Patent Description:
<CIT> describes a car navigation device including an inertial sensor.

<CIT> discloses a navigation device which includes a base unit which is mounted to a body of a vehicle, a front panel unit which is detachably mounted to and connected to the base unit, the front panel unit having a navigation function of displaying map data on a front panel and displaying a location of the vehicle on the map data, and an authentication unit which performs authentication to confirm that the base unit and the front panel unit have been connected to each other and, when confirmed, permits operation of an electrical control unit of the vehicle.

<CIT> discloses a sector of inertial measurement units.

<CIT> discloses a wedge three-axis inertial sensor damper suspension.

It is desirable that an inertial sensor mounted on a navigation device makes the same movement as the movement of a moving body such as a vehicle in which the navigation device is equipped. In conventional car navigation devices, consideration is not given to the installation position of the inertial sensor with respect to the fixed position of a vehicle side member. Therefore, when the installation position of the inertial sensor is far from the fixed position or the like, a deviation between the behavior of the inertial sensor and the behavior of the vehicle may become large due to deformation or vibration generated in the car navigation device caused by external forces or vibrations. As a result, the position of the vehicle on which the car navigation device is mounted may not be detected with high accuracy.

An object of one or more embodiments is to provide a navigation device and a method of manufacturing a navigation device with which the detection accuracy of the position of a moving body can be improved.

In accordance with the present invention, a navigation device and a method of manufacturing a navigation device as set forth in the appended claims is provided.

In accordance with the navigation device and the method of manufacturing a navigation device according to one or more embodiments, it is possible to improve the detection accuracy of the position of a moving body.

A navigation device according to one or more embodiments will be described by taking the navigation device <NUM> shown in <FIG> as an example. <FIG> is a perspective assembly view showing a structure of the navigation device <NUM> for mounting to vehicle-side fixing members <NUM>, which are moving body-side fixing members. For convenience of explanation, the directions of up, down, left, right, front, and back in the navigation system <NUM> are defined by the arrow directions shown in <FIG>. Further, an axis extending in the left-right direction is referred to as an X-axis, an axis extending in the front-back direction is referred to as a Y-axis, and an axis extending in the up-down direction is referred to as a Z-axis. The direction in which the X-axis extends may be referred to as a first direction.

The navigation device <NUM> is mounted on a moving body such as a vehicle, an airplane, or a ship. The navigation device <NUM> in the following description is a car navigation device mounted on a vehicle.

As shown in <FIG>, the navigation device <NUM> includes a substantially hexahedral body <NUM> in appearance. The body <NUM> includes a front panel portion <NUM> in the front, and the top and left and right sides are covered by an outer panel <NUM>. The front panel portion <NUM> includes an image display <NUM> for displaying images. The outer panel <NUM> includes an upper top plate 11b and a pair of left and right side plates 11a. The pair of side plates 11a are separated from each other in the left and right directions and face each other in parallel.

Each side plate 11a is provided with a fixing portion K on the front side into which a male screw can be screwed. In this example, a plurality of (four in this example) fixing portions 11a1 to 11a4 are provided as the fixing portion K. The fixing portions 11a1 to 11a4 are provided symmetrically at positions on the left and right side plates 11a.

In each side plate 11a, the fixing portions 11a1 to 11a4 are arranged at the vertices of a rectangle Ra whose sides extend up and down and to the front and back. Specifically, the fixing portion 11a1 is located at the front lower position, the fixing portion 11a2 is located at the rear lower position, the fixing portion 11a3 is located at the front upper position, and the fixing portion 11a4 is located at the rear upper position. In this way, when the four fixing portions 11a1 to 11a4 are at the vertices of the quadrangle, a hypothetical axis extending in the left-right direction through the diagonal center position of the quadrangle is defined as a fixed axis CL1.

A sensor board <NUM> on which the inertial sensor <NUM> is mounted is arranged at the front inside the body <NUM>. The inertial sensor <NUM> is arranged at a position sandwiched between the pair of fixing portions K. The inertial sensor <NUM> is set with detection reference axes 31X, 31Y, and 31Z, which are three orthogonal axes. The inertial sensor <NUM> is a <NUM>-axis sensor that detects acceleration in each axial direction and angular acceleration around each axis.

The vehicle-side fixing members <NUM> are a pair of members provided on the dashboard of the vehicle and separated to the left and right, for example. The pair of vehicle-side fixing members <NUM> are arranged apart from each other at an interval with which the pair of vehicle-side fixing members <NUM> are in substantially close contact with the pair of side plates 11a of the navigation device <NUM>. The vehicle-side fixing members <NUM> include four through-holes 71a corresponding to the fixing portions 11a1 to 11a4 in the side plates 11a of the navigation device <NUM>.

