Patent Description:
In general, refrigerators are apparatuses for keeping foods frozen or at a temperature slightly above freezing temperature by discharging cold air generated by a refrigeration cycle consisting of, for example, a compressor, a condenser, an expansion valve, and an evaporator to lower the temperature in a storage compartment thereof.

A typical refrigerator includes a freezing compartment, in which foods or beverages are kept frozen and a refrigerating compartment, in which foods or beverages are kept cold.

There are several kinds of refrigerators, including a top-mounting type refrigerator, in which a freezing compartment is located above a refrigerating compartment, a bottom-freezer type refrigerator, in which a freezing compartment is located below a refrigerating compartment, and a side-by-side type refrigerator, in which a freezing compartment and a refrigerating compartment are respectively located on left and right sides. The freezing compartment and the refrigerating compartment may be provided with respective doors, and may be accessed through the respective doors.

In addition to such refrigerators, which include a refrigerating compartment and a freezing compartment which are compartmentalized from each other, there is also a refrigerator which allows access to both the refrigerating compartment and the freezing compartment through a single door. This kind of refrigerator is mostly small-sized, and is typically constructed such that the freezing compartment is provided in a predetermined space within the refrigerating compartment.

Among the top-mounting refrigerators, there is also provided a French type refrigerator in which an upper refrigerating compartment is opened and closed by right and left doors. The freezing compartment of the French type refrigerator may also be opened and closed by right and left doors.

Recently, in addition to the original function of keeping foods refrigerated or frozen, the variety of functions provided by refrigerators is increasing. For example, a dispenser is installed to a door of the refrigerator to provide purified water and ice, and a display is installed on the front surface of the door to show the state of the refrigerator and to assist a user in controlling the refrigerator.

The door of a refrigerator is generally constructed to be opaque and to open and close the storage compartment of the refrigerator body. In other words, the door also serves as a thermal insulating wall that defines a refrigerating compartment or a freezing compartment. The difference resides in the fact that the door is a kind of thermal insulating wall that is capable of being opened and closed so as to allow a user to access to the refrigerating compartment or the freezing compartment. Accordingly, it is typical for a user not to know the type, location, etc. of objects stored in the storage compartment before opening the door.

A large amount of cold air is lost when the door of a refrigerator is opened. Accordingly, the loss of cold air accumulates as the door remains in the opened state.

Generally, objects having various shapes are stored in the refrigerating compartment of the freezing compartment. Accordingly, it typically takes a user a rather long time to find and take out a desired object. Specifically, a considerable time is required for the user to look all around the storage compartment and find a desired object in the state in which the door is opened.

That is, the inherent characteristics of the refrigerator inconvenience the user and lead to increased energy consumption.

In recent years, a refrigerator in which only part of a storage compartment is opened has been proposed. For example, a refrigerator which is provided with a sub door for opening and closing a sub storage compartment defined in a main door has been proposed. The sub storage compartment is a portion of the space of the main storage compartment, and is isolated from the main storage compartment by a partition wall. This kind of refrigerator may be referred to as a door-in-door (DID) refrigerator. This DID refrigerator is advantageous in that the outward leakage of cold air from the main storage compartment is considerably reduced when only the sub door is opened.

For example, stored objects, such as beverages, which are frequently taken out of and put back into the storage compartment, are stored in the sub storage compartment, and thus the sub storage compartment can be accessed by opening the sub door while maintaining the main door in the closed state.

There is also a home-bar refrigerator which is equipped with a home-bar door. The home-bar may be considered a very small sized sub storage compartment. Specifically, a small amount of beverages or the like may be stored in the home-bar, which is provided in the rear of the main door through a home-bar door mounted in a very small area of the main door.

A refrigerator in which the home-bar is further enlarged, compared to the home-bar refrigerator, may be referred to as the DID refrigerator.

However, the home-bar refrigerator and the DID refrigerator both have the same problem in that the volume of the sub storage compartment and the amount of objects stored in the sub storage compartment are increased. In other words, it takes a considerable time to open the sub door or the home-bar door and find an object to be taken out, which is inconvenient for the user and increases energy consumption.

<CIT> discloses a refrigerator including a door with a transmittance varying panel.

<CIT>discloses a refrigerator including a microphone element.

