JP4039497B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus having a cutter for cutting roll paper.
[0002]
[Prior art]
Conventionally, copying machines, plotters, facsimile machines, and the like are known as image forming apparatuses that use roll paper as a recording medium.
[0003]
Usually, an image forming apparatus having such roll paper is provided with a cutter for cutting the roll paper into a predetermined size.
[0004]
The blade of this cutter deteriorates as the roll paper is repeatedly cut, resulting in poor sharpness. Finally, a cut defect occurs and causes a paper jam. Therefore, it is necessary to replace the cutter (or its blade) at an appropriate time.
[0005]
[Problems to be solved by the invention]
In order to detect the life of the cutter, a method of counting the number of times the cutter has cut the roll paper can be considered. That is, when the number of cuts reaches a predetermined value set in advance, the display unit displays that the cutter needs to be replaced.
[0006]
However, since the life of the cutter also changes depending on the quality of the roll paper, the paper thickness, etc., it may not be said that the life of the cutter is generally reached even if the number of times of cutting reaches a predetermined value. For example, a thick roll paper has a greater degree of deterioration of the cutter per cut than a normal thickness roll paper. Therefore, when such roll paper cutting is repeated, there is a risk that the cutter will reach the end of its life before the number of cuts reaches a predetermined value, resulting in a defective cutting. In addition, when the roll paper that is thinner than usual is cut repeatedly, the cutter is instructed to be replaced even though the life still remains after the number of cuts reaches the planned value, and the cutter cannot be used effectively. There is a problem.
[0007]
In addition, in an image forming apparatus that employs a method of cutting while conveying roll paper in order to shorten the image forming time, there is an upper limit on the time that can be cut, and this upper limit is exceeded. If this happens, the roll paper cannot be transported properly, causing a paper jam. Therefore, in such an image forming apparatus, an increase in the time required for cutting due to deterioration of the cutter becomes a problem even before a cutting defect actually occurs.
[0008]
The present invention has been made in view of such a problem, and provides an image forming apparatus capable of detecting the deterioration of the cutter by detecting the time required for cutting the cutter for cutting the roll paper. is there.
[0009]
[Means for Solving the Problems]
An image forming apparatus according to the present invention is an image forming apparatus provided with a cutter for cutting roll paper, a time measuring means for measuring a time required for cutting to cut the roll paper, and the time measuring means. And determining means for determining whether or not it is necessary to replace the cutter based on the required cutting time, and notifying means for notifying the user when the determination means determines that the cutter needs to be replaced. .
[0010]
The inventor paid attention to the fact that the required time for cutting the roll paper becomes longer according to the deterioration of the cutting condition of the cutter, measured the actual time required for cutting the roll paper, and changed the cutter based on this measured value. I came up with the idea of whether or not it was necessary. According to this configuration, it is possible to determine whether or not the cutter needs to be replaced more accurately than in the prior art that counts the number of cuts.
[0011]
In addition, it is preferable to perform the measurement of the time required for cutting and the necessity determination of the cutter replacement every time the roll paper is cut. However, it can also be performed every predetermined multiple times.
[0012]
Another image forming apparatus according to the present invention is an image forming apparatus including a cutter for cutting roll paper and a cutter motor for driving the cutter, and a current measurement for measuring the magnitude of a current flowing through the cutter motor. A means for judging whether or not the cutter needs to be replaced based on the magnitude of the current measured by the current measuring means, and when the judgment means judges that the cutter needs to be replaced, informs the user of the fact. An informing means is provided.
[0013]
The magnitude of the current flowing through the cutter motor increases in accordance with the load on the cutter, and the load also increases when the cutting condition of the cutter deteriorates. Therefore, by measuring the current of the cutter motor, it is possible to determine whether or not it is necessary to replace the cutter in a more practical manner.
[0014]
More specifically, the determination unit compares the measurement value obtained by the measurement unit with a predetermined threshold value, and determines that the cutter needs to be replaced when the measurement value exceeds the predetermined threshold value.
[0015]
When the paper type of the roll paper to be used is not changed at all or almost, the predetermined threshold value may be a fixed value.
