aspect of the present invention is characterized in that, in the sheet conveying method according to any one of the first to fourth aspects, a print detecting device downstream of the inkjet head calculates a sheet conveying speed V as a main feature. . According to a sixth aspect of the invention, in the sheet conveying method according to any one of the first to fifth aspects,
The main feature is a sheet conveying method in which the ink is a lumilite ink type.

According to a seventh aspect of the present invention, in the sheet conveying apparatus using the sheet conveying method according to the fifth aspect, the sheet conveying speed V from the print detecting device to the conveying roller with respect to the predetermined sheet conveying speed V1 and the predetermined error E. Is E ≧ | V1-
The most main feature is a sheet conveying device provided with a feedback device for maintaining the expression of V | / V1 × 100 [%]. According to an eighth aspect of the present invention, in a sheet conveying device using the sheet conveying method according to any one of the first to fifth aspects, a plurality of sets of a conveying roller, an inkjet driving device, and an inkjet head are provided, and The most main feature is a sheet conveying device having different ejection patterns for each inkjet head. According to a ninth aspect of the present invention, in a sheet conveying device using the sheet conveying method according to any one of the first to fifth aspects, a plurality of sets of a conveying roller, an inkjet driving device, and an inkjet head are provided, and The most main feature is a sheet conveying device having different main scanning positions for ejecting ink for each inkjet head. According to a tenth aspect of the present invention, in the sheet conveying device using the sheet conveying method according to any one of the first to fifth aspects, a plurality of sets of a conveying roller, an inkjet driving device, and an inkjet head are provided, and The most main feature is a sheet conveying device in which each inkjet head has a different color. Claim 11
According to another aspect of the present invention, there is provided a sheet transporting apparatus that uses the sheet transporting method according to any one of claims 1 to 5, wherein the inkjet head has a driving unit that drives in a main scanning direction, and a predetermined time ΔT and inkjet are performed. Drive speed V
The most main feature is a sheet conveying device in which S has a relationship of VS · ΔT = constant. According to a twelfth aspect of the present invention, in the sheet conveying apparatus using the sheet conveying method according to any one of the first to fifth aspects, ink is ejected / non-ejected simultaneously in the width direction with respect to the sheet conveying direction. A sheet conveying device having at least two inkjet heads is the most main feature. According to a thirteenth aspect of the present invention, in the sheet transporting apparatus using the sheet transporting method according to any one of the first to fifth aspects, the sheet transporting apparatus in which the inkjet driving device and the inkjet head are detachable is the most important. It is a characteristic. A fourteenth aspect of the present invention is characterized in that, in the sheet conveying apparatus using the sheet conveying method according to any one of the first to fifth aspects, the sheet conveying apparatus having an on / off control switch is the most main feature. . The invention according to claim 15 is characterized in that, in the sheet conveying device according to any one of claims 7 to 13, the sheet conveying device whose ink is a lumilite ink type is a main feature. The sixteenth aspect of the present invention is most characterized by an image forming apparatus including the sheet conveying device according to any one of the seventh to fourteenth aspects.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. A sheet conveying method (and a sheet conveying apparatus, which will be hereinafter represented by a sheet conveying method) in the first embodiment will be described with reference to FIG. The sheet conveying method according to the first embodiment includes an inkjet head 10 and an inkjet drive device 11 for driving the inkjet head 10 on the downstream side of the conveying rollers 1 and 1 ′ in the conveying direction, and the sheet is conveyed by the conveying rollers 1 and 1 ′. When the sheet is conveyed in the direction 3-3 ′, ink droplets are ejected from the ink jet head 10 onto the surface of the sheet 2, and thereafter, a predetermined ejection time interval (previously set in the ink jet drive device 11 ( Ink droplets are ejected again after a lapse of (ΔT). After transporting the sheet 2, the sheet 2
In FIG. 2, an ink ejection start droplet 12a and an ink ejection end droplet 12b are printed by two ink droplets in the sheet conveyance direction 9, and the distance Δ between these ink droplets is printed.
By measuring L, the transport speed V of the sheet 2 is calculated by the following formula. V = ΔL / ΔT ...

