TWI426508B - Optical disc drive - Google Patents

Description

CD player

The present invention relates to an optical disk drive, and more particularly to a low cost optical disk drive capable of providing a high return loss margin.

In recent years, the development trend of optical disc drives has been toward light, thin, and portable. In general, most desktop computers use half-height disc players, while notebook computers use thin, thin, slim-type disc players.

Prior art optical disk drives include a housing and a disc tray. The tray can load a disc into the case for subsequent data access. The tray is provided with a spindle motor and an optical pickup unit (OPU), the former for rotating the optical disc and the latter for accessing the information of the optical disc. A main board is provided on the casing for carrying a motor driver and a control circuit. In order to receive host signals, or to transfer data between the motherboard, the optical read/write unit and the spindle motor, high-speed connectors such as Serial Advanced Technology Attachment (SATA) connectors are provided on the motherboard and the tray. After processing the host signal, the motor driver and control circuit will transmit signals to the tray through the corresponding connector and the flexible cable to control the operation of the spindle motor and the optical read/write unit. Since the processed host signal is transmitted to the tray, many pins are required for the connector and the flexible cable.

In view of this, the following technical solutions are provided:

The invention provides an optical disc drive comprising a casing; a tray which can slide into or out of the casing; a first circuit board located on the tray; and a first connector located on the casing For receiving a host signal, a control circuit is disposed on the first circuit board for processing the host signal, and a signal transmission medium is electrically connected between the first connector and the first circuit board.

The present invention further provides an optical disc drive comprising a casing; a tray that can slide into or out of the casing; and a signal transmission medium for providing a host between the casing and the tray The signal impedance matches one of the signal transmission paths.

The optical disc drive provided by the present invention can greatly reduce the number of pins.

Certain terms are used throughout the description and following claims to refer to particular elements. It should be understood by those of ordinary skill in the art that manufacturers may refer to the same elements by different nouns. The scope of this specification and the subsequent patent application do not use the difference of the names as the means for distinguishing the elements, but the difference in function of the elements as the basis for the distinction. The term "including" as used throughout the specification and subsequent claims is an open term and should be interpreted as "including but not limited to". In addition, the term "coupled" is used herein to include any direct and indirect electrical connection. Therefore, if a first device is coupled to a second device, the first device can be directly electrically connected to the second device or indirectly electrically connected to the second device through other devices or connection means.

Fig. 1A is an exploded perspective view showing a part of the structure of an optical disk drive of the present invention. Fig. 1B is a bottom view of the optical disk drive of the present invention. 2, 3A to 3C and 4 to 6 are diagrams showing the functions of the optical disc drive in operation.

In Fig. 1A, the optical disk drive of the present invention comprises a tray 10 and a casing 20. The casing 20 includes a lower casing 21 and an upper casing 22. The tray 10 is slidably disposed on the cabinet 20, and its gliding action can be guided by the rail assembly 12 and the slide rails 14 and the like. The track assembly 12 can be disposed on both sides of the tray 10, and the slide rails 14 are slidably coupled to the track assembly 12. The optical disk drive of the present invention can utilize a latching device (not shown) for securing the tray 10 within the housing 20, and an ejection device (not shown) for pushing the tray 10 out of the housing 20. A pop-up control button 16 for controlling the ejecting device is typically provided on the front side panel 18 of the tray 10. In the trace-out state, the tray 10 is pushed out of the casing 20 to allow the user to place a disc D. In the trace-in state, the tray 10 is pushed into the casing 20, and the optical disk drive can access the data of the optical disk D according to the host signal.

In FIGS. 1B, 2, 3A-3C, and 4-6, each of the optical disc drives includes a tray 10, a casing 20, a spindle motor 40, an optical read/write unit 50, a motor driver 60, and a control. Circuit 70. As shown in FIG. 1, the tray 10 can be slid into or out of the casing 20.

In the optical disk drive 101 of the first embodiment of the present invention shown in FIG. 2, a first circuit board 31 is disposed on the tray 10, and a second circuit board 32 is disposed on the casing 20. A spindle motor 40 is disposed on the tray 10 for rotating a disc. The optical read/write unit 50 is disposed on the tray 10 for storing information of the optical disc. The motor driver 60 is disposed on the first circuit board 31 for controlling the operation of the spindle motor 40. The control circuit 70 is disposed on the first circuit board 31 for processing data transfer between the optical disk drive 101 and a host (not shown). The host can be coupled to one of the high speed connectors C0 on the second circuit board 32. The high speed connector C0 can be a SATA connector for receiving host signals or transmitting signals to the host.

