JP2703058B2 - Paper feed control method in paper feeder - Google Patents

Description

Detailed Description of the Invention [Table of Contents] Overview Industrial application field Conventional technology (Figs. 11 to 16) Problems to be solved by the invention Means for solving the problem (Fig. 1) FIG. 1) Embodiment (FIGS. 2 to 10) Effects of the Invention [Overview] Regarding a paper feed control method in a paper feeder, when sending out forms, pick mistakes, slips, double feeds, etc. are eliminated, and a wide form specification and A paper feeder provided with a paper feeding section, a paper separation section having a torque limiter capable of changing a limit torque, and two paper position detection sensors, for the purpose of being able to cope with a wide range of environmental conditions. In the paper feed control method of
The applied voltage set as an initial value in the torque limiter is set higher than a standard value so that double feed of paper and forms is unlikely to occur, and slip is likely to occur. When slips and double feeds of documents are detected, the limit torque is changed by controlling the voltage applied to the torque limiter based on the detection information, so that paper can be fed without slips or double feeds. .

[Industrial applications]

The present invention relates to a printer, an optical character reading device (OCR) for feeding sheets, forms and the like one by one from a stack thereof.
And a sheet feeding section provided with a pick roller which presses and engages with the stack so as to sequentially feed sheets and forms from the stack, and the feeding mechanism. A sheet feeder having a sheet separating unit and a sheet position detecting sensor provided with a torque limiter capable of changing a limit torque and a separating rolling element rollingly engaged with the torque limiter for separating and sending out sheets and forms one by one. In the paper feed control method.

[Conventional technology]

Printers, optical character readers, etc., incorporate a paper feeder for feeding sheets or forms from a stack thereof one by one to a printing unit or a reading unit.
As one type of such a sheet feeding device, a sheet feeding section provided with a pick roller which presses and engages with the stack to sequentially feed the sheets and forms from the stack, and a sheet and forms which are fed out are provided. 2. Description of the Related Art There has been known a type including a torque limiter for separating and sending out one sheet at a time and a sheet separating portion provided with a separation rolling element which is rollingly engaged with the torque limiter.
Referring to FIGS. 11 and 12, the structure of such a paper feeder is schematically shown, the paper feeding section and the paper separating section are indicated by reference numerals 10 and 12, respectively.

The paper feeding section 10 is used to feed paper, P ₁ , P ₂ , and P ₃
A lifting table 14 is provided at the bottom side of the hopper structure for accommodating the stacked body S composed of the following components. The lifting table 14 can be moved up and down by a suitable driving source, and the top side of the hopper structure is as shown in FIG. The pick roller assembly 16 is provided. The pick roller assembly 16 includes a pick roller 18 and a drive roller 20, a support bracket 22 for rotatably holding both rollers, and a drive belt stretched between a gear of the pick roller 18 and a gear of the drive roller 20. 24. Support bracket 22 of pick roller assembly 16
Is supported on a suitable support frame (not shown) so as to be rotatable about the axis of rotation of the drive roller 20, and the support bracket 22 is provided with suitable elastic means, such as coil springs, at the location indicated by the reference numeral 25. the added elastic force, thereby brought into elastically pressed against the paper P ₁ of the topmost of the pick roller 18 is stack S. The drive roller 20 is connected to a drive motor M via a suitable clutch N, and when the clutch is engaged, the drive roller 20 is driven to rotate in a counterclockwise direction (FIG. 12), whereby the pick roller 18 is also driven. When the clutch is disengaged, the pick roller 18 is put in an idling state and idles when the clutch 24 is disengaged (see FIG. 12 (b)).

When the pick roller 18 in the sheet P ₁ and the pressure-contact state of the topmost portion is rotationally driven (in this case the above-mentioned clutch engagement state), the sheet P ₁ receives the feeding force from the pick roller 18 sheet stack S It will be fed out to the separation part 12. In this case, although it feeds only the paper P ₁ of the topmost from stack S is the ideal, in fact with the feeding of the sheet P ₁ is fed together also lower the sheet P ₂ and P ₃ of the Can be The sheets fed out in an overlapping manner are separated and fed one by one in the sheet separating section 12.

The paper separating section 12 is provided with a separation belt assembly 26, which cooperates with a torque limiter 28. The separation belt assembly 26 has three pulleys 3
0, 32, and 34, a support bracket 36 for rotatably holding these pulleys, and a separation belt 38 stretched over the pulleys 30, 32, and 34. Pulley 30 is connected to a suitable drive motor to function as a drive pulley, while pulleys 32 and 34 are functioned as driven pulleys.
The support bracket 36 is supported on a suitable support frame (not shown) so as to be rotatable about the axis of rotation of the drive pulley 30, and the support bracket 30 is provided with suitable elastic means at the location indicated by reference numeral 40. For example, an elastic force is applied by a coil spring, so that a part of the separation belt 38, that is, a belt running portion between the driving pulley 30 and the driven pulley 32 is elastically pressed against the torque limiter 28.
That is, in the example shown in FIG. 11, the separation belt 38 functions as a separation rolling element rollingly engaged with the torque limiter 28. The torque limiter 28 is kept in a non-rotating state when the value of the torque applied thereto is less than a predetermined value,
The rotation is started only when the torque value exceeds a predetermined value. The torque limiter 28 and the separation belt 38 are both made of a material having a large frictional force with respect to the paper to be fed.

