Abstract: To provide an electronic device having a rack and a pinion which reliably eliminates a backlash, and which is free from the occurrence of a delay of an operation during the rotation of the pinion, the rack is made of an elongated plate type base portion, and a plurality of teeth stood up in an inclined state at one side section of the base portion with a uniform pitch and formed integrally out of a flexible material. The teeth of the pinion are formed vertically so that the inclined teeth of the rack stand up substantially vertically and bend rearward when the teeth of the pinion are meshed with those of the rack.

Abstract: To provide a backlash-free rack simple in structure and small in size, still assuring that no backlash is caused in reciprocating a movable part in an electronic device toy, or watch et al, the rack structure comprises first and second toothed bars both integrally connected to each other by an intermediate joint made of a soft resin material to provide a linear toothed bar object. The linear toothed bar object is so folded about the intermediate joint that the first and second toothed bars are somewhat staggered and laid on each other with their teeth out of phase, thereby preventing the backlash which otherwise, would be caused between the teeth of the rack and those of the pinion.

Abstract: To provide a disc-transfer roll which can be applied to a disc circumference under pressure strong enough to allow the roll to rotate without slipping assuring that the disc can be transferred in a stable condition and can be put on the turntable with precision and can be easily mass-produced at an increased efficiency, it is made of an elastic material, and it comprises an inner cylindrical wall, an annular joint integrally connected to and extending radially outwards from one end of the inner cylindrical wall, and an outer cylindrical wall integrally connected to the annular joint and encircling the inner cylindrical wall, leaving a predetermined space between the outer and inner cylindrical walls.