BACKGROUND

Technical Field

The present disclosure relates to a capacitive-coupling electronic pen.

Background Art

An example of a prized capacitive-coupling electronic pen includes what is generally called an active capacitive-coupling electronic pen that performs a transfer (interaction) of a signal through capacitive coupling to a position detection sensor of a position detection apparatus. The position detection sensor is used to detect a position instructed by the electronic pen.

This type of capacitive-coupling electronic pen includes, in a hollow portion of a tubular housing, a battery (primary battery or secondary battery) as a power supply, a pen pressure detector, a circuit board on which a signal transmission circuit is mounted, and the like. The components are lined up and housed in an axial direction of the housing of the electronic pen (see, for example, Japanese Patent Laid-Open No. 2016-126503).

In this case, the circuit board is mounted on a board holder, and the pen pressure detector includes pressure sensing components and pressure transmission members housed in a housing for pen pressure detector. The pen pressure detector and the board holder are often coupled in the axial direction of the housing of the electronic pen to form a unit (form a module). The board holder includes a housing part for pen pressure detector in some cases.

FIGS. 9A and 9Billustrate an example of a configuration on a pen tip side of this type of existing capacitive-coupling electronic pen.FIG. 9Aillustrates a longitudinal cross-sectional view of the electronic pen.FIG. 9Bis an enlarged explanatory view of the part where the board holder includes the housing part for pen pressure detector and forms a unit.

An electronic pen100of this example includes a front cap102including a tapered tubular body, the front cap102fitted and attached to an opening on the pen tip side of a tubular housing101as illustrated inFIG. 9A. The housing101is made of a conductive material, such as metal, so that the housing101is earthed (grounded) through the human body when the user holds and operates the electronic pen100. The front cap102is made of an insulating material, such as a resin.

As illustrated inFIG. 9A, a core body103made of a conductive material is provided on the pen tip side such that the core body103can be inserted and freely moved in the axial direction, and the core body103is held by a core body holder111. The core body103made of a conductive material and the housing101made of a conductive material are electrically separated (insulated) through the front cap102.

As illustrated inFIG. 9A, a board holder105for placing, on a board mounting table portion105a, a printed circuit board104provided with circuit components, such as a signal transmission circuit, is housed in a hollow portion of the housing101.

The board holder105includes a tubular portion105bthat holds a tubular pressure sensing component holding portion105c, on the pen tip side with respect to the board mounting table portion105a. Pressure sensing components included in a pen pressure detector106are housed in the pressure sensing component holding portion105c. The pen pressure detector106of this example includes a variable capacitor in which the capacitance changes according to the pen pressure applied to the core body103.

The pressure sensing components of this example include a plurality of components including a dielectric107, a spacer member108made of an insulating material, a conductive elastic member109, and an engagement member110as illustrated inFIGS. 9A and 9B. The dielectric107has a disk shape, and although not illustrated, an electrode included in a first electrode of the variable capacitor is formed on one end surface on the engagement member110side in the axial direction of the disk shape.

The spacer member108is an insulating, elastic, ring-shaped member. The conductive elastic member109is made of, for example, conductive rubber, and a tip end surface of the conductive elastic member109is arranged to face an end surface on the other side of the dielectric107, thereby providing a second electrode of the variable capacitor.

The engagement member110is arranged on the side provided with an electrode of the dielectric107, and the engagement member110prevents the dielectric107from moving toward the back end in the axial direction.

In this example, the conductive elastic member109includes a fitting recessed portion109ato which the core body holder111is fitted.

The core body holder111is made of a conductive material. A recessed hole111afor housing a core body holding member112made of conductive elastic rubber and a rod-like portion111bfitted to the pen pressure detector106are integrated to form the core body holder111.

An end portion103bon the opposite side of a tip portion103aof the core body103is fitted to the conductive core body holding member112housed in the core body holder111made of a conductive material, and the core body103is coupled to and held by the core body holder111such that the core body103can be inserted and removed. The core body103and the core body holder111are displaced together in the axial direction according to the pressure applied to the tip portion103aof the core body103, and the pressure (pen pressure) applied to the tip portion103aof the core body103is transmitted to the pen pressure detector106.

A coil spring113that always biases the core body holder111toward the core body103is provided between the core body holder111and the tubular portion105bof the board holder105. The coil spring113is made of a conductive material, such as conductive metal. One end113aof the coil spring113is extended to the printed circuit board104as illustrated inFIG. 9Aand is electrically connected to the signal transmission circuit arranged on the printed circuit board104.

The core body holder111is made of a conductive material. Therefore, the core body103made of a conductive material installed on the core body holder111through the conductive core body holding member112is electrically connected to the signal transmission circuit arranged on the printed circuit board104through the coil spring113. In this way, a signal from the signal transmission circuit, which is a signal with a predetermined frequency f1in this example, is transmitted to the position detection sensor through the core body103.

In the electronic pen100of this example, the core body103is displaced inside of the housing101of the electronic pen100in the axial direction when pressure (pen pressure) is applied to the front end side of the core body103. Consequently, the core body holder111provided with the core body103is displaced together with the core body103in the axial direction, and the conductive elastic member109of the pen pressure detector106is displaced toward the dielectric107. The contact area of the conductive elastic member109and the dielectric107changes according to the applied pressure, and the capacitance of the variable capacitor including the pen pressure detector106changes according to the applied pressure. Therefore, the pen pressure can be detected from the capacitance of the variable capacitor including the pen pressure detector106.

