JPH09171337A - Speed fluctuation detecting device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rotation fluctuation detecting device preventing high frequency noise from being included in data in accordance with the position or the speed of a rotating member and detecting fluctuation in rotation with high accuracy by providing a means outputting a counted value in accordance with the speed of a moving member and calculating the speed fluctuation. SOLUTION: A 1st signal generation circuit 37 outputs an inputted encoder pulse to a frequency divider circuit 33 through a D-F/F32, and the circuit 33 frequency demultiplexes the encoder pulse at specified frequency division ratio (1:n'). By detecting the leading edge of the frequency division pulse and outputting a clear signal through the D-F/Fs 34 and 35 and a NAND circuit 36, a counter 38 is cleared. A 2nd signal generation circuit 41 detects the leading edge of the sample pulse and outputs an interruption requiring signal to the CPU 42, and a counted value output signal is given to the D-F/F 39 so that the stored counted value may be outputted to the CPU 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a velocity fluctuation detecting device for a moving member such as an image carrier and a transfer material conveying body of an image forming apparatus, and more particularly, it is superimposed on data according to the position or speed of the moving member. The present invention relates to a speed fluctuation detecting device for an image forming apparatus that eliminates high frequency noise and detects speed fluctuations of a moving member with high accuracy.

[0002]

2. Description of the Related Art Conventionally, as a speed fluctuation detecting device for detecting the position or speed of a rotary member such as an image carrier or a transfer material conveyer installed in an image forming apparatus while performing data sampling at a constant cycle, for example, JP-A-4-255
Some are disclosed in Japanese Patent No. 867. This speed fluctuation detecting device is provided with a rotary encoder on a rotary member, counts encoder pulse periods between sampling periods with clock pulses, and calculates a moving distance of the rotary member between sampling periods and an average velocity based on the counted value. Has a configuration.

In Japanese Laid-Open Patent Publication No. 4-255867, FIG.
As shown in FIG. 8, the encoder pulse ENCODER in the sampling cycle is counted based on the clock pulse CLK, and the moving distance and the average speed of the rotating member during the sampling cycle are calculated by the following (1) to
This is performed by the step (5). (1) From the start of the sampling period Sn, the engoder pulse period from the rising edge of the encoder pulse to the next rising edge is counted by the clock pulse CLK, and the latest count value Tn is stored. (2) The end of the sampling cycle Sn is detected, and the count value Δtn obtained by counting the clock pulse from the end time of the encoder pulse that completed one cycle to the end time of the sampling cycle Sn is stored.
(3) Fractional part α of encoder pulse that is less than one cycle
(0 <α <1) is calculated from Δtn / Tn. (4) The sampling period Sn is calculated by adding the fractional part α to the number N of encoder pulses completed during the sampling period Sn to calculate the total sum (N + α) of the encoder pulses and multiplying the moving distance per encoder pulse. The moving distance of the rotating member in the interval is calculated. (5) The sum of encoder pulses (N + α) is divided by the sampling period Sn to calculate the average frequency of the encoder pulses, and the average frequency is multiplied by the conversion coefficient to obtain the sampling period Sn.
The average speed of the rotating member during the period is calculated.

[0004]

However, according to the conventional speed fluctuation detecting device, the rotating member is actually rotating with speed fluctuation, and the fractional part of the encoder pulse which is less than one period is immediately before. Calculation is performed based on the cycle of the encoder pulse that is stored after completing one cycle, and the sum of the encoder pulses is calculated by adding it to the number of encoder pulses that have completed the cycle during the sampling cycle. The error (estimation error) according to is mixed.

In order to avoid the inclusion of this estimation error, if the rotation fluctuation of the rotary member is sequentially output based on the count value obtained by counting the encoder pulses completed during the sampling cycle with the clock pulse, for example, FIG. As shown in FIG. 6, when the period (A, B, and C) of the encoder pulse is 0.7 to 0.8 times the sampling period, the averaging effect of the clock pulse can be obtained based on the count value. However, as shown in FIG. 20, the cycle of the encoder pulse is 0.
When it is shortened to about 1 to 0.4 times, the count value decreases and the averaging effect of the clock pulse decreases, so the position or speed data (A ', B', and C ') is used. There is a problem that the high-frequency noise is superimposed and the S / N ratio is lowered, and as a result, the accuracy of detecting the rotation fluctuation is lowered. Therefore, an object of the present invention is to include high-frequency noise in the data according to the position or speed of the rotating member even when the period of the encoder pulse is as short as about 0.1 to 0.4 times the sampling period. It is an object of the present invention to provide a rotation fluctuation detecting device for an image forming apparatus, which is capable of suppressing this and detecting rotation fluctuation with high accuracy.

