Write protect switch for card connector

Details Write protect switch for card connector Write protect switch for card connector

2001-11-09

2004-03-23

Gushi, Ross (Department: 2833)

Electrical connectors

Having circuit interrupting provision effected by mating or...

C200S051100

Reexamination Certificate

active

06709281

ABSTRACT:

TECHNICAL FILED
The present invention relates to a card connector mounted on electronic devices, such as cellular phones, telephones, PDA (personal digital assistants), portable audio devices and digital cameras, and more specifically to a write protect switch for detecting a position of a write protect button on an IC card.
BACKGROUND ART
In electronic devices such as cellular phones, telephones, PDA and digital cameras, addition of a variety of functions and identification of a user are made by inserting an IC card with a built-in IC, such as a SIM (subscriber identity module) card, an MMC (multimedia card) (trade mark), a smart media (trade mark) and an SD (secure digital or super density) card.
The IC card of this kind normally has some means for inhibiting the write operation in order to protect information stored in its internal memory. A means is also provided to cancel the write protection to allow information to be written from an electronic device. into the memory of the IC card when the card holder so desires.
Various kinds of write protect methods have been proposed. One such means is a mode of the write protect button that can slide between two positions, as in a floppy disk. The mode of the write protect button is considered advantageous because it can be used repetitively and the construction is simple.
In such a slide button system, it is no secret that the card is provided with a write protect button that can slide between two positions and the electronic device is provided with an electric circuit which is set to a write inhibit state when the write protect button is situated at one position and to a write-enable state when it is situated at another position.
As a sensor structure for detecting the position of the write protect button, a optical sensor structure may be considered. The optical sensor structure, however, has drawbacks that a sufficient detection precision cannot be expected as the IC card becomes thinner and smaller and that the installation of a optical sensor can hinder promotion in downsizing and cost-reduction.
FIG.
6
A and
FIG. 6B
show the construction of a conventional write protect switch using a contact leaf spring.
In this conventional construction, a switch structure having a contact leaf spring
100
with a contact portion
100
a
and a stationary leaf spring
101
, detects the position of a write protect button
102
. In this switch structure, when the button
102
is situated at one position, the leaf springs
100
, the stationary leaf
101
are parted (FIG.
6
A); and when the button
102
is at the other position, a contact portion
100
a
of the contact leaf
100
, stationary leaf
101
are connected (FIG.
6
B).
In such a switch structure, the displacement of the contact leaf
100
basically depends on the height (thickness) of the button
102
. The connector and card have variations in dimensional error and there are parts and assembly tolerances. Thus, the actual displacement of the contact leaf spring
100
is obtained by subtracting the above-described errors from the thickness of the button
102
.
In many cases, the displacement of the contact leaf
100
is often not enough for button
102
detection.
Further, in the conventional technique described above, the elastically deflecting contact leaf spring
100
is constructed such that the difference between a length D and a length E is small, the length D being measured from a fixed portion
100
b
, which fixedly supports the contact leaf spring like a cantilever, to the engagement portion
100
c
that engages the write protect button
102
, the length E being measured from the fixed portion
100
b
to the contact portion
100
a
. Thus, the deflection obtained at the contact portion
100
a
is not greater than a deflection produced at the engagement portion
100
c
. This is combined with the above-described problem of error and assembly tolerances, making it impossible to secure a sufficient contact pressure of the contact portion
100
a
for making an electric connection. In the worst case, it is a problem since the position of the write protect button
102
may not be able to be detected stably and accurately.
The present invention has been accomplished under these circumstances. It is an object of the invention to provide a write protect switch for a card connector that can perform reliable and stable separably connecting operations of metal leaf springs and which can provide a necessary contact pressure of the contact portion for reliable electric connection between the two metal leaf springs.
DISCLOSURE OF INVENTION
According to one aspect, the present invention provides a write protect switch in a card connector for detecting a slide position of a write protect button on a card, wherein when the card having the write protect button of a predetermined height, which is slidable between two positions in a recess formed in an outer surface of the card, is loaded into the card connector, the write protect switch detects the slide position of the write protect button on the card according to an separably connecting of a pair of pieces of metal, the write protect switch comprising: a first piece of metal made from a stationary piece of metal; and a cantilevered second piece of metal having a holding portion at one end side thereof and a contact portion at the other end side thereof, the holding portion being rigidly held in a housing of the card connector, the contact portion being connected or separated with the first piece of metal, the second piece of metal also having a projecting touching portion between the holding portion and the contact portion, the projecting touching portion being adapted to touching one of the slide position of the write protect button in the recess; wherein the projecting touching portion is situated generally at a center position between the contact portion and the holding portion or on the holding portion side of the center position.
In the cantilevered metal leaf spring, one of the pieces of metal making up the write protect switch, the projecting touching portion that comes in contact with the write protect button is situated generally at the center position between the contact portion and the holding portion of the metal leaf spring, i.e., at the center position between the ends of the metal leaf spring, or on the holding portion side of the center position. With this write protect switch, therefore, the two metal pieces can be connected or separated by a displacement of the contact portion which is at least two times the height of the write protect button.
Thus, if various error factors exist, this invention enables a reliable, stable separably connecting of the two pieces of metal and provides an enough contact pressure to make electrical connection.


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