Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Reexamination Certificate
1998-12-04
2001-06-26
Estremsky, Sherry (Department: 3681)
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
C074S422000
Reexamination Certificate
active
06250169
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a power transmission system with a gearwheel and a toothed rack which ensures increased power transmission and protection of the toothing in the end region of a toothed rack and can be used as an automatic transport securing system in recording or playback equipment for optical, magneto-optical or other recording media as well as for other rack drive systems with increased power transmission in the end region of the rack.
BACKGROUND OF THE INVENTION
Recording or playback equipment for optical or magneto-optical recording media, such as for example laser disc, compact disc, minidisc or DVD players, are generally known. In such recording or playback equipment, a scanning device provided in the form of a movable writing or reading system is used for reading the information or data from the recording medium or recording it on the recording medium. The writing or reading system is arranged on a carriage, which is movable in order to be able to follow the track of the recording medium to be read or recorded onto. For the carriage to be movable, a rack which is driven by a gearwheel is provided on the carriage. The scanning device provided in the form of a movable writing or reading system is in this case either provided as a so-called linear drive or comprises a coarse drive and a fine drive. In the case of the scanning device comprising a coarse and fine drive, the coarse drive is provided as the carriage, on which the fine drive is arranged. This construction corresponds to a so-called CD-Mechadeck, as used for example in CD players. Such a CD-Mechadeck may, however, also be designed and used as a writing or reading system for other recording media, such as for example DVD or minidisc. The writing or reading system driven by a gearwheel via a toothed rack has a mass which causes the toothing of the rack and/or gearwheel to be damaged, in particular if the equipment is subjected to strong vibration during transport. In addition, to save an additional drive for a loading or unloading device for the recording medium, it is desirable to ensure the transmission of a high level of power with the drive system comprising the gearwheel and toothed rack, so that the loading or unloading device for the recording medium can be driven directly by the carriage. An obvious strengthening of the gearwheel and rack to ensure a higher power transmission and to prevent damage during transport is ruled out as a solution to the problem, however, since it involves increased expenditure on material and requires more space.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a power transmission system with a gearwheel and a toothed rack which ensures increased power transmission and protection of the toothing and can be used as an automatic transport securing system in recording or playback equipment for optical recording media without strengthening the gearwheel and rack.
This object is achieved by features specified in the main claims. Advantageous designs and developments are specified in subclaims.
One aspect of the invention is to provide a power transmission system with a gearwheel and a toothed rack which ensures increased power transmission and protection of the toothing. For this purpose, an engagement securing system is provided. Since a strengthening of the gearwheel and rack is ruled out as a solution, the starting point is for increased power transmission and protection of the toothing to be ensured by an engagement securing system which ensures secure engagement of the teeth of the gearwheel and the rack even under the conditions of increased power transmission between the gearwheel and the rack.
A further aspect of the invention is that the number of individual parts of the power transmission system comprising the gearwheel and the rack is not increased. This rules out the possibility of increased power transmission being accomplished by an additional clamping means for a shaft clamped only at one end, on which shaft the gearwheel is guided, even though a shaft clamped only at one end is to be regarded as one of the causes for the rack displacing the gearwheel out of its position and for the teeth coming into engagement with one another in another position. So-called chattering of the teeth of the rack over the teeth of the gearwheel disadvantageously leads to the teeth of the rack and/or gearwheel being damaged. On account of the high accuracy requirements which the guiding of the carriage with the rack and gearwheel have to meet for the tracking of the writing or reading system for optical recording media, such damage cannot be allowed. Therefore, an engagement securing system is provided to solve the problem. The engagement securing system of the power transmission system with a gearwheel and a toothed rack for movable writing or reading systems for optical recording media is preferably provided in the end region of the rack, since this is the customary position of the writing or reading system for optical recording media during the transporting and the loading or unloading of the recording medium. According to one design of the engagement securing system, the engagement securing system is formed by a lug of the toothed rack which engages in a guide connected to the gearwheel. The guide connected to the gearwheel is in this case preferably formed by a groove which is provided in a disk connected to the gearwheel. The lug of the rack engaging in the guide or groove of the disk of the gearwheel forms an engagement securing system, since it prevents displacement of the position of the gearwheel with respect to the rack and, as a result, the teeth of the gearwheel and rack cannot come into engagement with one another in another position. The clamping of the gearwheel and rack achieved with the lug and the guide ensures increased power transmission in the region of the engagement securing system. A gearwheel guided on a shaft clamped at one end can no longer be displaced out of its position by the rack. As a result, the engagement securing system both forms an automatic transport securing system and ensures increased power transmission, which can advantageously be used for driving a loading or unloading device for the optical recording medium. An additional drive for the loading or unloading device for the optical recording medium is saved as a result.
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*Corresponds to EP0688975A1, cited under reference AM.
*Corresponds to WO95/08172, cited under reference AP.
Deutsche Thomson-Brandt GmbH
Estremsky Sherry
Kiel Paul P.
Lewis Tisha D.
Tripoli Joseph S.
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