Seiko Epson Corporation

Hisashi Watamura

Hiroshi Shirotori

A printer includes a switching power supply circuit including a primary side circuit configured to perform a power switching operation, a secondary side circuit having a shunt regulator, a feedback configured to feed a comparison result between the output voltage output from the secondary side circuit and a reference voltage of the shunt regulator back to the primary side circuit to control the output voltage of the secondary side circuit, a control signal circuit configured to input a PSC signal input from an SOC to the photocoupler to control the output voltage of the secondary side circuit, and a switch circuit configured to cut off a current to be supplied to the shunt regulator in a case where the output voltage of the secondary side circuit is a low voltage in accordance with the input of the PSC signal.

Printing apparatus, control method thereof, and power supply circuit therefor

In a head drive circuit for an impact dot printer which performs printing by driving a print wire, a DC power source supplies a power source voltage. A switching element is on/off controlled to apply the power source voltage to a head coil for a predetermined time period. A voltage regulator converts an input voltage having a value higher than the power source voltage into an output voltage having a value as substantially same as the power source voltage. A voltage introducer inputs an inductive voltage, generated in the head coil when the switching element is turned off, into the voltage regulator as the input voltage. A voltage returner feeds back the output voltage of the voltage regulator to the DC power source.

Head drive circuit for impact dot printer

For a print head in an impact dot printer, a drive transistor is connected in series to a head coil that drives a print wire, and a pulse is used to turn the drive transistor on and off. Thus, the drive current i is supplied to the head coil to drive the print wire. The input end of a DC/DC converter is connected to the juncture of the head coil and the drive transistor , and the output end of the DC/DC converter is connected to the juncture of a power source and the head coil . The DC/DC converter clamps, at a constant level, e.g., 90V, the inductive electromotive force of a high voltage that is generated by the head coil when the drive transistor is rendered off. Then, the DC/DC converter transforms the clamped voltage to a voltage equivalent to the voltage level of the power source , e.g., 35V. As a result, instead of energy being wasted by the transistor , the energy accumulated by the head coil is returned to the power source and can again be employed, while the input voltage of the DC/DC converter is maintained at a constant level by an initial charger

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Nagano, Japan

Hisashi Watamura