In this configuration, the navigation device <NUM> is fixed to the vehicle-side fixing members <NUM> by passing the fixing screws N1 through the through-holes 71a of the vehicle-side fixing members <NUM>, and screwing and tightening the fixing screws N1 to the fixing portions 11a1 to 11a4 of the navigation device <NUM>. Hereinafter, the orientation of the navigation device <NUM> in a state where the navigation device <NUM> is fixed to the vehicle-side fixing members <NUM> is referred to as an installation orientation.

<FIG> is a left side view of the navigation device <NUM> in the installation orientation. As shown in <FIG>, the direction of gravity is defined as a vertical axis V (vertical axis), the axis in the front-back direction perpendicular to the vertical axis V is defined as a horizontal axis H (horizontal front-back axis), and the axis in the left-right direction perpendicular to the vertical axis V (front and back direction in the page space of <FIG>) is defined as the horizontal left-right axis LR. The X-axis of the navigation device <NUM> in the installation orientation coincides with the horizontal left-right axis LR, and the Y-axis and Z-axis are set in directions rotated clockwise by an angle θa with respect to the horizontal axis H and the vertical axis V, respectively. That is, in the installation orientation, the navigation device <NUM> is in an inclined orientation in which the front side is tilted upward by an angle θa with respect to the horizontal direction.

As shown in <FIG>, the chassis <NUM> and a bracket <NUM> are provided inside the body <NUM> of the navigation device <NUM>. The chassis <NUM> is arranged parallel to the top plate 11b above the vertical center line CL91 of the navigation device <NUM>. The chassis <NUM> is arranged at a position that does not correspond to the position of the fixing portions K, in other words, at a position separated from the fixing portions K when viewed from the X-axis direction. The bracket <NUM> is fixed to the chassis <NUM> and supports the sensor board <NUM> so as to be located below the chassis <NUM>.

In the installation orientation, the inertial sensor <NUM> is arranged at a position where it intersects with the fixed axis CL1. For example, the inertial sensor <NUM> is arranged so that the detection reference axis 31X coincides with the fixed axis CL1.

<FIG> is a perspective view showing the mounting mode of the chassis <NUM>, the bracket <NUM>, the sensor board <NUM>, and the inertial sensor <NUM>. <FIG> is a cross-sectional view taken at the S4A-S4A position and the S4B-S4B position in <FIG>. <FIG> is an exploded perspective view showing a method of attaching the bracket <NUM> and the sensor board <NUM> to the chassis <NUM>. <FIG> and <FIG> are perspective views of the relevant portion viewed diagonally from the lower right rear, and are shown so that the upper side in the page space is the lower side in the Z axis by inverting the top and bottom. In addition, <FIG> also shows regions M1 and M2 (details will be described later), which are simulation results of the amplitude response to the external vibration of the chassis <NUM>.

As shown in <FIG> and <FIG>, the chassis <NUM> is made of metal and is formed in a substantially rectangular plate shape. The chassis <NUM> includes a plurality of fixing portions <NUM> formed by cutting and raising for screwing to the top plate 11b of the outer panel <NUM>. In this example, the chassis <NUM> includes a pair of left-right separated fixing portions <NUM> and 221R at the front and a pair of left-right separated fixing portions <NUM> at the rear. The chassis <NUM> is fixed to the outer panel <NUM> by means of fixing screws N2, each of which is tightened to an unillustrated female thread formed in the top panel 11b.

Meanwhile, the bracket <NUM> is made of a metal plate and includes a base 23a, an overhanging portion 23b, a pair of inclined connecting portions 23c, and a pair of seat portions 23d. The base 23a is an elongated plate-shaped portion extending in the left-right direction. The overhanging portion 23b is a rectangular plate-shaped portion that is inclined backward and diagonally upward in the central portion in the left-right direction of the base 23a. The inclined connecting portions 23c are portions that extend outwardly and diagonally upward from both left and right ends of the base 23a to connect the base 23a and the seat portions 23d. The seat portions 23d are plate-shaped portions having a through-hole 23d1 (see <FIG>) through which the threaded portion of the fixing screw N3 is inserted, and extend parallel to the base 23a from the tip of the inclined connecting portions 23c. The upper surfaces of the pair of seat portions 23d are included in the same hypothetical plane. The base 23a connects the pair of seat portions 23d and connects the pair of inclined connecting portions 23c.

