JPH0450831A - Image forming device - Google Patents

Abstract

PURPOSE:To individually set an optimum output torque limiting value corresponding to a load by providing a means detecting the load torque of a driving means and a means variably setting the torque limiting value of the driving means corresponding to the detected load torque. CONSTITUTION:When the load torque of the driving means (DC motor 20) corresponding to the load is detected by load torque detecting means (current detecting circuit 24, comparator 25, etc.), a varying means (CPU 31) variably sets the output torque limiting value set to the driving means (DC motor 20) corresponding to the detected load torque, by an output port, etc. Thus, the output torque limiting value corresponding to the load can be individually set.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to an image forming apparatus equipped with a driving means for scanning a document table, and particularly to an image forming apparatus that is equipped with a driving means for scanning an original platen, and in particular, an image forming apparatus that is capable of adjusting the generated torque by following fluctuations in the load driven by the driving means. The present invention relates to an image forming apparatus to be adjusted.

[Background Art] With recent advances in electronic technology, image forming apparatuses are also becoming smaller and cheaper.

In order to reduce the size of this type of image forming apparatus, the image forming apparatus is usually configured as an original platen scanning type that scans an original platen, and is often configured to form an image on a photoreceptor through a fiber lens, for example.

By the way, the driving means for scanning and moving the document table is D.
It is composed of a single drive source composed of a C motor and the like.

In the image forming apparatus configured in this manner, the document scanning table reciprocates on a flat surface to a position where it leaves the end of the main body, so if a situation such as contacting an obstacle occurs during image formation, In order to prevent sudden torque from being applied to the drive means due to load fluctuations on the drive means, a torque transmitter or the like is provided to limit and control the current applied to the DC motor, for example, to prevent damage to the image forming apparatus and safety of the operator. are doing.

In addition, some motors use a mechanical mechanism to achieve a torque limit in response to the above-mentioned load fluctuations.

[Problems to be Solved by the Invention] However, in the conventional example using current limiting described above, the current limiting value is fixed, so it is necessary to take into account, for example, variations in load and motor characteristics, and load increases due to changes over time. , it was necessary to set the current limit value higher than necessary, that is, to increase the torque limiter value. For this reason, the strength of the mechanical mechanism must also be increased, which is a factor in increasing costs.

Further, even when the document table comes into contact with an obstacle or a user, the torque required until the document table stops is large and varies, which is disadvantageous in terms of safety.

Furthermore, when a torque limiter is provided using a mechanical mechanism, the mechanism becomes complicated, resulting in problems such as an increase in cost and a decrease in reliability.

The present invention has been made to solve the above problems, and by variably setting the output torque limit value set to the drive means for driving the load according to the detected load torque, the mechanical mechanism can be improved. The purpose is to reduce the strength burden and obtain a safe and highly reliable image forming apparatus.

[Means for Solving the Problems] An image forming apparatus according to the present invention includes a load torque detection means for detecting the load torque of the drive means with respect to the load, and a drive means that detects the load torque of the drive means in response to the load torque detected by the load torque detection means. and variable means for variably setting the output torque limit value set to .

Further, a switching means is provided for switching on/off the drive of at least one load, and while the arbitrary load switched by the switching means is being driven, the variable means changes the load torque detected by the load torque detection means. The output torque limit value set in the drive means is configured to be variably set.

Further, the load is configured to include a document mounting table driven by the driving means.

[Operation] In this invention, when the load torque detection means detects the load torque of the drive means with respect to the load, the variable means variably sets the output torque limit value to be set on the drive means according to the detected load torque. , it is possible to individually set the output torque limit value corresponding to the load.

Further, when the driving of at least one load is switched on/off by the switching means, while driving any switched load, the variable means changes the driving means according to the load torque detected by the load torque detecting means. The output torque limit value to be set is variably set, and it is possible to individually set the optimum output torque limit value for each negative drive accompanying execution of the image forming sequence.

Further, the load includes an original table that is driven by the driving means, and it is possible to individually set an optimum eight torque limit value for driving the original table when the image forming sequence is executed.

[Embodiment] FIG. 1 is a cross-sectional configuration diagram illustrating the configuration of an image forming apparatus showing an embodiment of the present invention. Reference numeral 1 denotes a document mounting table made of a transparent member such as glass, ) as a driving source and drives a solenoid 21 (described later) to scan the document by reciprocating in the direction of arrow a.

