KR101248992B1 - Letter feeder which can control the space between supplied letters - Google Patents

Abstract

Postal mail supply device 10 according to the present invention, the mail mail supply unit 310 for transporting the mails 600 standing up; A suction conveying unit 320 which vacuum-adsorbs the uppermost postal matter 601 located at the first end by vacuum suction when the postal matters 600 reach through the postal matter supplying unit 310, and separates them from the postal matters 600; A pair of engagement rollers 731 installed at the rear end of the suction conveying unit 320 so as to take the uppermost postal matter 601 conveyed by the suction conveying unit 320 and mesh the uppermost postal matter 601 from both sides. 732); And a control unit 200 for controlling driving of the postal matter supply unit 310, the suction transfer unit 320, and the engagement rollers 731 and 732. According to the present invention, it is possible to supply a single piece of mail efficiently through the vacuum suction method. In addition, it is possible to prevent the postal matters from being superimposed through various complementary means, for example, the stop plate 331, the stripper film 332, the air blower 331a, the stripper block 360, and the like. In addition, through the feedback control through the photosensors (741, 742, 751, 752) it is possible to control the transport interval of the mail uniformly to prevent the failure of the equipment or errors of automation in advance.

Description

Letter feeder which can control the space between supplied letters

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a postal mail supply device, and more particularly, to a postal mail supply device capable of controlling a delivery interval of a postal mail when supplying a postal mail to an automated postal mail processing facility.

The most important thing in the automatic mail processing automation facility, which is expressed in various ways, such as a small trade branch, a mail order separator, is to supply mails one by one to the automation facility. When stacking mails piled up one by one and supplying them to an automated facility, they need to be separated into sheets and supplied one by one so that barcodes can be correctly recognized for all mails without jams or skips. to be.

In Korea's postal intensive countries, automatic small commercial branches are introduced to reconsider the efficiency of postal delivery. Arrival / Shipping classification refers to classification of mail as a destination to be sent by performing postal code recognition, address recognition, barcode printing and reading. Prior to the introduction of the small trade branch, this was done manually.

The small trade branch was developed mainly for postal code recognition, address recognition, bar code printing and reading, but with the recent development of these recognition technologies, we have been interested in the smooth flow of mail. In order to ensure that the mail flows smoothly in the automated mail handling facility, the sheet feed must be preceded first. Until now, although there was interest in supplying a single piece of mail, there were many difficulties in the automation process due to the frequent phenomenon that several mails were overlapped and supplied.

Therefore, the problem to be solved by the present invention, when supplying the mail to the automatic mail processing equipment, it is possible to control the delivery interval of the mail at the same time to be supplied in a single sheet without overlapping multiple mails to provide an efficient mail supply device for automation of mail processing To provide.

Mailing device according to the present invention for achieving the above object,

A mail supply unit for transporting mails in an upright position;

A suction conveying unit which vacuum-sucks the highest-most postal matter positioned at the leading end when the postal items arrive through the postal mail supply unit and separates and transports them from the postal items;

A pair of engaging rollers installed at a rear end of the suction conveying unit so as to take the uppermost postal matters conveyed by the suction conveying unit and to convey the uppermost postal matters on both sides; And

And a control unit for controlling the driving of the postal matter supply unit, the suction conveyance unit, and the engagement roller.

The suction transfer unit,

A drive roller rotating by a motor;

A driven roller which rotates by receiving the rotational force of the driving roller;

Suction means provided between the driving roller and the driven roller to vacuum suction the uppermost postal matter of the postal mail supply unit; And

An adsorption belt which connects the driving roller and the driven roller so as to transfer the rotational force of the driving roller to the driven roller, and is installed to adsorb the uppermost postal matter sucked by the suction means; It is preferable to comprise a.

Here, it is preferable that a plurality of through holes are formed in the suction belt, and the suction belt is composed of a plurality of unit belts spaced apart from each other by a predetermined interval.

Two optical sensors are installed at predetermined intervals along the conveying direction of the post to detect the postal matter adsorbed by the adsorption belt and to detect the postal interval of the postal matter, and the control unit detects the postal matter through the two optical sensors. It is preferable to control the rotational speed of the drive roller by using the conveying interval of the mail as an input signal.

