JPH02118220A - Device for controlling drive of image forming device and the like - Google Patents

Abstract

PURPOSE:To prevent the shifting of an image caused by the dispersion of an electromagnetic clutch by counting the time up to the changing point of the exciting current of the electromagnetic clutch, comparing the time with a previously stored constant armature attracting time, and controlling the exciting voltage and exciting timing of the electromagnetic clutch. CONSTITUTION:When the armature attracting time of the electromagnetic clutch 28 of a conveying roller gets out of a previously set allowable range, this is automatically detected by a comparing/judging means 23, changing the exciting voltage of the exciting coil of the electromagnetic clutch by an exciting voltage control means 25 to keep the armature attracting time constant. Also, the exciting timing of the electromagnetic clutch is shifted by the amount of difference from the set value by an exciting timing control means 26 to stabilize the rotating speed of a rotor shaft. Thereby, a uniform attracting time can be obtained, coping with the dispersion of product of the electromagnetic clutch or the change in the armature attracting time in the case of a long-time use, stabilizing the engaging time of the electromagnetic clutch, a paper conveying quantity, the end margin of an image, etc.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a drive control device for a paper feeding or conveying device in an image forming apparatus such as a printer/copying machine or a facsimile machine using an electromagnetic clutch, and machine,
It relates to drive control devices for transportation machines, printing/marking machines, and other precision machines.

(Prior Art) In the various conventional machines described above, an electromagnetic clutch is used between the drive side and the conventional side as a drive transmission means for transporting, moving articles, etc., and drive control is performed according to the work.

FIG. 14 shows a schematic configuration diagram of a laser printer as an example.

Briefly explaining the operation of this laser printer, recording paper 2 is fed by a paper feed roller 17 in the direction of the arrow from the paper feed device 1, and is timed by a pair of registration rollers 3 to form a drum-shaped photoreceptor. The latent image carrier is conveyed to the latent image carrier consisting of 4.

The photoreceptor 4 is driven to rotate one clockwise direction, and at this time its surface is charged by a charging charger 5, and is irradiated with laser light from a laser optical system 6 to form an electrostatic latent image on the photoreceptor.

This latent image is made visible by toner when passing through the developing device 7, and this visible image is transferred to the recording paper 2 conveyed to the photoreceptor 4.
The transferred visible image on the recording paper is fixed by a fixing device 10 having a fixing roller 9 .

Then, the recording paper that has left the fixing device 10 is discharged by a paper discharge roller 18 to a paper discharge section 11 in the direction of arrow B.

On the other hand, residual toner is removed from the photoreceptor 4 after the visible image has been transferred by a cleaning device 13 having a cleaning blade 12 , and the charge is removed by a charge removal brush 14 . The toner removed from the photoreceptor is collected by a collection roller 16 into a toner collection chamber 15, where it is collected.

The path for conveying the recording paper 2 to the photoreceptor 4 of this laser printer is as shown in FIG. The skew of the paper is corrected at , and the paper is fed to the transfer section (transfer charger) 8 at a predetermined timing.

FIG. 16 shows a transmission configuration diagram with the electromagnetic clutch shown in FIG. 15, and its operation will be described based on the operation timing shown in FIG. 17.

Now, when there is a print start request PRINT, the PFMC signal of the paper feed electromagnetic clutch 17C becomes Low, the paper feed electromagnetic clutch 17C engages with the paper feed roller drive gear 17G, and the driving force of the main motor (circuit) is used to feed the paper. roller 17
The paper will be fed.

When the recording paper passes the registration sensor 19 (FIG. 15) and reaches the conveyance roller 3, the paper feed roller 17 temporarily stops rotating. (The signal RGST from the registration sensor 19 is O
0.5 seconds after turning to N "Low") At this time, the recording paper 2 is pressed against the conveyance roller 3, and the skew of the recording paper is corrected.

