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Speed Match/Lost Grating Detection Apparatus

IP.com Disclosure Number: IPCOM000051508D
Original Publication Date: 1981-Feb-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 5 page(s) / 86K

Publishing Venue

IBM

Related People

Bork, RH: AUTHOR [+3]

Abstract

In driving a print drum, it is desirable to operate the drum with a high speed motor during printing operations and with a low speed motor during paper load and unload operations. The above-shown apparatus can detect the speed of the drum to actuate a low-speed clutch when the drum is decelerating so as to engage the low speed motor with the drum on the fly. In addition, the apparatus can also detect lost grating signals in the event of failure in the grating sensing function. The apparatus is microprocessor-controlled; however, all of the real-time monitoring functions are performed by hardwire logic rather than the microprocessor. The microprocessor serves the function of a supervisor and sequencer of operations.

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Speed Match/Lost Grating Detection Apparatus

In driving a print drum, it is desirable to operate the drum with a high speed motor during printing operations and with a low speed motor during paper load and unload operations. The above-shown apparatus can detect the speed of the drum to actuate a low-speed clutch when the drum is decelerating so as to engage the low speed motor with the drum on the fly. In addition, the apparatus can also detect lost grating signals in the event of failure in the grating sensing function. The apparatus is microprocessor-controlled; however, all of the real- time monitoring functions are performed by hardwire logic rather than the microprocessor. The microprocessor serves the function of a supervisor and sequencer of operations.

In Fig. 1, the print drum 10 carries the sheet of paper 12 which can be printed on by an ink jet print head (not shown). During such printing operation, drum 10 would be driven at high speed by high speed motor 14.

After the printing operation is complnte, the drum 10 is decelerated by the high speed motor until it is very near the speed provided by a low speed motor 16 through gears 18. When there is an approximate match in speed between the decelerating drum 10 and the low speed drive provided by motor 16 through gears 18, high speed motor 14 is turned off, and clutch 20 is energized so that low speed motor 16 takes over driving drum 10. In effect, drum 10 is not stopped but is decelerated from high speed and caught on the fly by the low speed motor.

The control functions are provided by the drum control logic 22. The drum control logic responds to the pulses from the grating 24 and to commands from the microprocessor 26. In response to these signals, the drum control logic generates the control signals for high speed motor driver 28, clutch driver 30, and low speed motor driver 32. Clutch driver 30 is controlled to energize clutch 20 to engage low speed motor 16 with the drum 10 during paper sheet unload or load operations. High speed motor drive 28 can be used to accelerate or decelerate the drum. Low speed motor driver 32 has multiple speeds and can be operated in either direction.

In Fig. 2, the waveform GR is the signal from grating sensor 34 in Fig. 1 during a deceleration and speed matching operation. The timing pulses T01 of Fig. 2 will be explained hereinafter. These timing pulses represent the sampling interval used by the speed watching and lost grating detection apparatus.

Fig. 3 shows the portion of drum control logic 22 used to perform the speed matching and lost grating detection operations. The signal from grating sensor 34 is received by a grating sampling circuit 36. This sampling circuit provides the detection logic with immunity from noise for the signal from the grating sensor. The grating signal GR is passed to the grating transition detection circuit 38 in Fig. 3. The grating transition detection circuit 38 will set a latch every time two successive...