The control unit rotates the driving roller slowly when the conveyance interval of the postal matter detected by the two optical sensors is smaller than the reference setting value, and the control unit rotates the driving roller slowly. It is preferable to control the drive roller to rotate quickly.

Each of the optical sensors includes a light emitting unit and a light receiving unit which are installed to face each other with the suction belt interposed therebetween, so that the uppermost postal matter is detected through whether the light emitted from the light emitting unit reaches the light receiving unit. Do.

One of the two optical sensors is installed to detect the mail passing through the roller located in the conveying direction of the uppermost mail among the driving roller and the driven roller, and the other is installed to detect the mail passing through the engagement roller. desirable.

Each of the engaging rollers is provided with a conveying belt for drawing a closed curve, respectively, to engage the uppermost postal matter on both sides, one of the engaging rollers is a fixed roller and the other is variable to be spaced apart from the fixed roller. It is preferable to install as a roller.

According to the present invention, the postal matter may be supplied in a single sheet by vacuum suction. Furthermore, the possibility of overlapping feed, which may be manifested by the vacuum suction method, is prevented by various complementary means, such as the stop plate, stripper film, air blower, stripper block, air hose and the like. In addition, the feedback control through the optical sensor can be controlled to control the interval of mail delivery, so that it is possible to prevent equipment failure or automation errors in advance.

1 is an overall schematic diagram for explaining an automatic mail processing facility 1 to which a mail supply device 10 according to the present invention is applied;
2 is an external schematic view illustrating a mail supply apparatus 10 according to the present invention;
3 is a block diagram illustrating the mail supply apparatus 10 according to the present invention;
4 to 7 are views for explaining the driving unit 300;
8 to 10 are views for explaining the suction transfer unit 320;
11 and 12 are diagrams for describing feedback control through an optical sensor.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. The following examples are only presented to understand the content of the present invention, and those skilled in the art will be capable of many modifications within the technical spirit of the present invention. Therefore, the scope of the present invention should not be construed as limited to these embodiments.

[Postal Automation Processing Facility (1)]

1 is an overall schematic diagram for explaining an automatic mail processing apparatus 1 to which a mail supply apparatus 10 according to the present invention is applied. As shown in FIG. 1, the automated mail processing facility 1 includes a feeder module 10, a mechanical rejector module 20, a scanner module 30, and a delay module. module 40, printer module 50, reader module 60, conjunction module 70, vertical module 80, twisting module 90 , And a stacker module 100.

The mail supply device 10 performs a function of aligning mails and supplying them in a single sheet, and the pre-rejection module 20 is configured to provide a bad mail item such as an out-of-standard mail, a mail containing metal material, a mail that is floating or twisted and is not in a normal position. Perform the filtering function.

The scanner module 30 performs a function of reading a postal code and an address as an image, and the delay module 40 delays about 12 seconds to check the postal mail which is not recognized by the scanner module 30 and then rebuilds it. To perform the function.

The printer module 50 performs a function of printing a bar code barcode on the read mail, and the reader module 60 performs a function of reading and verifying a barcode printed by the printer module 50. The connection module 70 is a device for lying down and transferring mails for step sorting as a step before the image reading, printing, and verification work is finished, and the mails are determined to be transferred to the sorting box.

The vertical module 80 is a vertical transportation section that separates mails by destination, and the twisting module 90 is laid down in the connection module 70 to send the mails of which step separation is completed by destination to the destination pocket. It is a section that puts the mail in a vertical position again. The stacker module 100 is a section for classifying and loading mails in a division box assigned to each destination.

Although each module plays an important role in the above-mentioned automatic mail processing facility, in order to ensure that the mail flows smoothly in each module, the mail is supplied in a single sheet from the mail supply device 10. This is because when a plurality of mail items are supplied overlapped, a mail jam or a skip may occur.

The postal mail supply device 10 according to the present invention is not only applicable to the automated postal mail processing facility 1 of FIG. 1, but may be configured by modifying the postal mail supply device 10 in various forms.

[Postal supply device 10]

FIG. 2 is a schematic diagram for explaining the mail supply apparatus 10 according to the present invention, and FIG. 2 and 3, the mail supply device 10 according to the present invention is largely composed of a control unit 200 and the drive unit 300, the drive unit 300 is a mail supply unit 310, suction conveying unit ( 320 and engagement rollers 371 and 372.