[0006]

In order to achieve the above object, the present invention provides a pulse generating means for generating a pulse having a cycle corresponding to the speed of a moving member, and a predetermined sampling by expanding the cycle of the pulse. A measured pulse generating means for generating a measured pulse having a period shorter than the period and longer than a predetermined ratio of the predetermined sampling period, and a clock pulse over the period of the measured pulse in the predetermined sampling period Provided is a speed fluctuation detecting device for an image forming apparatus, which has a counting unit that counts the number of times and outputs a count value according to the speed of the moving member, and a calculating unit that calculates the speed fluctuation of the moving member based on the count value. To do.

In the speed fluctuation detecting device of the image forming apparatus described above, the measured pulse generating means has an average value of the pulse having a permissible value of speed fluctuation of the moving member, a predetermined sampling period, and a period corresponding to the speed of the moving member. The frequency dividing means may divide a pulse having a cycle corresponding to the speed of the moving member by a frequency dividing ratio determined based on the frequency dividing ratio. ], The frequency division ratio may be set to a maximum natural number n satisfying Teo × (1 + 0.01 × Vlim) × n ≦ Ts, where Ts is a predetermined sampling period and Teo is an average period of pulses. preferable. The pulse generating means may be at least one of a rotary encoder, a hall sensor, and mark detecting means for detecting marks formed at equal intervals on the moving member. It is preferable that the measured pulse generating means is configured to generate a measured pulse having a period of 70 to 80% of a predetermined sampling period. The mark detection means may be configured to have a light emitting element that irradiates the mark with light and a light receiving element that receives the reflected light from the mark, and
It may be an image sensor. The moving member may be at least one of an intermediate transfer member, a polygon mirror, a document scanner driving roll, a fixing roll, and a fixing belt.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A speed fluctuation detecting apparatus for an image forming apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an image forming apparatus according to the first embodiment of the present invention. This image forming apparatus includes an image input section 1 for scanning a document and an image output section 8 for recording an image on a recording sheet based on an image signal scanned by the image input section 1 and processed by an image processing section (not shown). It is configured.

The image input section 1 includes a lamp 3 for irradiating a document (not shown) placed on a transparent document table 2 with light.
Reflecting mirrors 4 and 5 that reflect the reflected light from the document, a lens 6 that focuses the light incident from the reflecting mirror 5, and the light that is focused by the lens 6 is received and separated into R, G, and B signals. It has a charge imaging device (CCD) 7 for reading by reading.

The image output unit 8 converts the R, G and B signals obtained by the image input unit 1 into Y (yellow), M (magenta) and C signals.
An IPS (Image Processing) (not shown) that complements and retains complementary colors of (cyan) and BK (black)
Polygon mirror 9A and polygon mirror 9A having a System) and deflecting laser light modulated based on image data obtained by performing image processing by IPS
An image writing unit 9 having a polygon mirror drive motor 9B for rotationally driving and an SOS sensor 9C for outputting a scanning start signal (SOS signal) of an exposure beam based on transmission of laser light deflected by the polygon mirror 9A, A reflection mirror 10 that reflects the laser light emitted from the image writing unit 9 in the scanning direction, a photosensitive drum 11 that forms an electrostatic latent image based on the scanning of the laser light, and toners of Y, M, C, and BK. The units are arranged at intervals of 90 degrees in the circumferential direction, and the rotary type developing unit 12 that rotates at the time of development to supply toner corresponding to each color to the surface of the photoconductor drum 11 and the photoconductor drum 11 before exposure. A charger 13 for giving a predetermined charge, and a cleaner 1 for removing the toner remaining on the photosensitive drum 11.
4, an intermediate transfer belt 15 that receives a toner image transferred from the photosensitive drum 11, a drive roll 17 that drives the intermediate transfer belt 15, support rolls 18 and 19 that rotatably support the intermediate transfer belt 15, A primary transfer corotron 20 that applies a predetermined charge to a primary transfer point where a toner image is transferred from the body drum 11 to the intermediate transfer belt 15, and a cleaner 2 that removes toner remaining on the intermediate transfer belt 15.
1, a rotary encoder 22 that generates a pulse having a cycle corresponding to the rotation speed of the support roll 18, a paper tray 23 that stores recording paper, a paper feed roll 24 that sends recording paper from the paper tray 23, and an intermediate transfer. Transfer the toner image on the belt 15 to the recording paper at the secondary transfer point 2
It has a next transfer roll 25 and a fixing unit 26 for fixing the toner image transferred onto the recording paper.

