Electronic device

An electronic device has an operating panel. A through-hole penetrating the operating panel is provided at a part of the operating panel. A partition board includes a board part and a partition part, and a step is provided between the board part and the partition part. In an area where the through-hole and the board part of the partition board are to be formed, a metal mold can be thickened. In an area where a narrow gap on a surface side of the operating panel is to be formed, the length of the metal mold can be reduced. Therefore, the strength of the metal mold can be maintained. Also, the step of the partition board, which separates the board part and the partition part, prevents visual recognition of the through-hole by a user.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an electronic device having plural operating buttons that are continuously arrayed.

2. Description of the Related Art

A conventional electronic device is disclosed, for example, in JP-A-2004-179241. The conventional electronic device has a front panel. A button insertion recess, a recording medium insertion hole and the like are formed on the front panel. In the button insertion recess, plural buttons for operating the device are inserted. Insertion holes are formed at the bottom of the button insertion recess and button holders are arranged in the insertion holes. Partition walls that separate the plural buttons are formed between the insertion holes. The partition walls are protruding from the bottom of the front panel to the surface of the front panel. These partitions are provided mainly for clarifying the classification of each button function and improving the operability. The partitions function to prevent erroneous operation of the buttons.

FIG. 6Ashows a partition board71between operating buttons in another conventional device. The partition board71is made of resin. A surface is formed one step deeper than an operating panel surface73, thus providing gaps72above and below the partition board71. In a structure shown inFIG. 6B, a partition board81is a separate component from a panel. The partition board81and an operating panel surface82are connected with each other by fitting parts83. Gaps84are formed in the operating panel surface82.

The gaps above and below the partition board have the following function. As viewed from the front side of the operating panel, there are gaps between buttons and the panel. The gaps are above and below the buttons. Similarly, gaps are provided above and below the partition board. The width of the gaps above and below the partition board is set to the same dimension as the gaps above and below the neighboring buttons. This dimensional setting enables integrated appearance of the neighboring buttons and is preferable in view of design.

Meanwhile, improved appearance around operating buttons has been demanded of the recent electronic devices. The gaps around the operating buttons tend to be narrower. Therefore, the gaps above and below the partition board must be narrower, too.

However, if the gaps above and below the partition board are narrowed, the following problem arises. Here, it is assumed that the operating panel is made of resin and that the partition board and the operating panel are integrally formed. In this case, narrow grooves are formed in the operating panel. These grooves serve as gaps between the panel and the partition board, and a part of the panel becomes the partition board. It is now assumed that the gaps between the operating buttons and the operating panel are narrowed to a certain extent or more and that the gaps above and below the partition board are accordingly narrowed to the same extent. In this case, to secure the strength of a metal mold used for molding, the depth of the gaps cannot be increased (i.e., narrow and deep grooves cannot be easily prepared). Therefore, the surface in the depth of the gaps can be seen and good appearance in view of design cannot be maintained. If the partition board is a separate component from the panel, narrow and deep gaps can be formed (FIG. 6B). However, the number of components increases and the assembly work become complicated.

SUMMARY OF THE INVENTION

This invention is made in view of the foregoing status of the art. It is an object of this invention to provide an electronic device in which gaps between an operating panel and a partition board can be narrowed while having a shape that maintains the strength of a metal mold used for molding the operating panel, and in which the operating panel and the partition board can be prevented from appearing continuous to each other, thus enabling improved appearance in view of design.

An electronic device according to an aspect of this invention includes a plurality of operating buttons, a button holding part that holds the plurality of operating buttons so that the buttons can move in a pressing direction, a wall part integrally formed with the button holding part and having a through-hole provided therein, and a partition board provided at least between one operating button of the plurality of operating buttons and another operating button next to the one operating button, wherein the partition board has a partition part having substantially the same height as the height of the foregoing at least one button, and a board part forming a part of a circumferential edge of the through-hole, and wherein the partition board is integrally formed with the wall part.

An electronic device according to an aspect of this invention includes a plurality of operating buttons, and an operating panel on which the plurality of operating buttons are provided. The operating panel has a vertical wall part that crosses a moving direction of the buttons, and a partition board that extends forward from the wall part between a first operating button and a second operating button of the plurality of buttons. The first operating button, the second operating button and the partition board have gaps of substantially the same size to the operating panel. The partition board has a partition part on forward side and a board part in the depth. A step is provided between the partition part and the board part, and the partition part is protruding from the board part in the direction of height. The wall part has a through-hole that is situated in the depth of the protruding part of the partition part.