[0016]
Even in this case, it is desirable that the predetermined threshold value can be variably set manually.
[0017]
When changing the paper type of the roll paper, a paper type detection unit that detects the paper type of the roll paper is provided, and a plurality of the predetermined threshold values are provided, and the determination unit detects the paper type detection unit. It is preferable to select and use one of the plurality of threshold values based on the result. This compensates for fluctuations in the required cutting time due to the change of the paper type. That is, even if conditions such as paper quality and paper thickness are changed by changing the paper type of the roll paper, it is possible to automatically set a more appropriate threshold value in accordance with the change.
[0018]
More preferably, it comprises threshold value changing means for dynamically changing the predetermined threshold value based on a measured value at the time of the first cut after the roll paper is replaced, and the determination means is concerned until the roll paper is replaced again. A determination is made as to whether or not cutter replacement is necessary using the changed threshold value. This makes it possible to more appropriately compensate for fluctuations in the required cutting time due to the change in paper type.
[0019]
Specifically, the threshold value changing means is based on an allowable upper limit value of a predetermined required cut time and the first measured value, and the first cutting time is within a range not exceeding the upper limit value. The predetermined threshold value is set so as to change following the measured value.
[0020]
This configuration that prevents the upper limit of the threshold from being exceeded is suitable for use in an image forming apparatus that employs a method of cutting while conveying roll paper.
[0021]
The time measuring means includes, for example, first and second cutter detection sensors respectively disposed at a first position before the cutting start of the cutter and a second position after the cutting is completed, and the cutter includes the first and second cutter detection sensors. And a timer that measures the time from when the first position is left to when the second position is reached.
[0022]
The current measuring means can be constituted by, for example, a resistor connected in series to the cutter motor and a means for detecting a potential difference between both ends of the resistor.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described in detail with reference to the accompanying drawings.
[0024]
FIG. 1 is a schematic configuration diagram of a roll paper cutter unit of an image forming apparatus to which the present invention is applied. Hereinafter, as an image forming apparatus, a copying machine using roll paper will be described as an example. However, the present invention is not limited to the copying machine, and any image forming apparatus having a cutter for cutting roll paper can be used. It can be applied to the device.
[0025]
In the configuration of FIG. 1, a cutter 1 for cutting the roll paper 13 is provided. The cutter 1 is attached to a cutter driving belt 14 that is stretched between a pair of pulleys 15 and 16. When cutting the roll paper 13, the cutter driving belt 14 is driven by the cutter motor 10, and the cutter 1 is scanned in a direction perpendicular to the conveyance direction of the roll paper 13. As means for measuring the time required for cutting the cutter 1, first and second positions respectively arranged at a first position before the cutter 1 starts cutting and a second position after the cutter 1 completes cutting. Cutter detection sensors 2 and 3 are provided.
[0026]
In the present embodiment, photosensors are used for the cutter detection sensors 2 and 3, but any sensor can be used as long as it can detect the presence of the cutter 1. For example, a micro switch can be used instead.
[0027]
Usually, pre-cutting is performed when the roll paper 13 (or the cutter 1) is replaced. Pre-cut refers to cutting the front end of the roll paper after the roll paper is replaced in order to adjust the size and shape of a new cut. As a means for detecting whether or not to perform this pre-cut, the reflective sensor 4 is disposed on the plate 17. This reflection type sensor 4 is a type of sensor that detects the reflected light of the emitted light, and can detect whether or not there is roll paper on the upper part. Specific operations at the time of precut and detection of precut by the precut sensor will be described later.
[0028]
In the present embodiment, it is necessary to cut the roll paper being conveyed in order to improve the speed of continuous copying. Therefore, as shown in FIG. 1, the roll paper is temporarily stopped at a portion where the cutter 1 cuts by adding a slack to the roll paper. However, the present invention is not limited to this, and the present invention can also be applied to those in which the conveyance of the roll paper is stopped and cut.