At this time, when the paper feed roller 17 starts rotating again, the transport electromagnetic clutch 3C is also turned ON (the TPMC signal is L).
OW), meshes with conveyance roller drive gear 3G,
The recording paper is sent to the transfer section 8 by the conveyance roller 3 (the upper part rotates and the lower part follows).

Then, the paper feed roller stops after 0.8 seconds of rotation (OF
F...High), that is, the conveyance roller 3 is set to 0N10 of the conveyance electromagnetic clutch 3C, similar to the paper feed roller 17.
Rotation is controlled by FF.

(Problems to be Solved by the Invention) The start timing of the conveyance roller 3 mentioned above is greatly influenced by the armature suction time of the conveyance electromagnetic clutch 3C.

FIG. 18 shows the excitation (applied) voltage waveform (a) of the conveyance electromagnetic clutch 3C, the excitation current waveform (a), and the rotation waveform (d) of the rotor shaft (driven side) as shown in Figure 0.
Applied) Voltage waveform (A) point a is applied (ON), point b is open (OFF), armature attraction is from point a of (A) for t8 hours as shown in exciting current waveform (A). At the time point a1 when the attraction current reaches a delay, attraction is started, and after a delay of t2 from point b in (A), the attraction current becomes zero and attraction is released. In addition, the rotor shaft of the transport electromagnetic clutch (
As can be seen from the rotation waveform (one) on the driven side, there is a delay of t3 time from the above t1 time.

That is, 11+1. The time becomes the time Tc required to connect the driving side and the driven side, and after that time the conveyance roller 3 reaches a steady rotation speed N. Note that in order for the steady rotational speed N to become zero, a stop time T that is delayed from the above point is required.

Since the above-mentioned armature suction time t1 of the conveyance electromagnetic clutch 3C greatly influences the start timing of the conveyance roller 3, especially when the linear velocity of conveyance is high, the transfer portion I! (the leading edge margin of the image) and causes so-called image position shift.

Furthermore, if the armature suction time changes due to variations in the transport electromagnetic clutch between products, the tip margin will change accordingly, so it is necessary to adjust the tip margin for each machine by adjusting the excitation timing, which is troublesome. Ta. On the other hand, changes in the armature suction time that occur over time are caused by friction between the armature surface (drive side) and rotor surface (driven side) of the conveyor electromagnetic clutch, and a decrease in the spring coefficient due to deterioration of the armature leaf spring. , there is a problem in that it causes a change in the leading edge margin of the image, as described above.

Conventionally, if the start timing of the transfer electromagnetic clutch deviates from the standard due to variations in the engagement time Tc between the driving side and the driven side due to variations in the armature time of the transfer electromagnetic clutch, there is no way to detect this, and as a result, Judgment was made from the positional shift (change in the leading edge margin) of the image that appears.

The present invention solves the above-mentioned conventional problems, monitors the armature suction time of the conveyance electromagnetic clutch, displays a warning, and automatically controls the armature suction time to be constant at all times. The purpose is to measure the drive control device that provides a margin.

(Structure and operation) In order to achieve the above object, the present invention provides an image forming apparatus using an electromagnetic clutch, a means for detecting a change point of an excitation current of the electromagnetic clutch, and a power side and a driven side of the electromagnetic clutch that come into contact with each other. or means for counting the time up to a change point of the excitation current during non-contact, means for storing steady values of standard and abnormal attraction times of the electromagnetic clutch, the storage means and the change point count means. a control means for changing the excitation voltage of the electromagnetic clutch and a control means for changing the excitation timing of the electromagnetic clutch in accordance with the comparison and judgment means; and a control means for changing the excitation timing of the electromagnetic clutch; The present invention is characterized by comprising a driving means for displaying an abnormality in the operation of the electromagnetic clutch, and a means for displaying an abnormality in the operation of the electromagnetic clutch.