FIG. 2 shows a speed fluctuation detecting device in the first embodiment of the image forming apparatus, which is a driving roll 17
And the intermediate transfer belt 15 stretched by the support rolls 18 and 19, a motor 28 that generates a rotation torque based on a drive voltage supplied from a motor drive circuit 27, and a rotation torque generated by the motor 28 is decelerated by a predetermined speed. Reduction gears 29A and 29B that reduce the speed to a certain ratio and transmit to the drive roll 17
A rotary encoder 22 that generates a pulse having a cycle corresponding to the rotation speed of the support roll 18, a position / speed calculation unit 30 that calculates the rotation speed of the intermediate transfer belt 15 based on the pulse input from the rotary encoder 22,
The control unit 31 outputs a drive control signal to the motor drive circuit 27 based on the output signal of the position / speed calculation unit 30.

At least one of the support rolls 18 and 19
One has a tension adjusting mechanism for adjusting the tension of the intermediate transfer belt 15. This tension adjusting mechanism uses a spring member to support the intermediate transfer belt 15 with the supporting roll 1.
A predetermined tension is applied by elastically contacting 8 or 19. Drive roll 17 and support roll 18,
The frame 19 is supported by frames (not shown) provided on both sides of the intermediate transfer belt 15.

The control unit 31 compares the output signal based on the position or rotation speed calculated by the position / speed calculation unit 30 with a reference signal to extract a rotation fluctuation signal, and generates a drive control signal from the rotation fluctuation signal. To do.

FIG. 3 shows the position / velocity calculation unit 30,
-Flip-flop (hereinafter referred to as DF / F) 32,
34 and 35, a first signal generating circuit 37 including a frequency dividing circuit 33 and a NAND circuit 36 for frequency-dividing the encoder pulse at a predetermined frequency dividing ratio, and a counter 38 for counting clock pulses. , D-F / F 39 and 40, a second signal generating circuit 41 for generating an interrupt request signal and a count value output signal, and a D-F / F 4
When an interrupt request signal is input from 0, the CPU 42 has a CPU 42 that inputs a count value obtained by counting divided pulses with a clock pulse from the D-F / F 39.
The count value of the clock pulse immediately before the clear signal is input to the counter 38 is read and stored.

The first signal generating circuit 37 outputs the input encoder pulse to the frequency dividing circuit 33 via the DF / F 32, and the frequency dividing circuit 33 outputs the encoder pulse to a predetermined frequency dividing ratio (1: n '). The counter 38 is configured to be cleared by detecting the rising edge of the divided pulse and outputting a clear signal via the DF / Fs 34, 35 and the NAND circuit 36.

When the second signal generating circuit 41 detects the rising edge of the sample pulse, it outputs an interrupt request signal to the CPU 42 and also supplies a count value output signal to the DF / F 39 to store the stored count value. CPU 42
Is configured to be output to.

The CPU 42 inputs the count value Nn of clock pulses from the DF / F 39 and multiplies the moving distance per encoder pulse by the frequency division number n ', thereby moving the moving distance Xn between sampling periods. To calculate. Further, the moving speed Xn between the sampling periods is divided by the product of the period of the clock pulse and the count value Nn of the clock pulse to calculate the average speed Vn between the sampling periods.

FIG. 4 shows a clock pulse CLK and an encoder pulse E output from the rotary encoder 22.
NCODER and the divided pulse DIVIDER output from the frequency dividing circuit 33 OUT and divided pulse DIVIDE
R The data DATA of the speed obtained based on the count value Nn of the clock pulse of OUT is shown.

The speed fluctuation detecting operation of the intermediate transfer belt 15 in the first embodiment will be described below with reference to the flow charts shown in FIGS.

When the image input section 1 reads a document placed on the document table 2, the image writing section 9 emits laser light modulated according to image information, and the reflecting mirror 1
The photosensitive drum 11 is scanned via 0. An electrostatic latent image is formed on the photosensitive drum 11 based on the scanning of the laser light, and the developing unit 12 develops the electrostatic latent image with toner. At the same time, a predetermined control signal is output from the control unit 31, and the motor drive circuit 27 generates a drive signal according to the control signal to drive the motor 28. When the motor 28 is driven, its rotation torque is transmitted to the drive roll 17 via the reduction gears 29A and 29B, and the intermediate transfer belt 15 is rotated at a predetermined speed.

When the support roll 18 rotates in response to the rotation of the intermediate transfer belt 15, the rotary encoder 22 outputs a pulse having a cycle corresponding to the position or the rotation speed to the position / speed calculator 30.

The position / velocity calculating section 30 operates on the basis of the data obtained by driving the intermediate transfer belt 15 separately from the velocity fluctuation detecting operation, based on the allowable value Vlim of the velocity fluctuation of the intermediate transfer belt 15 and the sampling period Ts. Is set (S ₁ ), and the average period Teo of the encoder pulse output from the rotary encoder 22 is calculated based on the rotation of the intermediate transfer belt 15 (S ₂ ).