In FIG. 1, an ink jet head 10 is shown.
Is installed downstream of the transport rollers 1, 1 ′, but may be installed upstream of the transport rollers 1, 1 ′. Further, by reducing the ejection time interval ΔT set in advance in the inkjet driving device 11, the distance ΔL between ink droplets can also be reduced, and, for example, the transport speed V of the sheet 2 fluctuates in a short time. Even in this case, it is obtained as the instantaneous sheet conveying speed V. For example, ΔT = 0.05
When [Delta] L = 17.0 [mm] is measured in [sec], the sheet conveying speed V is V = 340.0 [m] from the equation.
m / sec] is calculated. However, the injection time interval ΔT
Is required to be expressed by the following formula with respect to the minimum ink droplet ejection time interval (which is referred to as δT), which is related to the ink droplet ejection performance of the inkjet driving device 11 and the inkjet head 10. ΔT> δT ... At least two ink droplets may be ejected, but more ink droplets may be ejected. That is, when ΔT >> δT, when ink droplets are continuously ejected from the inkjet head 10 between ΔT, a line segment having a distance ΔL is visually drawn on the sheet 2 after being conveyed. In this case, ΔL is equivalent to measuring the line segment, and when measuring with a scale,
It is easy to apply a scale etc., and the measurement becomes easy. According to the present invention, unlike the prior art, for example, a method using a sheet detection device or the like, it is possible to measure the sheet conveyance speed with a simple configuration and at low cost, and thus to evaluate the characteristics of the conveyance roller.
The analysis is performed, and the accuracy of the sheet transportability of the transport rollers is improved.

Next, a sheet conveying method according to the second embodiment will be described by omitting illustration. When the material and shape of the conveying roller and the speed of the conveying roller change, the sheet conveying speed represented by the formula changes. In addition to the sheet conveying method in the first embodiment, the sheet conveying method in the second embodiment defines a delay of the sheet conveying speed V with respect to the conveying rollers as a slip ratio S, and the material and shape of the conveying rollers are calculated by the following equation. , And a sheet conveyance method for performing relative evaluation as a factor including various characteristics such as the speed of the conveyance roller. S = (V0-V) / V0 × 100 [%] By the formula, for example, the speed of the transport roller is 200 mm /
In the case of sec, 360 mm / sec, and the respective sheet conveying speeds are 190 mm / sec and 340 mm / sec, the slip ratios S are 5.0 [%] and 5.6, respectively.
[%] Is obtained, and relative comparison is performed without performing absolute comparison between sheet conveyance speeds. According to the present invention, the relative evaluation of the sheet conveying speed and the rotating speed of the conveying roller can be performed even if the material and shape of the conveying roller or the conveying speed are different, and thus the characteristic evaluation / analysis of the conveying roller is performed. The accuracy of the sheet transportability of the transport rollers is improved.

Next, a sheet conveying method according to the third embodiment will be described with illustration omitted. In addition to the sheet conveying method according to the third exemplary embodiment, the sheet conveying method according to the third exemplary embodiment has a slip ratio S determined by a formula that is greater than a predetermined threshold value due to, for example, deterioration over time, A sheet conveying method is characterized in that the conveying roller is replaced. For example, the predetermined threshold of the slip ratio is 1
The transport roller set to 0.0 [%] is 5.0 at the initial stage.
In the case of [%], it is 1 by transporting 500,000 [times]
If it becomes 0.4%, replace it with a new conveying roller. According to this, the replacement of the transport rollers is promoted, and the sheet transportability of the transport rollers with high accuracy can always be maintained.

Next, a sheet conveying method according to the fourth embodiment will be described with reference to FIG. In addition to the sheet conveying method according to the third embodiment, the sheet conveying method according to the fourth embodiment includes a sheet detecting device 13 downstream of the inkjet head 10, and the detection of the leading edge of the sheet 2 by the sheet detecting device 13 is ON. Is used as a trigger for starting ejection of ink droplets by the inkjet driving device 11 and the inkjet head 10.
With the above configuration, since the arrival of the leading edge of the sheet 2 at the sheet detection device 13 triggers the ink ejection,
As shown in the first embodiment, ink is ejected at a predetermined ejection time interval ΔT from the trigger time, and the distance ΔL between the ink enemies by the ink ejection start droplet 12a and the ink ejection end droplet 12b is measured, Thus, the transport speed V of the sheet 2 is calculated. According to this, it is possible to guarantee that the ink droplets for measuring the sheet conveying speed are always ejected onto the sheet surface, and it is possible to prevent the contamination caused by ejecting the ink droplets other than the sheet surface.

