An apparatus for driving an actuator according to an exemplary embodiment of the present invention will now be described more fully with reference to the accompanying drawings.
As illustrated in
A first power capacitor C1 in the actuator 120 in
The power unit 100 illustrated in
The sensing unit 140 senses a displacement of the suspended vibration plate 123 according to a result of sensing by the sensing plate 124.
The power provided to the first activating vibration plate 121 and that provided to the second activating vibration plate 122 are in reverse phases to each other so that an electrostatic force is generated at the first activating vibration plate 121 and the second activating vibration plate 122 respectively. Here, an AC considered as noise is transmitted to the sensing unit 140 by a parasitic capacitance in the actuator 120. Since the noise is also reversed in phase, it is offset and the signal-to-noise ratio is improved. However, in order to maximize the effect of the noise offset, the difference between a first parasitic capacitance formed by the first activating vibration plate 121, the suspended vibration plate 123, and the sensing plate 124 and a second parasitic capacitance formed by the second activating vibration plate 122, the suspended vibration plate 123, and the sensing plate 124 should be minimized. In order to gain the effect of the noise offset, a first outer capacitor Ce1 and a second outer capacitor Ce2 may be provided since the first parasitic capacitance and the second parasitic capacitance do not generally coincide.
The first outer capacitor Ce1 is provided between a first power terminal T1, which connects the power unit 100 to the actuator 120 in order to provide the first power, and a sensing terminal T3, which connects the sensing plate 124 of the actuator 120 to the sensing unit 140.
The second outer capacitor Ce1 is provided between a second power terminal T2, which provides the second power and connects the power unit 100 to the actuator 120, and the sensing terminal T3.
In order to minimize the noise made by the difference between the first parasitic capacitance and the second parasitic capacitance in the actuator 120, capacitance of one or both of the first outer capacitor (Ce1) and the second outer capacitor (Ce2) is adjusted so that the first parasitic capacitance and the second parasitic capacitance are similar. The adjustment may be done by means of a repeated test according to a result of sensing by the sensing unit 140 during the designing stage of the apparatus for driving the actuator 120.
{circle around (1)} in
{circle around (2)} in
The apparatus for driving the actuator 120 is provided so that an apparatus may form an image by using a device such as a printer or a scanner.
The apparatus for driving the actuator 120 according to the present invention, improves the signal-to-noise ratio by adding the outer capacitor that allows the parasitic capacitances to be similar to each other in order prevent an activating vibration signal mixing with a sensing signal, which generates noise through parasitic capacitance caused by the construction of the actuator 120 and vibration characteristics. Also, since the sensing unit 140 is embodied by using a simple capacitance detecting type circuit the cost of manufacturing the driving apparatus can be reduced.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Number | Date | Country | Kind |
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10-2006-0065074 | Jul 2006 | KR | national |