<CIT> relates to a refrigerator having a door which in one embodiment includes a liquid crystal dimming glass.

<CIT> discloses a door for a refrigerator.

Further relevant prior art document is <CIT>.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, which is equipped with a door for opening and closing a storage compartment, which is at least partially transparent so as to make the interior of the storage compartment visible without having to open the door.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, which is equipped with a see-through door which allows light to be transmitted therethrough, that is, a refrigerator equipped with a see-through door which allows the interior of a storage compartment behind the door to be visible through the door from the outside.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, which is equipped with a door capable of being selectively converted into a see-through door, that is, a refrigerator equipped with a door that normally does not allow a storage compartment to be visible through the door, but only allows the storage compartment to be visible when required by a user.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, which is constructed to enable a user to easily apply input for conversion into a see-through door and to reduce input error, recognition error, malfunctions, or the like, that is, a refrigerator capable of improving the recognition rate so as to correctly recognize user input.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, which is capable of efficiently detecting a user's tapping, that is, a knock input for conversion into a see-through door, thus making it easy to use.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, which is capable of efficiently detecting a user's tapping even if the position (knock input position) at which the user taps is spaced apart from the position (knock detecting position) at which the tapping is detected.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, in which the area of a door on which a user taps is expanded to the entire front surface of the door by employing the transmission of sound waves through a medium.

According to the present invention, there is provided a refrigerato in accordance with claim <NUM>, which is able to efficiently detect a knock input and is simplified in structure by eliminating expensive devices such as touch panels.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, which ensures reliable thermal insulation performance and stability and is easily fabricated.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, which is equipped with a door which normally operates as an opaque door but serves as a see-through door by activating a lighting device when required by a user, thus reducing the energy consumption required for conversion into a see-through door.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, in which the entire see-through area of a door is used as the knock input area and a sensor for detecting a knock input is mounted on an area other than a see-through area so as to prevent the sensor from interfering with the see-through area, thus providing an aesthetically pleasing appearance.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, in which a sensor for detecting a knock input is mounted on and in closed contact with a panel to which a knock input is applied so as to efficiently detect a knock input and prevent false detection caused by disturbances.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, in which the sensor detects a sound wave caused by a knock input and is in close contact with the panel with a hermetical space therebetween, thereby efficiently detecting a knock input and preventing false detection caused by external noises.

According to the present invention, there is provided a refrigerator in accordance with claim <NUM>, which has a structure capable of keeping a sensor, for detecting user input for conversion into a see-through door, in continuous close contact with a medium, thereby improving the durability and reliability of the action of the refrigerator relating to the see-through door.

<FIG> show embodiments being useful for understanding the invention, which are outside the subject-matter of the claims. <FIG> show embodiments according to the present invention, which disclose a refrigerator according to claim <NUM>.

The embodiments of the present invention are not limited to the above-mentioned type refrigerators.

Since a home-bar door is also hingedly coupled to the main door, such a home-bar door may be alternatively referred to as a sub door.

<FIG> are views showing a refrigerator according to an embodiment.

The refrigerator shown in the drawings is a bottom-freezer type refrigerator in which a refrigerating compartment is provided at an upper position of a cabinet <NUM> and a freezing compartment is provided at a lower position of the cabinet <NUM>. The refrigerating compartment or the freezing compartment may be considered part of the storage compartment or the main storage compartment <NUM> defined in the cabinet <NUM>.

As described above, the present invention is not limited to this type of refrigerator. The present invention may be applied to any type of refrigerator as long as the refrigerator includes a door for opening and closing the storage compartment.

In the embodiment shown in the drawings, a left refrigerating compartment door <NUM> and a right refrigerating compartment door <NUM>, which serve as doors for opening and closing the refrigerating compartment, are hingedly coupled to the left side and the right side of the cabinet <NUM>. Alternatively, a single refrigerating compartment door may be hingedly coupled to the cabinet <NUM>.

The left refrigerating compartment door <NUM> is an opaque door including a handle groove provided at the lower end thereof. In contrast, the right refrigerating compartment door <NUM> selectively becomes transparent such that a user can see the interior through the door <NUM>. In other words, the right refrigerating compartment door <NUM> may be embodied as a see-through door.

