Patent US1217570A successfully refreshed from Google Patents.
US3822643A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dampening control circuit for off-set printing apparatus
Assignee: Pitney Bowes Inc
•
Filing: 1973-01-26
•
Granted: 1974-07-09
•
Expires: 1993-01-26
Abstract
Abstract A control circuit for an off-set printing apparatus is described whereby a dampening roll, which is used to wet a printing surface with an ink repelling liquid, is automatically maintained at the proper level of wetness from start-up through completion of the printing operation. A rapid wetting network is employed to quickly wet the dampening roll by rotating a pan roll at a greater than normal speed. An AC liquid impedance signal is generated by applying an AC excitation signal across the dampening roll to sense its liquid impedance and thus the amount of liquid on the dampening roll. An AC amplified liquid impedance signal drives a pair of threshold detectors which respectively recognize a normally dry operating condition and an excessively dry condition of the dampening roll. The output signals of the threshold detectors operate a normal wetting motor and a rapid wetting motor with the latter motor limited in its wetting operation to bring the dampening roll quickly to an acceptable liquid dampening level.
Inventors
- 👤 D Mikan
- 👤 A Presti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 16:07
CPC Classifications
B; B41; B41F; B41F33/00; B41F33/0054; B41F7/00; B41F7/20; B41F7/24
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
258 words
A dampening control circuit for an off-set printing machine including means for carrying a printing plate having a printing surface, means for supplying a liquid, a rotatable dampening roll, and apparatus for depositing liquid from the supply means on the dampening roll to wet the printing surface, the control circuit comprising: an AC excitation signal source; liquid from the supply means responsive to the AC excitation signal from the source for producing a liquid impedance signal whose magnitude is representative of the amount of liquid on the dampening roll; means responsive to the liquid impedance signal for controlling the amount of liquid on the dampening roll; said controlling means including reference means establishing preselected normal and abnormal wetting demand ranges for the dampening roll which respectively correspond to normally dry and excessively dry conditions of the dampeniNg roll; and said controlling means further including means cooperative with the reference means for producing a normal wetting signal when the liquid impedance signal is within the normal wetting demand range of the dampening roll, means responsive to the normal wetting signal for controlling said apparatus to maintain the dampening roll in normally wet running condition for liquid wetting of the printing surface, means cooperative with the reference means for producing a rapid wetting signal when the liquid impedance signal is indicative of the preselected excessively dry condition of the dampening roll, and means actuated by said rapid wetting signal for controlling said apparatus to increase the wetting rate of the dampening roll until said excessively dry condition has been removed.
Claim 2
Dependent Claim
258 words
A dampening control circuit for an off-set printing machine including means for carrying a printing plate having a printing surface, means for supplying a liquid, a rotatable dampening roll, and apparatus for depositing liquid from the supply means on the dampening roll to wet the printing surface, the control circuit comprising: an AC excitation signal source; liquid from the supply means responsive to the AC excitation signal from the source for producing a liquid impedance signal whose magnitude is representative of the amount of liquid on the dampening roll; means responsive to the liquid impedance signal for controlling the amount of liquid on the dampening roll; said controlling means including reference means establishing preselected normal and abnormal wetting demand ranges for the dampening roll which respectively correspond to normally dry and excessively dry conditions of the dampeniNg roll; and said controlling means further including means cooperative with the reference means for producing a normal wetting signal when the liquid impedance signal is within the normal wetting demand range of the dampening roll, means responsive to the normal wetting signal for controlling said apparatus to maintain the dampening roll in normally wet running condition for liquid wetting of the printing surface, means cooperative with the reference means for producing a rapid wetting signal when the liquid impedance signal is indicative of the preselected excessively dry condition of the dampening roll, and means actuated by said rapid wetting signal for controlling said apparatus to increase the wetting rate of the dampening roll until said excessively dry condition has been removed.
Claim 3
Dependent Claim
32 words
The dampening control circuit as claimed in claim 1, wherein the controlling means includes means for deactivating said means actuated by said rapid wetting signal before excessive wetting of the dampening roll.
Claim 4
Dependent Claim
72 words
The dampening control circuit as claimed in claim 2, wherein said deactivating means includes means producing a periodically occuring trigger signal having a frequency of recurrence sleected to be shorter than the time needed to excessively wet the dampening roll after said excessively dry condition of the dampening roll has been removed; and means actuated by the trigger signal for terminating the operation of the means actuated by said rapid wetting signal.
Claim 5
Dependent Claim
68 words
The dampening control circuit as claimed in claim 1, wherein the responsive liquid includes liquid on the dampening roll, and said control circuit includes means for electrically coupling the AC excitation signal to said liquid on the dampening roll to sense a variation of the AC impedance thereof; and a high input impedance AC amplifier coupled across the coupling means to produce an amplified AC liquid impedance signal.
Claim 6
Dependent Claim
33 words
The dampening control circuit as claimed in claim 4 including means for reducing the level of the liquid impedance signal to desensitize the control circuit from noise variations in the liquid impedance signal.