Assuming that the entirety of the inclined connecting portion 23c and the seat portion 23d is a leg, the base 23a connects the pair of legs. The pair of legs are attached to the chassis <NUM> at positions separated from each other in the X-axis direction.

The sensor board <NUM> is screwed to the lower surface of the overhanging portion 23b by means of fixing screws N4. The inertial sensor <NUM> is mounted on the lower surface of the sensor board <NUM>.

The pair of seat portions 23d of the bracket <NUM> are fixed to the fixing portions Q1 and Q2 (see <FIG>) near the pair of front corners of the four corners of the chassis <NUM> by means of fixing screws N3. Further, in the vicinity of the pair of the front corners of the chassis <NUM>, the fixing portions <NUM> and 221R separated to the left and right are arranged as described above, and the chassis <NUM> is fixed to the top plate 11b. Therefore, the fixing portions Q1 and Q2 are portions having higher rigidity than the central portion of the chassis <NUM>.

As shown in <FIG> and <FIG>, the sensor board <NUM> is fixed to the bracket <NUM>, and the bracket <NUM> is attached to the chassis <NUM>. In this state, among the detection reference axes 31X, 31Y, and 31Z of the inertial sensor <NUM>, the detection reference axis 31X coincides with the fixed axis CL1 of the navigation device <NUM> as described above. Further, the detection reference axis 31Y extends parallel to the horizontal axis H, and the detection reference axis 31Z extends parallel to the Z axis.

Next, the details of the mounting position of the inertial sensor <NUM> in the above configuration will be described with reference to <FIG> is a diagram for describing the positional relationship between the inertial sensor <NUM> and the fixing portions 11a1 to 11a4 in the installation orientation of the navigation device <NUM>, and is a schematic view seen from the left side of the fixed axis CL1.

As shown in <FIG>, the inertial sensor <NUM> is set so that the center of gravity position G31 coincides with the position of the fixed axis CL1. In the navigation device <NUM>, the center of gravity position G31 is not limited to coinciding with the fixed axis CL1, and may be set within the range AR1.

The range AR1 is a rectangular range surrounded by a range ARh in the horizontal direction (horizontal axis H direction) and a range ARv in the vertical direction (vertical axis V direction). Specifically, the horizontal range ARh is the range between the center of the fixing portion 11a1 at the front position and the center of the fixing portion 11a4 at the last position in the horizontal axis H direction among the four fixing portions 11a1 to 11a4. The vertical range ARv is a range between the center of the fixing portion 11a3 at the uppermost position and the center of the fixing portion 11a2 at the lowest position in the vertical axis V direction.

When an external force or vibration in one direction is applied to the navigation device <NUM>, deformation of bending or twisting around the horizontal axis H and around the vertical axis V does not substantially occur in the inner portion of the range AR1 in the side plates 11a and the vehicle-side fixing members <NUM>. Therefore, when the center of gravity position G31 is within the range AR1, the navigation device <NUM> suppresses the deviation between the behavior of the inertial sensor <NUM> and the behavior of the vehicle, and can detect the position of the host vehicle with higher accuracy than in the case where the center of gravity position G31 is located in a range other than the range AR1. As a result, the navigation device <NUM> improves the detection accuracy of the position of the host vehicle.

Moreover, it is better that the center of gravity position G31 is within the narrower range AR1a included in the range AR1. The range AR1a is a quadrangular range in which the center positions of the fixing portions 11a1 to 11a4 are connected by line segments.

When an external force or vibration in one direction is applied to the navigation device <NUM>, the entire side plates 11a and the vehicle-side fixing members <NUM> may be deformed around an axis such as the Y-axis or the Z-axis, which are inclined with respect to the horizontal axis H and the vertical axis V. Even in this case, the inner portion of the range AR1a in the side plates 11a and the vehicle-side fixing members <NUM> is not affected by the deformation. Therefore, when the center of gravity position G31 is in the range AR1a, the navigation device <NUM> further suppresses the deviation between the behavior of the inertial sensor <NUM> and the behavior of the vehicle, and can detect the position of the host vehicle with higher accuracy than in the case where the center of gravity position G31 is in the range AR1. As a result, the navigation device <NUM> further improves the detection accuracy of the position of the host vehicle.

Further, as a response simulation for when vibration is applied from the outside, the amplitude distribution of the chassis <NUM> has been obtained when the vehicle-side fixing members <NUM> are vibrated in a random vibration direction in the mounting orientation. <FIG> shows the results of classifying the obtained amplitude distribution into three stages of small, medium, and large according to the magnitude of the amplitude. That is, the region M2 with cross-hatching is a region having a large amplitude, and the region M1 with single hatching is a region having a medium amplitude. The region M2 is located inside the region M1. The region other than the region M2 and the region M1 without hatching is a region having a small amplitude. The regions M1 and M2 can be regarded as regions in which resonance is generated with respect to the vibration applied from the outside.