The paper fed from the paper feeding unit 10 is a torque limiter.
The clutch is disengaged between the belt 28 and the separation belt 38 elastically pressed against the belt 28. At this time, the clutch is disengaged, and the pick roller 18 is allowed to idle. When ideal paper feeding is performed in the paper feeding section 10, that is, when only one sheet is fed, the torque limiter 28 is used.
Only one sheet of paper is introduced between the
At this time, the paper includes a torque limiter 28 and a separation belt 38.
Is driven with a large frictional force, the driving force of the separation belt 38 is transmitted to the torque limiter 28, and the paper is sent out from between the torque limiter 28 and the separation belt 38. On the other hand, when introduced between the sheet feeding unit 10 with a plurality of paper eg paper P ₁ and P ₂ are fed in overlapping state torque limiter 28 and the separation belt 38 (FIG. 11), the sheet P ₁ and frictional force between the P ₂ are smaller than the respective frictional force of the separating belt 38 and the torque limiter 28 for those sheets, never Therefore the driving force of the separation belts 38 is transmitted to the torque limiter 28, as a result the paper P only ₁ is to be fed from between the torque limiter 28 and the separating belt 38 in a state of being slid with respect to the sheet P _2.

Further, a gate plate 42 having a function of separating the fed paper is disposed on the paper feeding side of the paper feeding unit 10, and the paper fed from the paper feeding unit 10 passes over the gate plate 42 and is connected to the torque limiter 28, the separation belt 38, and the like. It is being introduced between. That is, when the fed sheet gets over the gate plate, the sheet receives resistance from the gate plate, and as a result, at least the lowermost sheet of the plurality of fed sheets is separated without being able to get over the gate plate. become. Such a separating action depends on the relative height of the gate plate 42 with respect to the feeding position of the sheet. If the height is too low, the separating function of the sheet is reduced. It becomes impossible to get over the gate plate 42. In short, the gate plate 42 functions to limit the number of sheets introduced between the torque limiter 28 and the separation belt 38,
Preferably, only one sheet of paper has a torque limiter
It is set to be introduced between 28 and the separation belt 38.

In order to ensure that the paper feeding device shown in FIGS. 11 and 12 performs the paper feeding operation as described above, various parameters as listed below must be set under predetermined conditions. Must.

P _PK : Load at the application point of the pick roller 18 Rh: Horizontal distance between the pivot of the support bracket 22 and the center of the pick roller 18 R _V : Vertical between the pivot of the support bracket 22 and the center of the pick roller 18 Distance r: radius of pick roller 18 W: load applied to point 25 of support bracket 22 R _W : horizontal distance between rotation fulcrum of support bracket 22 and point 25 G _P : load of center of gravity of pick roller assembly 16 R _GP: horizontal distance between Z ₁ between the center of gravity of the pivot point and the pick roller assembly 16 of the support bracket 22: drive belt 24 the number of the gear of the drive roller 20 meshing with Z _2: a pick roller 18 meshing with the drive belt 24 Number of gears P _SB : Load at the application point of separation belt 38 R _SB : Horizontal distance between the rotation fulcrum of support bracket 36 and the application point of separation belt 38 P _B : Load applied to location 40 of support bracket 36 R _B ： Between the pivot 40 of the support bracket 36 and the point 40 Horizontal distance G: Load of the center of gravity of the separation belt assembly 26 R _G : Rotating fulcrum of the support bracket 36 and the separation belt assembly
Horizontal distance from the center of gravity of 26 r _SB : Radius of drive pulley 30 Rr: Radius of torque limiter 28 T: Set torque value of torque limiter 28 μ _PK : Coefficient of friction between pick roller 18 and paper μ ₁ : Paper P ₁ and friction coefficient between the paper P ₂ mu _2: coefficient of friction mu _SB between the sheet P ₂ and the sheet P _3: coefficient of friction between the separating belt 38 and the paper P ₁ Myurr: the paper P ₂ coefficient of friction between the torque limiter 28 T _G: the resistance of the gate plate 42 f _1: Repetitive paper P ₁ at the sheet feeding unit 10 outputs f _2: Repetitive output F ₁ of the paper P ₂ of the sheet feeding unit 10 : sheet separating and conveying force of the sheet P ₁ in the portion 12 F _2: conveying force of the sheet P ₂ of the sheet separation section 12 first, the described feeding condition of the paper in the paper feeding section 10, the paper P ₁ Repetitive output Repetitive output f ₂ of f ₁ and the sheet P ₂ is defined by the following equation.

f ₁ = (μ _PK −μ ₁ ) P _PK … f ₂ = (μ ₁ −μ ₂ ) P _PK … The load P _{PK at} the application point of the pick roller 18 is obtained from the balance of the moment around the axis of the drive roller 20. Desired. _{That, W · R W + G P} · R GP -P PK · Rh + Z 1 / Z 2 · r · μ PK · P PK + μ
_{PK · P PK (R V +} r) = 0 W · R W + G P · R GP + (Z 1 / Z 2 · r · μ PK · + μ PK (R V +
_{r) -Rh) P PK = 0} P PK = (W · R W + G P · R GP) / (Rh-Z 1 / Z 2 · r · μ PK -
_{μ PK · (R V + r} ) ... paper for feeding unit sheet fed out of 10 is introduced between the torque limiter 28 rides over the gate plate 42 and the separating belt 38, the sheet P ₁ Repetitive output f ₁ must overcome the resistance of the gate plate 42. That is, the following equation must be satisfied.

f ₁ = (μ _PK −μ ₁ ) P _PK ≧ T _G … Needless to say, if f ₁ ≦ T _G , the paper is the gate plate 42.
Is not introduced between the torque limiter 28 and the separation belt 38, so that a so-called pick mistake may occur.

