US3820121A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for expressing a writing fluid
Assignee: Gerber Systems Corp
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Filing: 1972-10-13
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Granted: 1974-06-25
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Expires: 1992-10-13
Abstract
Abstract In a plotting device, a plotting pen and a recording medium are moved relative to one another in accordance with plotting commands to cause the pen to produce a line trace on the medium. A pump is connected to the pen to pressurize the writing fluid in the pen and thereby increase the rate at which the writing fluid is expressed during high speed plotting operations. The pump is driven by a motor controlled in accordance with the rate of relative movement between the pen and recording medium so that the writing fluid in the pen is pressurized by the pump exclusively at higher plotting speeds. With the additional pressurization the pen is capable of dispensing writing fluid to produce continuous and uniform lines at both low and high plotting speeds.
Inventors
- 👤 L Rich
- 👤 H Gerber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:42
CPC Classifications
G; G01; G01D; G01D15/00; G01D15/16; B; B43; B43L; B43L13/00; G01D15/18
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
194 words
Apparatus for expressing writing fluid from a plotting pen onto a recording medium while the pen and the recording medium are moved relative to one another in a plotting device in accordance with plotting commands supplied to the plotting device comprising: velocity signal generating means for producing a velocity signal representative of the rate of movement of the plotting pen and the recording medium relative to one another; fluid pumping means including a centrifugal pump permitting leakage of fluid through the pump in a static condition and connected to the plotting pen for forcing writing fluid from the pen at an increased rate; and control means connected between the velocity signal generating means and the pumping means for driving the pumping means in response to the velocity signal and having a predetermined threshold level which must be exceeded by the velocity signal to initiate driving of the pumping means and which inhibits operation of the pumping means until exceeded by the velocity signal, whereby the plotting pen is permitted to write upon the recording medium by dispensing fluid in a normal manner until the threshold level and the corresponding rate of movement are exceeded.
Claim 2
Dependent Claim
194 words
Apparatus for expressing writing fluid from a plotting pen onto a recording medium while the pen and the recording medium are moved relative to one another in a plotting device in accordance with plotting commands supplied to the plotting device comprising: velocity signal generating means for producing a velocity signal representative of the rate of movement of the plotting pen and the recording medium relative to one another; fluid pumping means including a centrifugal pump permitting leakage of fluid through the pump in a static condition and connected to the plotting pen for forcing writing fluid from the pen at an increased rate; and control means connected between the velocity signal generating means and the pumping means for driving the pumping means in response to the velocity signal and having a predetermined threshold level which must be exceeded by the velocity signal to initiate driving of the pumping means and which inhibits operation of the pumping means until exceeded by the velocity signal, whereby the plotting pen is permitted to write upon the recording medium by dispensing fluid in a normal manner until the threshold level and the corresponding rate of movement are exceeded.
Claim 3
Dependent Claim
42 words
Apparatus for expressing writing fluid from a plotting pen as defined in claim 1 wherein: the control means comprises shaping means receiving the velocity signal and producing an output signal varying in linear relationship with the velocity signal above the threshold level.
Claim 4
Dependent Claim
43 words
Apparatus for expressing writing fluid from a plotting pen as defined in claim 1 wherein: the control means includes shaping means receiving the velocity signal and producing an output signal varying in a nonlinear relationship with the velocity signal above the threshold level.
Claim 5
Dependent Claim
22 words
Apparatus for expressing writing fluid from a plotting pen as described in claim 3 wherein the shaping means comprises a resistor-diode circuit.
Claim 6
Dependent Claim
47 words
Apparatus for expressing writing fluid from a plotting pen as defined in claim 1 wherein: the control means has a predetermined threshold level adjusted to a value of the velocity signal corresponding to a rate of relative movement of the pen and recording medium of 200 ipm.
Claim 7
Dependent Claim
35 words
Apparatus for expressing writing fluid from a plotting pen as defined in claim 1 wherein the control means includes a threshold circuit including an amplifier and bias circuit connected to the input of the amplifier.
Claim 8
Dependent Claim
25 words
Apparatus for expressing writing fluid as defined in claim 6 wherein the threshold circuit further includes a diode connected to the poutput of the amplifier.
Claim 9
Dependent Claim
51 words
Apparatus for expressing writing fluid from a plotting pen as defined in claim 1 wherein: the pumping means includes a pump drive motor connected in driving relationship to the centrifugal pump; and the control means includes a closed servo drive loop connected to the pump drive motor and providing velocity feedback.
Claim 10
Dependent Claim
32 words
Apparatus for expressing writing fluid from a plotting pen as defined in claim 8 wherein the closed servo drive loop includes a tachometer driven by the motor and producing a velocity signal.
Claim 11
Dependent Claim
64 words
Apparatus for expressing writing fluid as defined in claim 1 further including: means responsive to the plotting commands for moving the plotting pen and recording medium into and out of writing relationship; and gating means also responsive to the plotting commands for interrupting the pressurizing of the writing fluid by the centrifugal pump when the pen and recording medium are out of writing relationship.
Claim 12
Dependent Claim
37 words
Apparatus as defined in claim 1 wherein: the control means includes a level detector receiving the velocity signal and defining a predetermined threshold level which must be exceeded by the signal to initiate operation of the pump.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |