Magnetic tape unit reel motor tension control

Claim 2

In a magnetic tape unit having tape buffer means, reversible capstan means disposed to supply tape to one side of said buffer means, and reversible reel means disposed to supply tape to the other side of said buffer means, the improvement comprising: reel control means responsive to the quantity of tape in said buffer means and to the direction of rotation of said capstan means, and connected in controlling relation to said reel means; said reel control means being effective to maintain a minimum quantity of tape in said buffer means when said capstan means is removing tape therefrom by instituting a drive mode of operation for said reel means to move tape into said buffer means when the quantity of tape in said buffer means is less than said minimum quantity, and to instituting a brake mode of operation for said reel means when the quantity of tape in said buffer means is more than said minimum quantity; said reel control means being effective to maintain a maximum quantity of tape in said buffer means when said capstan means is moving tape thereinto, by instituting a drive mode of operation for said reel means to remove tape from said buffer means when the quantity of tape is greater than said maximum quantity, and to institute a brake mode of operation when the quantity of tape in said buffer means is less than said maximum quantity; and means responsive to the direction in which the quantity of tape in said buffer means is changing, including means differentially sensing the tape speed on opposite sides of said buffer means, connected to modify the operation of said reel control means to inhibit the drive mode of operation of said reel means whenever said reel means is moving tape faster than said capstan means is moving tape and to additionally inhibit the brake mode of operation of said reel means when said reel means is moving tape slower than said capstan means is moving tape and said capstan means is removing tape from said buffer means.

Claim 3

A magnetic tape unit as defined in claim 1 wherein the inhibiting of said drive mode and the inhibiting of said brake mode institutes a coast mode of operation of said reel means.

Claim 4

institute a drive mode for said machine reel motor in a direction to remove tape from said machine vacuum column when the loop of tape in said machine vacuum column is in said lower zone,

Claim 5

institute a drive mode for said machine reel motor in a direction to remove tape from said machine vacuum column when the loop of tape in said machine vacuum column is in said lower zone,

Claim 6

institute a drive mode for said machine reel motor in a direction to move tape into said machine vacuum column when the loop of tape in said machine vacuum column is in said upper zone,

Claim 7

institute a drive mode for said machine reel motor in a direction to move tape into said machine vacuum column when the loop of tape in said machine vacuum column is in said upper zone,

Claim 8

institute a brake mode for said file reel motor when the loop of tape in said file vacuum column is above said lower zone, and

Claim 9

institute a brake mode for said file reel motor when the loop of tape in said file vacuum column is above said lower zone, and

Claim 10

institute a brake mode for said file reel motor when the Loop of tape in said file vacuum column is below said upper zone, and

Claim 11

institute a brake mode for said file reel motor when the Loop of tape in said file vacuum column is below said upper zone, and

Claim 12

A magnetic tape unit as defined in claim 2 wherein said means responsive to the direction in which the quantity of tape in said buffer means is changing includes a first tachometer driven by said capstan, a second tachometer driven by the tape on the reel means side of said buffer means, and means comparing the outputs of said tachometers.

Claim 13

A magnetic tape unit as deFined in claim 3 wherein said first and second tachometers are digital tachometers whose output frequency increases with the speed of rotation thereof, and wherein said comparing means compares said output frequencies to originate a reel-fast or a reel-slow output.

Claim 14

institute a drive mode for said file reel motor in a direction to move tape into said file vacuum column when the loop of tape in said file vacuum column is in said upper zone, first and second speed comparing means including a first digital tachometer driven in accordance with the speed of the tape adjacent said capstan means, second and third digital tachometers driven in accordance with the speed of the tape adjacent said file reel and said machine reel respectively, and first and second frequency comparator means each having one input connected to one of said second and third tachometers, said frequency comparator means providing a binary output indicative of the speed of the tape adjacent a reel as compared to the speed of the tape adjacent the capstan means, said first and second speed comparing means being responsive to the difference between the speed of the tape on opposite sides of said file and machine vacuum columns respectively, and connected to said first and second logic means, respectively, to inhibit the drive mode of that reel motor whose tape speed on the reel side of its vacuum column is the higher speed, and to inhibit the brake mode of said file reel motor when the tape speed on the capstan means side of said file vacuum column is the higher speed; and means connecting said first and second logic means in controlling relation to said file reel motor and said machine reel motor to institute the following control order for said motors when said capstan is moving tape in a backward direction from said machine reel to said file reel;

Claim 15

institute a drive mode for said file reel motor in a direction to move tape into said file vacuum column when the loop of tape in said file vacuum column is in said upper zone, first and second speed comparing means including a first digital tachometer driven in accordance with the speed of the tape adjacent said capstan means, second and third digital tachometers driven in accordance with the speed of the tape adjacent said file reel and said machine reel respectively, and first and second frequency comparator means each having one input connected to one of said second and third tachometers, said frequency comparator means providing a binary output indicative of the speed of the tape adjacent a reel as compared to the speed of the tape adjacent the capstan means, said first and second speed comparing means being responsive to the difference between the speed of the tape on opposite sides of said file and machine vacuum columns respectively, and connected to said first and second logic means, respectively, to inhibit the drive mode of that reel motor whose tape speed on the reel side of its vacuum column is the higher speed, and to inhibit the brake mode of said file reel motor when the tape speed on the capstan means side of said file vacuum column is the higher speed; and means connecting said first and second logic means in controlling relation to said file reel motor and said machine reel motor to institute the following control order for said motors when said capstan is moving tape in a backward direction from said machine reel to said file reel;

Claim 16

institute a drive mode for said file reel motor in a direction to remove tape from said file vacuum column when the loop of tape in said file vacuum column is in said lower zone, said first and second comparing means being additionally effective to inhibit the brake mode of said machine reel motor when the tape speed on the capstan means side of said machine vacuum column is the higher speed.