Also, if ideally the following equation is always satisfied, only the uppermost sheet of paper P ₁ That stack S is fed from the sheet feeding unit 10 to the sheet separating unit 12 side.

f ₁ = (μ _PK −μ ₁ ) P _PK ≧ T _G ≧ f ₂ = (μ ₁ −μ ₂ ) P _PK By the way, when the sheets are sequentially fed out of the stack S, the height of the topmost sheet is Since the level gradually decreases, the lifting table 14 is intermittently raised to compensate for the decrease, and the load W is kept constant, and therefore the pick roller 18 is fixed.
Is kept constant, but the friction coefficient μ _PK between the pick roller 18 and the sheet and the friction coefficients μ ₁ and μ ₂ between the sheets of the stacked body S are not constant but vary. Therefore, Repetitive output f ₂ of the formula and Repetitive output f ₁ sheet P ₁ defined by and the sheet P ₂ is always will vary. Therefore, during the sheet feeding operation, a relationship as shown in the following equation can be established. In this case, both sheets P ₁ and P ₂ are sent to the sheet separating unit 12 side, and a so-called double pick occurs. Will be.

f ₂ = (μ ₁ −μ ₂ ) P _PK ≧ T _G ... As is clear from the above description, the achievement of the sheet feeding in the sheet feeding unit 10 depends on the state of the formula or any one of the equations. Become.

Next, conditions for only paper P ₁ fed out from the paper separating unit 10 has the sheet P ₁ is sent securely from the paper separating unit 12 when introduced between the torque limiter 28 and the separation belt 38 State. In order to ensure reliable delivery of the paper P ₁ is to eliminate the slipping of the separation belts 38 for the sheet P _1, it shall transmit the driving force to the torque limiter 28. That is, by rotate with the torque limiter 28 by the drive of the drive belt 38 must to send out the sheet P ₁ from therebetween.
Delivery force or the conveying force F ₁ of the paper P ₁ at this time is defined by the following equation.

F ₁ = μ _SB・ P _SB −T / Rr−P _PK ′ ・ μ ₁₋ T _G ... P _PK ′ is a pick roller when the clutch of the drive roller 20 of the paper feeding unit 10 is disengaged. This is the load at the point of action 18 (at this time, the pick roller 18 is designed to be able to run idle), which can be expressed by the following equation.

P _PK ′ = (W · R _W + rG _P · R _GP ) / Rh... In other words, the expression ′ corresponds to the case where μ _PK = 0 in the expression.

The load _{PSB at the} point of action of the separation belt 38 is determined from the moment balance about the axis of the drive pulley 30. _{That, P B · R B + G} · R G -P SB · R SB + μ SB · P SB · r SB = 0 P B · R B + G · R G = (R SB -μ SB · r SB) P SB P _{SB = (P B · R B} + G · R G) / (R SB -μ SB -μ SB) ... second term of the equation (T / Rr) is the torque limiter overcomes set torque value of the torque limiter 28 Is the force required to rotate 28, and the third term in the equation (P _PK '· μ ₁ ) is the paper P ₁
This is the force required to pull out the succeeding portion from the paper feeding unit 10. The fourth term of the equation is, of course, the force required to overcome the resistance of the gate plate 42, not to mention (T _G ).

In order to be able feeding the paper P ₁ without slipping the separation belts 38 to the paper P ₁ is the relationship as shown below must be satisfied.

F ₁ = μ _SB · P _SB −T / Rr−P _PK ′ · μ ₁ -T _G ≧ 0 The formula is rewritten from the formula and as follows.
_{That, μ SB (P B · R} B + G · R G) / (R SB -μ SB · r SB) -T / Rr-
_{P PK '· μ 1 -T G} ≧ O μ SB · Rr (P B · R B + G · R G) / (R SB -μ SB · r SB) -μ
₁ · Rr · P _PK ′ −Rr · T _G ≧ T On the other hand, when the sheets P ₁ and P ₂ are introduced between the torque limiter 28 and the separation belt 38 in an overlapping state, the sheet P ₁
There will be described the conditions for being separated from the sheet P ₂ fed from the paper separating unit 12.

Torque limiter in a state where the paper P ₁ and P ₂ are overlapped
Paper P ₁ when introduced between separation belt 28 and separation belt 38 and
The sending power or carrying force of each of P ₂ is defined by the following equation.

That is, for the sheet P ₁ is, F ₁ for _{'= (μ SB -μ 1)} P SB -μ 1 · P PK' -T G ... sheet _{P 2, F 2 '= μ} 1 · P SB -T / _{rr- (μ 1 -μ 2) P} PK '-T G ... upper sheet P ₁ of the sheet P ₁ and P ₂ which overlap each other
In order for only paper to be sent out from between the torque limiter 28 and the separation belt 38, the relationship of F ₁ ′ ≧ F ₂ ′ must be established. On the contrary, the sheets P ₁ and P ₂ are separated from each other. The paper is sent out from the paper separating unit 12 without being subjected to the so-called double feed. The relationship of F ₁ ′ ≧ F ₂ ′ can be expressed as follows from the equation.