A short-focus imaging element array (array) 2 is arranged directly below the document platform 1, and the document image placed on the document platform 1 is illuminated by an illumination lamp 13, and the reflected light image is reflected from the array. 2, slit exposure is performed on the photosensitive drum 4. Note that the photosensitive drum 4 is driven by a DC motor 20 and rotates in the direction of the arrow. A charger 3 uniformly charges the photosensitive drum 4 coated with, for example, a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer.

The photosensitive drum 4 uniformly charged by the charger 3 is
Image exposure is performed by array 2 to form an electrostatic image. This electrostatic image is visualized by a developing device 5 using toner made of a resin or the like that softens and melts when heated. On the other hand, the recording paper P stored in the cassette S is
By means of a feeding roller 6 driven by a C motor 20 and a pair of conveying rollers 7 which are rotated in pressure contact with each other in the vertical direction at a timing synchronized with the image on the photosensitive drum 4,
It is fed onto the photosensitive drum 4. Then, the transfer discharger 8
As a result, the toner image formed on the photosensitive drum 4 is transferred onto the recording paper P.

Thereafter, the recording paper P separated from the photosensitive drum 4 by a known separation means is guided to the fixing device 10 by the conveyance guide 9, which is also driven by the DC motor 20, where it is heated and fixed, and then discharged onto the tray 11. Ru. Note that after the toner image is transferred, residual toner on the photosensitive drum 4 is removed by a cleaner 12.

C0NT is a controller section, which is composed of a CPU and its peripheral circuits.

In the image forming apparatus configured as described above, when the load torque of the drive means relative to the load is detected by the load torque detection means (in this embodiment, it is composed of the current detection circuit 24, comparator 25, etc.), the variable means (in this embodiment, the CPU 31 also serves as the driver) variably sets the output torque limit value set in the drive means (in this embodiment, the DC motor 20) according to the detected load torque by, for example, the output boat P7, and It is possible to individually set the output torque limit value corresponding to the

Further, when the driving of at least one load is switched on/off by the switching means (in this embodiment, the CPU 31 also serves), the load torque detection means (in this embodiment According to the output of the current detection circuit 24), the driving means (in this embodiment, the DC motor 2
By variably setting the output torque limit value set to 0), it is possible to individually set the optimal output torque limit value for each negative drive accompanying execution of the image forming sequence.

Further, as a load, an original table 1 . It includes the feeding roller 6 and the like, and makes it possible to individually set an optimal output torque limit value for driving the document mounting table 1 during execution of, for example, an image forming sequence.

FIG. 2 is a block diagram illustrating the configuration of the controller unit C0NT shown in FIG.
U has output ports P1 to P4. The output port P1 is connected to the driver 22, and the driver 22
The output is output to the solenoid 21. Solenoid 21
is connected to the power supply (VCC) 33, and the output port P
1 becomes active, the solenoid 21 is energized,
The configuration is such that the rotation of the DC motor 2o causes the aforementioned original scanning table 1 to reciprocate.

When the output board P2 is turned on, the constant speed control circuit 29 detects the rotational speed of the DC motor 20 and performs constant speed splitting. That is, when output port P2 is turned on, PWM
A waveform is output, and the output is output to the AND circuit 30. The output of the AND circuit 30 is output to the switching circuit 23, and when the output of the AND circuit 30 becomes ○N, the switching circuit 23 becomes conductive and the DC motor 20 is connected from the power supply 33.
, a current flows to the ground 34 via the current detection circuit 24. The current flowing through the DC motor 20 is detected by the current detection circuit 2.
4, and the voltage value is taken out as a voltage at comparator 25.
It is connected to a sample and hold circuit 26.

When the boat output P4 of the CPU 31 is on, sampling is performed when the sample and hold circuit 26 becomes active, and the output value is added by a predetermined voltage value in the adder 27 and output to the switch circuit 28. switch circuit 2
8 is applied with a reference voltage (VA) 32 when the output port P3 of the CPU 31 is off, and supplies a reference potential to the comparator 25.

On the other hand, the switch circuit 28 applies the output of the adder 27 to the comparator 25 when the output port P3 of the CPtJ31 is on. The comparator 25 compares the two voltage values and calculates D
When the value obtained by converting the current of the C motor 20 into voltage becomes high (for example, due to load fluctuations (for example, when the original table 1 comes into contact with an obstacle)), an off (0) signal is output to the AND circuit 30.

At this time, the output of the AND circuit 3o is turned off, and the comparator 2
When the 8 parts of 5 are on, the output of the constant speed control circuit 29 is AN.
This becomes the output of the D circuit 30. Therefore, under the control of the CPU 31, a current value that is sampled and held and to which a predetermined value is added or a current value corresponding to the reference voltage 32 becomes the limiter value of the current flowing through the DC motor 2o.