When the allowable value Vlim [%] of the speed fluctuation, the sampling cycle Ts and the average cycle Teo of the encoder pulse are set, it is confirmed that the cycle of the encoder pulse accompanied by the speed fluctuation is shorter than the sampling cycle Ts (S ₃ ),
The maximum natural number n that satisfies Teo × (1 + 0.01 × Vlim) × n ≦ Ts is calculated. (S ₄ ).

[0025] natural number n is calculated, as the division ratio of the encoder pulses in the frequency dividing circuit 33 n '(n' ← n ), the number of bits of the counter 38 checks whether sufficient (S ₅₎ . If sufficient number of bits, the division ratio of the encoder pulses in the frequency divider 33 1: set to n 'Reset (S ₆₎ counter 38 (S _7).

After that, the speed of the intermediate transfer belt 15 is detected, and the encoder pulse input from the rotary encoder 22 to the signal generating circuit 37 is output to the frequency dividing circuit 33 via the D-F / F 32 and n '. Divided, DF
It is input to the counter 38 as a clear signal via the / F 34, 35 and the NAND circuit 36 (S ₈ ). The counter 38 has been counting clock pulses since the rising edge of the previous divided pulse was detected (S ₉ ), and when the next rising edge is detected (S ₁₀ ), the D-F / F 39 receives the clock pulse. stores the count value (S _11), the count value of the clock pulse is cleared immediately thereafter (S _13).

For example, as shown in FIG. 4, when the frequency division ratio of the encoder pulse ENCODER is set to 1: 2 (n '= 2), the counter 38 is equivalent to two periods of the encoder pulse ENCODER in the sampling cycle S ₁ . Divided pulse DIVIDER equivalent to The period A from the rising edge of OUT to the next rising edge is counted by the clock pulse CLK.

On the other hand, the signal generation circuit 41 is connected to the control unit 31.
Input a sample pulse from D-F / F40 to C
Output an interrupt request signal to the PU 42 (S₁₆), DF
The count value of the clock pulse stored in / F39 to C
Read to PU42 (S ₁₇).

The CPU 42 receives the input clock pulse
Movement per encoder pulse based on the count value of
By multiplying the distance by the dividing number n ', the sampling
The moving distance Xn of the intermediate transfer belt 15 during the cycle
Calculate and move distance Xn of intermediate transfer belt 15 as a clock
By dividing by the product of the pulse period and the count value,
Average speed of the intermediate transfer belt 15 during the sampling cycle
The degree Vn is calculated (S ₁₈).

For example, in the case of the sampling period S ₁ in FIG. 4, the calculation result based on the count value of the clock pulse in the above-mentioned period A is obtained as the position / speed data A'shown as DATA, and CP
Interrupt processing of U42 is finished (S _19).

In this way, the sampling periods S ₁ , S
_{2. When} the position / speed data is output from the position / speed calculator 30 to the controller 31 for each ...
The calculation result of the speed calculation unit 30 is compared with the reference value to generate an error signal, and a control signal based on this error signal is output to the motor drive circuit 27. The motor drive circuit 27 is the control unit 3.
The position or the speed of the intermediate transfer belt 15 is controlled by driving the motor 28 based on the control signal input from 1.

In the present embodiment, the division ratio n'of the encoder pulse is set based on the average period of the encoder pulse, the allowable value of the speed fluctuation, and the sampling period, and the rising edge interval of the divided pulse is clocked. Since the moving distance and the average speed of the intermediate transfer belt 15 in each sampling cycle are calculated from the count value counted by the pulse, the averaging effect of the count value of the clock pulse counted in each sampling cycle is enhanced and the detection resolution of the speed fluctuation is improved. Can be improved.

Therefore, even if the period of the encoder pulse is shortened to 0.1 to 0.4 times the sampling period depending on the measurement conditions, the position of the intermediate transfer belt 15
Alternatively, since the frequency of the pulse output according to the speed can be set to 0.7 to 0.8 times the sampling cycle by the frequency dividing circuit 33, S due to superposition of high frequency noise on the count value of the clock pulse. It is possible to prevent a decrease in / N ratio and a decrease in detection resolution.

In the above embodiment, the pulse generating means for generating the pulse having the cycle corresponding to the moving speed of the intermediate transfer belt 15 is constituted by the rotary encoder. For example, as shown in FIG. The mark detector 46 may be provided with the marks 45 formed at the ends at equal intervals, the light emitting element and the light receiving element, and the mark detector 46 for detecting the mark 45. According to this configuration, by directly detecting the mark formed on the intermediate transfer belt 15,
More accurate drive control can be realized. Also,
The mark detector 46 may be composed of a line image sensor.

