EP0640491B1 - Method and apparatus for monitoring the operational state of an ink ribbon in a printer, particularly in a travel agency printer - Google Patents

Description

It is known for recognizing the functional state of an ink ribbon in a method, in particular in a travel agency printer to apply, in which the ribbon over a to the drive shaft of a Ribbon cassette connected electric rotary drive motor is transported and according to that of the rotary drive motor absorbed current to the size of the transmitted driving force is closed. Both Known methods sensors, sensors or switches are required are sensitive to temperature fluctuations, shocks or Pollution. In addition, for the corresponding facilities or Circuits an adjustment, a setting procedure or an adjustment necessary. There are further disadvantages of the prior art in that e.g. a ribbon tear, poor ribbon tension, a complete blockage of the ribbon or defective drive electronics cannot be determined due to the known switches.

From "Document Research Disclosure, No. 286, February 1988, New York, USA, Page 78, XP002001478, Anonymous ", is a device for recognizing the functional state a ribbon in a printer known to an electrical Rotary drive motor is connected, which operates from a pulsating Rotary drive motor exists. The drive torque required for the ribbon drive is compared to a specified value. The drive torque is from the DC motor removed and by a pulse width modulation control measured. As soon as the torque increases, the modulated pulse width also increases on. A deviation can therefore be measured and an error signal is generated and the engine is stopped. The default value and any increase or decrease the setpoint can be saved and displayed using a microprocessor. However, such a device requires measurement of the current values with all of the difficulties described above.

The invention specified in claim 1 addresses the problem, one Detection of the ribbon and at the same time the ribbon drive elements due to the increasing current in a (direct current) Rotary drive motor without measuring the current values.

• das Farbband fehlt oder ist gerissen
• das Farbband ist vorhanden und lauft normal
• das Farbband ist völlig blockiert.

The advantages achieved with the invention consist in particular in the fact that the following features can be distinguished primarily:

• the ribbon is missing or torn
• the ribbon is present and runs normally
• the ribbon is completely blocked.

Thus, the lack of the ink ribbon cassette can be determined, the tear of the ribbon, the complete blocking of the ribbon, a defective tension of the ribbon and also whether the Ribbon drive motor is defective or not connected at all Drive electronics or the wiring are defective or whether the Ribbon cassette has slipped out of the holder. This is still advantageous that no further sensors, sensors or switches are required existing circuit areas can be used, which is very inexpensive. The system is also insensitive against temperature fluctuations, shocks or pollution, and the electronic effort can be kept correspondingly low. There is no adjustment, no adjustment procedure and none during assembly Adjustment necessary. So there is hardly any function to be checked, that would not have been captured.

According to further features of the invention it is provided that the Threshold value is set such that it is only in the start-up phase of the Rotary drive motor or reached when the rotary drive motor is blocked becomes. The measuring process therefore consists of the time-limited Switch on the ribbon motor and evaluate the generated one Clock sequences. The periodic switching on of the motor has an effect increasing counter-emf and reduces the inrush current, so that it no longer reaches the threshold.

It is advantageously provided that the measurement by switching on the printer and / or triggered by closing a printer housing becomes. Thus, when a printer is operated, that is always the first Ribbon checked.

To avoid a special quality of the rotary drive motor, whereby of course, such a rotary drive motor is also used could become what would be correspondingly more expensive, it is envisaged that Measuring time, pulse frequency and duty cycle on the rotary drive motor be coordinated. This solution therefore does not set a minimum Variations of specimens in advance and also in the rotary drive motor used not with the mechanical connections to the ribbon cassette (Gear, translation, etc.). It is still possible to find the optimal one To determine pulse rate and an optimal pulse-pause ratio.

Another embodiment of the invention is that the Period of the switch-on cycles and the duty cycle of the Rotary drive motor can be optimized so that the Rotary drive motor reaches a minimum speed before returning is energized.

Furthermore, it is advantageous that at a lower number of cycles Ribbon as missing, torn or completely blocked and at one higher number of cycles the ribbon than available and mechanically correct is classified.

