JPS59108634A - Paper feeder - Google Patents

Abstract

PURPOSE:To make a degree of paper feeding power possible to be constant, by adjusting the speed of a paper feed roller detecting a variation in those of static drictional resistance, paper feeding roller pressure, the kinetic frictional resistance and acceleration, etc., of the paper feed roller caused by temperature and humidity, in case of a paper feeder for copying machines. CONSTITUTION:An MPU is inputted with a signal out of a hollow, medium cylindrical pressure sensor 110 installed in a paper feed roller and finds paper feed roller pressure F2. Also, it inputs signals out of a temperature sensor 120 made up of metallic film resistance or the like and a humidity sensor 130 made up of metallic selenate evaporation or the like and finds a static friction factor mu. Next, it detects a variation in kinetic frictional resistance mu caused by friction of the paper feed roller, material change or the like as well as a variation in acceleration alpha caused by load change, roller pressure change, etc. And, the MPU calculates a control command on the basis of information based on these data and controls the rotation of an DC motor M via a control unit 100 whereby the number of revolution is fed back by an encoder En. Thus the paper feeding power of the paper feed roller can be always kept constant so that stable paper feeding takes place without double-feeding, racing, etc.

Description

[Detailed description of the invention] Technical field The present invention relates to improvements in paper feeding devices for copying machines and the like.

Prior art In a conventional clutch-type paper feeder, the paper in the cassette? When feeding paper, the paper feeding rollers are configured to feed paper at the same speed regardless of whether there is enough paper in the cassette or not. Therefore, as the amount of paper decreases, the paper feeding roller pressure becomes stronger, and as a result, the dynamic frictional force fluctuates, and the roller pressure increases the heavy paper feeding rate such as 2-sheet feeding and 3-sheet feeding. This tendency becomes stronger when the number of sheets reaches about 5 sheets, and this is one of the paper feeding problems. Furthermore, the open-' and false coefficients change due to thermal fatigue of the paper, changes in humidity, etc., and this also causes paper feeding problems.

These problems are largely due to the feeding groove in which the feed rate is constant during paper feeding.

Figure 1 is a diagram to explain the physical relationship between paper feeding roller 1 and roller 2 during paper feeding.If the force of the paper feeding roller is F, then F is the force of paper feeding roller 1. It is established by the balun 4 of the rotational force F1 and the force F2 pushing up the paper feed roller of the cassette. However, the rotational force F of the paper feed roller is Fl−■
v1α-μivig (α: acceleration, μ: moving bank/friction coefficient)
The fourth generation force F is satisfied when F-Fl-F2>0. Therefore, in order to feed paper, Mα−μM
The relationship g-F2=M(α-μg)-F2-=K>0 is required, and in order to stably feed paper, it is necessary to keep the F value, that is, the value of K constant. Therefore, in order to keep K constant, it is necessary to control the variables α and μ. However, α,
Since μ fluctuates due to changes in conditions, the value of K increases or decreases, resulting in paper feeding errors such as short-side, idling, etc. The causes of this variation in K are: (1) A slight change in paper feed roller pressure when zero paper is set, that is, a variation in F2 due to the difference in spring pressure.

(2) Changes in μ due to temperature, humidity, paper quality, etc.

(3) Changes in μ due to wear of paper feed rollers, changes in grain quality, changes in hardness, etc.

(4) Variation of α due to load variation.

(5) Fluctuations in α and μ due to changes in the material of the paper feed roller.

etc. can be opened.

Purpose The present invention has been made in consideration of the above-mentioned actual situation. In particular, the present invention effectively absorbs the above-mentioned fluctuation factors (1) (α
-μg) - This was made for the purpose of stabilizing the F2 knee. To briefly explain the above objects of the present invention, the present invention includes: (I) detecting changes in paper feed roller pressure and determining friction coefficient μ and acceleration α; (3) Determine the number of threads per culm μ after detecting the current (warm, wet), etc. (3) Determine the introduction paper acceleration black 2 α and start the paper feed motor by the rotation command from the MPU. To do rotation ゛Senpaku 1, (4
), and to keep the sheet pressure constant by grasping the causes of each of the fluctuations in (1) to (3) from time to time.

