US3816727A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Echo check circuit
Assignee: Xerox Corp
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Filing: 1972-11-24
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Granted: 1974-06-11
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Expires: 1992-11-24
Abstract
Abstract A non-impact computer output printer is disclosed wherein characters distributed about a rotating drum are projected to a xerographic drum by means including a row of flash lamps located inside the character drum. The echo check circuit is used for informing the controller unit issuing the commands to the flash lamps whether or not the lamps fired. In this way the integrity of the resultant printed matter is controlled. The echo check circuit includes noise isolating means for operating in the electrically noisy environment associated with flash lamps.
Inventors
- 👤 Cann J Mc
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:08
CPC Classifications
G; G06; G06K; G06K15/00; G06K15/02; G06K15/12; G06K15/1238; B; B41; B41B; B41B17/00; B41B17/04; B41B17/10; B41B21/00; B41B21/08; B41B21/12; B41B27/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
173 words
In a non-impact Character printer of the type employing a plurality of flash lamps to illuminate selected characters from character sets moved relative to the flash lamps, the flash lamps being illuminated in response to flash command signals generated by controller means in a sequence controlled by timing pulses associated with the characters in the character sets. the flash signals being supplied to lamp ignition means coupled to the controller means and the flash lamps, the improvement comprising apparatus for generating an echo check signal indicating a lamp has flashed including: integrating means coupled to said lamp ignition means for generating at the time of a lamp flash, a first signal changing in amplitude between two limits within a time that determines the duration of the echo check signal, and gate means coupled to receive said first signal and to generate an echo check signal indicative of a lamp flash having a duration corresponding to the time required for the first signal to change amplitude from one to another of its two limits.
Claim 2
Dependent Claim
173 words
In a non-impact Character printer of the type employing a plurality of flash lamps to illuminate selected characters from character sets moved relative to the flash lamps, the flash lamps being illuminated in response to flash command signals generated by controller means in a sequence controlled by timing pulses associated with the characters in the character sets. the flash signals being supplied to lamp ignition means coupled to the controller means and the flash lamps, the improvement comprising apparatus for generating an echo check signal indicating a lamp has flashed including: integrating means coupled to said lamp ignition means for generating at the time of a lamp flash, a first signal changing in amplitude between two limits within a time that determines the duration of the echo check signal, and gate means coupled to receive said first signal and to generate an echo check signal indicative of a lamp flash having a duration corresponding to the time required for the first signal to change amplitude from one to another of its two limits.
Claim 3
Dependent Claim
57 words
The apparatus of claim 1 wherein said controller means is coupled to receive said echo check signal for performing a decision function when an echo check signal is not received subsequent to issuance of a flash command signal or an echo check signal is received when a flash command signal is not issued by said controller means.
Claim 4
Dependent Claim
53 words
The apparatus of claim 1 further including pulse generating means coupled between said lamp ignition means and said gate means for generating a second signal of fixed amplitude that is logically ANDed with said first signal to isolate further the echo check apparatus from electrical noise including that associated with a lamp flash.
Claim 5
Dependent Claim
56 words
The apparatus of claim 1 further including an isolation transformer having primary windings coupled between a power supply and the said lamp ignition means to protect the power supply during lamp flash and secondary windings coupled to said integration means to isolate further the integrating means from electrical noise including that associated with a lamp flash.
Claim 6
Dependent Claim
42 words
The apparatus of claim 4 wherein said isolation transformer is a saturable transformer having a saturation period corresponding to the time required for the gases in a flash lamp to deionize to a state in which the lamp can again be flashed.
Claim 7
Dependent Claim
39 words
The apparatus of claim 5 wherein said saturation period of the transformer is a multiple of the time spacing between characters in a character set and the duration of the echo check pulse is less than the inter-character spacing.
Claim 8
Dependent Claim
21 words
The apparatus of claim 1 wherein said integrating means includes a ramp generator producing a ramp signal as said first signal.
Claim 9
Dependent Claim
76 words
The apparatus of claim 7 further including a saturable transformer having its primary windings coupled between said lamp ignition circuit and a power supply and its secondary windings coupled to a pulse generating circuit and said ramp generator and wherein said pulse generator produces a second signal of fixed amplitude and is coupled to the gate means so the second signal is logically ANDed with said ramp signal for the production of said echo check signal.
Claim 10
Dependent Claim
162 words
In a non-impact character printer of the type employing a plurality of flash lamps to illuminate selected characters from character sets in response to flash command signals generated by controller means moved relative to the lamps in a sequence controlled by timing pulses associated with the characters in the characters sets, the improvement comprising the method of generating an echo check signal for informing the controller unit that a lamp has flashed including generating a first signal changing in amplitude between first and second limits within a time that determines the duration of the echo check signal in response to a flash of a lamp generating a second signal of fixed amplitude at the same time as said first signal, and comparing said first and second signals and generating said echo check sigNal during the time said first signal changes between said limits whereby said echo check signal is isolated from electrical noise including that associated with the flashing of said lamps.
Claim 11
Dependent Claim
162 words
In a non-impact character printer of the type employing a plurality of flash lamps to illuminate selected characters from character sets in response to flash command signals generated by controller means moved relative to the lamps in a sequence controlled by timing pulses associated with the characters in the characters sets, the improvement comprising the method of generating an echo check signal for informing the controller unit that a lamp has flashed including generating a first signal changing in amplitude between first and second limits within a time that determines the duration of the echo check signal in response to a flash of a lamp generating a second signal of fixed amplitude at the same time as said first signal, and comparing said first and second signals and generating said echo check sigNal during the time said first signal changes between said limits whereby said echo check signal is isolated from electrical noise including that associated with the flashing of said lamps.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-10 | 1977-12-10 | 1978-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-10 | 1981-12-10 | 1982-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-10 | 1985-12-10 | 1986-06-11 | $7700.00 | Window Closed / Lapsed |