Freezing compartment doors, which are provided under the refrigerating compartment door, may also include a left freezing compartment door <NUM> and a right freezing compartment door <NUM>, which are hingedly coupled to respective sides of the lower portion of the front surface of the cabinet <NUM>. Alternatively, a single freezing compartment door may be hingedly coupled to the cabinet <NUM>, or a drawer type door may be mounted in the cabinet <NUM> so as to be pulled forward from the cabinet <NUM> and pushed rearward into the cabinet <NUM>.

The left freezing compartment door <NUM> may be provided at the upper surface thereof with a handle groove <NUM>, and the right freezing compartment door <NUM> may also be provided at the upper surface thereof with a handle groove.

Referring to <FIG>, an embodiment in which some of the doors are embodied as see-through doors is shown. However, any door, which can be provided at a refrigerator, may be embodied as a see-through door, regardless of whether it opens and closes a refrigerating compartment or a freezing compartment, and regardless of whether it opens and closes a main storage compartment or a sub storage compartment.

As shown in <FIG>, the right refrigerating compartment door <NUM> may include a main door <NUM>, hingedly coupled to one side of the cabinet <NUM> by means of a main door hinge <NUM>, and a sub door <NUM>, hingedly coupled to the main door <NUM> or the cabinet <NUM> by means of a sub door hinge <NUM>. In other words, the refrigerating compartment may be accessed by opening both the main door <NUM> and the sub door <NUM>.

The main door <NUM> may be provided at the center with an opening, and may be provided at the back surface thereof with a sub storage compartment (not shown).

Accordingly, when the sub door <NUM> is opened, the sub storage compartment may be accessed through the opening in the main door <NUM>. In other words, a user can access the sub storage compartment by opening only the sub door <NUM> without having to open the main door <NUM>.

The sub storage compartment may be defined by a plurality of baskets (not shown) installed at different levels. Specifically, a cover (not shown) adapted to surround the plurality of baskets may be provided. The cover may serve as a partition wall for isolating the sub storage compartment and the main storage compartment from each other. Accordingly, the sub storage compartment may be positioned in front of the main storage compartment.

As shown in <FIG>, a plurality of mounting protrusions <NUM> for mounting a plurality of baskets (not shown) may be provided at rear regions of the inner surfaces of the opening <NUM> in the main door <NUM>. The plurality of baskets may be two or three baskets, which are vertically spaced apart from each other by predetermined distances. Accordingly, a user can access the sub storage compartment by opening the sub door <NUM> while leaving the main door <NUM> closed. When the sub door <NUM> is opened together with the main door <NUM>, the sub storage compartment <NUM> is, of course, rotated together with the main door <NUM>. Therefore, a user can access the main storage compartment provided behind the sub storage compartment <NUM>.

Since the relationship between the main door and the sub door and the relationship between the main storage compartment and the sub storage compartment are common in a DID refrigerator, descriptions thereof are omitted.

The sub door <NUM> is internally provided with a panel assembly <NUM> that selectively becomes transparent. Although the panel assembly may be constituted by a single panel, the panel assembly is preferably constituted by a plurality of panels. The panel assembly <NUM> may be selectively changed into a see-through panel assembly, and, as such, a user can see the internal space behind the door through the panel assembly <NUM>.

When the main door <NUM> and the sub door <NUM> are integrally formed into a single door, unlike the construction shown in the drawings, a user can see the main storage compartment through the panel assembly <NUM>. In this case, the main door <NUM> may be just the cabinet <NUM>, and the sub door <NUM> may be considered the door for opening and closing the storage compartment. In other words, the opening formed in the main door <NUM> may be considered to be an opening formed in the cabinet <NUM>.

As shown in <FIG>, the sub door <NUM> may be provided with a groove-shaped handle <NUM> formed at the left side of the panel assembly <NUM>. The handle <NUM> may be vertically elongated and may be the same length as the panel assembly <NUM>. The sub door <NUM> may, of course, be the left sub door provided at the left side of the cabinet <NUM>. In this case, the handle <NUM> may be positioned at the opposite side.

The sub door <NUM> may be rotated in the same direction as the main door <NUM>. Specifically, the main door <NUM> and the sub door <NUM> may be rotated about a vertical rotating shaft, as shown in <FIG>. However, the sub door <NUM> may be configured to be rotated about a horizontal rotating shaft like a home-bar.

