PULSE GENERATING DEVICE, ROTATOR MODULE, ROTATIONAL SPEED CONTROL DEVICE, AND IMAGE FORMING APPARATUS

• US 20110057822A1
• Filed: 09/07/2010
• Published: 03/10/2011
• Est. Priority Date: 09/09/2009
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: WATAHIKI, Tatsuya
• Granted Patent: US 8,410,743 B2
• Time in Patent Office: Days
• US Class Current: 341/116
• CPC Class Codes: G01D 5/34715 Scale reading or illumination devices
• CPC Class Codes: G01D 5/36 Forming the light into pulses
• CPC Class Codes: G01P 3/481 of pulse signals
• CPC Class Codes: G01P 3/486 delivered by photo-electric detectors
• CPC Class Codes: G01P 3/489 Digital circuits therefor
• CPC Class Codes: H03M 1/0678 using additional components or elements, e.g. dummy components
• CPC Class Codes: H03M 1/30 incremental

Abstract

A pulse generating device includes a rotatable disc having a plurality of patterns that are formed on a surface of the rotatable disc in a circumferential direction of the rotatable disc, and three pulse generators to each detect the plurality of patterns formed on the rotatable disc and to respectively generate three pulse signals each corresponding to a rotational speed of the rotatable disc based on the detected patterns. The three pulse generators are evenly spaced at intervals of 120 degrees of angle with respect to a rotational axis of the rotatable disc in the circumferential direction of the rotatable disc.

Claims

1. A pulse generating device comprising:

a rotatable disc having a plurality of patterns formed on a surface of the rotatable disc in a circumferential direction of the rotatable disc; and

three pulse generators evenly spaced at intervals of 120 degrees around the circumference of the rotatable disc, configured to each detect the plurality of patterns formed on the rotatable disc and to respectively generate three pulse signals each corresponding to a rotational speed of the rotatable disc based on the detected patterns.

2. A rotator module comprising:

a rotator configured to rotate in synchronization with the rotatable disc; and

the pulse generating device of claim 1.

3. A rotational speed control device for controlling a rotational speed of a rotator, the control device comprising:

a rotatable disc having a plurality of patterns that are formed on a surface of the rotatable disc in a circumferential direction of the rotatable disc, the rotatable disc configured to rotate in synchronization with the rotator;

three pulse generators evenly spaced at intervals of 120 degrees around the circumference of the rotatable disc, configured to each detect the plurality of patterns formed on the rotatable disc and to respectively generate three pulse signals each corresponding to a rotational speed of the rotatable disc based on the detected patterns; and

a controller configured to control the rotational speed of the rotator based on a signal from which an error component superimposed on the three pulse signals respectively generated by the three pulse generators is removed.

4. The rotational speed control device of claim 3, wherein the controller obtains an average value of the three pulse signals respectively generated by the three pulse generators so as to eliminate the error component.

5. The rotational speed control device of claim 3, further comprising:

a pulse detector configured to obtain pulse interval time data of the three pulse signals,

wherein the controller obtains an average value of the three pulse signals by calculating an average value of the pulse interval time data obtained by the pulse detector.

6. The rotational speed control device of claim 3, wherein the error component includes at least one of:

a one-cycle error component that is superimposed over one cycle of the pulse signals as the rotatable disc rotates one cycle; and

a two-cycle error component that is superimposed over two cycles of the pulse signals as the rotatable disc rotates one cycle.

7. The rotational speed control device of claim 3, wherein the rotator, the rotatable disc, and the three pulse generators form a single integrated rotator module.

8. An image forming apparatus comprising:

the rotational speed control device of claim 3.