Next, a sheet conveying method according to the fifth embodiment will be described with reference to FIGS. The sheet conveying method according to the fifth embodiment is similar to the first to fourth embodiments.
In any of the sheet conveying methods up to the embodiment of
It has a configuration in which a print detection device 14 is added downstream of the inkjet head 10, and has a configuration in which a distance ΔL ejected at an ejection time interval ΔT is measured and an equation is calculated. The print detection device 14 is, for example, a laser Doppler non-contact movement amount measuring sensor. The movement amount measurement sensor measures the movement amount of the sheet by detecting the interference fringe variable amount caused by the movement of the normally white sheet due to the laser light irradiation. At that time, the reflectance of the laser beam is reduced for the colors other than white, that is, for the ink color, and the interference fringes are not detected. Therefore, for example, as shown in FIG.
1a and the ink ejection end droplet 21b ejected after the ejection time interval ΔT and a distance ΔL behind the ink ejection start droplet 21a, the print detection device 14 first reflects the laser at the ink ejection start droplet 21a. The light is not detected, the movement amount is reset to zero from this, and thereafter, the movement distance ΔL-2r (however, of the white portion from the rear end of the ink ejection start drop 21a to the front end of the ink ejection end drop 21b)
r is the ink drop radius). Print detection device 1
In No. 4, the reflected light of the laser is not detected in the ink ejection end droplet 21b, and the distance ΔL-2r described above is stored from this, and for example, the ink droplet radius r is set in advance, and ΔL-2r + 2r is calculated as the correction calculation. = ΔL is calculated,
Obtain ΔL by the injection time interval ΔT. From the above, the transport speed V of the sheet 2 is calculated during the transport of the sheet 2 by calculating the expression from the injection time interval ΔT. According to this, the measurement result can be obtained in real time during the sheet conveyance without measuring the sheet conveyance speed after the sheet conveyance, and the measurement time can be shortened and the trouble can be avoided.

Next, a sheet conveying method according to the sixth embodiment will be described with reference to FIG. The sheet transporting method according to the sixth embodiment is similar to the sheet transporting method according to the fifth embodiment except that the print detecting device transfers to the transport roller.
With respect to the sheet conveying speed V1 and the error E which have been determined in advance, a feedback device 15 for maintaining the following expression is provided. E ≧ | V1−V | / V1 × 100 [%] ... From the configuration of the sheet conveying method in the sixth embodiment described above, as described in the sixth embodiment, the sheet 2 is conveyed during the conveyance of the sheet 2. After the transport speed V is calculated, the feedback device 15 causes the transport roller 1 determined by the formula to achieve the transport speed V of the sheet 2 that satisfies the formula,
The rotation speed V0 is updated to 1 ', and accordingly, the conveyance speed V of the sheet 2 is controlled to maintain a relative error E or less with respect to the predetermined conveyance speed V1 of the sheet. Further, the control of the formula may not be satisfied by one update of the rotation speed V0 of the transport rollers 1 and 1 ′, but in that case, the update is performed multiple times by the same procedure. Further, the above update may not be limited to the update within one sheet, but in that case, it is reflected in the update of the transport speed V of the sheet to be transported next or continuously.

Next, a sheet conveying method according to the seventh embodiment will be described with reference to FIGS. 6 and 7A. The sheet conveying method according to the seventh embodiment includes a plurality of sets of a conveying roller, an inkjet driving device, and an inkjet head, in addition to the sheet conveying method according to any one of the first to fourth embodiments, and each inkjet. Each head has a different ejection pattern. In the above configuration, in the case of FIG. 6, the first set of the carrying roller and the inkjet driving device and the inkjet head is the carrying rollers 1a and 1'a, the inkjet driving device 11a, and the inkjet head 10a, and the second set is the carrying roller. 1b and 1'b, the inkjet driving device 11b, and the inkjet head 10b. Further, in FIG. 6, there are two sets of sheet detection devices, and the sheet detection device 13a and the sheet detection device 13b are installed downstream of the inkjet heads 10a and 10b, respectively. Further, the sheet 2 is conveyed by the conveying rollers 1a, 1'a or the conveying rollers 1b,
The pattern of the ink droplets ejected from the inkjet head 10a and the inkjet head 10b when being transported in the transport directions 3a, 3'a or the transport directions 3b, 3'b by 1'b are as shown in FIG. As shown in FIG. 5, the print patterns 18a and 18b are different print patterns. That is, the print pattern 18a
Is a print pattern having only the ink ejection start droplet and the ink ejection end droplet, and the print pattern 18b is another droplet immediately after the trailing end of the ink ejection start droplet and another droplet at the trailing end of the ink ejection end droplet. From this, the difference between these two print patterns is identified as the print pattern ejected from the inkjet head after the specific transport roller. Therefore, in the case of FIG. 7A, the ink ejection in the print pattern 18a is performed. Based on the distance ΔL1 between the start droplet and the ink ejection end droplet, the transport speed of the sheet 2 after the transport rollers 1a, 1′a from the predetermined time ΔT1 is calculated as ΔL1 / ΔT1 from the formula, while the print pattern 18b
The distance ΔL2 between the ink jetting start droplet and the ink jetting ending drop in the conveyance roller 1b− from the predetermined time ΔT2.
The conveyance speed of the sheet 2 after 1′b is the same as ΔL2 /
Calculated as ΔT2.