The mail supply unit 310 includes a supply belt 311 and a separating blade 312, and the suction conveying unit 320 includes a driving roller 321, a driven roller 322, a suction belt 323, and a suction unit. 324, and a stripper block 360.

[Drive unit 300]

4 to 7 are diagrams for describing the driving unit 300, FIG. 4 is a plan view, and FIGS. 5 to 7 are perspective views.

4 to 7, the driving unit 300 is largely divided into the mail supply unit 310, the suction transfer unit 320, and the engagement rollers 371 and 372 as described above. The mail supply unit 310 is responsible for the function of transporting the mails 600 are arranged in series a plurality of postal mail, and comprises a supply belt 311 and the separating blade 312 and the like. In addition, the suction conveying unit 320 vacuum-adsorbs the uppermost postal matter 601 located at the top end by vacuum adsorption through the postal mail supplying unit 310 to separate the postal matter 600 from the postal matters 600, for example, a subsequent facility, for example. It is responsible for the transfer to the pre-reject module 20, and comprises a drive roller 321, driven roller 322, suction belt 323, suction means 324, stripper module 360 and the like. In FIG. 6, the illustration of the suction belt 323 is omitted for convenience of understanding.

Mail Supply Unit (310)

The postal matter supply unit 310 includes a supply belt 311, a separating blade 312, and the like, and the postal matters 600 are mounted on the supply belt 311 and transported. A separating blade 312 for pushing the posts 600 back on the feed belt 311 so that the posts 600 are moved to the suction conveying part 320 while standing up on the feed belt 311 without lying on the feed belt 311. It is installed perpendicular to the

The rail 313 is installed along the supply belt 311, and the rail block 314 is installed to slide horizontally along the rail 313. The separating blade 312 is installed to be connected to the rail block 314. A blade insertion groove 311a is formed in the supply belt 311, and the separating blade 312 is installed to be detachably attached to the blade insertion groove 311a. Therefore, the separating blade 312 moves together with the supply belt 311 while being fitted in the blade insertion groove 311a. The separation of the separating blade 312 from the blade insertion groove 311a may be implemented by using the elasticity between the rail block 314 and the separating blade 312 or installing the rail 313 to be elevated.

Suction transfer part 320

The suction conveying part 320 includes a driving roller 321, a driven roller 322, a suction belt 323, a suction means 324, and a stripper block 360, and the like of the separating blade 312. The front end mails 601 are vacuum- suctioned from the mails 600 at the front end, and the mails are sent to the subsequent equipment, for example, the pre-rejection module 20, in a single sheet.

The driving roller 321 and the driven roller 322 are installed to face the separating blade 312. The driving roller 321 is rotated by the servo motor, and the power transmission between the driving roller 321 and the driven roller 322 is made by the suction belt 323.

A suction means 324 having suction holes 324a and 324b is installed between the driving roller 321 and the driven roller 322 to vacuum suction the uppermost post 601 on the supply belt 311. The uppermost postal matter 601 sucked by the means 324 is sucked by the suction belt 323 and transported. Above the suction belt 323, a bracket 350 for guiding the movement of the uppermost postal matter 601 is installed.

When the front end mail 601 is transported by the suction belt 323, the remaining rear end mails are carried in the direction in which the front end mail 601 is transported by the frictional force between the mails and the suction force by the suction means 324. It is preferable that a stop plate 331 is installed on the side of the supply belt 311 so as not to be separated from the supply belt 311.

In order to more effectively prevent a plurality of pieces of mail from being absorbed by the adsorption belt 323 and accompanying movement at once, the stopper plate 331 is provided with a stripper film 332 at the end facing the adsorption belt 340. It is preferable.

Mails 600 on the supply belt 311 is because the mails may be stuck to each other by the electrostatic force or the like, so that the stop plate 331 to the posts 600 on the supply belt 311 so that they can easily fall into a single sheet An air jet port 331a for blowing air between the posts at the side of the posts 600 is preferably provided on the front side of the face.

Even if there is a stop plate 331, a stripper block (360) is installed at the rear of the stop plate 331 in fear that the mail may be transported to the suction belt 323 in a stack.