Referring to FIG. 2, one end of the signal transmission medium 90 is connected to the first circuit board 31 through a connector C1, and the other end is connected to the second circuit board 32 through a connector C2, so that the first circuit board 31 and the Signal transmission is performed between the two circuit boards 32. Referring to FIG. 1B simultaneously, a first region 91 of the signal transmission medium 90 can be floatingly disposed in a space between the lower casing 21 and the upper casing 22 of the casing 20, and the signal transmission medium 90 is second. The region 92 can be fixed to the lower casing 21 of the casing 20. It should be noted that, according to the design conditions of the structure of the casing 20 or the material of the signal transmission medium 90, the present invention can also elastically adjust the arrangement of the first region 91 and the second region 92, for example, the first region 91 and the second region. One of the 92 is disposed in a floating manner and the other region is disposed in a fixed manner. The first region 91 and the second region 92 are all disposed in a floating manner, or the first region 91 and the second region 92 are all disposed in a fixed manner.

The signal delivery medium 90 can provide a signal transmission path that matches the host signal impedance, the implementation of which will be described in more detail later in the specification. The signal transmission medium 94 is used for signal transmission between the first circuit board 31 and the spindle motor 40, and the signal transmission medium 96 is used for signal transmission between the first circuit board 31 and the optical read/write unit 50. Since the connectors C0-C2 and the signal transfer medium 90 are only used to transmit the original host signal, the number of pins can be greatly reduced.

3A to 3C are views showing the optical disk drives 102A to 102C in the second embodiment of the present invention. Similar to the structure of the first embodiment, the optical disk drive 102A of the second embodiment of the present invention is different in that the signal transmission medium 90 is directly connected to the second circuit board 32 using a hot bar surface mount technology. Similar to the structure of the first embodiment, the optical disk drive 102B of the second embodiment of the present invention is different in that the signal transmission medium 90 is directly connected to the first circuit board 31 using a hot press surface bonding technique. Similar to the structure of the first embodiment, the optical disk drive 102C of the second embodiment of the present invention is different in that the signal transmission medium 90 is directly connected to the first circuit board 31 and the second circuit board 32 using a hot press surface bonding technique. Hot-pressed surface adhesion technology reduces the number of connectors and reduces production costs.

Fig. 4 is a schematic view showing an optical disk drive 103 in the third embodiment of the present invention. Similar to the structure of the first embodiment, the optical disk drive 103 of the third embodiment of the present invention is different in that it further includes an energy converter 35. The energy converter 35 may include an element such as an inductor or a capacitor, and the function is to shift the bandwidth of the smaller return loss margin to the bandwidth of the other reflection loss boundary, thereby increasing the overall reflection loss boundary of the optical disc drive 103. . The energy converter 35 can be disposed on a single side or both sides of the signal transmission medium 90, for example, a set of energy converters 35 are disposed on the first circuit board 31, a set of energy converters 35 are disposed on the second circuit board 32, or both A set of energy converters 35 are provided on each of the first circuit board 31 and the second circuit board 32. Similarly, the embodiment shown in FIGS. 2, 3A to 3C may further include an energy converter 35.

Fig. 5 is a schematic view showing an optical disk drive 104 in the fourth embodiment of the present invention. Similar to the structure of the first embodiment, the optical disk drive 104 of the fourth embodiment of the present invention is different in that the connector C0 is directly disposed on the casing 20 without using the second circuit board 32 to reduce the production cost. As shown in FIG. 1, the connector C0 of the optical disk drive 104 can be directly disposed on the lower casing 21 of the casing 20. Similarly, the second circuit board 32 is not essential. In the embodiment shown in the second, third, third, and third embodiments, the connector C0 can be directly disposed on the casing 20 instead of the second circuit board. 32 to reduce production costs.