(Μ _SB -2μ ₁ ) P _SB ≧ −T / Rr + μ ₂ · P _PK ′...

(Μ _SB -2μ ₁ ) (R _B・ P _B + G.R _G ) / (R _SB −μ _SB・
_{r SB) ≧ -T / Rr +} μ 2 · P PK '∴- (μ SB -2μ 1) Rr (R B · P B + G · R G) / (R SB -
μ _SB · r _SB ) + μ ₂ · Rr · P _PK ′ ≦ T As is clear from the above description, the expression and the following are satisfied in order to reliably feed the sheets one by one from the sheet separation unit 12. That is the condition.

Here is a summary of what we have described above.

Regarding feeding of paper In order for the paper feeding unit 10 to eliminate the double picking of paper and to enable picking (feeding) of sheets one by one, the following expression is used: (μ ₁ −μ ₂ ) P _PK ≧ T _G This shows that it is sufficient to increase _TG and decrease _PK .

Meanwhile, in order to eliminate Pikkumisu of paper, wherein i.e., from _{(μ PK -μ 1) P PK} ≧ T G, reduces T _G, and μ _PK> μ _1, it is sufficient to increase the P _PK You can see that.

It should be noted that even if a paper double pick occurs in the paper feeding section 10, the sheets need only be separated in the paper separating section 12, so the paper feeding section 10 should focus on eliminating paper picking mistakes. is there.

To prevent slippage when feeding the only one paper sheet separating unit 12 for separating the paper, wherein _{i.e., μ SB · Rr (P B} · R B + G · R G) / (R SB -μ _SB・ r _SB ) −μ
_{From 1.}・ Rr ・ P _PK ′ −Rr ・ T _G ≧ T, it is necessary to increase P _B , decrease T, decrease _TG , decrease P _PK ′, and increase μ _SB. I understand.

Meanwhile, in order to prevent the double-feed of the sheet by the sheet separator 12, wherein _{i.e., - (μ SB -2μ 1)} Rr (R B · P B + G · R G) / (R SB -μ
_SB・ r _SB ) + μ From ₂・ Rr ・ P _PK ′ ≦ T, decrease P _B , increase T, decrease P _PK ′, μ _SB > μ
_It can be seen that it should be set to ₁ . Note that (R _SB −μ _SB
If r _SB ) takes a negative value, the separation belt 24 is braked, so that R _SB −μ _SB · r _SB > 0.

Referring to FIG. 6, the correlation of the parameters between the above-mentioned conditions is shown. In FIG. 13, the solid arrows show the conflicting relationship with respect to the resistance value (T _G ) of the gate plate 42. , And dashed arrows indicate conflicting relationships with respect to the load (P _PK and P _PK ′) at the point of action of the pick roller 18.
That is, if the resistance value (T _G ) of the gate plate 42 is increased in order to prevent double picking in the sheet feeding section 10, a pick mistake is likely to occur, and slip is likely to occur in the sheet separating section 12. On the other hand, when the load (P _PK and P _PK ′) at the application point of the pick roller 18 is increased in order to prevent a pick mistake in the paper feeding portion 10,
As a result, the double pick and the slip are likely to occur on the sheet separation side.

Further, referring to FIG. 14, the parameters mutually contradictory between the double feed condition and the slip condition in the paper separating unit 12, that is, the set torque value (T) of the torque limiter 28 and the location 40 of the support bracket 36 are applied. Load (P _B )
Is shown. In Figure 14, the slip generation region and double feed generation region is shown as a shaded area, respectively, which parameters are anti-slip condition when it is set to include both parameters T and P _B during the white area And the double feed prevention condition. The boundary between the slip occurrence area and the white area matches the equation, and the boundary between the double feed generation area and the white area matches the equation.

Further, as a conventional example, based on the configuration of the sheet feeding section 10 and the sheet separating section 12 shown in FIG. 11, the pick roller 18 and the support bracket of the sheet feeding section 10 shown in FIG. 11, that is, the sheet feeding section 10 shown in FIG. There is a structure in which 22 is lowered when the paper is fed, raised when the paper is separated, and separated from the paper. This is illustrated in FIG.

FIG. 16 (a) shows when the paper is fed out, and FIG. 16 (b) shows when the paper is separated.

The pick roller raising mechanism includes a solenoid 181 and an arm 182. When the solenoid 181 is turned off (when the paper is fed), the load of the pick roller assembly 16 itself is applied to the pick roller 18.
When the _PK is added and the solenoid 181 is ON, the pick roller
18 and the paper are separated, so _PKK '= 0. 183 is the center of rotation of the arm 182.

Therefore, at the time of separation, from the conditional expression for preventing the occurrence of slip, P _PK ′ = 0 and μ _SB · Rr (P _B · R _B + G · R _G ) / (R _SB- µ _SB · r _SB )-Rr
· T _G T, and the borders of this time in Figure 14 (-, -, -) is shifted upward as shown in FIG.