Hereinafter, the torque limiter limit value setting processing operation in the image forming apparatus according to the present invention will be explained with reference to the flowchart shown in FIG.

FIG. 3 is a flowchart illustrating an example of a torque limiter limit value setting process procedure in the image forming apparatus according to the present invention. Note that (1) to (7) indicate each step.

First, the output port P3 is turned off (1), and the current limiter limit value is set to a value corresponding to the reference voltage 32. This value should be sufficient to start the device.

Then, output port P2 is turned on (f2), and DC motor 2
Start rotation of 0. Next, wait for example for 02 seconds until the rotation of the DC motor 20 stabilizes.

Next, turn on and off the output port P4 4) (5)
The current value flowing through the DC motor 20 at that time is sampled and held. Next, turn on the output port P3 6),
A value obtained by adding a predetermined value to the held value becomes the current limiter limit value. Here, the predetermined value is the load that has not yet been activated, that is, the load corresponding to the document placement table 1 and paper feeding, plus a margin.

Next, turn on the output port P1 (7), and turn on the document placing table 1.
Start up and start exposing the original. After that, a predetermined sequence is executed and the process ends.

In the above embodiment, a case will be described in which the current applied to the DC motor 2o is limited by comparing the value of the reference voltage 32 output from the output port P3 of the CPtJ31 and the voltage value determined from the detected load current. However, CPtJ
The current limiter limit value may be set by the digital value output from 31.

FIG. 4 is a block diagram illustrating another configuration of the controller unit C0NT shown in FIG. 2, and the same components as in FIG. 1 are given the same reference numerals.

In the figure, P5. P7 is the output port;
5 sets the driver 63 to active and output port P
7 outputs digital current limiter limit value data output from the CPU 31 to the D/A converter 66. P6 is an input port, into which data output from the A/D converter 65, that is, a digital signal obtained by converting the voltage value detected by the current detection circuit 24 into a digital signal is input.

Note that 64 is a solenoid that drives the above-mentioned feeding roller 6.

The operation will be explained below.

When the CPU 31 turns on the output port P1, the solenoid 21 in the latter stage is energized, and the document table 1 reciprocates. Further, when the CPtJ31 turns on the output port P5, the solenoid 64 at the subsequent stage is energized, the above-mentioned feeding roller 6 is driven, and the recording paper P is conveyed.

Next, when the CPU 31 turns on the output port P2, the constant speed control circuit 29 operates, generates a PWM waveform, and inputs it to the AND circuit 30. At this time, if the output of the comparator 25, which is the other input, is in the ON state, the generated PWM waveform becomes the input to the switching circuit 23 as it is, and the energization to the DC motor 2o is controlled on/off.
Controlled at constant speed.

On the other hand, the current flowing through the DC motor 20 is
The output is converted into a voltage by the comparator 25 and the A/
It is output to the D converter 65. The data converted into digital data by the A/D converter 65 is input to the input port P6 of the CPtJ31.

Further, the output of the output port P7 of the CPU 31 is outputted to the D/A converter 66, converted into an analog signal, and sent to the comparator 25.
becomes the other input. At this time, the comparator 25 inputs the output value (Dl) of the D/A converter 66 and the input value (Dl) to the A/D converter 65.
D2), and when the input value D2 from the current detection circuit 24 to the A/D converter 65 is larger than the output value D1 of the D/A converter 66 (for example, if the original platen 1 is damaged). When the load increases due to contact with an object, etc.), the output of the comparator 25 is turned off, and as a result, the output of the AND circuit 30 is turned off, the switching circuit 23 is also turned off, and the DC motor 20
The power supply to is stopped. In this way, the CPU 31
Read the current value flowing through the motor 2o and determine the current limiter limit value (in this embodiment, the value output to the D/A converter 66)
FIG. 5 is a flowchart illustrating an example of another torque limiter limit value setting process procedure in the image forming apparatus according to the present invention. Note that fl) to (12) indicate each step.

First, the CPU 31 sets a predetermined value in the output port P7 (1) and sets it as the first current limiter limit value. This first
The current limiter limit value of
Set this value to as large a value as the capacity allows.

Next, turn on the output boat P2 and rotate the DC motor 20 (2). Next, wait for 0.2 seconds. 3) Wait for the rotation of the DC motor 20 to become stable.

