GB1173188A - Improvements in Control Units for Selecting Alternative Operation Positions, such as for Frequency Selection on Communication Equipment - Google Patents

Abstract

1,173,188. Key interlocks. S. H. SMITH. 9 Oct., 1967, No. 46045/67. Heading B6F. [Also in Divisions E2, H1 and H3] A control unit comprises a number of devices each of which can be locked in an operative position when operated, means being provided whereby if more than one device is operated simultaneously only one will be retained in its operative position. The invention is described in connection with a push-button unit for selecting crystals for tuning airborne communication equipment to a predetermined frequency (see Division H3), the button assembly having buttons smaller than the operator's finger. It is arranged that only the uppermost button is locked in although several are passed simultaneously. General construction. -The buttons are arranged in two pairs of vertical rows (Fig. 1, not shown) one pair bringing in a whole number of megacycles and the other pair a fraction of megacycles. The buttons 118-134 (Fig. 2) are of transparent plastic and are mounted on a panel 27 with an outer edge-lighted panel 28 also of transparent plastic. A lamp 13 illuminates the buttons from inside. Each button is attached to a slide, e.g. 118S in Fig. 3, the rear end of which actuates switch contacts Wa-Wj as described below. The slides of the buttons of two adjacent vertical rows, e.g. 118-121 are interleaved in a single vertical stack. Locking mechanism (Fig. 3).-Each button slide has a slotted plate 33 immediately above it, the slot CS co-operating with a pin, e.g. 118P, on a latch member,.e.g. 118L pivoted to the button slide at 41. When a button is pressed, the pin P moves along the slot of the plate 33 above it until it reaches the portion 40 of the slot when the latch member L is pivoted to lift a latch bar 45 which is common to all the buttons. This releases the previously pressed button. Further movement of the button causes the pin P to travel along the narrow portion 34 of the slot whereupon a notch 42 engages the latch bar 45 by a spring 51 and holds the button in. During the last part of the movement of the slide the plate 33 is moved slightly to the left, drawing the next button e.g. 119 slightly inwards. The surface 40 on the plate associated with slide 119 then causes the pin of the next button 120P to disengage from the latch bar 45 preventing this button from being latched in. Button 119 cannot latch in since its pin 119P cannot enter the narrow portion 34 of the slot 118CS. Thus even if buttons 118, 119 and 120 are pressed simultaneously only 118 will operate. If the buttons are in more than two vertical rows the corresponding latch bars 45 are linked together (201 in Fig. 12, not shown). Engagement of the pin P with the edge of the slot CS is facilitated by pivoting of the latch member L due to friction with the preceding slide. This is aided by a yieldable friction member (158 in Figs. 16, 17, not shown) around the pin P.