[0029]
FIG. 2 is a block diagram illustrating a hardware configuration of the image forming apparatus according to the present embodiment. The image forming apparatus includes a CPU 5 that performs overall control, the first and second cutter detection sensors 2 and 3, the precut sensor 4, a control program executed by the CPU 5, and various data in a nonvolatile manner. ROM 6 to be stored in the memory, RAM 7 used as a work area used for processing of the CPU 5 and a temporary storage area for data, and a timer 8 for measuring the time required for each cutting by the cutter 1 (time required for cutting). And a cutter motor driver 9 for driving the cutter motor 10. The precut sensor 4 shown in FIGS. 1 and 2 is used in a second embodiment to be described later, and is not particularly necessary in the present embodiment, but is illustrated for convenience.
[0030]
FIG. 3 shows a flowchart of processing for checking whether or not the cutter needs to be replaced in the first embodiment of the present invention.
[0031]
In this embodiment, every time the roll paper is cut, the time required for the cut is measured, and when the time exceeds a predetermined threshold, the user is notified that the cutter needs to be replaced. This embodiment is suitable when a certain paper type is used as the roll paper, and it is preferable that the threshold value can be variably set at the time of product shipment or manually by the user.
[0032]
In the process of FIG. 3, first, the CPU 5 starts cutting the roll paper by generating a drive instruction to the cutter motor driver 9 (S31). Therefore, it waits for the first cutter detection sensor 2 to be turned off (S32). When this OFF is detected, the timer 8 is started (S33) and waits for the second cutter detection sensor 3 to be turned ON (S34). When this ON is detected, the timer 8 is stopped, and a cut required time T is obtained based on a count value of a clock (not shown) by the timer 8 (S35). That is, by measuring the time from when the cutter 1 leaves the first position to the second position, the required cutting time T is obtained. Therefore, the required cut time T is compared with a predetermined threshold value Tth as shown in FIG. 4 (S36). When the cut required time T exceeds the threshold value Tth, a cutter replacement instruction is output to the display unit 18 (S37). When it is determined that the cutter needs to be replaced, the display unit 18 constitutes a notification unit that notifies the user to that effect. Based on this, the user calls a maintenance person or replaces the cutter 1 by himself.
[0033]
Next, a second embodiment of the present invention will be described. The hardware configuration of this embodiment may be the same as that shown in FIG.
[0034]
In the cutter 1 shown in FIG. 1, it is necessary to complete the cutting before the sag of the roll paper 13 disappears. The time from when the cutter l starts cutting until this slack disappears is set in advance in the ROM 6 as the upper limit time Tl that can be taken for the cutting process. Further, the RAM 7 stores at least a part of the threshold value (boundary time Tx, which will be described later) obtained based on the required cut time measured at the time of pre-cut, which is the first cut after the roll paper replacement, in a nonvolatile manner. The battery backup is performed for the area. Alternatively, a rewritable nonvolatile memory such as a flash memory may be employed for that purpose.
[0035]
The pre-cut sensor 4 detects that the roll paper 13 or the cutter 1 has been replaced. The precut sensor 4 is disposed at the position shown in FIG. After the roll paper 13 (or the cutter 1) is replaced, when the leading end of the roll paper 13 is inserted into the image forming apparatus main body, the leading end of the roll paper 13 is folded back as shown in FIG. In this state, when the first roll paper is cut after the roll paper 13 is replaced, the front end shape of the roll paper 13 is formed, and the normal cut shape and size of the roll paper 13 can be guaranteed. As described above, the CPU 5 can detect that the roll paper 13 has been replaced by using a special roll paper tip mounting state during pre-cutting.
[0036]
When performing this pre-cut, the timer 8 measures the time from when the first cutter detection sensor 2 is turned off to when the second cutter detection sensor 3 is turned on, as described above. This measured time becomes the initial time Ti. Based on the initial time Ti and the upper limit time Tl, the cut required time T is divided into a safe area and a dangerous area as shown in FIG. In the present embodiment, the boundary line between the safe area and the dangerous area is set at a point of 90% of the difference between the upper limit time Tl and the initial time Ti. That is,
Tx = Ti + (Tl−Ti) × 0.9 (1)
It was. The coefficient value 0.9 is merely an example, and may be any other numerical value as long as it is smaller than 1 and close to 1.