Generally, the cabinet of the refrigerator is provided at the front surface thereof with a door switch (not shown) for detecting opening in the door, and the storage compartment is provided therein with a lighting device (not shown) for illuminating the interior of the storage compartment when the door is opened.

According to the embodiment, the door is preferably changed into a see-through door by activation of the lighting device. Specifically, the door is preferably changed into a see-through door by the lighting device provided in the main storage compartment and/or the sub storage compartment such that the interior of the storage compartment becomes visible from the outside.

More specifically, it is preferable that the interior of the storage compartment become invisible upon deactivation of the lighting device and become visible upon activation of the lighting device. The interior of a room is not made clearly visible through a window glass by a bright outside. However, when the interior of the room is illuminated with a bright light, the interior of the room is clearly visible through the window glass. The see-through door utilizes this principle. The conversion of the see-through door is preferably performed by input of a user's command. Specifically, the door is preferably changed into a see-through door when a specific command is input to the refrigerator by a user.

The control process and control architecture associated with the conversion of the see-through door will be described later.

The specific construction of the sub door <NUM> is described with reference to <FIG>. As described above, the sub door <NUM> may be simply the main door for opening and closing the storage compartment. As shown in <FIG>, if the sub door is hingedly coupled to the main door or the cabinet, the sub door <NUM> may be superimposed on the main door <NUM>. In other words, the entire area of the sub door <NUM> may overlap the entire area of the main door <NUM>. At this point, the entire area of the main door <NUM> is covered by the entire area of the sub door <NUM>. Accordingly, since the main door <NUM> is shielded by the sub door <NUM>, the sub door <NUM> defines the appearance of the front face of the refrigerator.

The sub door <NUM> includes a door frame <NUM> having a central opening <NUM>. The door frame <NUM> constitutes the peripheral portion or the marginal portion of the sub door <NUM>. In other words, the door frame <NUM> constitutes upper and lower marginal portions and both lateral side marginal portions of the sub door <NUM>.

Specifically, the door frame <NUM> may include an outer door <NUM> constituting the marginal portion of the front face of the door and a door liner <NUM> constituting the marginal portion of the rear face of the door. The outer door <NUM> and the door liner <NUM> may also be provided with respective openings corresponding to the opening <NUM>.

The door frame <NUM> may include cap decorations <NUM>, which are respectively coupled to the upper ends and lower ends of the outer door <NUM> and the door liner <NUM>. The outer door <NUM>, the door liner <NUM> and the cap decorations <NUM> may constitute a door having a predetermined thickness and an internal space.

In conventional refrigerators, the internal space defined between the outer door <NUM>, the door liner <NUM> and the cap decorations <NUM> is typically filled with foamed material for thermal insulation. The door according to the embodiment, particularly the sub door <NUM>, preferably further includes the panel assembly <NUM> in addition to the door frame <NUM>. Preferably, further provided is a panel assembly <NUM> adapted to be converted into a see-through door. As described hereinafter, the panel assembly <NUM> is preferably constructed to have a thermal insulation function.

The panel assembly <NUM> is preferably provided at the central portion of the sub door <NUM>. Particularly, the panel assembly <NUM> is preferably configured to correspond to the opening in the door frame <NUM>.

In order to mount the panel assembly <NUM>, the door frame <NUM> may further include an inner frame <NUM> interposed between the outer door <NUM> and the door liner <NUM>. The inner frame <NUM> may also be provided at the center area thereof with an opening corresponding to the opening <NUM> in the door frame <NUM>.

The door frame <NUM> may further include a door decoration <NUM>. The door decoration <NUM> may be mounted on the peripheral area of the opening in the door frame <NUM> so as to substantially define the opening <NUM> in the door frame <NUM>.

The sub door <NUM> may further include an upper hinge bracket <NUM> and a lower hinge bracket <NUM> in addition to the panel assembly <NUM> so as to make the sub door <NUM> rotatable. The sub door <NUM> may include a handle <NUM>, which enables a user to open and close the sub door <NUM> while grasping the sub door <NUM>. The sub door <NUM> may further include a support <NUM>.

Hereinafter, the process of assembling the sub door <NUM> will be described with reference to <FIG>.