The device for recognizing the functional state of an ink ribbon in a printer, especially in a travel agency printer, the Ribbon in a ribbon cassette is endless and the Ribbon cartridge has a drive shaft connected to an electrical Rotary drive motor is connected, the pulsatingly operated rotary drive motor to an evaluation unit is connected, and the generated clock sequence or pulse sequence of the evaluation unit to a Microprocessor are forwardable, and also the microprocessor with the Motor driver circuit is connected and that the motor driver pulses as On / off signals can be directed to the rotary drive motor is further developed that the evaluation unit based on previously defined threshold value pulses recognizing the functional state of the ribbon by counting the dew sequence in the Microprocessor.

Fig. 1

ein Blockschaltbild mit Druckkopf, Druckwiderlager, Farbbandkassette, Auswerteeinheit, Mikroprozessor und Motortreiberschaltung,

Fig. 2

ein Diagramm des in eine Spannung umgewandelten Stroms, der durch den Drehantriebsmotor fließt,

Fig. 3

ebenfalls ein Spannungsverlaufsdiagramm, wobei der durch den Drehantriebsmotor fließende Strom jeweils bei jedem Einschaltimpuls den Schwellwert erreicht und

Fig. 4

ebenfalls ein Spannungsverlaufsdiagramm, wobei der durch den Drehantriebsmotor fließende der Strom sofort auf einen Maximalwert steigt.

An embodiment of the invention is shown in the drawing and will be described in more detail below. Show it:

Fig. 1

a block diagram with print head, print abutment, ribbon cassette, evaluation unit, microprocessor and motor driver circuit,

Fig. 2

1 shows a diagram of the current converted into a voltage which flows through the rotary drive motor,

Fig. 3

likewise a voltage curve diagram, the current flowing through the rotary drive motor reaching the threshold value for each switch-on pulse and

Fig. 4

also a voltage curve diagram, the current flowing through the rotary drive motor immediately rising to a maximum value.

1, a ribbon 1 is in circulation by a Ribbon cassette 2 out, the ribbon 1 by a Drive shaft 3 and a rotary drive motor 4 driven, i.e. is transported. The ribbon 1 is around the top of one Printhead 5 out, the back of a platen 6 opposite is moved, whereby at a zero distance of the print head 5 to Pressure abutment 6, the ribbon 1 can optionally be clamped. The printer always includes a device to adjust the distance of the To change print head 5 to the platen 6, adjust or adjust.

The rotary drive motor 4 is connected to an evaluation unit 7 which from a current detection (threshold value formation) 7a and one Pulse generation 7b exists. The pulse generation is on one Microprocessor 8 connected and this counts the pulses 10. Im Microprocessor 8 is a timer that is software controlled switches the rotary drive motor 4 on and off. The whole process is as measurement period 11 (FIGS. 2 to 4) with a voltage curve 12 set up.

There are now individual states that occur in practice in which the mentioned errors regarding the ribbon, the ribbon cassette, the drive system and the like. occur:

1. The ribbon is missing

In the absence of ribbon 1, the rotary drive motor 4 is not loaded and can run freely.

The motor current profile 12 is in the upper half of FIG. 2 shown. It can be clearly seen that the current in the Start-up phase of the rotary drive motor 4 rises to its maximum value and then decreases with increasing speed until it is switched off. During this first switch-on pulse, the current reaches the set threshold and runs through it several times. In the the lower half of FIG. 2 is the cycle sequence generated thereby 13 to see.

The clocks of the clock sequence 13 are in the microprocessor 8 evaluated, more precisely counted. The number depends on the smoothness the current curve and thus directly from the electromechanical Properties of the rotary drive motor 4.

Already at the second switch-on pulse and at all others built-up back emf so large that the set threshold at far from being achieved.

2. The ribbon is torn

When the ribbon 1 is torn, the rotary drive motor 4 becomes only slight through the mechanics of the ribbon cassette 2 (gears, rollers, Waves etc.), which hardly affects the current curve (Current curve 12) affects. The signal curve corresponds to FIG. 2.

3. The ribbon is present

The fact that the ribbon 1 during the measurement between the Printhead 5 and the platen 6 is clamped, the Rotary drive motor 4 no longer run freely.

3 differs significantly from that 2 and reaches the threshold at each Switch-on impulse.

The falling current curve shows that the Rotary drive motor 4 despite the jamming of the ribbon 1 too At the beginning of each switch-on process, turn freely for a certain time can. This is due to the tightening of the ribbon 1 in the Ribbon cartridge 2.

