Conveyor system and method for assuring a continual backlog

Claim 3

The method of claim 1 comprising the additional step of supporting said articles on a conveyor while conveying said articles so as to allow articles in said backlog on said conveyor to slip with respect to said conveyor while being sensed.

Claim 4

A conveyor system which assures an adequate and continuous supply of conveyed items at the output thereof comprising: a supply conveyor means including a variable speed drive means for conveying said items at a variable rate; an accumulator conveyor means having an input communicating with the output of said supply conveyor, said accumulator conveyor means including accumulator drive means for conveying said items at a faster rate than any said variable rate of said supply conveyor; a retarder conveyor means including a retarder drive means having an input communicating with the output of said accumulator conveyor means, the speed of said retarder conveyor means being less than the speed of said accumulator conveyor means so as to permit a backlog of mutually abutting items to accumulate at said accumulator conveyor output without stopping said items at said accumulator conveyor output; a sensor means associated with said accumulator conveyor means for sensing the backlog of said accumulator conveyor means said sensor means comprising a series of uniformly spaced optical sensors extending along said accumulator conveyor means, said optical sensors having a maximum spacing substantially equal to the maximum dimension of said conveyed items in the direction of advance along said accumulator conveyor means so as to provide a signal representing a count of mutually abutting and mutually spaced conveyed items on said accumulator conveyor means regardless of the position of said items on said conveyor means relative to said optical sensors; and a variable speed control means having an input coupled to said sensor means and an output coupled to said variable speed drive means so as to control the speed of said supply conveyor means and the advancement of said conveyed items to said accumulator conveyor means in response to said signal representing said count so as to assure an adequate backlog at said accumulator conveyor output.

Claim 5

A conveyor system which assures an adequate and continuous supply of conveyed items at the output thereof comprising: a supply conveyor means including a variable speed drive means for conveying said items at a variable rate; an accumulator conveyor means having an input communicating with the output of said supply conveyor, said accumulator conveyor means including accumulator drive means for conveying said items at a faster rate than any said variable rate of said supply conveyor; a retarder conveyor means including a retarder drive means having an input communicating with the output of said accumulator conveyor means, the speed of said retarder conveyor means being less than the speed of said accumulator conveyor means so as to permit a backlog of mutually abutting items to accumulate at said accumulator conveyor output without stopping said items at said accumulator conveyor output; a sensor means associated with said accumulator conveyor means for sensing the backlog of said accumulator conveyor means said sensor means comprising a series of uniformly spaced optical sensors extending along said accumulator conveyor means, said optical sensors having a maximum spacing substantially equal to the maximum dimension of said conveyed items in the direction of advance along said accumulator conveyor means so as to provide a signal representing a count of mutually abutting and mutually spaced conveyed items on said accumulator conveyor means regardless of the position of said items on said conveyor means relative to said optical sensors; and a variable speed control means having an input coupled to said sensor means and an output coupled to said variable speed drive means so as to control the speed of said supply conveyor means and the advancement of said conveyed items to said accumulator conveyor means in response to said signal representing said count so as to assure an adequate backlog at said accumulator conveyor output.

Claim 6

The system of claim 3 wherein said sensor means further comprises a series of relays associated with said series of optical sensors, said variable speed control means including resistors connected and disconnected by said relays so as to change the speed of said variable speed drive in response to the number of conveyed items on said accumulator conveyor.

Claim 7

The system of claim 3 wherein said retarder conveyor means comprises a pair of continually driven endless conveyor members engaging opposite sides of each of said conveyed items at said output end of said accumulator conveyor means.

Claim 8

The system of claim 5 wherein said pair of conveyor means includes downwardly extending lugs at spaced positions on said conveyor means so as to engage said conveyed items between a pair of lugs on each of said conveyor members at said output end of said accumulator conveyor means.

Claim 9

The system of claim 6 wherein said retarder conveyor means further comprises a pair of inclined slide members extending from said pair of conveyor members.

Claim 10

The system of claim 3 including additional sensor means associated with said accumulator conveyor means for sensing the absence of a backlog immediately adjacent the retarder conveyor means and relay means associated with said additional sensor means for interrupting advancement of said retarder conveyor means.

Claim 11

The system of claim 8 wherein said additional sensor means comprises an optical sensor.