Configuration As described above, the present invention has paper feeding force F −= M (α−
tzg) -F2:=K is constantly detected and stable paper feeding is performed based on that information.To do this, (1) Changes in static friction resistance μ due to temperature and humidity, t2)
, Changes in the feeding pressure F2 depending on the amount of disease, (3)
, Changes in dynamic frictional resistance μ due to friction of paper feed rollers, changes in material, etc. (4) Changes in acceleration α due to load fluctuations, roller pressure fluctuations, etc. are detected moment by moment, and the paper feed roller speed is controlled by the MPU. First, the detection methods of (1) to (4) above will be explained. (1), ? ! ! Detection of silent friction resistance using temperature and humidity sensors: Figure 2 is a diagram showing the relationship between humidity and temperature and the coefficient of static friction. 80 cm, temperature 20℃～;35℃ combination■
~ Create as many as 24 of O, and calculate Jψ friction coefficient μ for each combination.
As shown in FIG.
The data is stored in the data memory RAM and used as calculation data. Note that the humidity sensor and temperature sensor are small and sensitive sensors that are installed in the cassette.

(2) Detection of paper feed roller pressure depending on the amount of paper 2 To detect F2 and α due to changes in paper feed 7 rollers depending on the amount of paper, first, as shown in Fig. 5, the roller pressure p2 and temperature, Set the relationship of fitness degree, and based on it, A of supply g< iiS
The supply JtE force l speed 1 and α due to changes in the stock of
The data is classified into dozens of categories based on the relationship between paper feed roller pressure and χ product 1 color and 1φIK.The paper feed roller pressure during paper feeding is detected by sensor S shown in Figure 4, and the data is /D
I change the heat exchanger to the digital fan and turn it into an iVI PU.
This is done by storing the data in the data memory RAIVfK. Therefore, the minute flow from the sensor is processed by the circuit shown in Figure 4, and the 1n information of F2 is r
The next signal is output from the MPU and input manually to the control circuit of the servo motor.

(3) Detection of dynamic frictional resistance: All cheetahs of two series F2, α, μ are stored in memory for each digital and 1-7 in the cheetah program, - Used as data for Ul, this μ, α h+tj is calculated from M(α−μg) F22K in MPU, and if it is larger than the value of K, the α value is subtracted, and K If it is smaller than the value of , adjust α to add the shortfall to the value of α.In this way, if only the α value is considered, the best value can be obtained under the valley YML tear and humidity conditions, but in addition If it is controlled based on the overall evaluation with the values of , μ, better paper feed function can be obtained.

(4) Paper feed motor servo fIl based on α, μ information
lI (ILII: Figure 6 shows the servo control of the paper feed motor based on the acceleration layer information α from the paper feed to obtain rapid rise, fall υ, and stable rotational speed.
As shown in the figure, the encoder En1 is centered around the MPU.
It consists of four blocks controlled by a tacho generator Tach, a comparison circuit 1%com, and a pWM fllJ. The control command is calculated by lVf P U based on the μ and α information, and the control command determined by this is output to the D/A converter and output to the comparison circuit Com as analog information.
is input. Separately from this, the motor M starts rotating according to an optimal control program programmed in the MPU as a control sequence. The number of rotations is determined by counting the pulses of the encoder En cut by the MPU and detecting whether the number of rotations matches the number of rotations of the control program. Tacho generator T
ach The tacho voltage generated in proportion to the rotation speed is also M
The PU calculates and outputs speed and position signals, which are driven as PWM signals from the D/A converter and comparison circuit Com to control the rotation speed of the DC motor M. Further, the position is output as a stock signal to the position control comparator by counting the number of rotations at fvlP and U, and the motor stops at the target position.

Figure 47 is a servo diagram. As a servo, ■, Open loop ■ is used at startup to quickly reach the target rotation speed, ■, During operation, closed loop ■ is used to stabilize the rotation speed, ■. When falling, use position loop O to quickly stop at the desired position.

It has this feature.

FIG. 8 is a normal servo block diagram for performing the above-mentioned servo control, in which 1o is a voltage amplifier, 11 is a power intensifier, 12 is a motor, 13 is an encoder, and 14 is an F/V A conversion circuit, 15 is a 7 I/l/tor, 16 is a phase compensation circuit, and this control circuit belongs to the field of frequency control in feedback control. However, this eighth
The circuit groove bottom shown in the figure is suitable for constant speed control, but is unsuitable for control such as speed switching, position control, and stopping.