[0037]
According to this equation (1), the boundary time Tx changes following the change of the initial time Ti. That is, the boundary time Tx decreases as the initial time Ti decreases, and the boundary time Tx increases as the initial time Ti increases. However, the boundary time Tx does not exceed the upper limit time Tl.
[0038]
When the roll paper is cut for the second and subsequent times after roll paper replacement, the time required for cutting is measured by the same method as that for the pre-cut every time it is cut, and each point in the area shown in FIG. 6 is determined each time. to decide. If the determined point is in the dangerous area, it is determined that the cutter has reached the end of life, and a cutter replacement instruction is output to the display unit 18.
[0039]
Next, the operation in the present embodiment will be described with reference to a flowchart.
[0040]
FIG. 8 is a flowchart of processing executed when the image forming apparatus is powered on. This process is for checking whether or not pre-cutting is necessary. If pre-cutting is necessary, pre-cutting is performed and a new boundary time Tx is obtained.
[0041]
First, it is checked whether or not the precut sensor 4 is ON (S81). If it is not ON, this process is unnecessary, and the process ends.
[0042]
If the precut sensor 4 is ON, an instruction is issued to the cutter motor driver 9 to start precut (S82). Therefore, it waits for the first cutter detection sensor 2 to be turned off (S83). When this OFF is detected, the timer 8 is started (S84) and waits for the second cutter detection sensor 3 to be turned ON (S85). When this ON is detected, the timer 8 is stopped and the initial time Ti is obtained based on the count value of the timer 8 (S86). Further, based on the initial time Ti and the upper limit time Tl, the boundary time Tx is obtained based on the above equation (1) (S87). This boundary time Tx is stored in the nonvolatile area of the RAM 7.
[0043]
Next, FIG. 9 shows a flowchart of a normal roll paper cutting process for inspecting whether or not the cutter needs to be replaced.
[0044]
In the process of FIG. 9, first, the CPU 5 starts cutting the roll paper by issuing an instruction to the cutter motor driver 9 (S91). Therefore, it waits for the first cutter detection sensor 2 to be turned off (S92). When this OFF is detected, the timer 8 is started (S93) and waits until the second cutter detection sensor 3 is turned ON (S94). When this ON is detected, the timer 8 is stopped, and the required cut time T is obtained based on the count value of the timer 8 (S95). Therefore, the required cut time T is compared with the boundary time Tx (S96). When the cut required time T exceeds the boundary time Tx, a cutter replacement instruction is output to the display unit 18 (S97).
[0045]
Referring to FIG. 5 again, according to the present embodiment, each time the roll paper 13 is replaced, the initial time Ti required for cutting the new roll paper 13 is measured to obtain a new boundary time Tx. . Therefore, the boundary time Tx can be variably set according to the paper type and paper thickness. For example, when a roll of film paper (usually made of a semi-transparent, relatively hard material) is loaded, the required time for cutting becomes longer than usual due to its rigidity. However, since the boundary time Tx is set to be larger than usual, it can be prevented that the increase in the required time due to the paper type is mistaken as an increase in the required time due to the deterioration of the cutter. On the other hand, in the case of roll paper having a thinner paper thickness than usual, the time required for cutting is shorter than usual, so the boundary time Tx is also set shorter accordingly. As a result, it is possible to avoid problems such as a cut defect and a paper jam occurring in a visible manner because the cutter replacement time is delayed after continuing use beyond the service life.
[0046]
Next, a third embodiment of the present invention will be described.
[0047]
FIG. 10 shows the hardware configuration of the third embodiment. In this configuration, a paper type detection unit 19 is added to the configuration of FIG.
[0048]
In the present embodiment, by detecting the paper type of the roll paper 13 by the paper type detection unit 19, a plurality of threshold values Tth1 and Tth2 corresponding to the paper type with respect to the required cutting time T are set as shown in FIG. Set. For example, assuming that, for example, plain paper and film paper are selectively used as roll paper, a larger threshold Tth1 is applied to film paper, and a smaller threshold Tth2 is applied to plain paper. . Thereby, the life of the cutter 1 appropriate for the paper type can be determined.