Fig. 6 is a schematic view showing an optical disk drive 105 in the fifth embodiment of the present invention. Similar to the structure of the first embodiment, the optical disk drive 105 of the fifth embodiment of the present invention is different in that the spindle motor 40, the motor driver 60, and the control circuit 70 are all disposed on the first circuit board 31. Similarly, in the embodiments shown in FIGS. 2, 3A to 3C, and 4 to 5, the spindle motor 40, the motor driver 60, and the control circuit 70 may also be disposed on the first circuit board 31. As such, the spindle motor 40 only needs to be coupled to the first circuit board 31 using a shorter signal transmission medium 94, thereby reducing production costs.

In the present invention, the signal transmission medium 90 can be made of a different elastic material that can bend and bend in a narrow space, such as a flexible flat cable (FFC) or a flexible printed circuit (FPC). Fig. 7A is a top view of the signal transmission medium 90 of the present invention, and Fig. 7B is a cross-sectional view of the signal transmission medium 90 of the present invention taken along the F-F' direction.

In FIG. 7B, the signal transfer medium 90 can include a plurality of metal wires 55 disposed between the two insulating layers 54 with a plurality of insulating materials 56 interposed therebetween. The impedance of the signal transmission medium 90 is determined by the pitch p (the distance between the center points of the two adjacent metal wires 55), the width w of the metal wire, the thickness t of the metal wire, the dielectric constant (?) of the insulating layer 54, and the insulating layer 54. The thickness h is determined. By adjusting the values of the above parameters p, w, t, ε, and h, the signal delivery medium 90 can provide a signal transmission path that matches the impedance of the host signal. Impedance matching increases the overall reflection loss margin of the optical drive to meet high-speed authentication (eg, via SATA testing).

In Fig. 7A, a plurality of pins for transmitting signals are provided on both sides of the signal transmission medium 90. An adhesive material 75 (e.g., a glue) is attached to the back side of the signal delivery medium 90 such that the signal transfer medium 90 can be attached to a circuit board, a housing, or other structure. In the present invention, the surface area of the adhesive material 75 may be smaller than the surface area of the signal transfer medium 90 to achieve impedance matching. For example, the signal transmission path provided by the pin P1 has an impedance related to the dielectric constant of the air, and the signal transmission path provided by the pin P2 has an impedance related to the dielectric constant of the adhesive material 75. Since the dielectric constant of the adhesive material 75 is generally greater than the dielectric constant of air, the adhesive material 75 having a smaller surface area can enhance the overall impedance of the signal transfer medium 90 to match the high speed host signal.

8A is a cross-sectional view of the signal transmission medium 90 of the first setting mode of the present invention when it is received, and FIG. 8B is a cross-sectional view of the signal transmission medium 90 of the first setting mode of the present invention when it is ejected. According to the first setting mode, the first end of the signal transmission medium 90 is connected to the first circuit board 31 through the connector C1 (or using a hot-press surface bonding technology), and the second end of the signal transmission medium 90 is transmitted through the connector C2 (or The hot-pressed surface bonding technique is coupled to the second circuit board 32. The stretchable first region 91 of the signal transfer medium 90 is floating, and the second region 91 of the signal transfer medium 90 is fixed to the casing 20. Therefore, regardless of whether the tray 10 is in a revenue or pop-up state, the host signal can be transmitted to the first circuit board 31. Since the first area 91 is floating, the second area 92 may be touched in the revenue state, thereby changing the impedance encountered when the host signal passes through the first area 91. Since the second region 92 is fixed to the casing 20, the impedance encountered when the host signal passes is small. In order to enable the host signal to encounter the same impedance when passing through the first region 91 and the second region 92, the present invention can increase the thickness of the insulating layer 54 in FIG. 7B to reduce impedance variation or improve noise interference.

9A is a cross-sectional view of the signal transmission medium 90 of the second setting mode of the present invention at the time of income, and FIG. 9B is a cross-sectional view of the signal transmission medium 90 of the second setting mode of the present invention when it is ejected. According to the second arrangement, a protective layer 72 is further disposed between the second region 92 and the casing 20 for reducing impedance variation or improving noise interference.

10A is a cross-sectional view of the signal transmission medium 90 of the third embodiment of the present invention at the time of income, and FIG. 10B is a cross-sectional view of the signal transmission medium 90 of the third embodiment of the present invention when it is ejected. According to the third arrangement, a protective layer 82 is further disposed between the first region 91 and the second region 92 for reducing impedance variation or improving noise interference.

11A is a cross-sectional view of the signal transmission medium 90 in the fourth setting mode of the present invention, and FIG. 11B is a cross-sectional view of the signal transmission medium 90 in the fourth setting mode of the present invention. According to the fourth arrangement, a protective layer 72 is further disposed between the second region 92 and the casing 20, and a protective layer 82 is further disposed between the first region 91 and the second region 92 for reducing impedance variation or improving miscellaneous Interference.

12A is a cross-sectional view of the signal transmission medium 90 of the fifth setting mode of the present invention at the time of income, and FIG. 12B is a cross-sectional view of the signal transmission medium 90 of the fifth setting mode of the present invention when it is ejected. According to the fifth arrangement, a metal cover 81 is further disposed between the first circuit board 31 and the first region 91. In the revenue state, the signal transmission medium 90 will occupy a large space in the tray 10 and the casing 20 at the intersection of the first region 91 and the second region 92, and may contact the metal cover 81 at the turning point to cause impedance variation. Therefore, at a vicinity corresponding to the intersection of the first region 91 and the second region 92, the metal cover 81 can have a small thickness to prevent the signal transmission medium 90 from having different impedances in the income state and the pop-up state. For example, in a region corresponding to the intersection of the first region 91 and the second region 92, the metal cover 81 may include an opening 51 to reduce the thickness.

13A is a cross-sectional view of the signal transmission medium 90 of the sixth setting mode of the present invention at the time of income, and FIG. 13B is a cross-sectional view of the signal transmission medium 90 of the sixth setting mode of the present invention when it is ejected. In the revenue state, the signal transmission medium 90 will occupy a large space in the tray 10 and the casing 20 at the intersection of the first region 91 and the second region 92, and may contact the metal cover 81 at the turning point to cause impedance variation. Therefore, in the vicinity of the intersection corresponding to the intersection of the first region 91 and the second region 92, the casing 20 can have a small thickness to prevent the signal transmission medium 90 from having different impedances in the income state and the pop-up state. For example, in a region corresponding to the intersection of the first region 91 and the second region 92, the casing 20 may include an opening 52 to reduce the thickness.

14A is a cross-sectional view of the signal transmission medium 90 of the seventh setting mode of the present invention at the time of income, and FIG. 14B is a cross-sectional view of the signal transmission medium 90 of the seventh setting mode of the present invention when it is ejected. According to the seventh arrangement, a metal cover 81 is further disposed between the first circuit board 31 and the first region 91. In the revenue state, the signal transmission medium 90 will occupy a large space in the tray 10 and the casing 20 at the intersection of the first area 91 and the second area 92, and may contact the metal cover 81 or the casing 20 at the turning point. Causes impedance changes. Therefore, in the vicinity of the intersection corresponding to the intersection of the first region 91 and the second region 92, the metal cover 81 and the casing 20 may have a small thickness to prevent the signal transmission medium 90 from having different impedances in the income state and the pop-up state. For example, in a region corresponding to the intersection of the first region 91 and the second region 92, the metal cover 81 may include an opening 51 to reduce the thickness, and the casing 20 may include an opening 52 to reduce the thickness.

In the drawings of Figs. 12A to 12B and 14A to 14B, reference numeral 51 or 52 is shown as an open structure. However, the reference numeral 51 or 52 may also be a recess, which may reduce the thickness of the metal cover 81 or the casing 20 at a region corresponding to the intersection of the first region 91 and the second region 92.

15A to 17A are top views of the signal transmission medium 90 according to the first to seventh setting modes of the present invention, and the signal transmission medium 90 of the first to seventh setting modes of the present invention is popped up in the 15B to 17B. When the view is above. In Figures 15A and 15B, the first end of the signal delivery medium 90 is coupled to the tray 10 via a connector C1 (or using a hot press surface bonding technique), and the second end of the signal delivery medium 90 is passed through the connector C2 (or using heat) The pressure surface bonding technique is coupled to the casing 20, the stretchable first region 91 of the signal transmission medium 90 is floated, and the second region 92 of the signal transmission medium 90 is fixed to the casing 20. Since the first region 91 and the second region 92 completely overlap in the revenue state, the present invention can use the embodiments shown in FIGS. 8A-14A and 8B-14B to improve noise interference, such as increasing the thickness of the insulating layer 54. The protective layer 72 or/and 82 is provided, or the thickness of the metal cover 81 or/and the casing 20 is reduced at a region corresponding to the intersection of the first region 91 and the second region 92.

