1. Field of the Invention
The present invention relates to improvement in a rotating display element which is provided with a display surface member having four display surfaces and is adapted to select a desired one of the display surfaces by rotating the display surface member. Further, the invention pertains to improvement in a display unit using such a rotating display element.
2. Description of the Prior Art
The inventor of this application has proposed a rotating display element and a display unit using the same in Japanese Patent Application No. 219,803/85 (Japanese Patent Public Disclosure Gazette No. 79,495/87).
The rotating display element disclosed in the above prior application has a display surface member having four display surfaces and a permanent magnet type motor mechanism. The display surface member is mounted on rotor of the permanent magnet type motor mechanism housed therein, and the four display surfaces of the display surface member are arranged side by side around the axis of the rotor.
Either one of the rotor and the stator of the permanent magnet type motor mechanism has first and second double-pole permanent magnet members respectively having north and south magnetic poles and disposed side by side in the axial direction of the rotor.
The first double-pole permanent magnet member is a bar- or plate-like member of a narrow rectangular cross section in a direction perpendicular to the axis of the rotor and magnetized with north and south magnetic poles at its both free end faces spaced an angular distance of 180 degree apart around the axis of the rotor. The bar- or plate-like member is mounted on the rotor shaft, with the center of the former in the above cross section held with the center of the latter. The second double-pole permanent magnet member is also a bar- or plate-like member which of a narrow rectangular cross section in the direction perpendicular to the axis of the rotor and magnetized with north and south magnetic poles at its both free end faces spaced an angular distance of 180 degrees apart around the axis of the rotor. The bar- or plate-like member is mounted on the rotor shaft, with the center of the former in the above cross section held in agreement with the center of the latter. The north and south magnetic poles of the second double-pole permanent magnet member are disposed around the axis of the rotor at an angular distance of .+-..alpha..degree. (where 0.degree. .ltoreq..alpha..degree. &lt;180.degree.) from the north and south magnetic poles of the first double-pole permanent magnet member and at an angular distance of 180 degrees from each other.
The other of the rotor and the stator of the permanent magnet type motor mechanism has a first magnetic member provided with first and second magnetic poles which act on the north and south magnetic poles of the first double-pole permanent magnet member, a second magnetic member provided with third and fourth magnetic poles which act on the north and south magnetic poles of the second double-pole permanent magnet member, a first exciting winding wound on the first magnetic member in manner to excite its first and second magnetic poles in reverse polarities, and a second exciting winding wound on the second magnetic member in a manner to excite its third and fourth magnetic poles in reverse polarities. The first and second magnetic poles of the first magnetic member are disposed at an angular distance of 180 degrees around the axis of the rotor. The third and fourth magnetic poles of the second magnetic member are disposed around the axis of the rotor at an angular distance of .+-.90.degree. .+-..alpha..degree. from the first and second magnetic poles of the first magnetic member and at an angular distance of 180 degrees from each other. The first and second magnetic poles of the first magnetic member and the third and fourth magnetic poles of the second magnetic member respectively extend over an angular range of about 90 degrees around the axis of the rotor.
The display unit set forth in the aforementioned prior application has the above-described rotating display element and a drive unit therefor.
The drive unit has first power supply means for supplying power to the first exciting winding so that the first and second magnetic poles of the first magnetic member are magnetized with the north and south magnetic poles, second power supply means for supplying power to the first exciting winding so that the first and second magnetic poles of the first magnetic member are magnetized with the south and north magnetic poles, third power supply means for supplying power to the second exciting winding so that the third and fourth magnetic poles of the second magnetic member are magnetized with the north and south magnetic poles, and fourth power supply means for supplying power to the second exciting winding so that the third and fourth magnetic poles of the second magnetic member are magnetized with the south and north magnetic poles.
According to the above-described rotating display element, a selected one of the display surfaces of the display surface member can be turned to the front display position, simply by supplying power in desired polarity to the first and second exciting windings of the stator (or rotor) of the motor mechanism. This permits simplification of the arrangement for driving the display surface member to bring a selected one of its display surfaces to the front display position.
Even if the power supply to the first and second exciting windings is cut off after turning a selected one of display surfaces to the front display position, the selected display surface can be held there, because the first and second double-pole permanent magnet members of the rotor (or stator) of the motor mechanism still act on the first and second magnetic members of the stator (or rotor). This saves unnecessary power consumption.
Since the motor mechanism is housed in the display surface member, a display surface member driving mechanism need not be provided separately of the display element.
Further, since the display element has the afore-mentioned arrangement in which the rotor (or stator) of the motor mechanism has the first and second double-pole permanent magnet members each magnetized with north and south magnetic poles, the double-pole permanent magnet members are each formed by a bar- or plate-like member of a narrow rectangular cross section in the direction perpendicular to the axis of the rotor and has the north and south magnetic poles at its both free end faces spaced an angular distance of 180 degrees apart around the axis of the rotor, and the bar- or plate-like member is mounted on the rotor shaft, with the center of the former in the above-mentioned cross section held in agreement with the center of the latter, it is possible to rapidly and smoothly turn a selected display surface to the front display position and hold it there accurately.
The display unit described above employs the above-mentioned display element and the drive unit therefor including the first and second power supply means for the first and second exciting windings of the display element and the third and fourth power supply means for the second exciting winding. The display surface member can be driven to bring a desired one of the display surfaces to the front display position, simply by selecting the corresponding one of the first to fourth power supply means. Thus, the display element can be driven with a simple arrangement.
In the rotating display element described above, since the intensity of magnetization of the first and second magnetic poles of the first magnetic member and the third and fourth magnetic poles of the second magnetic member can be heightened by increasing the power supply to the first and second exciting windings, a large torque develops in the display surface member when it is driven, and consequently, a selected one of the display surfaces can be quickly brought to the front display position.
In this instance, however, since the first and second magnetic poles of the first magnetic member and the third and fourth magnetic poles of the second magnetic member each extend over as wide an angular range as 90 degrees or so about the axis of the rotor, the high-intensity magnetization of the first to fourth magnetic poles over their entire angular ranges calls for a sufficiently high power supply to the first and second exciting windings, inevitably resulting in a large power consumption.
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