Monarch 9835TM, 9830TM, 9820TM Lower Supply GUIDE/BI- Cell Sensor, Supply Feeding, Supply Sensing

9820/9830/9835 Service Manual Supply Sensing Systems

LOWER SUPPLY GUIDE/BI- CELL SENSOR

The supply guide assembly spans the feed module frame just behind and below the platen roller. It sits within two détentes on each frame edge to maintain proper positioning. It is held in place by individual plastic tabs engaging square holes on both sides of the frame.

Two center-justifying supply guides sit on top of a guide frame and are interlocked. A guide lock arm is positioned on the outside guide. The Bi-Cell supply sensor and housing are attached to the middle of the supply guide frame so that it is lined-up with the IR emitter in the upper supply guide. The sensor wiring harness attaches to the sensor housing and runs along the bottom of the guide frame and through the feed module frame to the Control Board Assembly.

Version 5.2 or greater:

The center justified reflective sensor is mounted on the lower supply guide support and provides an index signal when using black mark butt cut labels and black mark tags. The reflective sensor is surface mounted to the reflective sensor junction PCB assembly.

NOTE: The new supply guide mechanisms are not backward compatible.

SUPPLY FEEDING

The main components of supply feeding are the platen roller, 25VDC stepper motor, and supply guide.

Supply guides are used to capture the supply and maintain center-justified tracking. The supply must be positioned between the platen and printhead to feed properly. The printhead applies pressure to the supply to hold it against the platen roller. As the platen roller rotates, the supply is forced to move between it and the printhead. The stepper motor engages the platen drive gear (located behind the inner feed module wall) and drives the platen roller. The function is controlled by the Control Board Assembly.

SUPPLY SENSING

Supply sensing begins when the IR Emitter in the supply deflector, emits an IR beam through the supply. The Bi-Cell sensor located in the supply guide, receives the beam and changes it into corresponding voltage level. As the beam intensity changes, the associated voltage output of the Bi-Cell also changes. Voltages are reported to the Control Board Assy.

where they are compared to a known base-line voltage. When the input characteristics match (relative to predefined times, voltage levels, and expected supply position), a gap or black mark is sensed.

For the 9820/9830 printers, SENDFILE provides volts relating to the sensor’s activity as stock moves past the sensor. Two points are of interest: high point (must be approx. 176) and low count (must be approx. 79). Two sensor channels are used. One measures the paper’s presence. The other detects the transition from stock to gap and back. These transitions produce an analog waveform which changes from reference (typically -2.5 VDC or approx. 128 A/D counts). These voltages are continually monitored and adjusted by the microprocessor. Because of this microprocessor control, no meaningful static measurements can be made to the sensing circuitry. Paper to Gap is a negative waveform whose active threshold is +1.75VDC or 89 A/D counts. The waveform must drop approx. 10 A/D counts to be acted upon as a valid transition. Gap to Paper is a positive +waveform whose active threshold is +3.25VDC or 166 A/D counts.

The 9835 uses a new sensing system that is optimized for black mark sensing while still having the ability to detect die cut supplies. All 9835 printers contain a set of matched components that are factory adjusted. Our intent is to produce a sensing system that does not require physical alignment in the field. If a sensor fails, order a Sensor Kit (11879801). The kit contains a matched set of components that must be installed and configured using Sendfile Version 2.14 or later.

Version 5.2 or greater:

When a label advance command is received the software checks to see if the supply has been calibrated. If not Resync resets the A/D signal measuring parameters. When the supply starts moving forward the A/D signal value is captured. It is matched against the highest value saved and the lowest value saved. If the new value is larger then the current high value or lower than the current low value it replaces that value. In this way the differential between minimum and maximum signal can be determined. Sometimes this differential is referred to as the span. This cycle is repeated for each motor step interval while the motor is running during calibration.

The first transition edge of software significance is the BOF. This is defined as the leading edge of the feature. It is based on an algorithm that on every step checks to see if the AD count is at a value that has passed through a calculated threshold moving from white into the feature. Before the algorithm can be used the signal differential must be larger then a predefined minimum. Once this criteria has been

38 TC9830SM Rev. B 7/98 Confidential July 1998