The present invention detects the excitation current change point of the electromagnetic clutch, counts the time up to the change point, and compares it with a pre-stored steady armature suction time (count value),
If there is an abnormality, it is displayed, and the excitation voltage and excitation timing of the electromagnetic clutch are controlled to adjust the leading edge margin of the image. As a result, the armature suction time is constantly monitored and automatically adjusted to be constant, which has the effect of preventing image shift due to variations in the electromagnetic clutch and saving time and effort for adjustment.

(Embodiment) FIG. 1 shows a block diagram of an embodiment of the present invention, in which 20 is an excitation current change point detection means, and 21 is a change point count means for counting the output of the excitation current change point detection means. , 22 is a steady value storage means for storing the steady armature suction time of the electromagnetic clutch 28, 23 is a means for comparing and determining the steady value storing means 22 and the change point counting means 21, and 24 is a comparison and determining means. Display means when an abnormality is detected.

25 is a means for controlling the excitation voltage of the electromagnetic clutch 28 based on the abnormality detection output of the comparison and determination means 23; 26 is a means for controlling the excitation timing of the electromagnetic clutch 28 based on the abnormality detection output of the comparison and determination means 23; 27;
The electromagnetic clutch 28 is controlled by the control output of the excitation voltage control means 25 or the excitation timing means 26.
It is a means of driving.

Next, specific examples of each of the above means are shown in FIGS. 2 to 8.
Figure 2 is a block diagram of the control system in Figure 1.

30 is a microprocessor, and this processor has a ROM 31 having preset areas X, .

The reference value of the standard armature suction time of the electromagnetic clutch 28 is stored in xl, and the reference value of the abnormal suction time for determining that the armature is not suctioned is stored in x. This constitutes the steady-state value storage means 22 in FIG.

Further, it has a RAM 32 having work areas Y1 to Y, and from the excitation current i and excitation voltage v2 characteristics shown in FIG. 3 when the electromagnetic clutch is excited ON, Yl is the A/D of v2.
The current value for comparing the size of the converted value, Y, is the previous value A.
/D conversion value and Y3 store the actually counted armature suction time, respectively.

The input port A of the microprocessor 30 receives, via the A/D converter 20A, the excitation current i at section b (Fig. 3) when the armature of the electromagnetic clutch 28 contacts the rotor, that is, the change in voltage v2 of the detection resistor R2. , for example, as an 8-bit digital value. This part is indicated by diagonal lines.
(This circuit constitutes the excitation current change point detection means 20 of i!!l.

Further, an abnormality display is output from the output port B of the microprocessor 30 to the display means 24 (device), and the display panel 24P is shown in FIG.
S lights up.

Further, from the output port A, for example, an 8-bit digital value is converted into an analog value by a D/^ converter 25A, and a non-inverting amplification circuit consisting of a resistor R1, a variable resistor VR, a transistor Q1, and an amplifier 25B converts the digital value to an electromagnetic clutch 28.
The excitation voltage control means 25 (circuit) is constructed, and its software processing is shown in FIG.

Also, a means 27 (electromagnetic clutch drive circuit) for driving the electromagnetic clutch 28 by a driver 27A driven by a TPMC signal from the output port C of the microprocessor.
Configure.

Further, the change point counting means 21 in FIG. 1 is controlled by the microprocessor 3 by software processing shown in FIG.
Preset area X1 of ROM31 in 0. X, and RA
Perform with M32ノ'7-Kuniri7Y, ~Y.

Further, the comparison and determination means 23 shown in FIG. 1 determines whether the armature suction time of the electromagnetic clutch is normal or abnormal by software processing shown in FIG.

Further, the excitation timing control means 26 shown in FIG. 1 controls the excitation timing by the comparison of x1°Y3 by software processing shown in FIG.

Next, each operation of this embodiment will be explained using the above-mentioned FIGS. 2 through 8 and FIGS. 9 through 13.

When the excitation signal T P MC (the excitation voltage of TPMC in FIG. 13) of the electromagnetic clutch 28 (corresponding to 30 in FIG. 16) of the conveyance roller 3 is low from the output port C of the microprocessor 30, the driver 27A output is OV
(Low), the exciting current i flows through the electromagnetic coil 28I of the electromagnetic clutch 28, and the armature of the electromagnetic clutch is attracted to the rotor.

