Invalidity dossier
US 4567353
High-accuracy temperature control
Current assignee: Sharp Corp
Added 9/24/2026, 12:05:12 AM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US4567353A — "High-accuracy temperature control"
Title: High-accuracy temperature control
Inventor: Masahiko Aiba
Assignee: Sharp Corp (original and current assignee per listing)
Prior art date: 1977-04-07
Filing date: 1984-07-30 (application US06/634,674)
Publication/grant date: 1986-01-28
Legal status as listed: Expired – Lifetime (anticipated expiration 2003-01-28); Google notes this status is an assumption, not a legal conclusion.
Purpose. The invention relates to a temperature control capable of always keeping an object at a fixed temperature. The excerpt frames this against prior-art controls using bimetals, thermistors, or positive-temperature-characteristic thermistors in a feedback loop with a heating element, which the patent says struggle to hold a precise temperature because of heat resistance, heat capacity, and resulting time delays that make the control system unstable with relatively low gain. The disclosed embodiment applies the control to an ink jet printer, where unstable ink temperature can distort droplet splitting/printing. The ink is supplied to the nozzle through the temperature control means and a mask filter.
Plain-language scope (per the excerpt). A power transistor (16) both heats ink and acts as the temperature sensor, thermally coupled to a heat exchanger around the ink conduit, addressing a preference for low weight on a travelling carriage. The transistor has resistors R1 (emitter-to-base) and R2 (base-to-collector), with the emitter fed via R3 from supply V1; the emitter also drives the minus input of an operational amplifier whose plus input receives a variable reference voltage (divider R10, VR1, R11, R9). A transistor (19) is switched by a NAND gate receiving a clock (e.g., 2.5 kHz) and the Q output of a D-type latch; the op-amp output feeds the latch's D input. This time-multiplexes sensing and heating modes (FIG. 3 shows on/off behavior at low vs. high temperature). Heating current of about 0.6 A and about 10 W is described. The excerpt ends mid-sentence and mentions heat resistance between the transistor, its housing, and the heat exchanger as a problem for small power transistors.
Not established by the excerpt: the full claims, the omitted description text, any prior-art references, and any litigation, ownership-transfer, or validity matters (excluded per instructions).
Source: https://patents.google.com/patent/[US4567353](/patent/US4567353)/en (excerpt only; consult the source for omitted text).
Generated 10/1/2026, 9:32:05 PM
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Litigation summary
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PTAB challenges
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Assignment history
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Prior art
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Obviousness
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Extensions
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Derivative works
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