FIG. 8 shows an electrophotographic image forming apparatus according to a second embodiment of the present invention, in which a main frame 48 provided inside a main body case 47, a charger 49, a developing unit 50, and a photosensitive drum 51. , And transfer roll 58
And a rotary encoder 52 for detecting speed fluctuations of the photoconductor drum 51.
And the guide member 5 that supports the process cartridge 53.
4, an exposure unit 55 that exposes the photoconductor drum 51 based on an image signal, a drive motor 56 that generates a rotation torque according to a drive voltage, and a rotation torque of the drive motor 56 at a predetermined reduction ratio. 51, a reduction gear 57 that transmits the recording paper 59 to the process cartridge 53, a fixing roll 61 that fixes the toner image transferred onto the recording paper 59, and a recording paper on which the toner image is fixed. And a discharge tray 62 from which 59 is discharged.

The drive motor 56 is positioned on the main frame 48, transmits the rotational torque through the reduction gear 57 to drive the photoconductor drum 51, and the charger 49, the developing unit 50, the transfer roll 58, The paper feed roll 60 and the fixing roll 61 are driven. As the drive motor 56, a DC brushless motor whose shaft is subjected to gear cutting or a stepping motor is used.
When using a stepping motor, in order to reduce rotation fluctuation and power consumption, constant current driving is performed with a current value that is as small as possible while considering load torque.

The reduction gear 57 is made of polyacetal (POM) in order to suppress rotational fluctuations caused by tooth contact.
Use the helical gear of molding material.

FIG. 9 shows a second example of the electrophotographic image forming apparatus.
The speed variation detecting device in the embodiment of the present invention is shown, in which the drive motor 56 that generates the rotation torque according to the drive voltage output from the motor drive circuit 27, and the reduction gears 57A and 58.
A reduction gear 57 for transmitting the rotational torque of the drive motor 56 to the photosensitive drum drive gear 51A via B and 58C;
A rotary encoder 52 that generates a pulse having a cycle corresponding to the rotation speed of the photosensitive drum 51, and the photosensitive drum 5 based on the pulse input from the rotary encoder 52.
It has a position / speed calculation unit 30 for calculating the rotational speed of 1 and a control unit 31 for outputting a drive control signal to the motor drive circuit 27 based on the output signal of the position / speed calculation unit 30.
Since the operation of calculating the rotation fluctuation and the drive control of the photosensitive drum 51 are the same as those in the first embodiment, duplicated description will be omitted.

Also in the configuration of the second embodiment, as in the first embodiment, the drive control is performed on the basis of the data of the rotational fluctuation detected by the actual measurement, so that the photosensitive drum 51 can be driven with high accuracy. It can be driven, and it is possible to prevent uneven density of an output image and occurrence of misregistration.

FIG. 10 shows another color image forming apparatus according to the second embodiment. This color image forming apparatus scans an original (not shown) placed on the platen 64, an image sensor 65, and an image. An image input unit 66 having a motor 63 that drives a sensor 65, and an image input unit 6
An image output unit 6 for performing image recording on a recording sheet based on an image signal scanned by the image processing unit 6 and processed by an image processing unit (not shown).
It is composed of 7.

The image output section 67 emits a laser beam corresponding to image information and scans the photosensitive drum 70 via the reflection mirror 69, and an exposure unit 68, Y, M, C and B.
A developing unit 7 that includes a K color toner unit and supplies toner of a predetermined color to the surface of the photosensitive drum 70.
1, a paper feed roll 73 for feeding the recording paper 72, a paper feed path 74 for feeding the recording paper 72, a registration roll 75 for feeding the recording paper 72 to a transfer position at a predetermined timing, and a recording paper 72 for the recording paper 72. A suction charging device 76 that gives an electric charge and a transport drum 7 that transports the recording paper 72.
7, a transfer charger 78 that is provided at the transfer position of the transport drum 77 to apply a predetermined charge, a peeling charger 79 that applies a charge to strip the recording paper 72 from the transport drum 77, and the recording paper 72. The fixing unit 80 for fixing the toner image transferred onto the sheet, the sheet discharge tray 81 for discharging the recording sheet 72 having the toner image fixed thereon, and the photosensitive drum 70.
A cleaner 82 for removing the toner remaining on the photosensitive drum 70, a charger 83 for giving a predetermined charge to the photosensitive drum 70, a motor 84 for generating a rotational torque according to a driving voltage, and a rotational torque generated by the motor 84 for the photosensitive member. It has a timing belt 85 that transmits to the drum 70.

The timing belt 85 is selected with a pitch as small as possible in consideration of the load torque.
If the load torque is small, a steel belt may be used.

FIG. 11 shows a timing belt 85 in another configuration of the second embodiment. The timing belt 85 is a rotary encoder 70A provided on the photosensitive drum 70 and a pulley 84 provided on a motor 84.
The tension pulley 87, the support member 88, and the linear slide 8 are stretched between A and A to maintain a predetermined tension.
9 and a belt tensioner 86 including a spring 90.

