Tape guide block

#This invention relates to a tape guide block in a three piece type tape cassette which is composed of upper and lower cassette halves and the tape guide block, and a method of producing the same.

#Three piece type tape cassettes in which a tape guide block is formed separately from upper and lower cassette halves have been proposed for the purpose of solving the problems experienced with two piece type cassettes in terms of accuracy and manufacture. Such problems still remain with three piece type cassettes, and propositions for further improvements have been made with respect to the structure of the tape guide block and the method of forming the same. However, propositions heretofore put forward have only succeeded in partially solving these problems.

#For example, Japanese Patent Publication No. 50354/1981, Japanese Utility Model Laid-Open No. 87630/1978 and Japanese Utility Model Laid-Open No. 95817/1978 disclose arrangements in which mold drawing of injection molding is made in the direction of the reference level surface of a cassette half so as to set the tape guide surface of a tape guide block perpendicular to the reference level surface. Accordingly, it is necessary with such arrangements for a drawing inclination to be provided on each of the inner surfaces of upper and lower cassette halves. In Japanese Utility Model No. 95817/1978, a slanted surface is formed on a part of each of the upper and lower cassette halves on account of the need for such an inclination so that the tape guide surface is set accurately perpendicular to the reference level surface of the cassette halves. This arrangement necessitates a high degree of accuracy in manufacturing the cassette halves. On the other hand, the techniques disclosed in the other two publications do not take account of this need, and they therefore still involve the problem of difficulty in positioning the guide block accurately and stably in relation to the cassette halves.

#The present invention will now be described in detail with reference to the presently preferred embodiments illustrated in the accompanying drawings in which:

#FIG. 1 is a plan view showing a lower cassette half of a tape cassette and a guide block according to one embodiment of the invention;

#FIG. 2 is a perspective view of the guide block shown in FIG. 1;

#The present invention will now be described in detail by referring to the embodiments shown in the accompanying drawings.

#A first embodiment will be explained with reference to FIGS. 1 and 2.

#A tape cassette is provided with an upper cassette half (not shown) and a lower cassette half 12 and a guide block 20 secured between the upper and lower cassette halves. A metal material is drawn and thereafter cut perpendicularly in relation to the direction of the drawing at intervals slightly larger than the tape width, thus forming the guide block 20 having the upper and lower surfaces 30 and 32 which are flat and parallel with each other. The metal material is preferably aluminium, and alumite finish is applied on the surface of the blank so as to form a hard coat (wear resistant coat) thereon.