As can clearly be seen, with every switch-on pulse at least the number of bars generated without a ribbon in total be generated. This process means that the number of bars at existing ribbon 1 is at least 6 times higher (six Switch-on pulses) as without ribbon 1. By increasing the number the switch-on pulses can thus improve the interference immunity of the process can be increased arbitrarily, which is a further advantage.

4. The ribbon is present, but completely blocked (ribbon cassette 2 or drive defective).

It does not matter whether the ribbon 1 during the measurement is trapped or not, since it is a complete block anyway is available. As shown in Fig. 4, the current increases with each Switching on the rotary drive motor 4 immediately on his Maximum value, then does not drop as shown in FIGS. 2 and 3 the case is, but remains there until the shutdown. The reason for this is that the motor shaft is due to the blockage can no longer turn and therefore no back emf is built that reduces the electricity.

The threshold value is reached with each energization process and remains exceeded until it is switched off. There will be a total of six Clocks counted (six switch-on processes).

Taktzahl kleiner 20

Farbband fehlt, ist gerissen oder völlig blockiert;

Taktzahl größer 60

Farbband ist vorhanden und mechanisch in Ordnung.

In summary it can be stated that the condition of the ribbon can be determined depending on the number of cycles:

Number of bars less than 20

Ribbon is missing, torn, or completely blocked;

Number of cycles greater than 60

Ribbon is present and mechanically correct.

Reference list

1

Ribbon

2nd

Ribbon cartridge

3rd

drive shaft

4th

Rotary drive motor

5

Printhead

6

Pressure abutment

7

Evaluation unit

7a

Current detection / threshold value formation

7b

Pulse generation

8th

microprocessor

9

Motor driver circuit

10th

Motor driver impulses

11

Measuring time

12th

Current flow

13

Bar sequence

Claims (7)

1. Procedure for the recognition of the condition of functioning of an ink-ribbon in a printer, especially in a ticket-printer, whereby the ink-ribbon is transported by an electrical motor which is connected to the axis of revolution of the ribbon cartridge, and whereby the electrical current consumption of the electrical motor is equivalent with the amount of the propulsive power, characterised by a measuring duration (11) during which the electrical motor (4) is driven by signal pulses, and a defined treshold value is detected, that during this phase the signal pulses of the current value is compared with the treshold value in a system evaluator (7) and that by exceeding the treshold value the electronic level is changed at the exit of the system evaluator (7), so that the arising clock pulse rate is counted in a microprozessor (8) and the measuring result is measured in dependance of a defined number of clock pulses and is measured for a dependant indicating device.
2. Procedure according to claim 1, wherein the treshold value is defined in such a manner, that the treshold value is reached only during starting the run of the electrical motor or by blocking the electrical motor.
3. Procedure according one of the claims 1 or 2, wherein the measuring is caused by switching on the printer and / or by closing the printer-housing.
4. Procedure according one of the claims 1 to 3, wherein the measuring duration (11), the pulse frequency and the pulse duty factor are tuned to the electrical motor (4).
5. Procedure according one of the claims 1 to 4, wherein the period length of the cycles during switching on the electrical motor (4) and the pulse duty factor of the electrical motor (4) are brought to an optimum value in such a manner that the electrical motor (4) is reaching a minimum number of revolutions before it is powered again.
6. Procedure according claim 1, wherein based on a lower number of clocks the ink-ribbon (1) is missing, is teared or is totally blocked and wherein based on a higher number of clocks the ink-ribbon (1) is present and is mechanically working.
7. Device for the recognition of the condition of functioning of an ink-ribbon in a printer, especially in a ticket-printer, whereby the ink-ribbon is conducted endless in an ink-ribbon cartridge and the ink-ribbon cartridge has an axis of revolution which is connected to the electrical motor (4), whereby the electrical motor (4) is driven under pulse conditions and is connected to a system evaluator (7) and the generated clock pulse rate or impulse rate of the system evaluator (7) is given to a microprocessor (8) whereby the microprocessor (8) is connected with the motor driver circuit (9) and the motor driver pulses (10) are gated as ON- / OFF - signals to the electrical motor (4), characterised that the system evaluator (7) on the base of former defined treshold value pulses the recognition of the condition of functioning of the ink-ribbon is measured by counting the clock pulse rate in the microprocessor (8).

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