In Figures 16A and 16B, the first end of the signal delivery medium 90 is coupled to the tray 10 via a connector C1 (or using a hot press surface bonding technique), and the second end of the signal delivery medium 90 is passed through the connector C2 (or using heat) The pressure surface bonding technique is coupled to the casing 20, the stretchable first region 91 of the signal transmission medium 90 is floated, and the second region 92 of the signal transmission medium 90 is fixed to the casing 20. Since the signal transmission medium 90 overlaps only in the vicinity of the intersection of the first area 91 and the second area 92 in the income state, signal coupling and signal quality can be reduced. Meanwhile, the present invention can also further improve the noise interference by using the embodiments shown in FIGS. 8A-14A and 8B-14B, such as increasing the thickness h of the insulating layer 54, providing the protective layer 72 or/and 82, or The thickness of the metal cover 81 or/and the casing 20 is reduced at a region corresponding to the intersection of the first region 91 and the second region 92.

In Figures 17A and 17B, the first end of the signal delivery medium 90 is coupled to the tray 10 via a connector C1 (or using a hot press surface bonding technique), and the second end of the signal delivery medium 90 is passed through the connector C2 (or using heat) The pressure surface bonding technique is coupled to the casing 20, the stretchable first region 91 of the signal transmission medium 90 is floated, and the second region 92 of the signal transmission medium 90 is fixed to the casing 20. Since the signal delivery medium 90 does not overlap in the revenue state, it can reduce signal coupling and increase signal quality. Meanwhile, the present invention can also further improve the noise interference by using the embodiments shown in FIGS. 8A-14A and 8B-14B, such as increasing the thickness h of the insulating layer 54, providing the protective layer 72 or/and 82, or The thickness of the metal cover 81 or/and the casing 20 is reduced at a region corresponding to the intersection of the first region 91 and the second region 92.

In the present invention, control circuit 70 may additionally include an adjustable termination for impedance matching to improve the overall reflection loss boundary. At the same time, when the control circuit 70 is packaged into an integrated circuit, the present invention can use a shorter lead frame and a longer bonding wire, thereby improving the overall reflection loss boundary.

The optical disk drive of the present invention uses a plurality of connectors and a malleable signal transmission medium to transfer host signals from a casing to a slidable tray. A control circuit disposed on the tray handles the host signal to control the operation of the spindle motor and the optical read/write unit. Since only unprocessed host signals need to be transmitted, the number of pins of the connector, cable or signal transfer medium can be greatly reduced. At the same time, the signal transmission medium of the present invention provides a signal transmission path between a casing and a tray, and the impedance of the signal transmission medium matches the host signal. At the same time, the present invention can improve the overall reflection loss boundary of the optical disk drive. The present invention is applicable to various types of optical disk drives, especially thin optical disk drives.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

10. . . tray

12. . . Track assembly

14. . . Slide rail

16. . . Popup control button

18. . . Front side baffle

20. . . cabinet

twenty one. . . Lower housing

twenty two. . . Upper housing

31. . . First board

32. . . Second circuit board

35. . . Energy converter

40. . . Spindle motor

50. . . Optical read/write unit

54. . . Insulation

55. . . Metal wire

56. . . Insulation Materials

60. . . Motor driver

70. . . Control circuit

75. . . Adhesive material

91. . . First area

92. . . Second area

72, 82. . . The protective layer

51, 52. . . Opening

90, 94, 96. . . Signal delivery medium

C0, C1, C2. . . Connector

D. . . CD

P1, P2. . . Pin

101, 102A, 102B, 102C, 103-105. . . CD player

1A and 1B are exploded views showing a part of the structure of an optical disk drive of the present invention.

2, 3A to 3C and 4 to 6 are diagrams showing the functions of the optical disk drive in the operation of the embodiment of the present invention.

Figure 7A is a top view of the signal transmission medium setting mode of the present invention.

Figure 7B is a cross-sectional view of the signal transmission medium of the present invention.

8A to 14A are cross-sectional views showing the signal transmission medium of each setting mode of the present invention at the time of income.

8B-14B are cross-sectional views of the signal transmission medium of each setting mode of the present invention when it is ejected.

15A-17A are top views of the signal delivery medium of each setting mode of the present invention at the time of income.