As shown in <FIG>, the regions M1 and M2 are distributed in the front left-right central portion of the chassis <NUM> extending in the left-right direction. When the bracket <NUM> is fixed to the region M1 and the region M2, it is predicted that the resonance of the chassis <NUM> greatly affects the operation of the inertial sensor <NUM>. Therefore, in the navigation device <NUM>, the bracket <NUM> is fixed to portions of the chassis <NUM> where the amplitude is small. Specifically, in the chassis <NUM>, the fixing portions Q1 and Q2 that substantially correspond to the region M1 in the front-back direction and are outside the region M1 in the left-right direction are selected, and the bracket <NUM> is fixed at the fixing portions Q1 and Q2.

In this way, the bracket <NUM> is fixed to the chassis <NUM> at the fixing portions Q1 and Q2. Therefore, as compared with the case where the bracket <NUM> is fixed to the region M1 or M2 of the chassis <NUM>, the inertial sensor <NUM> is less likely to be affected by the excessive vibration due to the resonance of the chassis <NUM> even if an external force such as an external vibration is applied. That is, the inertial sensor <NUM> on the sensor substrate <NUM> fixed to the bracket <NUM> is unlikely to vibrate excessively even if the body <NUM> vibrates. As a result, the navigation device <NUM> can detect the position of the host vehicle with high accuracy even if external vibration is applied.

The navigation device <NUM> including the above-described configuration is manufactured by the following method. First, the navigation device <NUM> includes the pair of side plates 11a that are separated from each other in the X-axis direction, which is the first direction, and face each other in parallel. Further, the navigation device <NUM> includes the outer panel <NUM> having the fixing portions K (11a1 to 11a4) on the pair of side plates 11a to be fixed to the vehicle-side fixing members <NUM>. The fixing portions K fix the outer panel <NUM> to the pair of vehicle-side fixing members <NUM> located on both outer sides of the pair of side plates 11a by means of the fixing screws N1.

As a manufacturing method, the flat plate-shaped chassis <NUM> is arranged in an orientation orthogonal to the side plates 11a at a position not corresponding to the positions of the fixing portions 11a1 to 11a4 between the pair of side plates 11a when viewed from the X-axis direction. That is, the chassis <NUM> is arranged at a position separated from the fixing portions 11a1 to 11a4 when viewed from the X-axis direction.

In addition, the sensor board <NUM> on which the inertial sensor <NUM> is mounted is attached to the bracket <NUM> having a predetermined shape. The bracket <NUM> is fixed to the chassis <NUM> at portions of the chassis <NUM> where the amplitude when vibration is applied to the navigation device <NUM> is smaller than the amplitude at other portions, and the inertial sensor <NUM> is arranged at a position sandwiched between the pair of fixing portions K when viewed from the X-axis direction. Desirably, the inertial sensor <NUM> is arranged at a position corresponding to the position of the fixing portions K when viewed from the X-axis direction. The state in which the inertial sensor <NUM> is arranged at a position corresponding to the position of the fixing portions K when viewed from the X-axis direction means that the inertial sensor <NUM> is located at a position where the inertial sensor <NUM> overlaps the fixing portions K when viewed from the X-axis direction. At this time, the positions of the inertial sensor <NUM> in the Y-axis and Z-axis directions are substantially the same as the positions of the fixing portions K in the Y-axis and Z-axis directions.

The other portions in the chassis <NUM> are regions M1 and M2 where a relatively large amplitude is generated by resonance when vibration is applied to the navigation device <NUM>.

The present invention is not limited to one or more embodiments described above, and various modifications can be made without departing from the scope of the present invention.

The number of fixing portions included in the fixing portion K is not limited to four as described above. The number of fixing portions included in the fixing portion K may be two or three, for example.

As shown in <FIG>, when the fixing portion K is composed of two fixing portions α1 and α2, the center of gravity position G31 of the inertial sensor <NUM> may be set within the range AR2. The range AR2 is a range surrounded by a range ARh2 in the horizontal direction (horizontal axis H direction) and a range ARv2 in the vertical direction (vertical axis V direction). Specifically, the horizontal range ARh2 is the range between the centers of the fixing portion α1 at the front position and the fixing portion α2 at the last position in the horizontal axis H direction of the two fixing portions α1 and α2. The vertical range ARv2 is a range between the centers of the fixing portion α2 at the uppermost position and the fixing portion α1 at the lowest position in the vertical axis V direction.