Next, a sheet conveying method according to the eighth embodiment will be described with reference to FIGS. 6 and 7B. The sheet conveying method according to the eighth embodiment is the same as the sheet conveying method according to the first to sixth embodiments, and includes a plurality of sets of a conveying roller, an inkjet driving device, and an inkjet head, and ink for each inkjet head. Is different in the main scanning position for ejecting. That is, the sheet transporting method according to the eighth embodiment is different from the ink droplets ejected from the inkjet heads 10a and 10b (previously arranged so that the main scanning positions are different) in the sheet transporting method according to the seventh embodiment. However, as shown in FIG. 7B, print patterns 19a and 19b appear at different positions in the main scanning direction with respect to the sheet conveying direction 9. At that time, the print patterns 19a and 19b may be the same print pattern. In that case, since the ink is ejected to different positions in the main scanning direction described above, it may be the conveyance rollers 1a-1'a.
Alternatively, it is determined whether or not the conveyance rollers 1b-1'b are used. From the distance ΔL1 between the ink ejection start droplet and the ink ejection end droplet in the print pattern 19a and the predetermined time ΔT1, the transport speed of the sheet 2 after the transport rollers 1a-1′a is calculated as ΔL1 / ΔT1 from the formula. On the other hand, from the distance ΔL2 between the ink ejection start droplet and the ink ejection end droplet in the print pattern 19b and the predetermined time ΔT2, the transport speed of the sheet 2 after the transport rollers 1b-1′b is similarly calculated as ΔL2 / ΔT2. It From the above, different transport rollers 1a-1'a, 1b-
For 1'b, obtain each transport speed.

A sheet conveying method according to the ninth embodiment will be described with reference to FIGS. 6 and 7C. The sheet conveying method in the ninth embodiment is the same as the first to sixth embodiments.
The sheet conveying method according to the embodiment is characterized in that a plurality of sets of a conveying roller, an inkjet driving device, and an inkjet head are provided, and that each inkjet head has a different color. That is, in the sheet transporting method according to the ninth embodiment, the difference between the ink droplets ejected from the inkjet heads 10a and 10b (which ejects ink droplets of different colors in advance) in the sheet transporting method according to the seventh embodiment is As shown in FIG. 7C, the print patterns 20a and 20b having different colors appear.
Therefore, the print patterns 20a and 20b are not
a-1'a, or transport roller 1b-
It is determined whether or not it is due to 1'b. Print pattern 20
From the distance ΔL1 between the ink ejection start droplet and the ink ejection end droplet at a and the predetermined time ΔT1, the transport roller 1
The transport speed of the sheet 2 after a-1′a is calculated as ΔL1 / ΔT1 from the equation. On the other hand, the print pattern 20
From the distance ΔL2 between the ink ejection start droplet and the ink ejection end droplet in b, and the predetermined time ΔT2, the conveyance roller 1
Similarly, the conveyance speed of the sheet 2 after b-1′b is Δ
Calculated as L2 / ΔT2. From the above, the respective conveyance speeds are obtained for the different conveyance rollers 1a-1'a and 1b-1'b.