The stripper block 360 is installed to face the adsorption belt 323 so as to contact the front end post 601, thereby acting to distance the rear end post conveyed together with the front end post 601 through frictional force. To this end, the stripper block 360 is provided with a soft polymer material, such as urethane rubber, which can impart contact friction to the contact surface with the front end post 601.

Rather than the entire surface of the uppermost postal matter 601 conveyed by the supply belt 311 being sucked by the suction means 324 at one time, a portion of the surface touches the suction belt 323 and the suction belt 323 is caused by contact resistance. It is more advantageous for the mail sheet supply to be moved by the suction) by the suction means 324. To this end, the idle rollers 341a, 341b, adjacent to the adsorption belt 323 toward the opposite side of the moving direction of the foremost mail 601 by the adsorption belt 323 to support the mails 600 at the foremost mail 601 side, 341c) is installed.

Then, the top end post 601 provided through the supply belt 311 contacts the idle rollers 341a, 341b, and 341c and the driven roller 322 at the same time, and at this time, the suction belt 323 and the end post 601 The uppermost post 601 moves toward the suction means 324 along the suction belt 323 by the contact resistance, and is finally completely in contact with the suction belt 323 by the vacuum suction input of the suction means 324.

Engagement Rollers (371,372)

A pair of engagement rollers 371 and 372 which engage the front end post 601 on both sides at the rear end of the adsorption belt 323 so as to take over and transport the front end post 601 adsorbed and transported by the adsorption belt 323. Is installed. Each of the engagement rollers 371 and 372 is covered with conveying belts 371a and 372a which draw a closed curve, respectively, so that the uppermost post 601 which is adsorbed and conveyed by the adsorption belt 323 is a pair of conveying belts 371a and 372a. It is sandwiched between) and transported to subsequent modules.

One of the engagement rollers 371 and 372 is a fixed roller 371 and the other is provided as the variable roller 372 so that the gap between the engagement rollers 371 and 372 is automatically adjusted. The variable roller 372 is connected to the rocker arm (373) and the rotating shaft pin (373a) is installed in the middle portion of the rocker arm (373).

The variable roller 372 is brought into contact with the fixed roller 371 by the tension caused by the rotation (arrow direction) of the conveying belt 372a forming a closed curve, and the fixed roller 371 and the variable roller 372 When the uppermost postal matter 601 is inserted into the gap therebetween, the variable roller 372 is opened at the fixed roller 371. At this time, the rocker arm 373 rotates the rotary shaft pin 373a to the axis, and the tension due to the rotation of the conveying belts 371a and 372a continues to act so that the variable roller 372 pushes the postal material 601 at the uppermost stage. Still exists. In FIG. 5 and FIG. 6, one of the two conveying belts 371a and 372a is omitted.

[Suction suction unit 320]

8 to 10 are views for explaining the suction transfer unit 320 in more detail. 8 to 10, a plurality of through holes 323h are formed in the suction belt 323 such that the vacuum suction input by the suction means 324 extends to the uppermost postal matter 601, and also the suction belt 323. ) Is composed of a plurality of unit belts (323a, 323b, 323c, 323d) spaced apart from each other by a predetermined interval. The reason why the suction belt 323 is composed of a plurality of unit belts 323a, 323b, 323c, and 323d is not only for transferring the vacuum suction input as described above, but also as described below, and the filler levers 620a and 620b and the stripper block 360. It is also to install) efficiently.

Ring grooves R1 and R2 are formed in the rollers that meet the posts 600 supplied from the supply belt 311 among the driving rollers 321 and the driven rollers 322, and the filler levers are located near the ring grooves R1 and R2. 620a and 620b are installed. In the figure, a case in which ring grooves R1 and R2 are formed in the driven roller 322 is illustrated. The ring grooves R1 and R2 are installed to be located between the plurality of unit belts 323a, 323b, 323c, and 323d.

The ring grooves R1 and R2 are preferably formed in two upper and lower portions, and the filler levers 620a and 620b are also preferably installed in two upper and lower portions corresponding to the ring grooves R1 and R2. The filler levers 620a and 620b are pushed into the ring grooves R1 and R2 when the mails 600 are in contact with the suction belt 323, and restored out of the ring grooves R1 and R2 when the mails 600 are not in contact. It is installed as possible.