As described hereafter, other aspects of the invention exist. Thus, this summary of the invention is intended to provide a few aspects of the invention and is not intended to limit the scope of the invention described and claimed herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description refers to the accompanying drawings. Although the description includes exemplary implementations, other implementations are possible and changes may be made to the implementations described without departing from the spirit and scope of the invention. The following detailed description and the accompanying drawings do not limit the invention. Instead, the scope of the invention is defined by the appended claims.

This electronic device has plural operating buttons, a button holding part that holds the plural operating buttons so that the buttons can move in a pressing direction, a wall part integrally formed with the button holding part and having a through-hole provided therein, and a partition board provided at least between one operating button of the plural operating buttons and another operating button next to the one operating button. The partition board has a partition part having substantially the same height as the height of at least one button, and a board part forming a part of a circumferential edge of the through-hole. The partition board is integrally formed with the wall part.

With this structure, even when the gap between the operating panel and the partition board is narrowed, it is possible to realize a panel shape that can maintain the strength of a metal mold used for integrally forming the operating panel and the partition board. That is, the gap between the operating panel and the partition board can be reduced, using the panel shape that can maintain the strength of the metal mold. Moreover, the operating panel and the partition board can be prevented from appearing continuous to each other, thus improving the appearance in view of design.

In this electronic device, the wall part may be a retaining wall that limits movement of the operating buttons in the pressing direction. With this structure, a member having a pressing regulation function for the operating buttons, which is an essential function, is provided without providing particularly another wall parts having a through-hole. Therefore, the number of components can be reduced.

In this electronic device, the length of the partition part of the partition board in direction of depth may be equal to or longer than a pressing stroke (pressing length) of the operating buttons. With this structure, even if the partition board is exposed outward when the operating buttons are pressed, only the part of the same height (that is, the partition part) is exposed. That is, the lower part (board part) in the depth of the partition board is not exposed. Therefore, good appearance can be maintained even when pressing the operating buttons.

Moreover, the partition part may protrude forward more than the foregoing at least one button. Alternatively, the foregoing at least one button may protrude forward more than the partition part. With such a structure, the operating buttons and the partition board can be distinguished more clearly. Therefore, the erroneous operation prevention function in the case where the user operates the electronic device without watching the electronic device can be further improved.

This electronic device is useful when the gap around the operating buttons in the operating part is narrowed. While the operating panel has the shape that can maintain the strength of the metal mold used for molding, the gap between the operating panel and the partition board can be narrowed in accordance with the gap around the buttons. The connecting part between the partition board and the operating surface can be prevented from being seen. Thus, an electronic device having a design of good appearance can be provided.

Hereinafter, an electronic device according to an embodiment of this invention will be described with reference to the drawings.

FIGS. 1A and 1Bshow an electronic device according to an embodiment of this invention. In this embodiment, the electronic device is a car audio device.

In the following description, X-direction shown inFIG. 1Ais referred to as the direction of width, Y-direction is referred to as the direction of depth, and Z-direction is referred to as the direction of height.

InFIGS. 1A and 1B, a car audio device (electronic device)1has a casing2. Inside the casing2, a CD deck, a radio tuner, a printed board (substrate) and the like, not shown, are housed. On the printed board, an integrated circuit (IC) for electrically controlling the CD deck, the radio tuner and the like is mounted. An operating panel3is fitted with the front part of the casing2. The casing part deeper than the operating panel3is incorporated within a center console of an automobile. When the car audio device1is mounted on a vehicle, it appears that an operating part4is exposed to the user. The operating part4is mounted to achieve integrated appearance with the other indoor panels of the vehicle such as an air conditioner panel.

To operate each function of the car audio device1, the operator presses plural operating buttons5(5ato5f) provided on the operating panel3. The operator also turns a volume operating part6.

