TAPE RECORDING AND REPRODUCING APPARATUS

Abstract: A magnetic tape recording and reproducing apparatus comprising a magnetic head having a head gap and provided with tape guides (25) upstream and downstream of the head gap to constrain passage of tape past the head gap to be at a predetermined angle to the gap, the head being mounted on a base member provided with resilient biasing means (31) for biasing a cassette housing the magnetic tape in a direction so that the tape guides (25) contact the cassette body with one of surfaces while another surface of each tape guide contacts one edge of the tape.

Description: TAPE RECORDING AND REPRODUCING APPARATUS The present invention relates to tape recording and reproducing apparatus and more particularly to such apparatus which uses a cartridge or cassette. In.conventional cassette-type tape recording and reproducing apparatus it is customary for the cassette to be loaded into the apparatus and fixed in position and then for the head assembly to be moved relative to the cassette into an operative position with the transducing head in engagement with the tape. It is known that in order to accurately record and reproduce signals the gap in the magnetic circuit of the transducing head has to be at right angles to the direction of movement of the tape and in conventional apparatus this is done by means of an adjusting screw provided on one fixing mount for the head assembly. Rotation of the screw causes the head assembly to tilt about the other mounting point until it is determined that the head gap is at right angles to the theoretical path of movement of the tape. For conventional tape recorders this is an exceptable technique due primarily to the fact that the width of the tape is relatively substantial and the tape is itself moving quite slowly. However, for mass storage of data such as is required for a computer it is necessary to run the tape at very high speeds and this makes accurate location of the head gap at right angles to the tape critical especially when one considers that data recorded on the tape oy one machine will more than likely have to be replayed on a different machine. For accurately reproducable results it is necessary to ensure that the disposition of the head gap relative to the direction of the tape is accurately and reproducably defined. ' The present invention proyides tape recording and reproducing apparatus including a magnetic transducer head assembly provided with tape guide members arranged to contact the bottom edge of a magnetic tape upstream and downstream of the head gap. The head assembly is fixed in position on a base which is provided with biasing members for biasing a cassette towards the tapes guides. The arrangement is such that in use and when the cassette is in position, the bottom surfaces of the tape guide members abut the inner surface of the bottom of the cassette while the tape itself is guided by the upper surfaces of the tape guide members. Preferably an upper tape guide member is provided upstream of the head gap so as to limit vertical movement of the tape in use. This arrangement requires that the tape guide members be accurately positioned with respect fcό the head gap to ensure that the tape moves at right angles to the head gap across the transducing head assembly. Advantageously, the guide members are provided on side plates which have extensions for engaging the base of the apparatus and the head assembly is fixed in position by means of resilient members extending on either side of the head assembly to ensure that when in position the head gap disposition remains unaltered due to the fixing. Features and advantages of the present invention OMPI ^iϊNATi - 3 - will become apparent from the following description of an embodiment thereof given by way of example in which:- Figure 1 shows a plan view of a portion of tape recording and reproducing apparatus according to the present invention; Figure 2 shows a side view of a transducing head assembly used with the apparatus shown in Figure 1; and Figure 3 shows a plan view of the head assembly shown in Figure 2. The preferred form of tape recording and reproducing apparatus is partially shown in Figure 1 and comprises a transducing head assembly 10 fixedly attached to a base member 11. A tape cassette (part of which is shown in broken lines) is arranged to be inserted into the apparatu in the direction of arrow A and when in position, the head assembly 10 contacts the magnetic tape. A tape drive rolle 12 engages at a point on one side of the cassette and uses a roller in the cassette as the co-operating pinch roller. A pawl member 17 is provided on a resilient arm 19, one end 20 of which is fixed and the other end 21 is arranged to abut the cassette body when the cassette is in position. The result is that when the cassette is pushed into the apparatus in the direction of the arrow A, the pawl member engages a ratchet (not shown) on the drive roller 12 to prevent rotation of the roller 12 until the cassette is in position whereupon the end 21 abuts the cassette body and is pushed back by the cassette body to release the pawl member 17 from the ratchet and permit free rotation of the roller under the action of the motor. The cassette is retained in position with the tape in contact with the transducing head and is biased towards the drive roller 12 by an angled surface 13 and a leaf spring 14 as well as a protrusion 15 arranged to co-operat with a mating surface on the side of the cassette. Two posts 22 limit movement of the cassette in the direction of the arrow A and two spring loaded members 23 urge the " * T inward end of the cassette upwards. As will be best seen in Figures 2 and 3, tape guide members 25 are provided up¬ stream and downstream of the head gap or gaps of the head assembly 10. The upper surfaces 25 are arranged to engage 5 and guide the lower edge of the tape. The lower surfaces 25b of the tape guide members 25 are arranged to abut the internal surface of the lower member of the cassette body due to the action of the resilient members 23 urging the cassette body upwards against them. 10 The resilient members 23 are formed as spring loaded ramps so that the bottom surfaces of the lower guide members 25 reference the cassette body with respect to the head gap while the upper surfaces 25a of the tape guides cause the tape to move across the head gap at right angles .there 15 As is best seen in from Figure 2, there is a further, tape guide 26 located upstream of the head gap and whose lower surface 26a is arranged to abut the upper edge of -th tape to limit vertical movement of the tape across the hea gap, 20 Although the cassette is referenced to the head gap means of the guide members 25, it is still convenient to ensure that as far as possible the head gap is at right angles to the base of the apparatus since this eases assembly. In order to achieve this, the tape guides have 25 to be accurately located on either side of the transducing head gap very accurately. This is done by having each of the tape guides 25 provided on a separate member 28 which is each separately positioned with respect to the head gap before being welded in position. The weld points 30. are shown in Figure 2 and are indicated by the reference numerals 29. Further, in order to ensure that the head ga is at right angles to the base member each of the members provided with the tape guides 25 is also provided with dow wardly projecting extensions 30 which form legs for suppor 35 ing the head assembly on the base. The assembly 10 is the fixed to the base by means of resilient extensions 31 shown in Figure 3 * The provision of the resilient extensions ensures that no alteration in the disposition of the head gap occurs when the head assembly is fixed to the base of the apparatus. From the above description, it will be appreciated that the only movable member is in fact the cassette; the head assembly is fixed. Further, and in contrast with the prior art the head assembly is not on a movable frame and because of that the accuracy with which the head gap can be positioned is improved with a consequent improvement in the signal reproduction. OMPI ^ Λ?

Claims: CLAIMS: 1. A magnetic tape recording and reproducing apparatus comprising a magnetic head having a head gap and provided with tape guides upstream and downstream of the head gap to constrain passage of tape past the head gap to be at a predetermined angle to the gap, the head being mounted on a base member provided with resilient biasing means for biasing a cassette housing the magnetic tape in a direction so that the tape guides contract the cassette body with one of surfaces while another surface of each tape guide contacts one edge of the tape. 2. Apparatus according to claim 1 and comprising a further tape guide upstream of the head gap and arranged to contact the the other edge of the tape.

Inventors: SOUTHWARD DAVID CONNOR, SOUTHWARD, DAVID, CONNOR
Applicants: SINCLAIR RES LTD, SINCLAIR RESEARCH LIMITED
Application year: 1984
Main classification: G11B15
IPC codes: G11B5, G11B15