A sheet conveying method according to the tenth embodiment will be described with reference to FIGS. 8, 9 and 10. The sheet conveying method according to the tenth embodiment is the same as the sheet conveying methods according to the first to sixth embodiments, the inkjet head has a driving unit that drives in the main scanning direction, and the ejection time interval ΔT is: The driving speed (this is referred to as VS) is characterized by having the following relationship. VS · ΔT = constant As shown in FIG. 8, the inkjet head 10 moves 16 in the main scanning direction with respect to the sheet conveying direction 9. During this movement 16, for example, when ink droplets are ejected at three ejection time intervals ΔT1, ΔT2, and ΔT3,
The respective ink droplets correspond to the ink ejection start droplets and the ink ejection end droplets, that is, in the main scanning direction, as shown in FIG. 9, they are separated by ΔX1, ΔX2, and ΔX3 in the sheet conveying direction and in the main scanning direction. ΔL1, ΔL2, ΔL3
Only three ink drops are printed. However, based on the equation, since ΔX1 = ΔX2 = ΔX3, printing is performed at equal intervals in the main scanning direction. As a result, the conveying speed of the sheet 2 is ΔL1 / ΔT1 and ΔL, respectively, based on the equation.
Calculated as 2 / ΔT2 and ΔL3 / ΔT3. See also FIG.
As shown in FIG. 5, for the sheet 2 on which the ink droplets are ejected, the product VS · T, where T is the integrated value of the driving velocity VS and the general ejection time interval, is plotted on the horizontal axis, while the sheet conveyance direction 9
Assuming that the general distance of the sheet 2 conveyed to D is D, each break point is the above-mentioned ink droplet, which is a break point graph. However, the horizontal axis may be considered by dividing VS, that is, as the injection time T. In that case, if the folding points are connected by a straight line, a sheet conveying speed line 17 is shown. This sheet conveying speed line 17 is
Since the inclination represents the conveyance speed V of the sheet 2, it is a visual explanatory view of the conveyance state of the sheet 2. In the above description, since the value of the equation is set relatively large, ΔX1, ΔX2, ΔX
3, or ΔL1, ΔL2, ΔL3 is visually long,
By making the value of the expression small, an extremely smooth line graph, a line graph or a curve graph may be obtained. According to this, a graph in which the horizontal axis is the amount proportional to the sheet transport time and the vertical axis is the sheet movement amount, in other words, the sheet transport speed diagram can be created by simply transporting the sheet, Enables roller design evaluation.

A sheet conveying method according to the eleventh embodiment will be described with reference to FIGS. 11 and 12. The sheet carrying method according to the eleventh embodiment is the same as the sheet carrying method according to any one of the first to sixth embodiments.
It is characterized by having at least two or more ink jet heads that simultaneously eject and non-eject the ink in the width direction with respect to the sheet conveying direction. As shown in FIG. 11, the inkjet heads 10a and 10b are installed at different positions in the main scanning direction with respect to the sheet conveying direction 9. As a result, when the sheet 2 is transported by the transport roller 1 in the transport direction 9, for example, when the ink jet start droplets and the ink jet end droplets are jetted at the jet time intervals ΔT1 and ΔT2, the inkjet head 10a transports the sheet 2 in the sheet transport direction 9. As opposed to
Two distances ΔLa1 and ΔLb1 are printed, and ΔLa2 and ΔLb are printed more than the other inkjet head 10b.
2 is printed. Therefore, at different positions in the main scanning direction of the two inkjet heads 10a and 10b, first, the transport speeds of the sheet 2 of ΔLa1 / ΔT1 and ΔLb1 / ΔT1 are measured, and ΔLa2 / ΔT2 and ΔLa2 are calculated.
The conveyance speed of the sheet 2 having Lb2 / ΔT2 is measured. If the sheet 2 is obliquely conveyed by the conveying roller 1, the sheet 2 is different in the main scanning direction. The degree of skew is compared based on the above conveying speeds. The degree of skew may be compared depending on the difference in ink droplet position. According to the present invention, it is possible to measure the skew of the sheet, in other words, the degree of skew, and thus the characteristic evaluation / analysis of the transport roller is realized, and the accuracy of the sheet transportability of the transport roller is improved.

