Abstract: Two guide members cooperatively constitute a chuck portion for holding a screw head. Opening and closing of the chuck portion is regulated depending on a mutual position between a machine body and a member into which a screw is driven. Guide pin portions of respective guide members engage with a stopper portion of a push lever until a screw is driven to a predetermined depth. The chuck potion tightly holds the screw head until a screw fastening operation is substantially finished, thereby suppressing the lifting of a machine body.

Abstract: An on-demand multi-nozzle ink jet head includes a diaphragm and a plurality of piezoelectric stacks. The diaphragm forms at least one wall of a pressurizing chamber used to increase the pressure of the ink. When print signals are applied to the piezoelectric stacks. The stacks generate pressure fluctuations in the walls of the pressurizing chamber. An elastic material with adhesive properties is used to bond the diaphragm to the piezoelectric stacks, which elastic material has a Shore hardness of less than 80 on the A scale and less than 30 on the D scale.

Abstract: An ink jet printer has a plurality of piezoelectric elements arranged in a matrix form in which each piezoelectric element is connected between one of TS lines and one of selection lines. The TS lines are connected, one by one and in a time sharing manner, to a voltage source E.sub.1 so as to be enabled. The remaining TS lines are connected to a voltage source E.sub.2 so as to be disabled. The selection lines are selectively connected to a voltage source E.sub.3 so as to be enabled. Non-selected selection lines are connected to a voltage source E.sub.4 so as to be disabled. A selected piezoelectric element connected between enabled TS line and enabled selection line is applied with a driving voltage. A non-selected piezoelectric element connected between enabled TS line and disabled selection line, or between disabled TS line and enabled selection line, or between disabled TS line and disabled selection line, is applied with a non-driving voltage.

Abstract: A printed paper sheet, on which plural pages of image are formed, is cut by detecting the position of conveying, the dimension of paper width and the amount of skew of the printed paper sheet, and by controlling the position of a slitter for cutting the printed paper sheet based on the detected result. The plural sheets of the cut printed paper sheets are divided so as to pass through plural routes to pile them in order of page.

Abstract: To prevent undue elevation of temperature in a hammer assembly but to maintain the maximum printing speed, when a scheduled number of drivings at which print hammers are to be driven during one scan of a manner bank which follows the currently performing scan, exceeds a first reference number, one dot line printing is completed with a plurality of scans of the hammer bank so that dot line print density in each scan of the hammer bank does not exceed, for example, 35%. If, however, high density printing exceeding 25% continues for an extended period of time more than one scan time, the printing operation is temporarily halted.

Abstract: A saber saw assembly includes a vice for clamping an object to be cut and a saber saw having a saw blade to be operated in reciprocating motion. The saber saw is arranged to cut the object with the reciprocating saw blade while the object is clamped by the vice. The vice is in the form of a pipe wrench. The pipe wrench clamps the object when rotated in a clamping direction while releases the object when rotated in a releasing direction opposite to the clamping direction. Accordingly, by using the pipe wrench for the vice, the clamping and releasing operations for the object are simplified to enhance the working efficiency for cutting the object.

Abstract: In a printing sheet conveying device in which a sheet bearing a toner image is passed through a heating roll and a pressure roll, and which has means for changing the right and left contact pressures of these rolls to correct the meandering movement of the sheet when conveyance of the sheet is started; in which when conveyance of the sheet is started, the contact pressure of the rolls is made higher on one of the right and left sides than on the other side, and in a predetermined period of time the contact pressures on both sides are made equal to each other.

Abstract: An orbital finishing sander includes a sandpaper clamp mechansim which has a sandpaper holder angularly movably supported on a bottom plate. A sanding sheet placed over a platen attached to the bottom plate is gripped by gripping teeth of the sandpaper holder under the bias of a spring. When a lever mounted on a frame of the sander is turned through about 90.degree., a presser on one end of the lever successively cams slanted and flat surfaces of the sandpaper holder downwardly to lift the gripping teeth off the bottom plate, thus releasing the sanding sheet. The sanding sheet is removed, and a new sanding sheet is placed on the platen, after which the lever is turned back to allow the gripping teeth to grip the new sanding sheet under the spring force.

Abstract: In an internal-combustion piston driving apparatus comprising a housing, a cylinder cover fixed to the housing, a cylinder slidably provided to the housing, a piston reciprocally slidably provided in the cylinder, a combustion chamber defined by the housing, the cylinder, and the piston, a fuel supplying device for supplying fuel to the combustion chamber, and an ignition control device for producing a high voltage to ignite the fuel supplied to the combustion chamber, piston position detector for detecting a position of the piston is provided at the wall of the cylinder between top dead point and bottom dead point of the piston. Besides, a decompression channel is provided so as to connect the combustion chamber placed upper than the top dead point with atmosphere for exhausting a combusted gas in the combustion chamber when the piston passes the piston position detector. The decompression channel is opened and closed by means of slide of the cylinder.

Abstract: A battery charger has a recess for accommodating a battery pack, and charging electrodes projecting into the recess. The battery pack is charged when the battery pack is inserted into the recess and battery electrodes of the battery pack are brought into contact with the charging electrodes. In an improvement of the battery charger, the recess has portions of different shapes corresponding to respective shapes of a plurality of different battery packs for accommodating the different battery packs, and the charging electrodes have portions projecting into the recess portions respectively.

Abstract: A tightening apparatus includes a drive motor and a bit are coupled to each other by engagement of a clutch mechanism, the engagement thereof being maintained by a force of a spring one end of which is coupled to the clutch mechanism and the drive motor is released from engagement with the bit when the tightening torque of the bit exceeds a value corresponding to the force of the spring. The tightening apparatus comprises a cylinder and a plunger encased in the cylinder for holding the other end of the spring. The plunger is movable by a drive mechanism such that the force of the spring is varied, whereby the tightening force to be applied to the bit is adjustable in accordance with the position of the plunger as adjusted by the drive mechanism.

Abstract: An automatic nailing apparatus includes a housing having a piston driving system for driving a piston, a percussion rod having a concave at only the tip thereof, a nosepiece having a round channel being provided with a pair of nail head guide rails, and a nail magazine for supplying interconnected nails. The forefront nail of the interconnected nails can be nailed in a direction normal to a workpiece because a point of application on nailing exists on the center axis of the forefront nail.

Abstract: A speed controller for a DC motor includes a semiconductor switching device connected in series with it in a DC power circuit. The switching circuit is turned on and off with a duty ratio variable as a function of motor load. A time constant circuit including a capacitor is connected in parallel with the switching device to develop a voltage which is compared with a reference variable between high and low levels in response to the exceedance of the varaible reference. The switching device is turned on when the voltage developed by the capacitor is higher than the lower reference voltage to energize the motor, and is turned off when the capacitor voltage is lower than the higher reference voltage to de-energize the motor.

Abstract: A fixing device for fixing the toner on the recording medium comprising a pair of fixing rollers which face each other and rotate in opposite direction to form a nipping and fusing section for toner fixing, with at least one of the rollers internally provided with a heating element, and a recording medium guiding device for changing the length of contact area of the recording medium to the fixing roller with heating element in accordance with the recording medium thickness, which is provided at the downstream side extending from the nipping and fusing section. This allows the device to be reduced in size and the fixing strength to be increased independent of the recording medium thickness.