To this end, the upper pillar lever 620a is installed such that one end is located in the upper ring groove R1 and the other end is located near the pillar lever proximity sensor 710. In addition, a rotary shaft pin 621 is installed at the center of the upper pillar lever 620a. When one end of the upper pillar lever 620a is pressed into the upper ring groove R1, the upper pillar lever 620a shafts the rotary shaft pin 621. The other end of the upper filler level 620a is rotated away from the filler lever proximity sensor 710. Then, the filler lever proximity sensor 710 recognizes such a distance and detects that the postal items 600 have reached the driven roller 322. A spring 711 is installed between the pillar lever proximity sensor 710 and the upper pillar lever 620a, and the upper pillar lever 620a is the spring 711 when the posts 600 do not touch the driven roller 322. By the pulling force of) is restored to the original state close to come out of the upper ring groove (R1).

Similarly to the upper pillar lever 620a, the lower pillar lever 620b is provided with a rotating shaft pin 621, a pillar lever proximity sensor 710, and a spring 711. The reason why the filler levers 620a and 620b are installed at the top and the bottom is that when only one of the upper and lower portions of the uppermost post 601 comes into contact with the adsorption belt 323, the adsorption may not be performed properly. . That is, to determine whether the upper and lower surfaces of the uppermost postal matter 601 have reached the adsorption belt 323.

If it is detected that the upper and lower pillar levers 620a and 620b are pushed into the upper and lower ring grooves R1 and R2 through the pillar lever proximity sensor 710 corresponding to the upper and lower pillar levers 620a and 620b, the controller The control unit 200 receives the input signal as an input signal to rotate the driving motor 321 and also stops the feeding of the supply belt 311.

The idle rollers 341a, 341b, and 341c retreat back when pressed by the mails 600, and are installed to be restored again when the enjoyment by the mails 600 is released. To this end, an idle roller lever 342 is installed in each of the idle rollers 341a, 341b, and 341c. The idle roller lever 342 is installed such that one end is connected to the idle rollers 341a, 341b, and 341c, and the other end is located near the idle roller lever proximity sensor 720. In addition, a rotation shaft pin 343 is installed at the center of the idle roller lever 342. Therefore, when the idle rollers 341a, 341b, and 341c are pushed backward, the idle roller lever 342 rotates the rotary shaft pin 343 to the axis to move away from the idle roller lever proximity sensor 720, and the idle roller lever proximity sensor 720 is Through this distance, the idle rollers 341a, 341b, and 341c are pushed back excessively than the reference value.

If it is detected that the idle rollers 341a, 341b, and 341c are pushed back beyond the reference value through the idle roller lever proximity sensor 720, the control unit 200 receives this as an input signal and stops the feeding of the supply belt 311. To control. The idle roller lever proximity sensor 720 may be installed to correspond to the idle rollers 341a, 341b, and 341c, respectively, but at least one of the idle roller levers adjacent to the suction belt 323, as shown in FIG. You can see the effect.

On the other hand, the optical sensor 730 is installed so as to look at the front end 601. The optical sensor 730 detects a gap between the uppermost postal matter 601 and the optical sensor 730 and feeds it back to the control unit 200, and the control unit 200 supplies the positional information of the uppermost postal matter 601 according to the position information. The conveyance of the belt 311 is controlled. For example, when the uppermost postal mail 601 is located far from the optical sensor 730, the feeding speed of the supply belt 311 is increased. When the rollers 341a, 341b, and 341c are excessively pressed in the position corresponding to the position, the safety belt may serve to stop the feeding of the supply belt 311.

[Light sensor]

The first optical sensors 741 and 742 and the second optical sensor 741 are spaced apart by a predetermined distance along the conveying direction of the uppermost postal matter 601 in order to detect a transport interval of the uppermost postal matter 601 that is adsorbed and transported by the suction belt 323. Optical sensors 751 and 752 are installed. Each optical sensor is composed of light emitting parts 741 and 751 and light receiving parts 742 and 752.

The light emitting units 741 and 751 are installed to irradiate light to the light receiving units 742 and 752 across the upper portion of the suction belt 323, and the light emitted from the light emitting units 741 and 751 is applied to the light receiving units 742 and 752. If it does not reach, the first postal mail 601 is detected as present, and in this manner, the transport interval of the first postal mail 601 in the section between the first optical sensors 741 and 742 and the second optical sensors 751 and 752. Will be able to figure out.