In the other configuration of the second embodiment as well, as in the first embodiment, the drive control is performed on the basis of the data of the rotational fluctuation detected by the actual measurement, so that the photosensitive drum 70 is raised. It is possible to drive with high accuracy, and it is possible to prevent the occurrence of density unevenness in the output image and misregistration. Further, the transport drum 77 can also be configured to perform drive control by detecting rotation fluctuations.

FIG. 12 shows the arrangement of the position / speed calculator 30 and the controller 31 in the second embodiment, and the position / speed calculator 30 and the controller 31 are shown in FIG. 12 (a). As described above, the front panel 67A of the image forming apparatus 67
12B, when a computer 91 capable of remote control is connected to the image forming apparatus 67, as shown in FIG. 12B, the computer 91 is made to have the above-mentioned function and substitute. You can also

FIG. 13 shows a third embodiment of the present invention. A polygon mirror 93 for deflecting the laser light emitted from the light source 92, a polygon mirror drive motor 94 for rotationally driving the polygon mirror 93, and a polygon. A rotary encoder 95 for detecting a rotation fluctuation of the mirror drive motor 94 may be provided, and the rotation fluctuation may be detected based on a pulse output from the rotary encoder 95, and the polygon mirror drive motor 94 may be drive-controlled.

FIG. 14 shows a fourth embodiment of the present invention, in which a motor 63 for driving an image sensor 65 located under the platen 64 and a driving force in a direction opposite to the driving direction of the motor 63 are generated. Elastic member 63C, pulleys 63A and 63B that stretch a wire 65A provided on the image sensor 65, and a rotary encoder 63 that generates a pulse having a cycle corresponding to the rotation speed of the pulley 63A.
It is also possible to have D, detect the speed fluctuation based on the pulse output from the rotary encoder 63D, and drive and control the motor 63.

FIG. 15 shows a fifth embodiment of the present invention. As shown in FIG. 15A, a fixing roll 80A supported by the frame 101 and a rotational torque according to a driving voltage are generated. The recording medium 100 includes a motor 96, a reduction gear 97 for transmitting the rotation torque of the motor 96 to the transfer roll shaft 98, and a rotary encoder 99 provided on the transfer roll shaft 98. As shown in FIG. The motor 9 detects the speed fluctuation of the nip fixing roll 80A.
6 may be drive-controlled. Further, even when the fixing belt is used, drive control can be similarly performed.

FIG. 16 shows a color image forming apparatus according to a sixth embodiment of the present invention, in which a paper feed roll 103 which receives a rotational torque generated by a motor 102 to feed a recording paper in an arrow direction and a motor 104. The paper transport belt 105 that transports the recording paper supplied from the paper feed roll 103 in response to the rotation torque generated in
And a motor 107 for adsorbing the recording sheet onto the adsorber 106.
a to 107d through the reduction gears 108a to 108d, exposure units 110a to 110d for exposing the photosensitive drums 109a to 109d to form an electrostatic latent image on the surface, and Toner units 111a for Y, M, C, and BK for developing the electrostatic latent images formed on the body drums 109a to 109d by toner
111d and transfer rolls 112a-1 to transfer the color toner images formed on the photoconductor drums 109a-109d onto the recording paper conveyed through the paper conveyance belt 105.
12d and the photosensitive drums 109a to 109a after the formation of the electrostatic latent image.
Charging devices 113a to 113d for charging 09d, and a fixing roll 114 for fixing the transferred image on the recording paper which has been transferred.
have.

In such a color image forming apparatus,
A motor 104 for driving the paper transport belt 105 and Y,
Clock pulse count values of rising edge intervals of divided pulses in each sampling period obtained by actual measurement of the motors 107a to 107d that drive the M, C, and BK photosensitive drums 109a to 109d, respectively, by the above-described speed fluctuation detection device. If the control is performed based on the above, it is possible to control the paper transport belt 105 and each of the photoconductor drums 109a to 109d with high accuracy, and it is possible to suppress each speed fluctuation. Therefore, it is possible to prevent the occurrence of density unevenness and registration shift of the output image.

Further, as shown in FIG.
Driven by the intermediate transfer belt 115 and the motor 11
When the speed fluctuation detecting device is applied to the color image forming apparatus having the paper feed roll 118 that rotates in accordance with the rotation torque of No. 7, the secondary transfer roll 119 is applied to the recording paper supplied to the secondary transfer point by the paper feed roll 118. As a result, it is possible to prevent the occurrence of density unevenness and registration deviation when transferring a color toner image.

In the above embodiment, the rotary encoder is used as the pulse generating means, but the present invention is not limited to this.
It is also possible to use a hall sensor or a detector that can obtain an output signal with a cycle according to the speed fluctuation of the moving member.

Although the present invention has been clarified from the above description, the reason why the effects of the present invention are obtained will be repeatedly described as follows.