A sheet conveying method according to the twelfth embodiment will be described by omitting illustration. The sheet carrying method according to the twelfth embodiment is characterized in that the inkjet driving device and the inkjet head are detachable in addition to the sheet carrying methods according to the first to eleventh embodiments. As the attaching / detaching means, for example, when the inkjet driving device and the inkjet head are fixed on the surface of the prismatic material or the plate material, and at least at this time only the inkjet head is fixed so as to face the sheet, the attachment / detachment of each prismatic material or the plate material is performed. It will be composed. In that case, there is a method of fixing the prismatic material or the plate material to a side plate or the like which is perpendicular to the axis of the transport roller, which is provided separately, by a bracket or a screw. Maintenance and ink replenishment can be easily performed by attaching and detaching the inkjet drive device and the inkjet head. A sheet conveying method according to the thirteenth embodiment will be described by omitting illustration. The sheet carrying method in the thirteenth embodiment is a sheet carrying method in which drive control of the sheet carrying method in any of the first to twelfth embodiments is performed, that is, ON / OFF switching control is performed. . As described in the first embodiment, the ON / OFF switch switches the execution / non-execution of the ink ejection / non-ejection operation itself from the inkjet head by the inkjet driving device. As a result, only normal sheet conveyance is performed when OFF, and sheet conveyance in which ejection / non-ejection from the inkjet head is performed when ON. The ON / OFF trigger is performed, for example, by user control, so if the user does not want to measure the sheet conveyance speed,
Turn off the N / OFF switch and turn it on for measurement.
To

A sheet conveying method according to the fourteenth embodiment will be described by omitting illustration. The sheet conveying method according to the fourteenth embodiment is characterized in that the ink is lumilite ink. Lumilite ink is an ink type that is invisible under visible light such as a white light source but visible under ultraviolet light such as black light. With the above configuration, when an image is formed on the sheet during sheet conveyance, for example, ink droplets cannot be seen under visible light, that is, the formed image does not interfere, and the sheet conveyance speed can be measured. It is exposed to ultraviolet rays and carried out. A sheet conveying method according to the fifteenth embodiment will be described by omitting illustration. First
The sheet carrying method in the fifth embodiment is a sheet carrying method in which the sheet carrying in the fourteenth embodiment is always performed at the time of sheet carrying. By the sheet conveying method according to the fifteenth embodiment described above, for example, when image formation is performed on a sheet during sheet conveyance as described in the fourteenth embodiment, for example, the formed image may be stretched or stretched. If there is shrinkage, check the ink droplets by exposing them to UV light, and measure the sheet transport speed from these ink droplets to investigate the effect of the sheet transport speed on the image. A guideline can be obtained by which it can be determined whether or not the formation was affected. FIG. 13 shows an image forming apparatus incorporating the above-described sheet conveying device. The image forming apparatus incorporates a sheet conveying apparatus / unit for sheet feeding, conveying, discharging, etc., and an image forming apparatus / unit for forming an image using rollers, and the sheet conveying method in any one of the above is executed. It Here, the sheet is a concept including not only a transfer sheet but also a document. Also, although not particularly shown,
The components such as the inkjet head shown in each of the above-described embodiments are arranged at appropriate positions on each sheet conveying path.

[0020]

As described above, according to the invention described in claim 1, unlike the prior art, for example, the method using the sheet detecting device, the sheet conveying speed is simple and the cost is low. The measurement can be performed, and the characteristic evaluation and analysis of the transport roller can be performed, and the accuracy of the sheet transportability of the transport roller can be improved. According to the second aspect of the present invention, the relative evaluation of the sheet conveying speed and the rotation speed of the conveying roller can be performed even if the material and shape of the conveying roller or the conveying speed are different. The analysis is performed,
The accuracy of the sheet conveyance property of the conveyance roller is improved. Claim 3
According to the above-described invention, the replacement of the transport roller is promoted, and the sheet transportability of the transport roller with high accuracy can always be maintained. According to the fourth aspect of the invention, it is guaranteed that the ink droplets for measuring the sheet conveying speed are always ejected onto the sheet surface, and therefore stains and the like caused by ejecting the ink droplets other than the sheet surface are obviated. It can be avoided.