Furthermore, as shown in <FIG>, when the fixing portion K is composed of three fixing portions β1 to β3, the center of gravity position G31 of the inertial sensor <NUM> may be set within the range AR3. The range AR3 is a range surrounded by a range ARh3 in the horizontal direction (horizontal axis H direction) and a range ARv3 in the vertical direction (vertical axis V direction). Specifically, the horizontal range ARh3 is the range between the centers of the fixing portion β1 at the front position and the fixing portion β2 at the last position in the horizontal axis H direction among the three fixed portions β1 to β3. The vertical range ARv3 is a range between the centers of the fixing portion β3 at the uppermost position and the fixing portion β2 at the lowest position in the vertical axis V direction.

When an external force or vibration in one direction is applied to the navigation device <NUM>, deformation of bending or twisting around the horizontal axis H and around the vertical axis V does not substantially occur in the inner portion of the range AR2 or AR3 in the side plates 11a and the vehicle-side fixing members <NUM>. Therefore, when the center of gravity position G31 is within the range AR2 or AR3, the navigation device <NUM> suppresses the deviation between the behavior of the inertial sensor <NUM> and the behavior of the vehicle, and can detect the position of the host vehicle with higher accuracy than in the case where the center of gravity position G31 is located in a range other than the range AR2 or AR3. As a result, the navigation device <NUM> improves the detection accuracy of the position of the host vehicle even when the fixing portion K is composed of two or three fixing portions.

When the fixing portion K includes two fixing portions, it is better that the center of gravity position G31 is on the line segment LN1 connecting the fixing portion α1 and the fixing portion α2 shown in <FIG>. When the fixing portion K includes three fixing portions, it is better that the center of gravity position G31 is within the range AR3a shown in <FIG>. The range AR3a is a triangular range connecting the center positions of the fixing portions β1 to β3 by line segments.

When an external force or vibration in one direction is applied to the navigation device <NUM>, the entire side plates 11a and the vehicle-side fixing members <NUM> may be deformed around an axis such as the Y-axis or the Z-axis, which is inclined with respect to the horizontal axis H and the vertical axis V. Even in this case, the portion on the line segment LN1 and the inner portion of the range AR3a in the side plates 11a and the vehicle-side fixing members <NUM> is not affected by the deformation. Therefore, when the center of gravity position G31 is on the line segment LN1 or in the range AR3a, the navigation device <NUM> further suppresses the deviation between the behavior of the inertial sensor <NUM> and the behavior of the vehicle, and can detect the position of the host vehicle with higher accuracy than in the case where the center of gravity position G31 is in the range AR2 or AR3. As a result, the navigation device <NUM> further improves the detection accuracy of the position of the host vehicle.

The inertial sensor <NUM> is not limited to the board mounting type. The inertial sensor <NUM> may be attached directly to the base 23a of the bracket <NUM>. That is, the inertial sensor <NUM> may be indirectly attached to the base 23a of the bracket <NUM> via another member such as the sensor board <NUM>, or may be directly attached to the base 23a.

The navigation device <NUM> may also mounted on a moving body other than a vehicle. When the navigation device <NUM> is mounted on a moving body other than a vehicle, all of the instances of the word "vehicle" in the above description can be replaced with "moving body".

Claim 1:
A navigation device (<NUM>) comprising:
an outer panel (<NUM>) including a pair of side plates (11a) separated from each other in a first direction and facing each other in parallel; and
a pair of fixing portions (K) provided on the pair of side plates (11a) and to be fixed to moving body-side fixing members (<NUM>); and
characterized in that
the navigation device (<NUM>) further comprises:
a chassis (<NUM>) that is arranged in an orientation orthogonal to the pair of side plates (11a) at a position not corresponding to positions of the pair of fixing portions (K) between the pair of side plates (11a) when viewed from the first direction;
a bracket (<NUM>) having a predetermined shape;
a sensor board (<NUM>) that is attached to the bracket (<NUM>); and
an inertial sensor (<NUM>) that is mounted on the sensor board (<NUM>) , wherein
the bracket (<NUM>) is fixed to a portion in the chassis (<NUM>) where an amplitude is smaller than an amplitude at other portions in the chassis (<NUM>) when vibration is applied to the navigation device (<NUM>), and
the inertial sensor (<NUM>) is arranged at a position sandwiched between the pair of fixing portions (K) in the first direction.