Magnetic tape driving system having rotating member with increased angle of rotation

A pinch arm driving device comprising:

• a pinch arm for supporting a pinch roller;
• a pinch arm driving member, operatively connected with said pinch arm, having a guide portion for guiding a direction of movement of said pinch arm driving member, and for press-contacting said pinch roller through said pinch arm with a capstan;
• and
• a cam follower provided on said pinch arm driving member;
• a cam gear, having a cam portion formed on one of a top and a bottom surface of said cam gear, for engaging with said cam follower and driving said pinch arm driving member through said cam follower;
• and
• a drive source for driving said cam gear,
• said cam portion comprising a first cam portion for driving said cam follower in a radial direction in which a distance from the center of said cam gear increases or decreases, and a second cam portion, contiguous to said first cam portion, for directly moving said cam follower in a direction of rotation of said cam gear upon rotation of said cam gear, whereby when said cam gear rotates to drive said cam follower, said cam follower is moved first by said first cam portion within a range in said radical direction, and said cam follower is then directly moved by said second cam portion upon rotation of said cam gear, so that an amount of movement of said cam follower is greater than said range in said radial direction.

In a tension servo device including tension detecting means for detecting a tape tension of a tape supplied from an S-reel stand;

• a lever connected to said tension detecting means to be turnable in response to the tape tension;
• a brake member integrally formed on said lever and formed of two materials which are stuck together and comprise a thin film as a first material disposed on a side of a member being braked and an elastic body as a second material;
• a cylindrical portion which is provided on said S-reel stand and disposed in a position corresponding to said brake member to constitute the member being braked;
• a spring for urging said lever to turn;
• said brake member being press-contacted by a biasing force of said spring with said cylindrical portion, to apply a braking torque on said S-reel stand, and said lever turning in response to the tape tension detected by said tension detecting means to change the press-contacting force of said brake member to increase or decrease the applied braking torque, the improvement wherein said elastic body is deformed in such a manner that said thin film comes into full contact with said cylindrical portion over an entire width of said thin film, thereby producing a braking torque.

A magnetic recording/play back apparatus comprising:

• (a) a tape guide post driving device comprising:
• a gear having a cam,
• a rotating member having a cam-shaped portion and assuming two angular positions established upon rotation of the cam of said gear, and
• a tape guide post provided on said rotating member,
• wherein a contact point between the cam-shaped portion of said rotating member and the cam of said gear is positioned near a middle point between the center of rotation of said rotating member and the center of said gear, and the cam-shaped portion of said rotating member is positioned near the center of rotation of said rotating member, so that an angle through which said rotating member is rotated, upon rotation of said gear, is maximized;
• (b) a pinch roller driving device comprising:
• a pinch arm for supporting a pinch roller,
• a cam gear, having a cam portion formed on one of a top and bottom surface of said cam gear, for transmitting a driving force from a drive source to said pinch arm when said pinch roller is press-contacted with a capstan,
• a pinch arm driving member, operatively connected with said pinch arm, having a guide portion for guiding a direction of movement of said member, and
• a cam follower portion for engaging with said cam portion,
• said cam portion comprising a first cam groove extending toward a rotation axis of said cam gear and a second cam groove extending in a circumferential direction of said cam gear,
• wherein an amount of movement of said cam follower portion caused by rotation of said cam gear, is greater than a maximum distance of said cam portion from the rotation axis of said cam gear;
• (c) a guide post, provided on a drive member for loading a magnetic tape on a rotary head cylinder and for guiding said magnetic head, said guide post having a projection formed thereon for guiding said magnetic tape, and
• a leaf type resilient member having a sloped surface between the projection of said guide post and said drive member,
• wherein the sloped surface of said resilient member is always urged against the projection of said guide post by resilient force of said leaf type resilient member;
• and
• (d) a tension servo device comprising:
• tension detecting means for detecting a tension of a tape supplied from an S-reel stand,
• a lever which is turnable in response to the tape tension detected by said tape tension detection means,
• a brake member, formed on said lever and comprising (i) a thin film positioned on said brake member to face a member to be braked and (ii) an elastic body positioned on said brake member to face said lever, said thin film and said elastic body being bonded together into one piece,
• said S-reel stand having a cylindrical rotating member at a position corresponding to said brake member and serving as said member to be braked, and
• a spring for urging said lever to turn in a direction of press-contacting said brake member with said cylindrical rotating member,
• wherein said brake member is press-contacted by spring force with the cylindrical rotating member of said S-reel stand to apply a braking torque to said S-reel stand, and the press-contract force of said brake member is changed in response to the tape tension detected by said tape detecting means so as to increase or decrease the braking torque.