According to the fifth aspect of the invention, the sheet conveying speed can be obtained in real time during the sheet conveying without measuring the sheet conveying speed after the sheet conveying, and the measurement time can be shortened.
The effort is avoided. According to the sixth and fifteenth aspects of the present invention, the ink droplets for measuring the sheet conveying speed are not visible under visible light, and when the image is separately formed on the sheet, the image quality is deteriorated by the ink droplets. In addition, the measurement of the sheet transport speed realizes two uses, in which the speed is measured by ultraviolet irradiation. According to the invention described in claim 7, it is possible to maintain the target sheet conveying speed. According to the invention described in claim 8, the above effect can be achieved at a plurality of transport roller portions in the process of transporting one sheet. According to the invention of claim 9,
It is possible to easily confirm the difference in ink droplets at each location of the plurality of transport rollers, and to easily calculate the sheet transport speed at the locations of the plurality of transport rollers. According to the tenth aspect of the invention, when the ink droplets are easily selected at the respective positions of the plurality of transport rollers, the colors of the ink droplets are different, and therefore the identification of the ink droplets at the respective positions of the plurality of transport rollers is further improved. It will be easier and less measurement errors will occur. Moreover, the configuration does not become complicated. According to the invention described in claim 11, a graph in which the horizontal axis represents an amount proportional to the sheet transport time and the vertical axis represents the sheet movement amount, in other words, the sheet transport speed diagram can be created only by transporting the sheet,
This makes it possible to evaluate the transport roller design at a glance. According to the invention described in claim 12, it is possible to measure the skew of the sheet, in other words, the degree of skew, and it is possible to evaluate and analyze the characteristics of the transport roller, and improve the accuracy of the sheet transportability of the transport roller. To do. According to the thirteenth aspect of the present invention, maintenance of the inkjet driving device and the inkjet head, for example, ink replacement, cleaning of the inkjet head surface, and wiring inspection are facilitated, and good measurement of the sheet transport speed can always be maintained. According to the fourteenth aspect of the present invention, for example, when the user wants to measure the sheet conveyance speed, the switch is turned on to reduce unnecessary power supply to the ink jet drive device and the ink jet head and maintain the life. Is possible. Claim 1
According to the invention described in 6, the design and development of the image forming apparatus in which the above-described sheet conveying apparatus is mounted can be realized.

[Brief description of drawings]

FIG. 1 includes one inkjet drive device and an inkjet head downstream of a transport roller according to the present invention.
6 is a schematic diagram of a sheet conveying method.

FIG. 2 is a schematic diagram of a print sheet.

FIG. 3 is a schematic diagram of a sheet conveying method including a sheet detection device downstream of an inkjet head.

FIG. 4 is a schematic diagram of a sheet conveying method including a print detection device downstream of an inkjet head.

FIG. 5 is a schematic diagram of a sheet conveying method including a feedback device from a print detection device to a conveying roller.

FIG. 6 is a schematic diagram of a sheet conveying method including a plurality of sheet conveying methods including one inkjet head downstream of a conveying roller.

7A is a schematic view of different print patterns ejected from different inkjet heads, FIG. 7B is a schematic view of different print positions ejected from different inkjet heads, and FIG. 7C is ejected from different inkjet heads. , Schematic diagrams of different print colors.

FIG. 8 is a schematic diagram of a sheet conveying method including an inkjet that moves in a main scanning direction.

9 is a schematic diagram of a print pattern by the sheet conveying method of FIG.

FIG. 10 is a schematic diagram of a sheet conveyance speed diagram.

FIG. 11 is a schematic diagram of a sheet conveying method including two inkjet heads in the sheet width direction.

12 is a schematic diagram of a print pattern according to the sheet conveying method of FIG.

FIG. 13 is a schematic diagram of an image forming apparatus.

FIG. 14 is a schematic diagram of a print pattern for the print detection device.

FIG. 15 is a schematic diagram of a sheet conveying method including one sheet detecting device downstream of a conveying roller.

FIG. 16 is a schematic diagram of a sheet conveying method including two sheet detecting devices downstream of a conveying roller.

FIG. 17 is a schematic diagram of a sheet conveying method including one print detecting unit downstream of the conveying roller.

FIG. 18 is a schematic diagram of a print sheet.

