Trackball module structure

A trackball module structure is provided. In the structure, a Hall IC is integrated in a flexible printed circuit, and the integrated structure and a trackball device are disposed on the base to be located. Afterwards, a lid is used to fix the integrated structure and the trackball device to form a module. The module is easy to be disposed on an electronic device. This not only solves the problem that the conventional trackball is hard to locate, but also prevents the ESD with the cooperation of a metal base and a metal lid.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a trackball module structure adapted to an electronic device and, more particularly, to a trackball module structure in which a trackball device and a control chipset are integrated to be a single module.

2. Description of the Related Art

Generally, a trackball is disposed on an electronic device to move a cursor. Especially to a portable electronic device such as a personal digital assistant, the trackball may facilitate the operation of a user. As shown inFIG. 1, it is a schematic diagram showing a conventional trackball. A trackball device70is formed by a ball71, four magnetic rollers73and a casing72covering them. Afterwards, the trackball device70is disposed on the motherboard75of the electronic device. The motherboard75has four Hall ICs74corresponding to the magnetic rollers73.

Thus, when the user rolls the ball71, the magnetic rollers73rotate along with the rotation of the ball71. Then, the Hall ICs74sense the magnetism change of the magnetic rollers73to make the cursor move according to the calculation of the electronic device. Thus, the relationship of the magnetic rollers73and the Hall ICs74may determine the sensing precision of the trackball.

However, to facilitate the operation of the user, the trackball device70should be fixed at the casing of the electronic device (not shown). The Hall ICs74are welded on the motherboard75. Since manufacturing tolerance and assembling tolerance may exist between the trackball device70and the casing, the casing and the motherboard75and the motherboard75and the Hall ICs74, the tolerance is accumulated, and the tolerance between the magnetic rollers73and the Hall ICs74may be large and is hard to be controlled. This not only affects the precision of the trackball, but also may affect the sensing ability and the operation of the user.

In the conventional technology, a reed switch is used to replace the Hall IC to reduce the cost and improve the reliability. However, since the assembly mode of the reed switch and the trackball device is not changed, the problem that the tolerance accumulates still exists. Once the sensing ability is not good, even if the manufacturing cost is reduced, the reliability cannot be improved.

BRIEF SUMMARY OF THE INVENTION

The trackball module structure according to the invention includes a base, a flexible printed circuit, a trackball device and a lid. The base has a recess to dispose the flexible printed circuit, and the flexible printed circuit has a carrying portion and a connecting portion which are connected to each other. The carrying portion has a control chipset which is disposed in the recess of the base through the carrying portion. The connecting portion extends out of the recess, and it may be electrically connected to the circuit board of the electronic device. Then, the trackball device is disposed in the recess of the base corresponding to the control chipset and is fixed by the lid. Thus, the trackball device and the control chipset are modularized via the base. After located, the module is connected to the electronic device by the connecting portion of the flexible printed circuit. Thus, the conventional problem that the sensing ability is not good due to the difficult location of the trackball device and the control chipset is solved.

In another aspect, the base and the lid may be made of metal, and thus the problem of the electrostatic discharge (ESD) is solved.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown inFIG. 2, according to the trackball module structure disclosed in the invention, it is a schematic diagram showing the trackball module structure in an embodiment of the invention. The trackball module structure includes a base10, a flexible printed circuit20, a trackball device30and a lid40. The base10includes a recess11. The recess11has a lateral opening for disposing the flexible printed circuit and the trackball device30. The flexible printed circuit20has a connecting portion22and a carrying portion21which are connected to each other. The carrying portion21has a control chipset which is composed of four Hall ICs24and a push switch23. The Hall ICs24may sense the rotation of the ball31of the trackball device30. The push switch23is used to receive the motion of pressing the ball31.

The trackball device30includes a ball31and four magnetic rollers32. They are disposed in a frame33. When the ball31rotates, it drives the magnetic rollers32to rotate. With the change of the magnetism of the magnetic rollers32and the sense of the Hall ICs24, the moving distance is determined. The lid40has an opening41, and the opening41corresponds to the ball31of the trackball device30to locate and expose the ball31.

As shown inFIG. 3AtoFIG. 3C, they are schematic diagrams showing the assembly of the trackball module structure in an embodiment of the invention.

As shown inFIG. 3A, the flexible printed circuit20is disposed in the recess11of the base10. The flexible printed circuit20has multiple locating holes25. Cooperating with the recess11of the base10and multiple locating pillars12at the edge of the recess11, the locating pillars12pass through the locating holes25, and thus the flexible printed circuit20is fixed and located in the recess11of the base10. The locating mode is not limited to use the locating pillars12and the locating holes25. If the size of the carrying portion21of the flexible printed circuit20is as large as that of the recess11of the base10, the locating effect also may be achieved. In another aspect, if the flexible printed circuit20needs to be fixed on the base10stably, glue also may be used to stick the flexible printed circuit20in the recess11of the base10.

As shown inFIG. 3B, after the flexible printed circuit20is located and fixed, the trackball device30is disposed in the recess11of the base10corresponding to the control chipset of the flexible printed circuit20. In other words, the bottom of the ball31of the trackball device30corresponds to a push switch23of the flexible printed circuit20. The magnetic rollers32of the trackball device30correspond to the Hall ICs24of the flexible printed circuit20. Thus, when the ball31is pressed, the push switch23is triggered, and when the ball31drives the magnetic rollers32to rotate, the Hall ICs24sense the rotation and output the corresponding signal.

At last, as shown inFIG. 3C, the lid40is connected in the recess11of the base10. The opening41of the lid40corresponds to the ball31of the trackball device30. Thus, the ball31is located and exposed. The lid40has slots42at both sides, and hooks13are disposed in the inner sides of the recess11of the base10. With the cooperation of the slots42and hooks13, the lid40is fixed at the position. A screw50also may be used to pass the fixing hole43of the lid40and the fixing hole26of the flexible printed circuit20to be locked in the screw hole13of the base10. This makes the module more stable. In the invention, the trackball module structure is fixed in the electronic device, and only the connecting portion22is electrically connected to the motherboard of the electronic device (not shown). This may improve the locating effect.

The trackball device30now is a mature element, and the sensing method using magnetic rollers32and the Hall ICs24is only one of the aspects. Trackball devices30using other sensing elements also may be adapted to the invention. Since the trackball device30is different from the conventional structure, that is, the trackball device30is held and sandwiched by the base10and the lid40, and the base10and the lid40are made of metal, this may prevent the electrostatic discharge (ESD) effectively.

In another aspect, as shown inFIG. 4, it is a schematic diagram showing the trackball module structure in another embodiment of the invention.

To make it convenient to fix the structure at the electronic device, extending portions15extend from the two sides of the base10, and the extending portion15has a fixing hole16to be fixed at the electronic device (not shown). The flexible printed circuit20may have a keypad circuit board27having multiple keypad connectors28to allow the electronic device to be used directly. Thus, the function of the trackball module structure is more complete. The extending portion15is not limited to be the aspect in the drawings, and the flexible printed circuit20also may have additional functions or provide different keypad connectors28.

According to the trackball module structure in the invention, the trackball device and the control chipset are modularized using the base and the lid, and the whole module may be disposed on the electronic device. Thus, the disadvantages that tolerance may generate and accumulate and the sensing ability are not good when the trackball device is disposed at the casing and the control chipset is disposed at the motherboard is overcome. In addition, the base and the lid are made of material, and this may prevent the ESD.