[0049]
As the configuration of the paper type detection unit 19, a known technique as disclosed in, for example, Japanese Patent Laid-Open No. 4-250086 can be used. This is to determine the paper type of the recording medium by detecting the reflected light of the light irradiated to the recording medium on two regions having different reflectivities. In the example of FIG. 11, the threshold value is set to two levels. However, a multi-level threshold value can be adopted as long as the paper type can be determined at multiple levels.
[0050]
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
[0051]
In any of the first to third embodiments, the life of the cutter 1 is detected based on the time required for cutting when the roll paper is actually cut. The life of the cutter 1 is to be detected based on the magnitude of the current of the cutter motor 10. When the cutting condition of the cutter deteriorates, the load on the cutter motor increases, and the current flowing through the motor increases. Therefore, it is possible to determine the degree of cutting of the cutter by detecting the change in current.
[0052]
FIG. 13 shows a hardware configuration of the fourth embodiment. The same components as those shown in FIG. 2 are given the same reference numerals. A difference from the configuration of FIG. 2 is that a current measuring circuit 11 is added instead of the first and second cutter detection sensors 2 and 3 and the timer 8 being deleted.
[0053]
As shown in FIG. 14, the current measurement circuit 11 includes a resistor 21 inserted in series with the cutter motor 10 (a DC motor in the present embodiment), a subtraction circuit 22 that detects a potential difference between both ends of the resistor 21, An A / D converter 23 is provided for converting the analog output of the subtracting circuit 22 into a digital signal. The digital output of the A / D converter 23 is read by the CPU 5.
[0054]
FIG. 12 shows a graph similar to FIG. The vertical axis of this graph is not the required cutting time T but the current amount I of the cutter motor 10. Similarly to the upper limit time Tl, initial time Ti, and boundary time Tx in FIG. 5, an upper limit current Il, initial current Ii, and boundary current Ix are defined.
[0055]
FIG. 15 shows a flowchart of processing executed when the image forming apparatus is turned on in the fourth embodiment. This process is for checking whether or not pre-cutting is necessary. If pre-cutting is required, pre-cutting is performed and a new boundary current Ix is obtained.
[0056]
First, it is checked whether or not the precut sensor 4 is ON (S151). If it is not ON, this process is unnecessary, and the process ends.
[0057]
If the precut sensor 4 is ON, an instruction is issued to the cutter motor driver 9 to start precut (S152). Therefore, the initial current Ii of the cutter motor 10 is measured (S153). Based on the initial current Ii and the upper limit current Il previously stored in the ROM 6, the boundary current Ix is expressed by the following equation (2) similar to the above equation (1).
Ix = Ii + (Il-Ii) × 0.9 (2)
(S154). This boundary current Ix is stored in the nonvolatile area of the RAM 7.
[0058]
Next, FIG. 16 shows a flowchart of a normal roll paper cutting process for inspecting the necessity of cutter replacement in the fourth embodiment.
[0059]
In the process of FIG. 16, first, the CPU 5 starts cutting the roll paper by generating an instruction to the cutter motor driver 9 (S161). Therefore, the current I of the cutter motor 10 is measured (S162). The measured current I is compared with the boundary current Ix (S163). If the measured current I exceeds the boundary current Ix, a cutter replacement instruction is output to the display unit 18 (S164).
[0060]
Although the preferred embodiments of the present invention have been described above, various modifications can be made without departing from the spirit of the present invention. For example, in the fourth embodiment, the cut time measurement of the second embodiment is replaced with the motor current measurement, but the cut time measurement of the first and third embodiments is replaced with the motor current. Another embodiment in which measurement is replaced is also conceivable.
[0061]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, by measuring the time required to cut the roll paper, the life of the cutter is detected, and the time for replacing the cutter is known before the paper jam occurs. be able to. Further, it is possible to prevent the adverse effect of replacing the cutter earlier than necessary.
[0062]
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a schematic configuration of a roll paper cutter unit of an image forming apparatus to which the present invention is applied.
FIG. 2 is a block diagram illustrating a hardware configuration of the image forming apparatus according to the embodiment of the present invention.