Claim 7
Dependent Claim
104 words
The dampening control circuit as claimed in claim 4, wherein the controlling means includes means responsive to the amplifier output for rectifying the amplified AC liquid impedance signal to provide a DC signal whose magnitude is proportional to the impedance of the sensed liquid on dampening roll; and wherein the reference means for producing the normal wetting signal and the rapid wetting signal includes a pair of threshold detectors connected to respectively receive the DC signal, said threshold detectors being selected to respectively sense the occurence of different magnitudes of the DC liquid impedance signal for normal and rapid wetting of the dampening roll.
Claim 8
Dependent Claim
253 words
In a dampening control circuit for an off-set printing apparatus having a dampening roll for applying an ink repelling liquid to a printing plate with the liquid being supplied from a rotatable pan roll by a ductor roll moving between the pan roll and an electrically conductive oscillator roll in contact with the dampening roll and with an electrically conductive detector roll being located in contact with the dampening roll, the improvement comprising: a source of AC signals; means coupled to the detector and oscillator roll for supplying the AC signals thereto and producing a liquid impedance signal having a magnitude representative of the impedance between the detector and oscillator rolls; means responsive to the liquid impedance signal for producing a normal wetting signal representative of a normal running range of impedance between the detector and oscillator rolls and further producing a rapid wetting signal representative of an abnormal running range of impedance corresponding to an excessively high range of impedance between the detector and oscillator rolls; means actuated by the normal wetting signal for cOntrolling the operation of the ductor roll to maintain a desired running dampening condition of the dampening roll; and means actuated by the rapid wetting signal for increasing the speed of rotation of the pan roll to increase the rate at which the ductor roll supplies liquid from the pan roll to the oscillator roll and thus to the dampening roll in contact with the oscillator roll to establish the desired running dampening condition of the dampening roll.
Claim 9
Dependent Claim
253 words
In a dampening control circuit for an off-set printing apparatus having a dampening roll for applying an ink repelling liquid to a printing plate with the liquid being supplied from a rotatable pan roll by a ductor roll moving between the pan roll and an electrically conductive oscillator roll in contact with the dampening roll and with an electrically conductive detector roll being located in contact with the dampening roll, the improvement comprising: a source of AC signals; means coupled to the detector and oscillator roll for supplying the AC signals thereto and producing a liquid impedance signal having a magnitude representative of the impedance between the detector and oscillator rolls; means responsive to the liquid impedance signal for producing a normal wetting signal representative of a normal running range of impedance between the detector and oscillator rolls and further producing a rapid wetting signal representative of an abnormal running range of impedance corresponding to an excessively high range of impedance between the detector and oscillator rolls; means actuated by the normal wetting signal for cOntrolling the operation of the ductor roll to maintain a desired running dampening condition of the dampening roll; and means actuated by the rapid wetting signal for increasing the speed of rotation of the pan roll to increase the rate at which the ductor roll supplies liquid from the pan roll to the oscillator roll and thus to the dampening roll in contact with the oscillator roll to establish the desired running dampening condition of the dampening roll.
Claim 10
Dependent Claim
93 words
The improved dampening control circuit as claimed in claim 7, wherein the ductor roll controlling means includes first means for rotating the pan roll at a preselected normal running speed to provide a normal supply of liquid for the ductor roll to wet the oscillator roll for normal wetting of the dampening roll; and wherein the pan roll speed increasing means includes a rapid wetting motor coupled to rotate the pan roll at an elevated speed; and a one-way clutch operatively coupled between the first means and the pan roll speed increasing means.
Claim 11
Dependent Claim
30 words
The improved dampening control circuit as claimed in claim 7 including pulse generating means coupled to the speed increasing means to terminate operation of the pan roll speed increasing means.
Claim 12
Dependent Claim
70 words
The improved dampening control circuit as claimed in claim 8 wherein the control circuit includes pulse generator means for producing pulses at selected intervals corresponding to a maximum allowable time for preventing excessive wetting of the dampening roll; and means driven by said pulses for inhibiting operation of said pan roll speed increasing means to prevent further rapid wetting of the dampening roll upon removal of the rapid wetting signal.
Claim 13
Dependent Claim
139 words
In an off-set printing apparatus having a dampening network to control the amount of liquid transferred to a dampening roll from a pan roll operating in a supply of liquid, the improvement comprising means for producing a dampening signal representative of the amount of liquid on the dampening roll; means responsive to a predetermined normal operating range of the dampening signal for maintaining the dampening roll supplied with liquid for a normal running operation of the off-set printing apparatus; means responsive to the dampening signal for producing a rapid wetting signal when the dampening signal is representative of a preselected excessively dry condition of the dampening roll; and means actuated by said rapid wetting signal for supplying the dampening roll with liquid at an increased rate until said dampening signal has been returned to said predetermined normal operating range.