Also, from the conditional expression of double feed prevention, P _PK ′ = 0
As _{- (μ SB -2μ 1) ·} Rr (R B · P B + G · R G) / (R SB -
_μSB · _rSB ) T, and the boundary line at this time is (− − −) in FIG.
Shift down as shown in-).

As described above, in the second conventional example, the white blank portion in FIG. 14, that is, the area where the paper separation can be reliably performed is increased.
This is effective for stabilizing and improving paper, report specifications, and paper supply capacity in relation to the environment.

However, in the second conventional example, the operation time is long because the support bracket 22 is moved mechanically.

In today's high-speed continuous paper (form) processing, the processing speed of the apparatus becomes slow, so that it cannot be used anymore. For this reason, it was necessary to use the above-described first conventional apparatus (a configuration without a mechanism for raising the pick roller).

In short, in the conventional paper feeding device, various parameter values are set to be mutually compromised under the above-mentioned conditions, so that a reliable paper feeding operation of the paper feeding device can be obtained.

In the above-described conventional example, the separation belt 24 cooperates with the torque limiter 28 as a separation rolling element. However, a sheet feeding apparatus in which a separation roller cooperates with the torque limiter as a separation rolling element is also known. The paper feeding principle is the same as the case where the separation belt is used. The advantage of using the separation belt is that the load _PSB at the point of action can be made smaller than that of the separation roller, thereby reducing the contamination between pencil-written forms.

[Problems to be solved by the invention]

With the recent spread of printers, optical character readers, and the like, the types of paper and forms used therein have been diversified. For this reason, paper feeders incorporated in printers, optical character readers, etc. Also various diversified paper,
It is desired that high-speed processing be performed over a wide range of forms. However, in practice, it is extremely difficult to make the paper feeding device correspond to a wide variety of diversified sheets and forms. This is because of the diversified forms of paper, forms,
Among the above parameters, μ _PK , μ ₁ , μ ₂ , μ _SB and μrr fluctuate widely due to paper quality, presence or absence of perforations, etc., and various parameters are compromised to satisfy the above conditions. It is virtually impossible to do so. Also, the parameters μ _PK , μ ₁ , μ ₂ , μ _SB and μrr change depending on environmental conditions such as temperature and humidity, so the paper feeder can be used for a wide variety of papers and forms. It is more difficult to do so. Furthermore, especially in the case of an optical character reader, in order to handle a form written with a pencil, it must be prevented from being transferred to another form, so that the load (P _PK And P _PK ′)
And the load ( _PSB ) at the application point of the separation belt 38 are limited. In this case, the paper feeding device is diversified into various types of paper,
It becomes increasingly difficult to deal with a wide range of forms.

Table I below shows the size of paper, forms, ream, paper quality,
The tendency of pick mistakes, double feeds and slips due to the presence or absence of perforations is shown, and Table II shows the tendency of pick mistakes and double feeds due to changes in temperature and humidity. In Tables I and II, ○ indicates a tendency to occur, and X indicates a tendency to not occur.

As shown in Table I, the larger the size of the paper and the form and the larger the continuous amount thereof, the more the tendency of pick mistakes and slips to occur. I mean,
If the size of paper and forms and the amount of ream increase,
This is because the weight of the stack increases and the friction between the paper surfaces increases. On the other hand, when the continuous amount of paper and forms is reduced, the tendency of double feed is increased. Table I
As shown in the figure, double feed is more likely to occur with ordinary PPC paper than with OCR paper.
Compared with OCR paper, static electricity is more likely to be generated on a single PPC paper,
This is because this apparently acts to increase the frictional force between the paper surfaces. Furthermore, perforated forms are often used in optical character reading devices (OCR), etc.
Since this acts to increase the apparent frictional force between the perforated paper surfaces, the tendency of double feed is increased in the case of a perforated form.

As shown in Table II, under high temperature and high humidity environments, the tendency for double feed to occur increases, because in such environments, the friction between the paper surfaces decreases. On the other hand,
In a low-humidity environment, the tendency of occurrence of pick errors increases. The reasons are that friction between the pick roller and the paper surface increases, and that the paper surfaces tend to attract each other electrostatically.

Table III below shows the parameters μ _PK , μ ₁ , μ ₂ , μ
_It shows how the tendency of occurrence of pick mistake, double feed and slip changes with the increase and decrease of _SB and μrr. In Table III, the upward-sloping arrow indicates the increasing tendency and the downward-sloping arrow indicates the tendency. Indicates a decreasing trend.

As is clear from the above table, the parameters μ _PK , μ ₁ , μ ₂ , μ _SB and μrr are large depending on the paper to be fed, the size of forms, ream weight, paper quality, presence or absence of perforations, etc. Therefore, in the conventional sheet feeding device, the sheets and forms that can be appropriately fed are limited to a predetermined narrow range. In other words, the fixed parameters, ie, (μ _PK , μ ₁ , μ ₂ , μ
_{When the} parameters (except _SB and μrr) are set to predetermined values, the papers and forms that can be appropriately fed are determined by the fixed parameters.

The present invention improves the above points, and when sending out forms,
An object of the present invention is to eliminate pick mistakes, slips, double feeds, etc., and to be able to respond to a wide range of report specifications and a wide range of environmental conditions.

[Means for solving the problem]

 FIG. 1 is a principle diagram of the present invention, which will be described below.

