Seiko Epson Corporation

Akihiko Ikegami

Shinichi Miyazaki

Yoshikazu Koike

Osamu Shinkawa

Hidetsugu Shimura

Hajime Kurihara

Kunio Tabata

Hiroshi Tanaka

Yoshiro Koga

Tomoe Aruga

Takehiko Okamura

Takashi Hama

Akihito Uetake

Kenjiro Yoshioka

Keiji Hara

Yasuhito Hirashima

Kenjirou Yoshioka

A printer includes a reversal transportation path which transports a paper to which ink ejected from liquid ejecting heads has adhered toward a downstream side in the transportation direction. In the printer, the reversal transportation path is formed between a pair of guiding plates having a substantially circular arc shape along the transportation direction of the paper and opening holes which blow out wind toward the reversal transportation path from a blowing unit are provided on an inner guiding plate of the pair of the guiding plates, which is positioned at the center side of the circular arc shape.

Liquid ejecting apparatus

A pulse signal is output from a position detector or the like provided on an object to be driven by the motor as the object to be driven travels, and the commutation of the motor is controlled on the basis of the pulse signal. More specifically, the object to be driven is driven by the motor, so that the travel of the object to be driven is proportional to the rotational amount of the motor, and the rotational state of the motor can be detected from the traveling state of the object to be driven, thus enabling the detection of the position of the rotor. Hence, by controlling the commutation of the motor on the basis of a detection signal from the position detector, a commutation timing can be precisely detected even if the motor is in a low speed zone.

Motor driving apparatus

When a rotor of a brushless motor is at rest, excitation is performed three times such that excitation phase is switched each time an excitation is performed thereby to ensure that the rotor rotates. When the rotor has stopped after the third excitation, a commutation reference point is set at the rest position. A position detector outputs pulses in response to movement of an object driven by the brushless motor. The pulses output from the position detector are monitored and commutation is controlled on the basis of the number of pulses as counted starting from the commutation reference point. For example, the number of pulses output during a period starting from the commutation reference point and ending at a point of time at which commutation should be performed is measured as a predetermined number in advance. When the counted number of pulses with respect to the commutation reference point becomes equal to the above predetermined number, it is determined that a commutation timing has reached, and commutation is performed.

Sensorless motor driving apparatus

A stepping motor ( ) which has rotor pole teeth ( ) disposed with a predetermined pitch (P ) on a rotor ( ) and stator pole teeth ( ) formed on a stator pole ( ) so to oppose the rotor pole teeth ( ), wherein the stator poles ( ) are provided with n sets of tooth groups ( ) consisting of the stator pole teeth ( ) in the number of m, a pitch P of the stator pole teeth ( ) in the tooth groups ( ) is in the relation P &ne;P , and a pitch P of the tooth groups ( ) is in the relations P &ne;m&middot;P and P &ne;m&middot;P (where, P , P and P denote an electrical angle, and m and n are integers of 2 or more), and a three-phase stepping motor in which the fourth harmonic and the sixth harmonic are decreased.

Stepping motor, printing device using it or paper feeding device, and printer

The present invention relates to a control method and a control device for a position sensorless motor which has position sensorless operation and synchronized operation, wherein a rotation position of a rotor is detected on the basis of counter electromotive forces generated in stator coils in the position sensorless operation, the stator coils are excited in synchronization with the detected rotation position of the rotor to rotate the rotor and a deviation between a target position and the present position is determined from a target rotation position according to the position command signal and the detected rotation position, position sensorless close loop drive is made on the basis of the determined deviation, and when the synchronized operation is made, the stator coils of the motor are excited in synchronization with the position command signal to rotate the rotor.

Method and device for controlling position sensorless motor

When the brushless motor at rest is started, phase excitation is performed twice such that different phases are excited. A commutation reference point is set at a position at which a rotor has stopped after the second-time excitation. A position detector outputs pulse signals in response to a movement of an object driven by the brushless motor The pulse signals output from the position detector are monitored and commutation is controlled on the basis of the number of pulse edges of the pulse signals as counted starting from the commutation reference point. For example, the number of pulse edges output during a period starting from the commutation reference point and ending at a point of time at which commutation should be performed is measured in advance. When the number of pulse edges with reference to the commutation reference point becomes equal to the above predetermined number, it is determined that commutation timing has reached, and commutation is performed.

A PM type stepping motor is provided capable of further reducing the higher harmonic component of detent torque. n sets of teeth groups, each consisting of m stator polar teeth, are set for each of an outer yoke and an inner yoke, and the pitch P of the stator polar teeth, the pitch P of the teeth groups, and the pitch P of the N and S poles of permanent magnets are set such that the relationship: P &ne;P , P &ne;m&middot;P , and P &ne;m&middot;P holds true, where P , P and P are electrical angles, and m and n are integers equal to or larger than 2.

PM type stepping motor

A stepping motor includes a pair of internally fitted members,and,, one disposed at each end portion of a stator,in an axial direction thereof. Each internally fitted member,and,includes a first fitted portion,internally fitted to an inner peripheral surface of the corresponding end portion of the stator,. The stator,is sandwiched in a radial direction thereof by the first fitted portions,and second fitted portions,of a pair of brackets,and,, one externally fitted to the outer peripheral surface of each end portion of the stator,in the axial direction thereof. The internally fitted members,and,and the brackets,and,are separately formed so that the brackets,and,can be freely positioned with respective to the respective internally fitted members,and,in a radial direction thereof.

Stepping motor

A structure for mounting a rotary member is provided including employing a pair of opposed spaced sheet members. First and second supporting structures are respectively formed at opposed locations on the sheet members, the supporting structures each being one of a projecting part and a barring part. The rotary member is formed with one of an axial shaft or an axial bore on each side thereof for engagement with and support by a corresponding opposed pair of supporting structures. The support structures may be either projecting parts, or barring parts. An image forming apparatus is also provided employing this improved structure for mounting a rotary member. The support structures are formed on frame portions of the image forming apparatus.

Structure for mounting a rotary member and image forming apparatus using

A charger capable of reliably and uniformly maintaining a discharging gap formed in the vicinity of a contact portion between a charging member and a photosensitive member. A charging member 101 is arranged by supporting and fixing both ends of a flexible film 102 by means of support members 103 to 105. The film 102 forms a flexible portion oriented downwardly from fixed ends S1, S2. The film 102 is brought into contact with the member 110 to be charged in a state in which an unsupported side of the film 102 is oriented toward the downstream side in the rotating direction of the member 110 to be charged. Then, the film 102 is brought into contact with the member 110 to be charged in a contact area N, and the radius of curvature of the film 102 in a zone P2 located downstream of that zone N in the rotating direction of the member 110 to be charged becomes smaller than the radius of curvature of the film 102 in an upstream zone P1.

Charger apparatus

A contact charge supply device for externally controlling the charges, which are supplied to a member to be charged by bringing a contact member appled with an external voltage into contact with the member to be charged, which at least includes an underlayer, and holds the following inequality

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Suwa, Japan

Akihiko Ikegami