As shown in FIG. 3, the drive current i at this time has a waveform with a temporary change point (constriction) as shown in section b when the armature comes into contact with the rotor. This constriction is caused by the magnetic circuit (change in inductor L) caused by the armature coming into contact with the rotor.

The point of change of this excitation current i coincides with the point of change of the voltage v3 of the detection resistor R2 in terms of timing. Therefore, during the armature attraction time (Y3), the electromagnetic clutch 28 is excited and the voltage v2 of the detection resistor R2 is at the change point a.
It can be detected by counting the time until it reaches a peak like this. Therefore, in this embodiment, the voltage v2 is converted into a digital quantity (8 bits in rotation) using the A/D converter 20A.
and microprocessor 3 through input port A.
It is input to 0. These operations correspond to the excitation current change point detection means 20 in FIG.

A of the voltage v2 input to this microprocessor 30
The /D conversion value is processed by software by the control unit CPU as shown in Fig. 6, and as a result, the armature suction time Y,
is found.

That is, in FIG. 6, the RA of the microprocessor 30
Zero clear with Y3 of M32 (1) → Excite the electromagnetic clutch ON (TPMC HIGH → LOW) (2) → V
, (7) Store the previous (IA/D converted value in RAM32c7) Y, D (3) → V, store the current A/D converted value in RAM32 Y
, the voltage VO shown in FIG. 3 is determined.

That is, (a) Judgment D1 (5) (71 YES means voltage v, if it is in the falling state of ■... (current value Y□ is the same previous value Y2) (b) No in judgment D1 (5) means voltage v2 If is in the rising state of ■...(Current value Y is not the same previous value Y2) (T)
The judgment (6) is YES when the voltage v2 is in the falling state of (2). In addition, the process s * (7) counts the time until the change point is reached in order to obtain the armature suction time Y, and the process S3 (8) makes the time contributing to the path of the count loop α constant. Adjusting the timing.

Judgment D3 (9) and Judgment D4 (10) are armature suction time check routines, and Judgment DJ (9) is
Compare the standard suction time reference value XX (tolerance ±α...see Figure 3) of the armature suction time set in advance in the ROM 31 with the actually counted armature suction time Y3, and find that Y is within the above tolerance. If it is not within the range, it is determined to be abnormal (No), and the flag F2 is turned on (processing s, (ti
)). Also, if Y is abnormally large for some reason and the armature suction time is too long, judgment D4 (1o) will also be made if the reference value X2 of the abnormal suction time is reached.
Do the same as NO in (9).

FIG. 7 shows that as a result of the armature suction time check routine in FIG. 6, flag F2 is ON (process 54 (11) in FIG.
)), a warning display is output to the display means (device) 24. That is, the flag F2 is determined, and if YES, the display process is executed, and if NO, the main process is executed.

Processing judgment D3 in FIG. 6 mentioned above. D and the processing judgment shown in FIG. 7 correspond to the comparison judgment means 23 shown in FIG.

Next, the 8-bit digital value output from the output port A of the microprocessor 3o in FIG. 2 corresponds to the voltage v2 of the excitation current change point detection means (circuit) 20. This is converted into an analog quantity (voltage) by the D/A converter 25A and guided to the non-inverting input of the amplifier 25B (voltage = VIN) - Here, the digital quantity output from the output port A (horizontal axis), D/A converter 25A
The output V+N (vertical axis) of is in a proportional relationship as shown in FIG. On the other hand, the amplifier 25B constitutes a non-inverting amplifier circuit with a resistor R□, a variable resistor VR for adjusting the amplification gain, and a transistor Q1, and its output V. . , is shown by the following equation.