In a paper feeding device such as an OCR, a paper feeding section provided with a pick roller which presses and engages with the stack to sequentially feed the paper and forms from the stack, and one sheet of the fed sheets and forms. A paper separating section provided with a torque limiter for separating and sending out the sheet and a separate rolling element rollingly engaged with the torque limiter, and a limit torque can be varied by controlling a voltage applied to the torque limiter. To

Also, a sensor (DS1) provided near the torque limiter and capable of monitoring the position of paper and the like and detecting how many sheets have been inserted, and a separate paper position detection provided in the transport system ahead of the sensor position Provide a sensor (DS2).

Then, like fed out form if sent to the normal no-slip even doublefeed, the time required to reach the DS2 through said sensor DS1 to t _1.

If the initial torque limiter applied voltages V ₁ and feeding the sheet such as a constant value, the time after passing through the sensor DS1 to reach the DS2 can be judged that no slip occurred if t ₁ below.

In this case, double feed sensor DS1 is successful if undetected, but, if the double-feed DS1 is detected, raising the voltage applied to the torque limiter V ₃ (V ₃
> V ₁ ), increase the limit torque.

As a result, the lower sheet (torque limiter side) is stopped by the torque limiter, and the first sheet eventually passes through the sensor DS1 and becomes a single sheet.

Where it again lowering the applied voltage is V ₁ undo the limit torque value.

Further, when the transit time between sensors DS1 and DS2 is greater than t _1,
It can be determined that a slip has occurred.

At this time, lower the limit torque by lowering the applied voltage of the torque limiter to V ₂ (V ₂ <V ₁ ). Then, no longer slip, the paper tip reaches the sensor DS2 after again proceeds t ₂ hours.

Furthermore the paper proceeds from this position, a strong feed time entering the rollers (t ₃ hours later) was raised again limit torque Mihakara' grip force (the applied voltage is V ₁₎ processing such as the following form Prepare for.

The applied voltage set as an initial value in the torque limiter is set higher than a standard value so that double feed of papers and forms is less likely to occur and slippage is more likely to occur.

[Action]

Since the present invention is configured as described above, the following operation is provided.

When sending out a form or the like, the position and amount (double feed) of the form or the like are detected using two sensors, and the limit torque is varied by controlling the applied voltage of the torque limiter using this detection signal. .

As a result, it is possible to actively suppress double feed and slippage of a form or the like.

In addition, it is possible to set a paper feed unit in advance of slipping so that double feed is unlikely to occur under any conditions, and to perform processing without operator intervention.

 Therefore, the paper feeding performance can be stabilized and improved.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

2 to 10 are views showing one embodiment of the present invention. FIG. 2 is an explanatory diagram of parameters, FIGS. 3 and 4 are explanatory diagrams of a boundary region, and FIG. FIG. 6 is a block diagram of the main part of the control system, FIG. 7 is a diagram showing the load and voltage characteristics of the torque limiter, and FIGS. 8 to 10 are diagrams for explaining the voltage applied to the torque limiter.

In the present invention, the parameter T (limit torque) related to the double feed and the slip is made variable,
It adapts to differences in forms and environments.

As described above, the expansion of the form specifications requires the apparatus to have an allowance such as a size, a continuous amount, a paper type, and the presence or absence of perforations.

The relationship between the environment and pick mistakes, double feed, and slip is also as described above, such as changes in the friction coefficient between forms or the transfer member (roller, belt) and the slip, static electricity and meshing of perforations, etc. Changes in the force acting between them affect picking mistakes, double feed, and slip.

Therefore, how the resistance _TG parameter of the gate is moved in the sheet of the standard specification and the sheet feeder adapted to the standard environment (normal temperature and normal humidity) will be described below.

As an example, let us consider a case where general paper, which easily generates static electricity at a low temperature, is used. In this case, the parameter μ _PK
And μ _SB tend to decrease, and the parameter μ ₁
And mu ₂ tends to increase. In this example, the parameter μrr is assumed to be constant.

(A) Pick error The occurrence of a pick error is indicated by (μ _PK −μ ₁ ) P _PK T _G (a).

Now, in FIG. 2, when the standard μ _PK and μ ₁ ,
Assume that the boundary line of the equation (a) is a, and the current setting of T _G and P _PK is point A.

Now, in this example, when μ _PK decreases and μ ₁ increases,
The boundary line a moves to a '. For this reason, the setting of the point A is above the boundary line a ', and a pick mistake occurs.

(B) Double feed The occurrence of double feed is expressed by the following equation (b).

In FIG. 3, the boundary line of the equation (b) when each μ value is a standard is a straight line b.

In this example, μ _PK decreases (change amount Δμ _PK ), μ ₁ and μ ₂ increase (change amounts Δμ ₁ , Δμ ₂ ), μ _SB decreases (change amount Δμ _SB ), and μ rr does not change.

In the above equation (b), If μ ₂ R _r P ' _PK = B, Becomes

Whether the slope of the boundary increases or decreases depends on the following conditions.

◎ Conditions of increase In this equation, as one example when applied to an OCR device, R _SB = 37, r _SB = 14, μ _SB = 1.4, In the case of this example, since Δμ ₁ > 0 and Δμ _SB <0 Does not hold, so the slope of the boundary decreases.

In addition, at about B, △ μ ₂ increases due to the increase. In this state, as shown in FIG. 3, the slope of the straight line b decreases, and the intercept increases to become a straight line b '.