In the case of an in-vehicle electronic device such as the car audio device1, the user of the device is often the driver of the vehicle. Therefore, it is desired that blind touch on the operating panel should be easy. In this embodiment, the plural operating buttons5and the like are held on the operating panel3so that these operating buttons5can be pressed. A partition board7is provided together with these plural operating buttons5. The partition board7facilitates tactile recognition of the layout of the operating buttons5and it plays the role of preventing erroneous operations. Also, the functions of the buttons are divided by the partition board7. For example, the operating button5ahas a function of switching the mode between a radio mode, a CD reproduction mode, a cassette reproduction mode and the like. The mode is switched every time the operating button5ais pressed. The operating buttons5bto5eare separated from the operating button5aby the partition board7. In the radio mode, each of the operating buttons5bto5ehas a radio station selection function. In the CD reproduction mode, each of the operating buttons5bto5ehas an instruction function to instruct execution of fast-forward, rewind or the like. In the other modes, the buttons5bto5ehave their respective functions. The partition board7thus contributes to improvement in operability and prevention of erroneous operations.

The operating part4of the car audio device1constructed as described above will now be described in detail with reference toFIGS. 2,3A,3B and4.

InFIG. 2, the operating part4includes the operating panel3, switches9, an operating board (substrate)10and the like. These are arranged from the forward side into the direction of depth. The operating panel3holds the plural operating buttons5. The switches9are situated in the pressing direction of the operating buttons5(substantially the same direction as the direction of depth). The switches9are provided with switch pressing parts8. An electronic circuit is mounted on the operating board (substrate)10. As one of the switch pressing parts8is touched, the circuit is electrically continued and an operation signal is generated. Thus, the function of the car audio device1is executed as instructed by the operation of the button.

The plural operating buttons5are engaged or fitted with a button holding part11formed in the operating panel3(seeFIG. 3A). The plural operating buttons5are held on the operating panel3and can move in the pressing direction. In the depth in the direction of the depth of the button holding part11(that is, the casing2side), a retaining wall12is provided. The retaining wall12limits the movement of the buttons in the pressing direction. The retaining wall12prevents the operating buttons5from going through the button holding part11when the operating buttons5are pressed.

It is now assumed that the operator pressed one of the operating buttons5. For example, the operating button5is pressed with a finger. The operating button5presses the switch pressing part8of the switch9situated below that operating button5. The switch pressing part8moves against the elastic force of an elastic member, not shown, within the switch9, and thus causes a short circuit of wiring on the rear side. After that, the operator cancels the pressing of the operating button5. For example, the finger is removed from the operating button. The elastically deformed elastic member generates a repulsive force to restore the state before the pressing. This repulsive force causes the operating button5to move back to the forward side of the operating panel3along the button holding part11. Here, the retaining wall12regulates the movement of the operating button5so that the button will not excessively move back toward the forward side.

The operating board10has components and the like for generating instruction signals to operate each function of the car audio device1. These components are connected with each other by printed wiring. In this embodiment, the wiring printed on the operating board10has an open end. A voltage of several volts is applied to its one end and the other end is grounded to the ground level. The switch pressing part8causes a short circuit of the wiring on the rear side against the elastic force of the elastic member, not shown, in the switch9. Interlocked with the pressing of the button, the opening end forms a short circuit. The signal level of the operation instruction signal changes. This change in the signal level is detected and various operation functions are executed.

The operating board10also has an illumination component (not shown) such as LED or lamp to illuminate each button. The volume operating part6is also mounted on the operating board10. The volume operating part6is provided for turning on/off the power of the car audio device1, adjusting the volume, selecting a radio station, adjusting the sound quality, and the like. The volume operating part6includes a supporting shaft13that applies a rotational force, and a volume cap14. The supporting shaft13penetrates a hole in the operating panel3, and the volume cap14is fitted with the supporting shaft13.

Next, the button holding part11will be described. The button holding part11is integrally formed with the operating panel3.FIG. 3Ais a sectional view of an operating button5(one of operating buttons5ato5f). InFIG. 3A, the button is cut on a plane passing the center in the direction of width and extending in the direction of height.FIG. 3Bis a view showing the operating button and its peripheries shown inFIG. 3A, as viewed from the rear side of the operating panel. InFIG. 3A, the operating button5includes a button cap15and a pressing piece16. The button cap15and the pressing piece16are situated on both sides of the retaining wall12provided in the operating panel3. The button cap15is on the forward side in the direction of depth and therefore arranged on the side that can be seen by the user. The pressing piece16is arranged in the depth in the direction of depth of the operating panel3. The pressing piece16has a pressing surface17. The pressing surface17can contact the switch pressing part8situated in the depth in the direction of depth of the pressing piece16.