Therefore, in the present invention, ■ Rotation control by direct counting of rotations from an encoder, ■ Position control, position control by a comparator, ■ PWM control by a tacho generator and comparator, ■ Stop control by a strobe signal from the MPU, ■ By controlling the entire sequence using the comprehensive control of the MPU, the servo diagram shown in FIG. 7 is executed, making it possible to control both performances. This makes it possible to control the paper feed with less slippage in the paper feed roller compared to the conventional clutch method. In addition to the above, the paper feed motor is controlled by P'LL+1I4S or PL system which performs phase control.
A mixture of L control and frequency reduction may also be considered.

Detection of paper feed roller pressure The paper feed roller pressure is detected as shown in FIG.
-8, amplified by the operational amplifier OPK, converted into a digital signal by the A/D conversion circuit,
■0 is inputted to fνiPU according to 10 and outputted from the data program as an α signal. In Jimen 1,
The paper feed roller with pressure sensor is made of PCM (BaTiO3
゜PbTxO3PbZro3) , L T T (Pb
(M 1/3 Nb 2/3 ) Oa ), etc., is coated with rubber material 21, which is the material of the paper feed roller, on the pressure element 2°, which has a cylindrical inner wall. .

Figure 10 is a diagram showing the strain direction of the pressure sensor equipped paper feed roller with arrows. This pressure sensor paper feed roller has the characteristics shown in Table 1 and generates a d air signal according to the pressure do. This electrically converted voltage V is amplified and calculated as described above, is inputted to the MPU through the entire A/D converter, and outputs acceleration information α from the data program.

Table 1 Note that strain gauges such as metal resistance 1-sieve strain cages and semiconductor strain gauges are also widely used as pressure measurement means. Therefore, paper roller pressure can also be detected using these strain gauges in addition to the above embodiments. You can also.

FIG. 11 is a diagram showing an example of a paper feeding roller pressure detection circuit using a strain cage, and FIG. 12 is a block diagram showing the overall circuit configuration in that case. 12
This is a detailed electrical circuit diagram of the block diagram in the figure. In Figure 12, 3fXl is a stabilized power supply circuit 1.31 is an oscillator,
is strain gauge (pressure sensor S), 3:3 is amplifier,
In this case, the strain gauge part S
(32) is embedded in the surface of the paper feed roller and detects one ball of the paper feed roller and outputs the output 'voltage e'.

is represented by H,l in the circuit of FIG. 11, and its output is input to the MPU through the A,7 converter, as described above. Note that the resistor used in this circuit is preferably of a gold film type with a value of 0.5 or less, and the operational amplifier is preferably a low-drift type. In this way, by detecting the paper feed roller pressure using a strain gauge metal, it becomes possible to make the device smaller and lighter, and to measure static pressure and dynamic pressure.

Temperature detection τ knee A degree is static friction l! Since it is a characteristic that determines the elements of , it is necessary to improve linearity as much as possible. In this embodiment, this temperature detection was performed using a single mister, but in order to improve linearity, a metal thin film resistor with a large temperature coefficient was used.

FIG. 14 is a diagram showing an example of a temperature detection circuit suitable for use in the temperature sensing circuit 1 to 1 of the present invention, and FIG. 15 is its output characteristic diagram. If the resistance value at time is R825 and the temperature coefficient is α,
Resistance value Rst of temperature sensitive resistor Rs at temperature t °C
is expressed as Rst=-Rss Jl+α(t-25)1, and the output Vout of the amplifier AMP is as follows.

Here, if γ0''-R82!1, Vout becomes.Here, Rszs=r.=IKΩ, Ro=3.
9 KΩ, α=3900 pprn/'C,
+Vcc = -1-12V.

Rf/Ri=21.5, Rx7'R2=0.
If you select 982, the output voltage will be 0 to 1. O.V.
Since it is not possible to obtain a linear output voltage, this output voltage is converted into a digital signal using an A/D converter.
Enter in U. In addition to the above-mentioned thermistor, other detection elements such as thermoelectrons can be used as the moisture sensitive element r- in a linear manner.