The first optical sensor 741, 742 is a roller located in the conveying direction of the front end post 601 of the driving roller 321 and the driven roller 322, that is, the mail passing through the driving roller 321 in this embodiment It is preferably installed to sense, and the second optical sensor 751, 752 is preferably installed to detect the postal matter passing through the engagement rollers 371, 372.

 The control unit 200 controls the rotational speed of the driving roller 321 using the feed intervals of the postal matters detected through the first optical sensors 741 and 742 and the second optical sensors 751 and 752 as input signals. For example, if the conveyance interval of the postal matter is smaller than the reference setting value, the drive roller 321 will be slowly rotated. If the conveyance interval of the postal matter is larger than the reference setting value, the drive roller 321 will be rapidly rotated.

According to the present invention as described above, it is possible to supply a single piece of mail efficiently through the vacuum suction method. In addition, it is possible to prevent the postal matters from being superimposed through various complementary means, for example, the stop plate 331, the stripper film 332, the air blower 331a, the stripper block 360, and the like. In addition, through the feedback control through the photosensors (741, 742, 751, 752) it is possible to control the transport interval of the mail uniformly to prevent the failure of the equipment or errors of automation in advance.

1: mail automated processing equipment 10: mail feeder
20: pre-deny module 30: scanner module
40: delay module 50: printer module
60: reader module 70: connection module
80: vertical module 90: twisting module
100: stacker module 200: control unit
300: drive unit 310: mail supply unit
311: Supply belt 311a: Blade insertion groove
312: Separating Blade 313: Rail
314: rail block 320: suction feed
321: driving roller 322: driven roller
323: suction belt 323a, 323b, 323c, 323d: unit belt
323h: through hole 324: suction means
324a, 324b: suction hole 331: stop plate
331a: air outlet 332: stripper film
341a, 341b, 341c: idle roller 342: idle roller lever
343, 621: Rotary pin 350: Bracket
360: stripper blocks 371, 372: engagement roller
371a, 372a: Transport belt 600: Mail items
601: Best mail 620a, 620b: Filler lever
710: pillar lever proximity sensor 711: spring
720: Idle roller lever proximity sensor 730, 741, 742, 751, 752: Light sensor
R1, R2: Ring Groove

Claims (9)

A mail supply unit for transporting mails in an upright position;
A driving roller which is rotated by a motor, a driven roller which is rotated by receiving the rotational force of the driving roller, suction means installed between the driving roller and the driven roller so as to vacuum-suck the postal matter at the end of the mail supply portion, and the drive; A suction conveying unit which connects the driving roller and the driven roller so as to transfer the rotational force of the roller to the driven roller, and has a suction belt which absorbs the most postal matter sucked by the suction means and separates and transports the postal matter;
A pair of engaging rollers installed at a rear end of the suction conveying unit so as to take the uppermost postal matters conveyed by the suction conveying unit and to convey the uppermost postal matters on both sides;
Two pieces are installed at predetermined intervals along the conveying direction of the post to detect the postal matter adsorbed on the adsorption belt and to detect the conveying interval of the postal material, one of which is the transfer of the postal material among the driving roller and the driven roller. An optical sensor installed to detect a postal matter passing through a roller positioned in a direction, and the other is installed to detect a postal matter passing through the engagement roller; And
A control unit which controls to rotate the drive roller slowly when the conveyance interval of the postal items detected through the two optical sensors is smaller than the reference set value, and to rotate the drive roller quickly when it is larger than the reference set value; , ≪ / RTI >
Each of the optical sensors includes a light emitting unit and a light receiving unit which are installed to face each other with the adsorption belt interposed therebetween, and are installed to detect the mail through whether the light emitted from the light emitting unit reaches the light receiving unit. Mail feeder. delete The mail supply apparatus according to claim 1, wherein a plurality of through holes are formed in the suction belt. The mail supply apparatus according to claim 1, wherein the suction belts comprise a plurality of unit belts spaced apart from each other by a predetermined interval. delete delete delete delete According to claim 1, wherein each of the engaging rollers is conveyed to each of the conveying belts to draw a closed curve to engage the mail on both sides, one of the engaging rollers is a fixed roller and the other is spaced apart from the fixed rollers Mail supply device characterized in that installed as a variable roller can be.

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