The button cap15is provided with an engagement protrusion18. The pressing piece16is provided with an engagement hole19. The engagement protrusion18is an elastic member and an engagement pawl18ais provided at the distal end of the engagement protrusion18. The engagement protrusion18passes through the through-hole in the operating panel3and becomes engaged with the engagement hole19. The button cap15and the pressing piece16are thus assembled together and become integrally movable.

The button holding part11is provided mainly in the depth in the direction of depth of the retaining wall12. The pressing piece16is provided with upper and lower holding protrusions21. The upper and lower holding protrusions21are provided at upper and lower parts of the pressing piece16in the direction of height. The upper and lower holding protrusions21have upper and lower guide grooves20, respectively. The button holding part11has upper and lower guide rails22at positions corresponding to the upper and lower holding protrusions21. The upper and lower guide rails22are provided into the direction of depth. When the pressing piece16is engaged with the button cap15, the upper and lower guide rails22are fitted in a slidable manner in the upper and lower guide grooves20of the upper and lower holding protrusions21. Thus, the operating button5is held on the operating panel3with respect to the direction of height in the state where the operating button5is movable in the direction of depth. Similarly, the operating button5is held by the button holding part11with respect to the direction of width. The pressing piece16has left and right guide rails23. The left and right guide rails23are provided on the left and right sides, respectively, in the direction of width of the pressing piece16. The button holding part11has left and right guide grooves24at positions corresponding to the left and right guide rails23. The left and right guide grooves24are provided into the direction of depth. When the pressing piece16is engaged with the button cap15, these left and right guide rails23are fitted in a slidable manner in the left and right guide grooves24, respectively. Thus, the operating button5is held on the operating panel3with respect to the direction of width in the state where the operating button5is movable in the direction of depth.

As the pressing piece16is held in a slidable manner by the button holding part11, the integrated component formed by the button cap15and the pressing piece16engaged with each other (that is, operating button5) is held in a slidable manner in the direction of depth (that is, pressing direction). However, the retaining wall12provided in the operating panel3is formed to abut against the outer circumference of the button cap15. The retaining wall12prevents the operating button5from moving more than necessary into the direction of depth. Even when the operator strongly presses the operating button5, the operating button5can be prevented from falling off the operating panel3.

In the above description, the button holding part11is integrally formed with the operating panel3. However, the upper and lower guide rails22, the left and right guide rails23, the upper and lower guide grooves20, the left and right guide grooves24and the like may be attachable/detachable. An appropriate structure may be employed in consideration of the validity of product design, easiness in manufacturing, cost and the like.

Next, the partition board7will be described in detail with reference toFIG. 4. As described above, the partition board7separates a desired operating button and an operating button situated next to this button of the plural operating buttons5held in the button holding part11.

FIG. 4is a perspective view schematically showing the positional relation between the operating button5, the button holding part and the partition board7. InFIG. 4, the button holding part, the retaining wall12and the partition board7are integrally formed with the operating panel3.

Above the top surface of the operating button5, a part of the operating panel3is provided substantially parallel thereto. This panel part is arranged like a roof of the operating button5and the panel part covers the top surface of the operating button5. A small gap25in the direction of height is provided between the top surface of the operating button5and the operating panel3. Also below the bottom surface of the operating button5, a part of the operating panel3is similarly arranged. A small gap25is provided between the bottom surface of the operating button5and the panel part. Moreover, the operating panel3has the retaining wall12in the depth in the direction of depth of the operating button5. These three board parts (the upper and lower panel boards and the retaining wall12in the depth) form a panel recess part in the operating panel3. The panel recess part is formed by the three bent boards (walls). The sectional shape of the panel recess part is a U-shape that is turned sidelong (with each corner having a right angle). The panel recess part has an open part on the forward side in the direction of depth.

The length (depth) of the panel recess part in the direction of depth is approximately equal to the sum of the thickness of the button cap15and the button stroke (pressing length). The thickness of the button cap15is the dimension in the direction of depth. The button stroke is the distance that is moved when the operating button5is pressed. The switch9is arranged in the depth in the direction of depth of the operating panel3and the operating button5. The plural switches9are provided corresponding to the plural operating buttons5. The elastic force of each switch9is transmitted by the switch pressing part8and thus biases each operating button5. This realizes integrated appearance on the surface of the operating part4.

