Please select the most similar patent number from A, B, C and D. Which number is?
A music box using a punched tape, comprising a base (1) and a sound production piece (2) disposed on the base (1). The music box further comprises: a first roller (3) which is provided with pinch rollers (4), wherein the first roller (3) is disposed on the base (1); a second roller (5) which is disposed on the base (1); spacers (17) which are provided on the second roller (5), wherein the surfaces of the pinch rollers (4) and the spacers (17) together limit a punched tape when the punched tape passes through a space between the first roller (3) and the second roller (5), and the spacers (17) and the second roller (5) together form at least one gear slot (18); a toothed gear (6) which comprises at least three teeth (601), wherein the toothed gear (6) is rotatably fitted in the gear slot (18), and the tooth (601), driven by a hole on the punched tape, rotates the toothed gear (6) with respect to the second roller (5) and flicks the sound production piece (2) to produce a sound. According to the music box having said structure, the pinch rollers on the first roller and the spacers together limit the punched tape, and another tooth of the toothed gear flick the sound production piece to produce a sound. Thus, the sound production of the music box is controlled by the punched tape, and the music box plays different tunes by means of changes of the hole configuration on the punched tape.
A: A hand-cranked music box comprising a housing, a sound cylinder (8) provided with multiple protrusions, and, fitted with the sound cylinder (8), a transmission gear (6) and sound plates (7), also comprising a crank handle (3) provided with a drive gear (31) that is meshed with the transmission gear (6), a fixing frame (4), and a fixing element (5) fittingly fixed with one extremity of the sound cylinder (8) onto the fixing frame (4), where the transmission gear (6) is fittingly fixed with the other extremity of the sound cylinder (8) onto the fixing frame (4). Because the sound cylinder (8) is fixed within the housing by fitting the fixing element (5) with the fixing frame (4) and by fixing the transmission gear (6) with the fixing frame (4), damages due to being squeezed are prevented. One extremity of the sound cylinder (8) is fixed with the transmission gear (6), when the crank handle (3) is cranked, the drive gear (31) drives the transmission gear (6), the transmission gear (6) drives the sound cylinder (8) into rotation, the protrusions on the sound cylinder (8) generate vibrations with the sound plates (7) to generate sounds, thus producing music.
B: A machine core of a packing machine. A delivery and returning belt and dragging belt device of the machine core comprises a first roller (1) and a second roller (2). The second roller (2) is controlled by a control mechanism to move to a first matching state with the first roller (1), and to move out of the first matching state with the first roller (1) to a second matching state. The first roller (1) is connected with a first transmission gear (10) capable of driving the first roller (1) to rotate. The second roller (2) is connected with a second transmission gear (20) capable of driving the second roller (2) to rotate. The second transmission gear (20) and the second roller (2) conduct synchronous displacement. The first transmission gear (10) receives power through a gear transmission mechanism to drive the first roller (1) to rotate. The second transmission gear (20) receives power through the gear transmission mechanism. The second transmission gear (20) moves into a first gear matching state with a gear transmitting the power to the second transmission gear (20) through the displacement, and moves out of the first gear matching state. The machine core has a simple structure, is capable of reducing failure rate, and has a good packing effect. In addition, the binding force, the length of belt delivery, the temperature, and the ironing connection delay of the machine core can be adjusted through a potentiometer.
C: A tensioning device for automobile production, comprising a base (1), wherein a first support post (2) is fixedly connected to an upper surface of the base (1), a second support post (3) is fixedly connected to the upper surface of the base (1), and a third support post (4) is fixedly connected to the upper surface of the base (1); a first through hole (6) is opened at a middle part of one side of the first support post (2); the first support post (2) and first rollers (5) are movably connected by means of the first through hole (6); a gap is retained between the first rollers (5); and a top part of the first support post (2) is provided with a lever (7). The described tensioning device for automobile production is provided with the lever (7), and a weight block (12) is added to one end of the lever (7) so that the tensioning device may automatically tighten. By means of being provided with the weight block (12), the degree of tightness of the tensioning device may be changed by means of changing the weight of a placed article. By means of being provided with a gear (18) and racks (14, 17), the effect of manually adjusting the degree of tightness of the tensioning device may be achieved.
D: A mutually restrictive safe multi-drawer locking device, comprising a guide groove (1), a first sliding part (2) and a plurality of second sliding parts (3) that are slidingly arranged in sequence within the guide groove (1) and wedge blocks (6) arranged on the front portions of the side faces of drawers. The guide groove (1) is arranged on the front portion of the side faces of the drawers on multiple layers in the sliding direction and extends from the drawer on the top layer to the drawer on the bottom layer, wherein a limiting part is arranged at the lower end of the guide groove (1); the position of the first sliding part (2) corresponds to the drawer on the top layer and comprises a first sliding piece (2-1) and a first roller (2-2) which is rotationally arranged on the first sliding piece (2-1); the positions of the plurality of second sliding parts (3) correspond to the drawers on each layer below the drawer on the top layer respectively, and each second sliding part (3) comprises a second sliding piece (3-1), and a limiting block (3-2) and a second roller (3-3) that are arranged top to bottom on the second sliding piece (3-1), the second roller (3-3) being rotationally arranged on the second sliding piece (3-1). The described locking device has a simple structure and may ensure that one drawer is drawn out at a time, thereby avoiding safety problems such as drawers on multiple layers being drawn out at the same time causing a cabinet to topple over.
Answer: A