Claim 14
Dependent Claim
139 words
In an off-set printing apparatus having a dampening network to control the amount of liquid transferred to a dampening roll from a pan roll operating in a supply of liquid, the improvement comprising means for producing a dampening signal representative of the amount of liquid on the dampening roll; means responsive to a predetermined normal operating range of the dampening signal for maintaining the dampening roll supplied with liquid for a normal running operation of the off-set printing apparatus; means responsive to the dampening signal for producing a rapid wetting signal when the dampening signal is representative of a preselected excessively dry condition of the dampening roll; and means actuated by said rapid wetting signal for supplying the dampening roll with liquid at an increased rate until said dampening signal has been returned to said predetermined normal operating range.
Claim 15
Dependent Claim
72 words
The improved dampening network as claimed in claim 11, wherein said means for supplying liquid to the dampening roll at an increased rate includes a rapid wetting motor coupled to the pan roll, said rapid wetting motor providing an increase in the rate of rotation of the pan roll to enable it to remove an increased amount of liquid from the supply for transfer to the dampening roll at said increased rate.
Claim 16
Dependent Claim
91 words
The improved dampening network as claimed in claim 12 wherein said means for maintaining the dampening roll supplied with liquid for normal running operation includes a normal wetting motor and a ratchet drive driven by the normal wetting motor and coupled to rotate the pan roll, and a one-way clutch operatively coupled between the rotational output of the ratchet drive and the rapid wetting motor, said one-way clutch being operable to prevent rotational drive of the rapid wetting motor by the ratchet drive in the absence of a rapid wetting signal.
Claim 17
Dependent Claim
191 words
In a dampening control circuit for an off-set printing apparatus having a dampening roll for applying a liquid to a printing plate with the liquid being transferred from a pan roll by a ductor roll reciprocating between the pan roll and an electrically conductive oscillator roll which is in contact with the dampening roll and with an electrically conductive detector roll being located in contact wIth the dampening roll to enable the sensing of the amount of liquid on the dampening roll, the improvement comprising: means for producing an excitation signal to generate a liquid dampening signal across the detector and oscillator rolls representative of the amount of liquid on the dampening roll; means actuated by the liquid dampening signal for controlling the reciprocation of the ductor roll to maintain a normal running wetting range of the dampening roll; and means actuated by the liquid dampening signal for increasing the available supply of liquid on the pan roll for transfer to the oscillator roll when the liquid dampening signal represents a predetermined excessively dry condition of the dampening control until said normal running wetting range of the dampening roll is achieved.
Claim 18
Dependent Claim
191 words
In a dampening control circuit for an off-set printing apparatus having a dampening roll for applying a liquid to a printing plate with the liquid being transferred from a pan roll by a ductor roll reciprocating between the pan roll and an electrically conductive oscillator roll which is in contact with the dampening roll and with an electrically conductive detector roll being located in contact wIth the dampening roll to enable the sensing of the amount of liquid on the dampening roll, the improvement comprising: means for producing an excitation signal to generate a liquid dampening signal across the detector and oscillator rolls representative of the amount of liquid on the dampening roll; means actuated by the liquid dampening signal for controlling the reciprocation of the ductor roll to maintain a normal running wetting range of the dampening roll; and means actuated by the liquid dampening signal for increasing the available supply of liquid on the pan roll for transfer to the oscillator roll when the liquid dampening signal represents a predetermined excessively dry condition of the dampening control until said normal running wetting range of the dampening roll is achieved.
Claim 19
Dependent Claim
82 words
The improved dampening control circuit as claimed in claim 14 wherein the pan roll liquid increasing means includes a rapid wetting motor operatively coupled to rotate the pan roll at a speed selected to increase the available amount of liquid thereon; means responsive to the liquid dampening signal for producing a rapid wetting signal when the liquid dampening signal signifies an excessively dry condition of the dampening roll; and means actuated by the rapid wetting signal to energize the rapid wetting motor.
Claim 20
Dependent Claim
102 words
The improved dampening control circuit as claimed in claim 15 wherein said wetting motor energizing means includes an SCR having a gate coupled to the rapid wetting signal; a semiconductor AC switch coupled in series with the rapid wetting motor; a relay having a relay coil in series connection with the SCR and having a pair of relay controlled switches; one of the relay controlled switches being coupled to the semiconductor AC switch to energize the motor; and means including the other relay controlled switch for short circuiting said SCR at predetermined intervals to terminate the energization of the rapid wetting motor.
Claim 21
Dependent Claim
94 words
The improved dampening control circuit as calimed in claim 16 wherein said SCR short circuiting means includes means for producing pulses at regular intervals selected to prevent excessive wetting of the dampening roll by the rapid wetting motor operation; means actuated by said pulses and connected across the SCR for effectively shorting the power electrodes thereof, said other relay controlled switch being effectively connected to the latter means for effective enabling thereof when the relay is energized by the rapid wetting signal and for inhibiting said latter means when the relay is not energized.
References Cited (Backward Citations)
US3227951A
Cited
US3191528A
Cited
US3412677A
Cited
US3499383A
Cited
US3584579A
Cited
US3688696A
Cited
US3730086A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-08 | 1978-01-07 | 1978-07-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-08 | 1982-01-07 | 1982-07-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-08 | 1986-01-07 | 1986-07-09 | $7700.00 | Window Closed / Lapsed |