[Explanation of symbols]

1, 1 ': Conveying rollers, 1a, 1'a: Conveying rollers, 1
b, 1'b: transport rollers, 2: sheet, 3, 3 ': sheet transport direction, 3a, 3'a: sheet transport direction, 3b,
3'b: sheet conveyance direction, 4: sheet detection device, 5a:
First sheet detection device, 5b: Second sheet detection device, 6:
Print detector, 7: print sheet, 8: print pattern,
9: sheet conveying direction, 10: inkjet head, 1
0a: inkjet head, 10b: inkjet head, 11: inkjet drive device, 11a: inkjet drive device, 11b: inkjet drive device, 12a: ink ejection start droplet, 12b: ink ejection end droplet, 13: sheet detection device, 14: Print detection means, 1
5: feedback device, 16: movement, 17: sheet conveying speed line, 18a: print pattern, 18b: print pattern, 19a: print pattern, 19b: print pattern, 2
0a: print pattern, 20b: print pattern, 21a:
Print pattern, 21b: Print pattern, L1: Distance, L
2: distance, ΔL: distance, ΔL1: distance, ΔL2: distance,
ΔL3: Distance, ΔLa1: Distance, ΔLa2: Distance, ΔL
b1: distance, ΔLb2: distance, ΔX1: distance, ΔX2:
Distance, ΔX3: distance, r: ink droplet radius 1

Claims (16)

[Claims] 1. A sheet conveying method for feeding a sheet in a sheet conveying direction by rotating one sheet conveying roller which abuts a sheet or a pair of sheet conveying rollers which abut on the front and back sides of a sheet, either a front portion or a rear portion of the sheet conveying roller. When the predetermined time for the ink jet heads arranged on one side to eject ink droplets is ΔT, and the distance from the start droplet to the end droplet in the transport direction of the ink droplets ejected on the sheet is ΔL,
A sheet conveying method, wherein the sheet conveying speed V is derived from an equation of V = ΔL / ΔT. 2. The sheet conveying method according to claim 1, wherein when the conveying roller rotation speed is V0, a relative comparison between the sheet conveying speed V and the conveying roller rotation speed V0 is S = (V
0-V) / V0 × 100 [%] slip ratio S
A method of transporting a sheet, characterized in that: 3. The sheet conveying method according to claim 2, wherein when the slip ratio S exceeds a predetermined threshold value, it is determined that it is time to replace the conveying roller. 4. The sheet conveying method according to claim 1, wherein an ON signal of a sheet detection device downstream of the inkjet head is used as a trigger for starting ejection of ink droplets. Sheet transportation method. 5. The sheet conveying method according to claim 1, wherein a print detection device downstream of the inkjet head calculates a sheet conveying speed V. 6. The sheet conveying method according to claim 1, wherein the ink is a lumilite ink type. 7. A sheet conveying apparatus using the sheet conveying method according to claim 5, wherein for a predetermined sheet conveying speed V1 and a predetermined error E, a sheet conveying speed V from the print detecting device to the conveying roller is E ≧ | V1. -V | / V1 x 100
A sheet conveying device comprising a feedback device for maintaining the expression [%]. 8. A sheet transporting apparatus using the sheet transporting method according to claim 1, comprising a plurality of sets of a transporting roller, an inkjet driving device, and an inkjet head, and each inkjet head. The sheet conveying device is characterized in that the ejection patterns of the sheets are different from each other. 9. A sheet carrying device using the sheet carrying method according to claim 1, wherein a plurality of sets of a carrying roller, an inkjet driving device and an inkjet head are provided, and each inkjet head is provided. Sheet transporting device, characterized in that the main scanning positions for ejecting the ink are different. 10. A sheet carrying device using the sheet carrying method according to claim 1, wherein a plurality of sets of a carrying roller, an inkjet driving device, and an inkjet head are provided, and each inkjet head is provided. A sheet conveying device characterized by different colors. 11. A sheet conveying apparatus using the sheet conveying method according to claim 1, wherein the ink jet head has a driving unit for driving in a main scanning direction, and the ink jet head has a predetermined time ΔT and an ink jet. The sheet conveying apparatus, wherein the driving speed VS has a relationship of VS · ΔT = constant. 12. A sheet transporting apparatus using the sheet transporting method according to claim 1, wherein at least two ink jetting / non-jetting inks are simultaneously ejected in the width direction with respect to the sheet conveying direction. A sheet conveying apparatus comprising the above inkjet head. 13. A sheet conveying device using the sheet conveying method according to claim 1, wherein an inkjet driving device and an inkjet head are detachable. 14. A sheet conveying apparatus using the sheet conveying method according to claim 1, further comprising an on / off control switch. 15. The sheet conveying device according to claim 7, wherein the ink is a lumilite ink type. 16. An image forming apparatus, comprising the sheet conveying device according to claim 7.