When detecting the rotation fluctuation of the rotating member by using the pulse fluctuation detection device which is currently commercially available and counts the measured pulse train with the clock pulse and sequentially outputs the cycle fluctuation, the cycle of the encoder pulse is sampled. If the period is about 0.7 to 0.8 times, the noise is small and the detection resolution can be secured. On the other hand, when the cycle of the encoder pulse is shortened to about 0.1 to 0.4 times the sampling cycle, the averaging effect of the count data is weakened,
High frequency noise is added to the data and the S / N ratio deteriorates. In addition, the nominal (average) count value of the counter (hereinafter, referred to as No) is reduced, so that the apparent resolution of the rotation fluctuation is reduced. For example, when No = 1000, the detection resolution is 1/1000 = 0.1 [%], but when No = 400, the detection resolution is 1/400.
= 0.25 [%].

In the present invention, the division ratio n'of the encoder pulse is determined from the allowable value of the speed fluctuation, the sampling period, and the nominal period of the encoder output pulse, and the n'divided encoder pulse period is read by the reference clock. Since it is configured to calculate the speed fluctuation of the moving member during the sampling cycle, even if the encoder pulse cycle is shortened to about 0.1 to 0.4 times the sampling cycle depending on the measurement conditions, the measured object is measured. Since the pulse period can be set to about 0.7 to 0.8 times the sampling period, S is compared with the case where the rotational fluctuation of the rotating member is detected by using the currently commercially available speed detecting device.
It is possible to prevent the deterioration of the / N ratio and the detection resolution, and it is possible to obtain a sufficiently accurate detection result.

[0056]

As described above, according to the speed fluctuation detecting device of the present invention, the encoder pulse is divided based on the allowable value of the speed fluctuation of the moving member, the sampling cycle, and the average cycle of the encoder pulse, and this frequency division is performed. Since the speed fluctuation is detected based on the count value obtained by counting the circular pulses with the clock pulse, even if the cycle of the encoder pulse is 0.1 to 0.4 times the sampling cycle, the position or speed of the moving member is not changed. The corresponding data does not include high frequency noise, has an excellent S / N ratio, and can detect rotation fluctuation with high accuracy.

[Brief description of the drawings]

FIG. 1 is a color image forming apparatus equipped with a speed fluctuation detecting device according to a first embodiment.

FIG. 2 is an enlarged view of the speed fluctuation detection device according to the first embodiment.

FIG. 3 is a position / velocity calculation unit 3 according to the first embodiment.
It is explanatory drawing which shows 0.

FIG. 4 is a timing chart of the speed fluctuation detection device in the first embodiment.

FIG. 5 is a position / velocity calculation unit 3 according to the first embodiment.
It is a flow chart which shows operation of 0.

FIG. 6 is a position / velocity calculation unit 3 according to the first embodiment.
It is a flow chart which shows operation of 0.

FIG. 7 is an intermediate transfer belt 15 according to the first embodiment.
It is explanatory drawing which shows the other structure.

FIG. 8 is an electrophotographic image forming apparatus equipped with the speed fluctuation detecting device according to the second embodiment.

FIG. 9 is an explanatory diagram showing a speed fluctuation detection device according to a second embodiment.

FIG. 10 is an explanatory diagram showing another color image forming apparatus according to the second embodiment.

FIG. 11 is an explanatory diagram showing a timing belt 85 in another configuration of the second embodiment.

FIG. 12 is an explanatory diagram showing an arrangement of a position / velocity calculation unit 30 and a control unit 31 according to the second embodiment.

FIG. 13 is an explanatory diagram showing a third embodiment.

FIG. 14 is an explanatory diagram showing a fourth embodiment.

FIG. 15 is an explanatory diagram showing a fifth embodiment.

FIG. 16 is an explanatory diagram showing a color image forming apparatus according to a sixth embodiment.

FIG. 17 is an explanatory diagram showing another configuration of the color image forming apparatus according to the sixth embodiment.

FIG. 18 is a timing chart showing the operation of the conventional speed motion detecting device.

FIG. 19 is a timing chart showing the operation of the conventional velocity motion detecting device.

FIG. 20 is a timing chart showing the operation of the conventional speed motion detecting device.