The retaining walls12a,12bare situated corresponding to the neighboring operating buttons5a,5b, respectively. The partition board7is protruding forward in the direction of depth from the area between the retaining walls12a,12b.

The partition board7includes a board part26and a partition part27. The board part26is a specific part in the depth in the direction of depth of the partition board7. The partition part27is a specific part on the forward side in the direction of depth of the partition board7. The board part26and the partition part27are integrated with each other. The height of the board part26is set to be lower than the height of the partition part27.

More specifically, a step28is provided at a predetermined position in the direction of depth of the partition board7. The step28is the boundary between the board part26and the partition part27. The board part26is behind the step28, and the partition part27is on the forward side of the step28. The step28causes the partition part27to be higher than the board part26. In other words, the partition part27is protruding upward from the board part26.

The shape of the partition board7is vertically symmetrical and the partition board7has the same structure in its upper and lower parts. Also in the lower part of the partition board7, the partition part27is protruding with respect to the board part26. The partition part27is downwardly longer (higher) than the board part26. The panel shape or the like around the partition board7has the same structure in its upper and lower parts. In the following description, the structure of the upper part of the partition board7will be mainly described. However, the same structure can be seen in the lower part, too.

The height of the partition part27is set to be substantially the same as the height of the operating buttons5next to the partition board7. This height represents the vertical position as viewed from the front. The operating buttons5and the partition part27are provided very closely to the upper and lower surfaces of the above-described panel recess part via substantially the same gap25. This realizes integrated appearance of the partition part27and the operating buttons5, thus improving the appearance in view of design.

The position of the step28of the partition board7is set to be deeper in the direction of depth than the surface position of the operating buttons5in the state where the operating buttons5are pressed to the deepest point. As the position of the step28is set in this manner, when the operating button5is pressed, the step28between the partition part27and the board part26cannot be seen and the board part26is not exposed. Even when the operating part4is seen from a position obliquely deviated from the front of the car audio device1, the step28cannot be seen. Therefore, good appearance of the car audio device1in view of design can be maintained.

A through-hole29is formed between the retaining wall12and its neighboring retaining wall12and on upper and lower sides in the direction of height of the board part26. Parts of the closest sides of the neighboring retaining walls12a,12band the upper side and/or lower side of the board part26form the circumferential edge of the through-hole29.

The major part of the through-hole29exists at a position overlapping the partition part27as viewed from the front side of the operating panel3. More specifically, the partition board7is protruding from the board part26in the direction of height (upwardly and downwardly). The through-hole29is situated behind this protruding part along with the direction of depth. The through-hole29thus overlaps the partition part27. Therefore, when the car audio device1in ordinary use is seen from the front, the through-hole29can hardly be seen. The gaps25above and below the partition board7are recognized as partitions that separate the partition board7and the operating buttons5from the operating panel3.

The through-hole29need not be provided at the two positions, that is, the upper and lower sides of the partition board7. For example, if the lower gap25need not be set narrowly in view of design, the through-hole29can be provided corresponding only to the upper gap25.

The partition board7is protruding to such an extent that it becomes substantially flush with the surface of the operating panel3. This realizes its integrated appearance with the surface of the operating panel3. The partition board7also has the function of preventing erroneous operations by the user. Thus, the partition board7may be protruding forward in the direction of depth from the surface of the operating panel3. Alternatively, the partition board7may be recessed to the rear side in the direction of depth from the surface of the operating panel3. Here, the partition board7may be protruding or recessed within such a range that it is substantially flush with the surface of the operating panel3. With such a structure, the user can more easily recognize which part of the operating panel3he/she is touching. Therefore, the effect of preventing erroneous operations can be further improved.

Now, a metal mold structure for integrally molding the above-described partition board7and operating panel3will be described with reference toFIG. 5.

The operating panel3in this embodiment is made of resin and is manufactured by integral forming. Two metal molds having recesses and protrusions inside are joined with each other. Then, resin is poured (or injected) into the space within the metal molds to mold the operating panel3.