Excitation type R pressure V applied to the coil 28I of the electromagnetic clutch 28. As shown in FIG. 10, 09 has an amplification gain of (1+, ) and is variable depending on VIN (horizontal axis). That is, the excitation voltage Voov (vertical axis) can be controlled by digital output to the output port A of the microprocessor 30.

Further, the armature attraction time (vertical axis) of the electromagnetic clutch is the excitation voltage V. ,,? (horizontal axis) shows the characteristics as shown in FIG. 11, and the curves a, b, and c in the figure are determined by the amount of air gap between the armature and rotor of the electromagnetic clutch, the leaf spring coefficient of the armature, etc.

This shows that even if the excitation voltage is the same, variations occur in the characteristics.

The operation of the excitation voltage control means (circuit) 25 in FIGS. 9, 10, and 11 described above is performed by the microprocessor 30.
When the output voltage VIN of the D/A converter 25A increases at the output of the output port A of (FIG. 9), when VIN of is input, the output voltage V of the non-inverting amplifier circuit (amplifier 25B, etc.) increases.
. 0. also increases proportionally (Figure 10), and as the output at output port A decreases and VIN decreases, V. , also descends (Figures 9 and 10).

In this way, the excitation voltage of the electromagnetic clutch 28 can be controlled, and the armature attraction time can also be controlled.

FIG. 5 is a flowchart when the armature suction time is monitored by software processing of the microprocessor 30, the output of the output port A is controlled, and the armature suction time is corrected.

For example, if the characteristics of the armature suction time of the electromagnetic clutch 28 are as shown in FIG. 11, the armature suction time (vertical axis) is the standard suction time (
xl) and +α (see Figure 3). In this case, in order to increase the excitation voltage voov and reduce the armature suction time, the process S S (Fig. 5) of increasing the output of the output port A (horizontal axis) is repeated several times, and the output of the output port A is ", and the armature suction time is decreased from point b' to x1+α.

In addition, in the case of characteristic C, the armature suction time is below the lower limit of the allowable range of the standard suction time (Xl) and -α, so in this case, the excitation voltage vaov is lowered and the armature suction time is increased. Therefore, output port A
Repeat the process SS (Fig. 5) several times to reduce the output of
The output of output port A is decreased to point c'', and the armature suction time is increased from point C' to xl-α.

In this way, the armature suction time of the electromagnetic clutch is kept within the allowable range of x1±α. The excitation voltage control circuit shown in FIG. 2 and the excitation voltage control routine shown in FIG. 5 that have been described above constitute the excitation voltage control means 25 shown in FIG.

FIG. 13 shows the excitation voltage (T M P
In relation to the excitation current when C signal (1)) is applied, the standard armature suction time (A), the long armature suction time (B), and the case after correction (
C).

In the case of FIG. 13(B), the start timing of the conveyance roller 3 is delayed by the difference in armature suction time (CX-C or y3-xl). However, it is assumed that the time A from when the armature is attracted and joined to the rotor until the rotor shaft reaches stable rotation is constant. This is processed by the software processing of the microprocessor 30 (Fig. 8).
), the timings of the excitation voltage (6), excitation current (7), and rotor shaft rotation speed (8) are corrected as shown in (C), and the rotor shaft rotation speed (5) in (B) becomes ( 8), the standard start timing of (A) (3)
matches.

In addition, if the armature suction time is shorter than the standard time, contrary to case (B), the excitation timing is delayed by the difference in suction time (X□-y a ) using process S in FIG. The start timing of the transport roller 3 is corrected to the standard one.

The software processing shown in FIG. 8 corresponds to the excitation timing control means 26 in FIG.

(Effects of the Invention) As explained above, the present invention automatically detects when the armature attraction time of the electromagnetic clutch of the conveyance roller deviates from a preset tolerance range, and adjusts the excitation voltage to the excitation coil of the electromagnetic clutch. The armature suction time can be kept constant. Further, when the above automatic detection is performed, the excitation timing of the electromagnetic clutch is shifted by the difference from the set value so that the start timing of the electromagnetic clutch is constant, thereby stabilizing the rotor shaft rotation speed.