(C) Slip The condition for the occurrence of slip is given by the following equation.

In FIG. 3, a boundary line based on the above equation when each μ value is a standard is indicated by a straight line c.

In the above equation (c), The increase and decrease in the slope of the boundary line are as follows.

That is, the condition of increase is △ μ _SB > 0, and the condition of decrease is Δμ
_SB <0. Therefore, in the case of the present example, since Δμ _SB <0, the value decreases.

Moreover, the E around is increasing because of the [Delta] [mu ₁ increases, the slope of the straight line c in the graph shown in FIG. 3 is decreased, the sections becomes linearly c 'decreases.

Considering the above-mentioned considerations of double feed and slip, in FIG. 3, the inside of point efg, which is initially surrounded by straight lines b and c, is an area where double feed and slip can occur and stable paper feeding (separation) is possible. What was there
When the environment and the paper of this example are used, the state changed to a state where the inside of the point hij surrounded by b 'and c' is stable.

At this time, the point where various parameters are set considering the margins from the straight lines b and c inside the point efg according to the standard form or the standard environmental conditions cannot enter the point ijk. Will cause slippage.

Here, the following describes how the limit torque T according to the present invention is made variable.

(1) Pick error Since the parameter T is independent, it is necessary to reduce the gate resistance so that the pick can be picked up with a margin when the environment changes or when the form is thick, large, or with perforations (T _G
→ small) or increase the pick pressure (P _PK → large).

In addition, a combination of these (lowering the gate resistance and increasing the pick pressure) is applied.

A → A ′ in FIG. 2 corresponds to a change in T _G → small.

A → A ″ in FIG. 2 corresponds to a change in _PKP → large.

A → A in FIG. 2 corresponds to a change of _TG → small and _PK → large.

(2) Double feed and slip When _TG and _PK are changed, they change as follows.

◎ T _G → small (See Fig. 3) Double feed conditions Does not change because it is independent with respect to _TG .

Conditions for slipping , If T _G → small, the term (−RrT _G ) decreases,
In FIG. 3, the straight line c ′ shifts upward to become c ″,
As a result, a portion surrounded by an area klj in which neither double feed nor slip occurs stably, and the point B has not yet entered the stable area (but has come closer to the stable area).

Here, if the operation of varying the limit torque of the torque limiter of the present invention is performed and T → Small, the state of the sheet feeding section shifts from point B → B ′, and neither double feed nor slip occurs.

◎ P _PK → Large (See Fig. 4) Conditions for double feed In this case, if P _PK → large, the term (μ ₂ RrP ′ _PK ) increases, and the boundary line b ′ shifts upward to b ″ as shown in FIG.

The conditions for slipping , The term (-μ ₁ RrP _PK ) decreases when P _PK → increases, and the boundary c ′ shifts downward to c ″.

At this time, the stable region (region where neither double feed nor slip occurs) is in the range of klm, and point B further moves away from the stable region.

Here, when the operation of changing the limit torque of the torque limiter according to the present invention is performed and T is reduced, the state of the sheet feeding unit shifts from B to B 'and enters a stable region where double feed and slip do not occur.

As described above, by making T variable, stable paper feeding capacity can be obtained. However, when setting the value of T, the initial value should be increased in advance so that double feed does not easily occur and slip occurs easily. There is a merit when using a device such as OCR.

The form that has been double-fed is stopped at the paper feeding unit. If the limit torque value T of the torque limiter is lowered in this state, the document enters the reading unit and normal reading is performed.

In advance, set strongly for double feed,
The point of the present invention is to change the limit torque value of the torque limiter as required.

FIG. 5 is an explanatory view of the mechanism in one embodiment of the present invention, and the same reference numerals as those in FIG. 11 denote the same parts.

In the figure, 10 is a paper feeding section, 12 is a paper separating section, MO is a motor, CL is a clutch, BE is a belt, 18 is a pick roller, S is a stack of paper, P ₁ , P ₂ , and P ₃ are paper ( Papers such as forms), 30, 32, and 34 are pulleys, 38 is a separation belt, 28 is a torque limiter, 36 is a support bracket, LO is a transport roller, and DS1 and DS2 are paper position detection sensors.

As the torque limiter 28, an electromagnet type torque limiter having a structure capable of varying the limit torque by changing the voltage applied to the exciting coil is used.

Each of the paper position detection sensors DS1 and DS2 is a light-transmitting type (has a light-emitting unit and a light-receiving unit, and detects paper by receiving light from the light-emitting unit that has passed through the paper with the light-receiving unit)
The position of the paper is monitored (detection of the paper) using the sensor of (1).

In particular, the DS1 not only detects the position of the paper, but also the amount of paper. For example, whether one sheet of paper
This is for detecting whether the sheet is a sheet (in the case of double feed) or the like.

The paper position detecting sensor DS1 is
And DS2 is provided near the transport roller LO provided in the transport system prior to DS1.

FIG. 6 is a block diagram of a main part of a control system in the above embodiment.

In the figure, DS1 and DS2 are paper position detection sensors, 28 is a torque limiter, SP is a sensor signal processing unit, MC is a main control unit, M
D indicates a mechanical drive circuit (mechanical drive circuit).

The mechanical drive circuit MD sends a control voltage to the torque limiter 28 according to an instruction from the main control unit MC, and generates a predetermined limit torque.