There are various types of humidity sensing elements and 17, such as Ge vapor-deposited thin film elements, selenium vapor-deposited thin film elements, and magnetite element tubes, all of which utilize changes in resistance with respect to humidity. In this case too,
As in the case of temperature, it is best to have a structure as linear as possible and to operate over a wide range of humidity, so a metal selenium vapor deposition sensor was used. The change in electrical resistance of this sensitive layer element is made similar to the above-mentioned warm/thickness detection circuit, and its output voltage is set to O to IOV, and is input to the iVI P U through the A/D converter. In addition to the above-mentioned materials, ceramics and the like can be used as the selection-sensitive element, and these can also be used in the same manner as described above.

For reference, Fig. 16 shows a humidity characteristic diagram of the selenium vapor-deposited film moisture-sensitive element, and Fig. 17 shows a temporal change characteristic diagram.
In Fig. 16, curve A is the characteristic of amorphous selenium, and curve B is the characteristic of metallic selenium at Δ)°C.In Fig. 17, curve A is the characteristic of amorphous selenium, and curve B is the characteristic of metallic selenium at 50% humidity and temperature. This is the aging characteristic at 30°C.

Further, Fig. 18 shows a configuration diagram of the vicinity of the cassette, and Fig. 19 shows a comprehensive control block diagram.
1 is paper, 5 is a temperature sensor, 6 is a humidity sensor, 7 is a cassette, and 8 is a pressure sensor.
00 is the control circuit, M is the motor, En is the encoder, 11
0 is a pressure projection circuit, 12° is a temperature detection circuit, and 130 is a humidity detection circuit.

Effects As is clear from the above explanation, according to the present invention, it is possible to always control the paper feeding force of the paper feeding roller at a constant level,
Therefore, stable paper feeding without double feeding, idle rotation, etc. can be performed.

[Brief explanation of the drawing]

Figure 1 is a diagram to explain the physical relationship between paper feed rollers and paper, Figure 2 is a diagram showing the relationship between humidity, temperature, and static friction coefficient, and Figure 3 is a diagram showing the processing flow of static friction information. FIG. 4 is a diagram showing an example of a processing circuit, FIG. 5 is a diagram showing the relationship between paper feed roller pressure, temperature, and humidity, and FIG. 6 is a servo control circuit according to the present invention. Figure 7 shows an example of
Servo diagram, Figure 8 is a diagram showing an example of a normal servo control circuit, Figures 9 and 10 are sectional views showing an example of a paper feed roller, and Figure 11 is a diagram showing an example of a paper feed roller. Paper roller pressure detection circuit, Fig. 12 is an overall block diagram of the paper feed roller pressure detection circuit, Fig. 13 is a detailed circuit diagram of Fig. 12, and Fig. 1
Figure 4 is a diagram showing an example of the 6th degree or humidity detection circuit.
Figure 5 is a temperature-output characteristic diagram of the circuit in Figure 14, Figures 16 and 17 are characteristic diagrams of the humidity detection element, Figure 18 is a diagram of the configuration near the cassette, and Figure 19 is the overall control. It is a block diagram. IVI PU Microcomputer, 100 ・
Control circuit, M...Motor, En encoder, 110
・Pressure sensor, 120 Temperature sensor, 130・Humidity sensor. Patent applicant Ricoh Co., Ltd. Figure 1 f J2 Figure 3 @ Figure 4 Figure 5 Figure 6 I! lL organ (°C) phase @renxiang (7-) Fig. 18 Fig. 19 203

Claims (2)

[Claims] (1) A piezoelectric element that detects a change in paper feeding pressure depending on the amount of paper in the cassette, a means for receiving a signal from the piezoelectric element and outputting a paper feeding speed signal, and a means for receiving the paper feeding speed signal. A paper feeding device comprising: a control circuit that controls the speed of a paper feeding motor. (2) a detection element for detecting the temperature and/or humidity inside the cassette; a means for receiving a signal from the detection element and outputting a paper feed speed signal; and a means for outputting a paper feed speed signal in response to the paper feed speed signal; A paper feeding device characterized by having a control circuit that performs speed control.