FIG. 5is a sectional view showing the periphery of the partition board7when the two metal molds are joined with each other. InFIG. 5, one of the two metal molds is a core metal mold30and the other is a cavity metal mold31. The position of the core metal mold30is fixed. The cavity metal mold31is movable. The relative positions of the core metal mold30and the cavity metal mold31can be thus aligned with each other. After the positions of the two molds are aligned, a resin material that has been caused to be liquid at a high temperature is poured therein. The resin material is cooled within the metal molds and the operating panel3is thus molded.

InFIG. 5, the shaded parts represent the metal molds and the solid part represents the panel. As already described, the operating panel3has the narrow gap25between the partition part27(partition board7) and the wall of the panel recess part above the partition part27. This gap25is formed by the distal end part (protrusion) of the cavity metal mold31. Since the board part26is lower than the partition board27, the gap between the board part26and the panel board above it is large. The through-hole29of the retaining wall12is situated behind this large gap. This part (the large gap and the through-hole29behind it) is formed by the core metal mold30. Moreover, the metal molds are shaped and aligned in position so that the distal end part of the cavity metal mold31contacts the distal end part of the core metal mold30. Thus, in the area where the narrow gap25is to be formed, the distal end part of the cavity metal mold31can be shortened (its dimension in the direction of depth can be reduced). Also, the gap that should be formed by the core metal mold30increases and the metal mold can be thickened.

Now, the metal mold structure will be described further in detail with reference toFIGS. 4 and 5. In this embodiment, the strength of the metal molds can be maintained by improving the shape of the operating panel. First, in the operating panel3, the partition board7has the step28. Therefore, the partition part27is higher than the board part26in the direction of height, and the partition part27is protruding. The gap25above the partition part27is small whereas the gap above the board part26is large. Also, behind the partition part27(protrusion), the through-hole29is provided in the retaining wall12. The through-hole29continues to the large gap above the board part26.

In such a structure, the narrow gap25is limited to the area above the partition part27, that is, it is limited to the area before the step28. Therefore, the distance of the narrow gap25(length or dimension in the direction of depth) is short. This short gap25is formed by the protruding part (distal end part) of the cavity metal mold31. Therefore, the cavity metal mold31can secure sufficient strength.

The gap above the board part26exists behind the gap25. This gap is broad. In addition, the through-hole29is provided behind this gap. Therefore, the gap above the board part26can be formed by the core metal mold30on the rear side (instead of the forward metal mold). Moreover, since the gap is broad, the metal mold in this area can be thick. Therefore, also the core metal mold30can secure sufficient strength.

In this manner, even when the gap25is extremely narrowed, the two metal molds for molding the operating panel3can maintain strength and the partition board7can be integrally formed with the operating panel3. Moreover, since the protrusion of the partition part27is on the forward side, the through-hole29cannot be seen from the front.

In this embodiment, the size (in the direction of height) of the gap25can be set in accordance with the size of the gap around the operating buttons5. The length (dimension) in the direction of depth of the board part26can be decided arbitrarily from the strength of the metal molds for molding the operating panel3.

In the electronic device according to this embodiment, the through-hole29penetrating the operating panel3is provided at a part of the operating panel3, as described above. The step is provided on the partition board7, thus dividing the partition board7into the board part26and the partition part27. This enables maintenance of the strength of the metal molds even when a narrow gap is formed on the surface side of the operating panel3. More specifically, the metal mold can be thickened in the area where the through-hole29and the board part26of the partition board7are to be formed. Also, the length of the metal mold can be reduced in the area where the narrow gap25on the surface side of the operating panel is to be molded. Therefore, the strength of the metal mold can be maintained. Moreover, the step28of the partition board7, which separates the board part26and the partition part27, prevents the through-hole29from being seen by the user.

In this manner, even if the gap around the operating buttons is narrow, the operating panel3and the partition board7can be integrally formed with a simple structure. An electronic device in which the connecting part between the partition board and the operating panel is prevented from being seen without increasing the number of components and which has a design of good appearance can be provided.

Persons of ordinary skill in the art will realize that many modifications and variations of the above embodiments may be made without departing from the novel and advantageous features of the present invention. Accordingly, all such modifications and variations are intended to be included within the scope of the appended claims. The specification and examples are only exemplary. The following claims define the true scope and spirit of the invention.