The sensor signal processing unit SP processes the detection signals from the sheet position detection sensors DS1 and DS2, detects the position and amount of the sheet, and sends a signal to the main control unit MC.

FIG. 7 is a diagram showing an example of a load (holding torque) voltage characteristic of the torque limiter in the above embodiment.

In the figure, the horizontal axis shows the voltage [V] applied to the torque limiter, and the vertical axis shows the transport force F of the torque limiter.
[G] and limit torque T [g-cm].

In this example, the radius of the electromagnet type torque limiter is 2.25.
[Cm], and the applied voltage rating was 24 [V]. In addition,
The relation between the limit torque T and the conveying force F is T = 2.25F.

FIG. 8 to FIG. 10 are explanatory diagrams of the voltage applied to the torque limiter in the above embodiment.

A torque limiter having characteristics as shown in FIG. 7 is used, and the limit torque is made variable by controlling the applied voltage (electromagnetic torque limiter).

Further, using the mechanism as shown in FIG. 5, the paper position detection sensors DS1 and DS2 are arranged at the positions shown in the figure.

The voltage applied to the torque limiter a constant voltage V _1, leave the limit torque constant (see FIG. 8 A).

Start the feeding of the paper in this state, double feeds also the time required when passing between slip without any sensor DS1 and DS2 and t ₁ (FIG. 8 see B, C).

Assuming that the slip has occurred, it can be detected by the sensor DS1 since the beginning paper no paper entering the sensor DS2 to ₁ hour after t.

In this case, when it is confirmed that paper does not enter the sensor DS2 even after _one hour elapses after the paper enters the sensor DS1 (see FIG. 9B) (see FIG. 9C), the voltage is applied to the torque limiter. The voltage (limit torque) is reduced to V ₂ (V ₂ <V ₁ ) (see FIG. 9A).

In this way, no longer slip, the paper proceeds again, the tip enters t ₂ hours after sensor DS2 (see FIG. 9 C).

Furthermore, the paper proceeds from here, or provided with a strong feed roller to enter the time again limit torque is sure to allow (t ₃ hours after) grip force to processing, such as raising the following form to V _1, or, V Leave as ₂ .

When a double feed occurs and the sensor DS1 detects it (see Fig. 10B), the voltage applied to the torque limiter is reduced.
Increase from V ₁ to V ₃ (V ₁ <V ₃ ) (see FIG. 10A).

As a result, the lower sheet is stopped by the torque limiter, and the first sheet is soon passed (see FIG. 10C), and after ₄ hours t, the sheet becomes a single sheet.

Here the V ₁ is returned back to the original limit torque value (the
Prepare for the next process, or leave the limit torque value (V ₃ ) as it is, and when it is determined that a slip has occurred, perform the process for the above-mentioned slip.

By performing the above control in combination, a series of sheet feeding operations can be performed.

〔The invention's effect〕

As described above, the present invention has the following effects.

(1) By combining two paper position detection sensors and a torque limiter capable of arbitrarily varying the limit torque, double feed and slip can be actively suppressed.

(2) Since the torque limiter can change the limit torque only by changing the applied voltage, the paper feed performance can be stably and improved by simple control.

(3) If the paper feed section is set in advance in advance of slipping so that double feed is unlikely to occur under any conditions,
Paper feed processing can be performed without operator intervention.

[Brief description of the drawings]

FIG. 1 is a principle diagram of a sheet feeding control method in a sheet feeding device according to the present invention, FIG. 2 is an explanatory diagram of parameters in one embodiment of the present invention, and FIG. 3 and FIG. Fig. 5, Fig. 5 is an explanatory view of the mechanism in the above embodiment, Fig. 6 is a block diagram of a main part of the control system in the above embodiment, Fig. 7 is a diagram of load and voltage characteristics of the torque limiter, Figs. FIG. 10 is an explanatory diagram of a voltage applied to the torque limiter, FIG. 11 is an explanatory diagram of a paper feeding principle of a conventional paper feeding device, FIG. 12 is an explanatory diagram of a main part of the device shown in FIG. 13 Figure is a diagram depicting the contradictory parameters, FIG. 14 is an explanatory view showing a slip occurrence, the double feed occurrence in relation to the parameters T and P _B, FIG. 15, parameters illustration, FIG. 16, It is a partial explanatory view of a mechanism. 10 ... Paper feeding section, 12 ... Paper separation section, 28 ... Torque limiter (electromagnetic type), DS1, DS2 ... Paper position detection sensor.

Claims (1)

(57) [Claims] 1. A sheet feeding section provided with a pick roller which presses and engages with a stack in order to sequentially feed sheets and forms from the stack, and separates and feeds the fed sheets and forms. Paper limiter having a variable torque limiter and a paper separating section having a separate rolling element that is rollingly engaged with the torque limiter, and detects the position and amount of fed-out paper and forms, etc. In a paper feed control method of a paper feeder provided with a sensor, an applied voltage set as an initial value to the torque limiter is set to a standard value so that double feed of paper and forms is hardly generated and slip is easily generated. When the paper position detection sensor detects slippage or double feed of paper and forms, the torque limiter is set based on the detection information. By controlling the applied voltage to change the limit torque, whereby the paper feed control method in the sheet feeding device being characterized in that to allow the paper feed in the absence of slippage or double feeding.