Next, the output data DATA1 (this value corresponds to the current value when neither the recording paper P nor the original platen 1 is driven) of the A/D converter 65 is taken from the input port P6 (
4) Determine whether the output data DATA1 is larger than a predetermined value (51) If YES, it is determined that the load is abnormally high, and the process proceeds to step (6), where the output boat P2 is turned off and the DC motor 20 is stopped. After that, error processing such as error display is executed.

On the other hand, if the determination in step (5) is No, the initial load is determined to be normal, and a value obtained by adding a predetermined value α1 to the output data DATAI is set in the output port P7. Set as limiter limit value. In addition, the value α1
corresponds to a value obtained by adding a margin to the torque required to convey the recording paper P.

Next, the output boat P5 is turned on, the solenoid 64 is energized (8), and conveyance of the recording paper P is started.

Next, wait for 0.2 seconds until the rotation of the DC motor 20 stabilizes (9), and then connect the A/D converter 65 from the input boat P6.
The output data DATA2 is fetched (10), and a value obtained by adding a predetermined value α2 to the output data DATA2 is set in the output port P7 (11), and the current limiter limit value is updated. Note that the value α2 is the torque required to move the document mounting table 1 plus a margin. Next, the output boat P1 is turned on (12), and the reciprocating movement of the original table 1 is started. Thereafter, a predetermined sequence is performed and the copy operation is completed. In this way, by controlling all inputs and outputs from the CPU 31, it is possible to set the current limiter limit value, and the appropriate limiter value corresponding to the driving state of each load can be controlled in multiple stages. 1
The limiter limit value for the load itself can also be controlled individually.

In the above embodiment, an image forming apparatus that executes a copying process has been described as an example, but an image forming apparatus in which the driving means drives a plurality of loads in conjunction with each other, such as a facsimile machine 9
The present invention can also be applied to image reading devices, handy printers, and the like.

[Advantageous Effects of the Invention 1] As explained above, the present invention includes a load torque detection means for detecting the load torque of the drive means with respect to the load, and a load torque detection means for detecting the load torque of the drive means with respect to the load. A variable means for variably setting the output torque limit value is provided, and the output torque limit value for the drive means, which was conventionally set to a constant value, can be individually set in accordance with the load.

Further, a switching means for switching on/off the driving of at least one load is provided, and while driving any load switched by the switching means, the variable means changes the load torque detected by the load torque detecting means. Since the output torque limit value set to the drive means is configured to be variably set, the output torque limit value for the drive means, which was conventionally set to a constant value, can be adjusted to correspond to each arbitrary load during the execution of an image forming sequence. Can be set individually.

Further, since the load is configured to include the document placing table driven by the driving means, an optimum output torque limit value can be set when the driving means drives the document placing table.

Therefore, the optimum output torque limit value can be individually set corresponding to at least one or more loads driven by the drive means, so that the output torque limit value set when the power is turned on can be exceeded while the image forming sequence is being executed. From an abnormal situation,
Energization to the drive means can be controlled over a wide range up to abnormal situations when the output torque limit value is set at maximum load.

Moreover, even if the load and the driving means change in condition due to changes over time, etc., it is possible to always set the optimum output torque limit value for the load and the driving means.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram illustrating the configuration of an image forming apparatus showing an embodiment of the present invention, FIG. 2 is a block diagram illustrating the configuration of the controller section shown in FIG. 1, and FIG. A flowchart illustrating an example of the torque limiter limit value setting process procedure in the image forming apparatus according to the invention, FIG. 4 is a block diagram illustrating another configuration of the controller section shown in FIG. 2, and FIG. 3 is a flowchart illustrating an example of another torque limiter limit value setting process procedure in the image forming apparatus according to the present invention. In the figure, 1 is a document placement table, 20 is a DC motor, 24 is a current detection circuit, 31 is a CPTJ, and C0NT is a controller section. Figure 2 20: DC motor diagram

Claims (3)

[Claims] (1) In an image forming apparatus that forms an image by driving a plurality of loads with a single drive means, a load torque detection means that detects the load torque of the drive means with respect to the load;
An image forming apparatus comprising: variable means for variably setting an output torque limit value set to the drive means in accordance with the load torque detected by the load torque detection means. (2) A switching means is provided for switching on/off the drive of at least one load, and while driving any load switched by the switching means, the variable means responds to the load torque detected by the load torque detection means. 2. The image forming apparatus according to claim 1, wherein the output torque limit value set to the drive means is variably set. (3) The image forming apparatus according to claim 1 or 2, wherein the load includes a document mounting table driven by a driving means.