FIG. 3 is a flowchart of processing for checking whether or not cutter replacement is necessary in the first embodiment of the present invention.
FIG. 4 is an explanatory diagram for explaining a threshold Tth for a required cut time according to the first embodiment of the present invention.
FIG. 5 is an explanatory diagram for explaining a danger area and a safety area of a required cut time according to the second embodiment of the present invention.
FIG. 6 is an explanatory diagram illustrating a state of a normal precut sensor and roll paper in the second embodiment.
FIG. 7 is an explanatory diagram showing a state of a precut sensor and roll paper at the time of precut according to the second embodiment of the present invention.
FIG. 8 is a flowchart of processing executed when the image forming apparatus is powered on in the second embodiment of the present invention.
FIG. 9 is a flowchart of a normal roll paper cutting process for inspecting the necessity of cutter replacement in the second embodiment of the present invention.
FIG. 10 is a block diagram illustrating a hardware configuration according to a third embodiment of this invention.
FIG. 11 is an explanatory diagram for explaining a risk area and a safety area of a required cut time according to the third embodiment of the present invention.
FIG. 12 is an explanatory diagram for explaining a danger area and a safety area of a required cut time according to the fourth embodiment of the present invention.
FIG. 13 is a block diagram illustrating a hardware configuration according to a fourth embodiment of this invention.
14 is a circuit block diagram illustrating a configuration example of the current measurement circuit illustrated in FIG. 13;
FIG. 15 is a flowchart of processing executed when the image forming apparatus is powered on in the fourth embodiment of the present invention.
FIG. 16 is a flowchart of a normal roll paper cutting process for inspecting whether or not a cutter needs to be replaced in the fourth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Roll paper cutter, 2 ... 1st cutter detection sensor, 3 ... 2nd cutter detection sensor, 4 ... Precut sensor, 5 ... CPU, 6 ... ROM, 7 ... RAM, 8 ... Timer, 9 ... Cutter motor driver DESCRIPTION OF SYMBOLS 10 ... Cutter motor, 11 ... Current measurement circuit, 13 ... Roll paper, 14 ... Cutter drive belt, 15, 16 ... Pulley, 17 ... Plate, 18 ... Display part, 19 ... Paper type detection part.

Claims (7)

In an image forming apparatus provided with a cutter for cutting roll paper,
Means for conveying the roll in the conveying direction;
Means for scanning the cutter in a direction perpendicular to the roll paper transport direction;
Time measuring means for measuring the time required for cutting the roll paper by the scanning ;
A judging means for judging whether or not it is necessary to replace the cutter based on the required cutting time measured by the time measuring means;
When the determination means determines that the cutter needs to be replaced, notification means for notifying the user to that effect;
An image forming apparatus comprising: The determining means, the comparing the measured values by the measuring means with a predetermined threshold value, the image forming apparatus according to claim 1, wherein it is determined that the cutter replacement necessity when the measured value exceeds the predetermined threshold. 3. The image forming apparatus according to claim 2, wherein the predetermined threshold value can be variably set manually. A paper type detecting means for detecting the paper type of the roll paper is provided, and a plurality of the predetermined threshold values are provided, and the judging means is one of the plurality of threshold values based on a detection result of the paper type detecting means. The image forming apparatus according to claim 2 , wherein the image forming apparatus is selected and used. Threshold change means for dynamically changing the predetermined threshold value based on a measured value at the time of the first cut after replacement of roll paper is provided, and the determination means is configured to change the threshold value until roll paper is changed again. The image forming apparatus according to claim 2, wherein a determination is made as to whether or not cutter replacement is necessary. The threshold value changing means follows the measurement value at the time of the first cut within a range not exceeding the upper limit value based on the upper limit value of the predetermined required cut time and the first measurement value. 6. The image forming apparatus according to claim 5, wherein the predetermined threshold value is set so as to change.   The time measuring means includes first and second cutter detection sensors respectively disposed at a first position before the cutting start of the cutter and a second position after the cutting is completed, and the cutter has the first position The image forming apparatus according to claim 1, further comprising: a timer that measures a time until the second position is reached after leaving the position.

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