In the electronic pen100of this example, a peripheral electrode114made of a conductive material surrounding the core body103is provided as illustrated inFIG. 9A. The peripheral electrode114is electrically connected to the circuit components of the printed circuit board104, although not illustrated inFIG. 9A. The peripheral electrode114is used to transmit a signal from the signal transmission circuit to the position detection sensor to detect the tilt of the electronic pen100or to receive an indication signal transmitted from the position detection apparatus through the position detection sensor.

In the electronic pen100of this example, a tubular insulating member105dfor ensuring the insulation between the set of core body103and core body holder111and the peripheral electrode114is fitted to a peripheral portion of the tubular portion105bof the board holder105.

As illustrated inFIG. 9A, a tubular portion102cpierced through the core body103is provided inside and near an opening102aof the front cap102, and the peripheral electrode114is also electrically separated (insulated) from the core body103due to the existence of the tubular portion102c. The front cap102also plays a role of electrically separating (insulating) the peripheral electrode114and the housing101of the electronic pen100as illustrated inFIG. 9A.

As described above, in the existing capacitive-coupling electronic pen100, the conductive core body103and the signal transmission circuit provided on the printed circuit board104are electrically connected by fitting the core body103to the core body holder111made of a conductive material and using the coil spring113made of a conductive material electrically connected to the core body holder111.

This is because the core body103can be inserted into and removed from the electronic pen, and the pen pressure displaces the core body103in the axial direction so that direct and electrical connection of the core body103and the signal transmission circuit is difficult. The coil spring113is used to prevent poor electrical connection caused by the displacement and to ensure the electrical connection of the core body and the signal generation circuit even if the core body103is displaced together with the core body holder111in the axial direction according to the pen pressure applied to the tip portion103a.

In this way, the conductive core body holder111needs to be used, and the coil spring113needs to ensure the electrical connection of the core body103and the signal generation circuit in the existing electronic pen. There is a problem that it is difficult to reduce the thickness of the electronic pen due to the existence of the core body holder111and the coil spring113.

There is also a problem that the coil spring113adversely affects the detected pen pressure when the pen pressure detector106detects the pen pressure applied to the tip portion103aof the core body103. More specifically, even if the pen pressure detector is adjusted to provide uniform transmission characteristics with respect to the load, and the adjusted pen pressure detector is provided as the pen pressure detector106, there are variations in the coil spring113if there are variations in the transmission characteristics with respect to the load in the coil spring113. There is a problem that the transmission characteristics with respect to the load vary in the pen pressure detection of the electronic pen100.

BRIEF SUMMARY

In view of the problems, an object of the present disclosure is to provide a capacitive-coupling electronic pen that can supply a signal to a conductive core body without using an elastic member even when the electronic pen has a pen pressure detection function.

To solve the problems, provided is a capacitive-coupling electronic pen including: a tubular housing; a signal transmission circuit arranged in the housing; a tubular conductor fixed and arranged at a predetermined position in the housing such that an axial direction of the tubular conductor corresponds to an axial direction of the housing; a conductive core body including a front end protruding from an opening on one side of the housing in the axial direction of the housing, and an opposite end that is opposite the front end and that is inserted into a hollow portion of the tubular conductor such that the opposite end is movable; and a connection member that electrically connects the signal transmission circuit and the tubular conductor. A signal from the signal transmission circuit is transmitted to the core body through capacitive coupling between the tubular conductor and the core body and transmitted to an outside of the electronic pen from a tip portion of the core body when the tubular conductor electrically connected to the signal transmission circuit and the core body are not in contact with each other.

In the electronic pen configured as described above, the tubular conductor is fixed and arranged at the predetermined position in the housing, and the opposite end of the conductive core body that is opposite the front end of the conductive core body is inserted into the hollow portion of the tubular conductor such that the opposite end is movable. The signal transmission circuit and the tubular conductor are electrically connected through the connection member.

Both the core body and the tubular conductor are conductors. Therefore, if the core body and the tubular conductor are in contact with each other, the signal from the signal transmission circuit is supplied to the core body through the connection member and the tubular conductor and sent out to the position detection sensor from the front end of the core body.

When the core body and the tubular conductor are not in contact with each other, the signal from the signal transmission circuit is transmitted through the connection member to the core body through the capacitive coupling between the tubular conductor and the core body and is transmitted to the outside from the tip portion of the core body.

In this way, the electronic pen is configured to supply the signal of the signal transmission circuit to the core body through the tubular conductor fixed and arranged at the predetermined position in the housing. Therefore, core body holder and a coil spring made of a conductive material do not have to be provided to supply the signal from the signal transmission circuit to the core body unlike in the electronic pen described at the beginning, and it is only necessary to arrange, at the fixed position in the housing, the tubular conductor into which the core body is inserted. Therefore, there is an advantageous effect that the thickness of the electronic pen can be reduced. The conductive coil spring is not necessary, and this can prevent the variations in transmission characteristics with respect to the load of the pen pressure detector after adjustment even when the pen pressure detector is provided on the electronic pen.