Claim 12

The conveying system of claim 3 wherein said variable speed control means comprises: Ac power supply means; a silicon-controlled rectifier coupled to said power supply means and said variable speed drive means comprising a DC motor for applying DC power to said DC motor in response to the firing of said silicon-controlled rectifier; a DC source; a firing pulse control circuit coupled to said silicon-controlled rectifier for firing said rectifiers in timed relationship with the AC power generated by said power supply means, said pulse generating means comprising a pulse generator and variable resistance means controlling the timing of the pulses generated by said pulse generating means, said variable resistance means including: a first series of resistors; and a second series of resistors having a total resistance equal to the total resistance of said first series of resistors; said first series of resistors being connected in series with said second series of resistors across said DC source, the junction of said first series and said second series forming a control terminal connected to said pulse generator; and a plurality of switch means associated with said first series of resistors and said second series of resistors, each of said switch means capable of short-circuiting one resistor in one of said series so as to remove said one resistor from said one series while simultaneously placing another resistor in the other of said series in response to said sensor means so as to vary the voltage at said control terminal without varying the effective resistance in said first series and said second series across said DC signal source.

Claim 13

The system of claim 10 wherein said sensor means comprises a series of optical sensors extending along said accumulator conveyor means, said optical sensors having a spacing substantially equal to the maximum dimension of said conveyed items in the direction of advance along said accumulator conveyor means, said plurality of switch means being connected and responsive to said series of optical sensors.

Claim 14

The system of claim 3 further comprising a series of light sources extending along said accumulator conveyor means on one side thereof, said optical sensors being located on the other side of said accumulator conveyor means and aligned with said light sources such that items on said accumulator conveyor means will interrupt light beams directed across said accumulator conveyor means from said light sources to said optical sensors the width of said light beams as measured in the direction of advance along said accumulator means being substantially less than said maximum dimension of said conveyed items.

Claim 15

A conveyor system which assures an adequate and continuous supply of conveyed items at the output thereof comrpising: a supply conveyor means including a variable speed drive means for conveying said items at a variable rate; an accumulator conveyor means having an input communicating with the output of said supply conveyor, said accumulator conveyor means including accumulator drive means for conveying said items at a faster rate than any said variable rate of said supply conveyor; a retarder conveyor means including a retarder drive means having an input communicating with the output of said accumulator conveyor means, the speed of said retarder conveyor means being less than the speed of said accumulator conveyor means so as to permit a backlog of mutually abutting items to accumulate at said accumulator conveyor output without stopping said items at said accumulator conveyor output; a sensor means associated with said accumulator conveyor means for sensing the backlog of said accumulator conveyor means said sensor means comprising a series of uniformly spaced sensors extending along said accumulator conveyor means, said sensors having a maximum spacing substantially equal to the maximum dimension of said conveyed items in the direction of advance along said accumulator conveyor means so as to provide a signal representing a count of mutually abutting and mutually spaced conveyed items on said accumulator conveyor means regardless of the position of said items on said conveyor means relative to said sensors, said sensors having a sensing area measured in the direction of advance along said accumulator conveyor means substantially less than the maximum dimension of said conveyed items in the direction of advance along said accumulator conveyor means; and a variable speed control means having an input coupled to said sensor means and an output coupled to said variable speed drive means so as to control the speed of said supply conveyor means and the advancement of said conveyed items to said accumulator conveyor means in response to said signal representing said count so as to assure an adequate backlog at said accumulator conveyor output.

Claim 16

A conveyor system which assures an adequate and continuous supply of conveyed items at the output thereof comrpising: a supply conveyor means including a variable speed drive means for conveying said items at a variable rate; an accumulator conveyor means having an input communicating with the output of said supply conveyor, said accumulator conveyor means including accumulator drive means for conveying said items at a faster rate than any said variable rate of said supply conveyor; a retarder conveyor means including a retarder drive means having an input communicating with the output of said accumulator conveyor means, the speed of said retarder conveyor means being less than the speed of said accumulator conveyor means so as to permit a backlog of mutually abutting items to accumulate at said accumulator conveyor output without stopping said items at said accumulator conveyor output; a sensor means associated with said accumulator conveyor means for sensing the backlog of said accumulator conveyor means said sensor means comprising a series of uniformly spaced sensors extending along said accumulator conveyor means, said sensors having a maximum spacing substantially equal to the maximum dimension of said conveyed items in the direction of advance along said accumulator conveyor means so as to provide a signal representing a count of mutually abutting and mutually spaced conveyed items on said accumulator conveyor means regardless of the position of said items on said conveyor means relative to said sensors, said sensors having a sensing area measured in the direction of advance along said accumulator conveyor means substantially less than the maximum dimension of said conveyed items in the direction of advance along said accumulator conveyor means; and a variable speed control means having an input coupled to said sensor means and an output coupled to said variable speed drive means so as to control the speed of said supply conveyor means and the advancement of said conveyed items to said accumulator conveyor means in response to said signal representing said count so as to assure an adequate backlog at said accumulator conveyor output.