[Explanation of symbols]

 1, image input 2, platen 3, lamp 4, reflection mirror 5, reflection mirror 6, lens 7, charge imaging device 8, image output unit 9A, polygon mirror 9B, polygon mirror drive motor 10, reflection mirror 11, photosensitive Body drum 12, developing unit 13, charging unit 14, cleaner 15, intermediate transfer belt 17, drive roll 18, support roll 19, support roll 20, primary transfer corotron 21, cleaner 22, rotary encoder 23, paper tray 24, feeding Paper roll 25, secondary transfer roll 26, fixing unit 27, motor drive circuit 28 motor 29A, reduction gear 29B, reduction gear 30, position / speed calculation unit 31, control unit 32, D-flip flop 33, frequency dividing circuit 34 , D-flip-flop 35, D-flip-flop 36, NAN D circuit 37, signal generation circuit 38, counter 39, D-flip flop 40, D-flip flop 41, signal generation circuit 42, CPU 45, mark 46, mark detector 47, main body 48, main frame 49, charger 50 , Developing unit 51, photosensitive drum 51A, photosensitive drum drive gear 52, rotary encoder 53, process cartridge 54, guide member 55, exposure unit 56, drive motor 56A, reduction gears 57, 57A, 57B, 57C, reduction gear 58 , Transfer roll 59, recording paper 60, paper feed roll 61, fixing roll 62, paper discharge tray 63, motor 63A, pulley 63B, pulley 63C, elastic member 63D, rotary encoder 64, platen 65, image sensor 65A, wire 66, Image input 67, image output unit 67A, front panel 68, exposure unit 69, reflection mirror 70, photoconductor drum 71, developing unit 72, recording paper 73, paper feed roll 74, paper conveyance path 75, registration roll 76, adsorption charging Device 77, Conveying Drum 78, Transfer Charging Device 79, Separating 2 Electric Device 80, Fixing Unit 80A, Fixing Roll 80B, Fixing Roll 81, Discharge Tray 82, Cleaner 83, Charger 84, Motor 85, Timing Belt 86, Belt tensioner 87, tension pulley 88, support member 89, linear slide 90, spring 91, calculator 92, light source 93, polygon mirror 94, polygon mirror drive motor 95, rotary encoder 96, motor 97, reduction gear 98, transfer roll shaft 99 ,rotary Encoder 100, recording paper 101, frame 102, motor 103, paper feed roll 104, motor 105, paper transport belt 106, suction devices 107a to 107d, motors 108a to 108d, reduction gears 109a to 109d, photoconductor drums 110a to 110d, Exposure units 111a to 111d, toner units 112a to 112d, transfer rolls 113a to 113d, charger 114, fixing roll 115, intermediate transfer belt 116, motor 117, motor 118, paper feed roll 119, secondary transfer roll

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G03G 15/04 114 G03G 15/04 114 H04N 1/113 H04N 1/04 104A 1/04 1/12 A

Claims (8)

[Claims] 1. An image forming apparatus for forming an image while suppressing a speed variation of a moving member such as an image carrier, a transfer material conveying body, and a document scanner, wherein a pulse having a cycle corresponding to the speed of the moving member is generated. Pulse generating means, and a measured pulse generating means for expanding the cycle of the pulse to generate a measured pulse having a cycle shorter than a predetermined sampling cycle and longer than a predetermined ratio of the predetermined sampling cycle; Counting means for counting clock pulses over the cycle of the pulse under measurement in the predetermined sampling cycle and outputting a count value according to the speed of the moving member; and speed fluctuation of the moving member based on the count value. A speed fluctuation detecting device for an image forming apparatus, which has a calculating means for calculating 2. The measured pulse generating means determines the amount determined based on an allowable value of speed fluctuation of the moving member, the predetermined sampling period, and an average period of pulses having a period corresponding to the speed of the moving member. 2. The speed fluctuation detecting device for an image forming apparatus according to claim 1, wherein the speed fluctuation detecting device is a frequency dividing device that divides a pulse having a cycle corresponding to the speed of the moving member according to a circumference ratio. 3. The frequency division means, wherein Vlim [%] is a permissible value of the speed fluctuation of the moving member, Ts is the predetermined sampling period, and Teo is the average period of the pulse, and the frequency division ratio is 3. The speed fluctuation detecting device for an image forming apparatus according to claim 2, wherein is set to a maximum natural number n that satisfies Teo * (1 + 0.01 * Vlim) * n≤Ts. 4. The structure according to claim 1, wherein the pulse generating means is at least one of a rotary encoder, a hall sensor, and mark detecting means for detecting marks formed on the moving member at equal intervals. A speed fluctuation detection device for an image forming apparatus. 5. The speed fluctuation detection of the image forming apparatus according to claim 1, wherein the measured pulse generation means generates the measured pulse having a period of 70 to 80% of the predetermined sampling period. apparatus. 6. The speed variation of the image forming apparatus according to claim 4, wherein the mark detecting means includes a light emitting element for irradiating the mark with light and a light receiving element for receiving reflected light from the mark. Detection device. 7. The speed fluctuation detecting device for an image forming apparatus according to claim 4, wherein the mark detecting means is an image sensor. 8. The speed fluctuation detection of the image forming apparatus according to claim 1, wherein the moving member is at least one of an intermediate transfer member, a polygon mirror, a document scanner driving roll, a fixing roll, and a fixing belt. apparatus.