By automatically adjusting the excitation voltage and excitation timing, it becomes possible to obtain various armature suction times in response to product variations in electromagnetic clutches and changes in armature suction time during long-term use. . Further, there is an effect that the engagement time of the electromagnetic clutch, the paper conveyance amount, the leading edge margin of the image, etc. are stabilized.

Furthermore, when the armature suction time exceeds the allowable range, a warning is displayed accordingly, informing the operator of an abnormality in the electromagnetic clutch and allowing the operator to take prompt action.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of the control system shown in FIG. 1, and FIG. FIG. 4 is a front view of the operation panel showing an example of the display means 24 in FIG. 1, and FIG. 5 shows the excitation voltage by software processing of the excitation voltage control means 25 in FIG. 1. Control routine, FIG. 6 shows an armature suction time check routine performed by software processing of the change point counting means 21 shown in FIG. 1, FIG. 7 shows a display routine performed by software processing of the display means 24 shown in FIG. 1, and FIG. 9 is a characteristic diagram of the output VIN of the D/A converter 25A of FIG. 2 and the digital quantity, and FIG.
Fig. 0 is a characteristic diagram of the output v o o v of the non-inverting width circuit composed of the amplifier 25B etc. in Fig. 2 and the output v1 of the D/A converter 25A, and Fig. 11 is a characteristic diagram of the excitation voltage vf of the electromagnetic clutch, □ FIG. 12 is an explanatory diagram for controlling the variation in armature suction time to a permissible range using the output of the output port A of the microprocessor 30 in FIG. 2, and FIGS. An explanatory diagram for adjusting the armature suction time controlled in FIG. 12,
14 is a schematic configuration diagram of a laser printer in which the present invention is implemented, FIG. 15 is a diagram of the relationship between the registration roller pair 3 (conveyance roller) and paper feed roller 17 in FIG. 14, and FIG. 16 is a diagram in FIG. 15. FIG. 17 is a diagram showing the operation timing of FIG. 16, and FIG. 18 is a waveform diagram showing each operation timing of the excitation voltage, current, and rotor shaft rotation of the electromagnetic clutch. 3... Registration roller pair (conveyance roller). 17... Paper feed roller, 19... Registration sensor,
20... Excitation current change point detection means. 21... Change point counting means, 22... Steady value setting means, 23... Comparison/judgment means, 24... Display means,
25... Excitation voltage control means, 26... Excitation timing control means, 27... Drive means, 27A... Driver 28... Electromagnetic clutch, 28I...
Electromagnetic clutch coil, 30...Microprocessor, 31...ROM, 32...RAM, 20A...
・A/D converter, 25A...D/A converter, 25B...amplifier, R2...detection resistor. Patent Applicant Ricoh Co., Ltd. - Jj/liON (TPMC=H+gh-Low) Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 1 (00000000) b (00001111) b (11111111) Figure Figure (0000111+)b Fig. 8, Transfer element
- The killer! +1-0. Paper ejection section 12, -cree 2°7
Tsubushido 13.
-Removed T file L-, Repu L Fig. Fig. 2 Recording paper Fig.

Claims (1)

[Claims] In an image forming apparatus or the like using an electromagnetic clutch, there is provided a means for detecting a change point of the excitation current of the electromagnetic clutch, and a time taken to the change point of the excitation current when the power side and the driven side of the electromagnetic clutch are in contact or non-contact. means for counting, means for storing steady values of standard and abnormal attraction times of the electromagnetic clutch, means for comparing and determining the magnitude relationship between the values obtained from the storing means and the changing point counting means; A control means for changing the excitation voltage of the electromagnetic clutch according to the output of the comparison determination means, a control means for changing the excitation timing of the electromagnetic clutch, a drive means operated by both the control means, and an abnormal operation of the electromagnetic clutch is displayed. 1. A drive control device for an image forming apparatus, etc., comprising: means.