15B-17B are top views of the signal transmission medium of each setting mode of the present invention when popped up.

10. . . tray

16. . . Popup control button

18. . . Front side baffle

20. . . cabinet

40. . . Spindle motor

50. . . Optical read/write unit

60. . . Motor driver

70. . . Control circuit

90. . . Signal delivery medium

91. . . First area

92. . . Second area

C0, C1, C2. . . Connector

Claims (19)

An optical disc drive comprising: a housing; a disc tray that can slide into or out of the casing; a first circuit board located on the tray; a connector on the casing for receiving a host signal; a control circuit on the first circuit board for processing the host signal; and a signal transmission medium electrically connected to the first connection Between the first circuit board and the first circuit board, comprising: a malleable first region; a second region fixed to the casing; and a protective layer disposed between the first region and the second region Or between the second area and the casing. The optical disk drive of claim 1, further comprising: a spindle motor on the tray for rotating a disk; an optical pickup unit located on the tray; Information for accessing the optical disc; and a motor driver located on the tray for controlling the operation of the spindle motor. The optical disk drive of claim 2, wherein the spindle motor, the control circuit, and the motor driver are located on the first circuit board. The optical disk drive of claim 1, further comprising: a second circuit board located on the casing for carrying the first connector. The optical disk drive of claim 4, wherein the signal transmission medium comprises: a first end coupled to the first circuit through a second connector or using a hot bar surface mount technology And a second end coupled to the second circuit board via a third connector or using the hot press surface bonding technique. The optical disk drive of claim 5, further comprising a metal cover disposed between the first circuit board and the first area, wherein the metal cover meets at the first area and the second area One of the points has a thinner thickness. The optical disk drive of claim 5, wherein the casing comprises an opening or a recess, and the opening or the location of the recess corresponds to an intersection of the first area and the second area. The optical disk drive of claim 5, further comprising: an adhesive material attached to a back surface of the signal transmission medium to fix the first area to the casing, wherein a surface area of the adhesive material is smaller than the the first The surface area of one of the areas. The optical disk drive of claim 1, wherein the signal transmission medium overlaps only at a intersection of the first area and the second area when the tray is located within the casing. The optical disc drive of claim 1, wherein the signal transmission medium comprises a plurality of metal wires disposed between the two insulating layers and spaced apart from each other by a plurality of insulating materials, a spacing between the two metal wires, and the metal wires a width, a thickness of the one of the metal wires, a thickness of the insulating layer, and a dielectric constant of the insulating layer such that the signal transmitting medium provides the host signal between the first connector and the first circuit board Impedance matches one of the signal transmission paths. The optical disk drive of claim 1, further comprising an energy converter for adding a return loss margin in a frequency shifting manner. The optical disk drive of claim 1, wherein the control circuit includes an adjustable termination for impedance matching. An optical disc drive comprising: a casing; a tray that slides in or out of the casing; and a signal transmission medium for providing a host signal impedance matching between the casing and the tray A signal transmission path that includes: a malleable first region; a second region fixed to the casing; and a protective layer disposed between the first region and the second region or between the second region and the casing. The optical disk drive of claim 13, wherein the signal transmission medium further comprises: a first end coupled to the tray; and a second end coupled to the casing. The optical disk drive of claim 14, wherein the casing comprises an opening or a recess, and the opening or the location of the recess corresponds to an intersection of the first area and the second area. The optical disk drive of claim 14, further comprising a metal cover disposed between the tray and the first area, wherein the metal cover corresponds to one of the intersections of the first area and the second area The position is thinner. The optical disk drive of claim 14, further comprising: an adhesive material attached to a back surface of the signal transmission medium to fix the first area to the casing, wherein a surface area of the adhesive material is smaller than the The surface area of one of the first regions. The optical disk drive of claim 13, wherein the signal transmission medium comprises a plurality of gold a wire disposed between two insulating layers and spaced apart from each other by a plurality of insulating materials, a spacing between the two metal wires, a width of the metal wire, a thickness of the metal wire, and a thickness of the insulating layer And a dielectric coefficient of the insulating layer matches the impedance of one of the signal transmitting medium and the impedance of the host signal. The optical disk drive of claim 13, wherein the signal transfer medium overlaps only at the intersection of the first area and the second area when the tray is located within the casing.