Claim 17

institute a drive mode for said file reel motor in a direction to remove tape from said file vacuum column when the loop of tape in said file vacuum column is in said lower zone, said first and second comparing means being additionally effective to inhibit the brake mode of said machine reel motor when the tape speed on the capstan means side of said machine vacuum column is the higher speed.

Claim 18

A magnetic tape unit having a vacuum column, a tape reel located on one side of the vacuum column, a motor connected to said reel, and a bidirectionally rotatable capstan located on the other side of the vacuum column, the improvement comprising: sensing means including two position sensors, providing binary outputs, spaced along the vacuum column to define an upper, an intermediate and a lower zone therein; a binary signal source indicative of the direction of capstan rotation; logic means controlled by the binary outputs of said position sensors and by the direction of rotation of the capstan, and connected to control the reel motor to institute a drive mode of operation for the motor in a direction to move tape into said column when the loop is in the upper zone and the capstan is removing tape from said column; to institute a drive mode of operation for the motor in a direction to move tape out of said column when the loop is in the lower zone and the capstan is moving tape into said column; and to institute the brake mode of operation for the motor when the loop is in the intermediate zone; and speed comparing means responsive to the speed of the tape on the reel side and on the capstan side of the vacuum column, and providing a binary output which is connected to control said logic means, said binary output having one state which is effective to inhibit said drive modes when the speed of the tape on the reel side of the vacuum column is the higher speed, and having a second state which is compared to the binary signal source indicative of the direction of capstan rotation to selectively inhibit said brake mode when the speed of the tape on the capstan side of the vacuum column is the higher speed and the direction of rotation of said capstan is such as to remove tape from the vacuum column; said speed comparing means including first and second digital tachometers, one of which is driven in accordance with the speed of the tape adjacent the reel and the other of which is driven in accordance with the speed of the tape at the capstan, and frequency comparator means having input means connected to said tachometer and providing said binary output.

Claim 19

A magnetic tape unit having a vacuum column, a tape reel located on one side of the vacuum column, a motor connected to said reel, and a bidirectionally rotatable capstan located on the other side of the vacuum column, the improvement comprising: sensing means including two position sensors, providing binary outputs, spaced along the vacuum column to define an upper, an intermediate and a lower zone therein; a binary signal source indicative of the direction of capstan rotation; logic means controlled by the binary outputs of said position sensors and by the direction of rotation of the capstan, and connected to control the reel motor to institute a drive mode of operation for the motor in a direction to move tape into said column when the loop is in the upper zone and the capstan is removing tape from said column; to institute a drive mode of operation for the motor in a direction to move tape out of said column when the loop is in the lower zone and the capstan is moving tape into said column; and to institute the brake mode of operation for the motor when the loop is in the intermediate zone; and speed comparing means responsive to the speed of the tape on the reel side and on the capstan side of the vacuum column, and providing a binary output which is connected to control said logic means, said binary output having one state which is effective to inhibit said drive modes when the speed of the tape on the reel side of the vacuum column is the higher speed, and having a second state which is compared to the binary signal source indicative of the direction of capstan rotation to selectively inhibit said brake mode when the speed of the tape on the capstan side of the vacuum column is the higher speed and the direction of rotation of said capstan is such as to remove tape from the vacuum column; said speed comparing means including first and second digital tachometers, one of which is driven in accordance with the speed of the tape adjacent the reel and the other of which is driven in accordance with the speed of the tape at the capstan, and frequency comparator means having input means connected to said tachometer and providing said binary output.

Claim 20

A magnetic tape unit having a file reel, a motor connected thereto, a file vacuum column adjacent said file reel, a machine reel, a motor connected thereto, a machine vacuum column adjacent said machine reel, and capstan means disposed intermediate said vacuum columns, the improvement comprising: means providing a binary output signal indicative of forward or backward rotation of said capstan means; first and second position sensing means, including two spaced position sensors in each of said vacuum columns to define an upper, an intermediate and a lower zone in each column, each of said sensors providing a binary output in accordance with the loop position; first and second logic means controlled by said first and second position sensing means respectively and by the direction in which said capstan means is moving tape; means connecting said first and second logic means in controlling relation to said file reel motor and said machine reel motor to institute the following control order for said motors when said capstan is moving tape in a forward direction from said file reel to said machine reel;

Claim 21

A magnetic tape unit having a file reel, a motor connected thereto, a file vacuum column adjacent said file reel, a machine reel, a motor connected thereto, a machine vacuum column adjacent said machine reel, and capstan means disposed intermediate said vacuum columns, the improvement comprising: means providing a binary output signal indicative of forward or backward rotation of said capstan means; first and second position sensing means, including two spaced position sensors in each of said vacuum columns to define an upper, an intermediate and a lower zone in each column, each of said sensors providing a binary output in accordance with the loop position; first and second logic means controlled by said first and second position sensing means respectively and by the direction in which said capstan means is moving tape; means connecting said first and second logic means in controlling relation to said file reel motor and said machine reel motor to institute the following control order for said motors when said capstan is moving tape in a forward direction from said file reel to said machine reel;