The outer door <NUM> is first assembled with the door decoration <NUM>, and the handle <NUM> is then coupled to the assembly. A handle support <NUM> may be interposed between the handle <NUM> and the outer door <NUM> or the door decoration <NUM>. The handle support <NUM> may be constituted by a metal rod so as to reinforce the rigidity of the handle <NUM>. The door decoration <NUM> may be coupled to the rear surface of the outer door <NUM>. In the embodiment, the handle <NUM> may be coupled to the left end of the outer door <NUM> when viewed in <FIG>.

Subsequently, the inner frame <NUM> is assembled with the rear surface of the outer door <NUM>, and the supports <NUM> are assembled with the hinge brackets <NUM> and <NUM>.

The supports <NUM> are provided at upper and lower ends of the panel assembly <NUM>, and the supports <NUM> may be provided to correspond to the four corners of the opening <NUM>. The supports <NUM> are provided to correspond to the four corners of the panel assembly <NUM> so as to protect the panel assembly <NUM>. In other words, the supports <NUM> support the panel assembly <NUM> such that the weight of the panel assembly <NUM> is uniformly distributed to the door frame <NUM>.

The supports <NUM> are assembled with the hinge brackets <NUM> and <NUM>. Accordingly, the supports <NUM> further serve to reinforce the strength of the hinge regions.

Thereafter, the cap decorations <NUM> are coupled to the outer door <NUM> from the rear. The cap decorations <NUM> may be coupled to the outer door <NUM> by being respectively fitted on the upper and lower ends of the outer door <NUM>.

Subsequently, the panel assembly <NUM> may be coupled to the outer door <NUM> from the rear, and the door liner <NUM> may be coupled to the outer door <NUM> from the rear. Specifically, the door liner <NUM> may be securely coupled to the outer door <NUM> by means of screws.

Finally, a gasket <NUM> is mounted on the rear surface of the door liner <NUM>, thus completing the assembly of the sub door <NUM>.

The upper hinge bracket <NUM> and the lower hinge bracket <NUM> may be provided with respective sub door hinges <NUM> coupled thereto. When the sub door <NUM> is closed with respect to the main door <NUM>, the gasket <NUM> serves to seal the clearance therebetween, thus preventing the leakage of cold air through the clearance.

As shown in <FIG>, the panel assembly <NUM> may include a front panel <NUM>, which is exposed from the front surface of the sub door <NUM>. The front panel <NUM> may be made of a transparent material, and its rear surface may have a metal vapor-deposited thereon. The deposited metal layer may function to make the front panel <NUM> opaque when light is not transmitted therethrough and make the front panel <NUM> transparent when light is transmitted therethrough.

Of course, the front panel <NUM> may include a color coating film, or may be constituted by a color panel. Specifically, although the front panel <NUM> is opaque under low-intensity light conditions, the front panel <NUM> may become transparent under relatively high-intensity light conditions.

This means that the front panel <NUM> is opaque when the lighting device behind the front panel <NUM> is deactivated, and is converted into a transparent panel, that is, a see-through door, when the lighting device is activated. Accordingly, although the interior of the storage compartment becomes invisible when the interior is dark, the interior of the storage compartment becomes visible through the front panel <NUM> when the interior is bright.

The panel assembly <NUM> may include a thermal insulation panel provided behind the front panel <NUM>. The thermal insulation panel may include a plurality of thermal insulation panels. <FIG> shows an example in which two thermal insulation panels <NUM> and <NUM> are provided. A spacer rod <NUM> may be disposed between the front panel <NUM> and the thermal insulation panel <NUM>.

The front panel <NUM>, which is made of a transparent material, is mounted at the central opening in the sub door <NUM> so as to constitute the front surface of the sub door <NUM>.

The internal space defined in the door frame <NUM> of the sub door <NUM> excluding the panel assembly <NUM> is preferably filled with a thermal insulation material. Specifically, the space between the outer door <NUM> and the door liner <NUM>, that is, the space <NUM> provided at the marginal portion of the sub door <NUM>, may be filled with a thermal insulation material so as to prevent cold air from leaking between the gasket <NUM> and the panel assembly <NUM>.

Accordingly, the marginal portion of the sub door <NUM> is thermally insulated by the thermal insulation material, for example, polyurethane, and the central portion of the sub door <NUM> is thermally insulated by the thermal insulation panels <NUM> and <NUM>.

The space <NUM> is filled with the foamed material after the sub door <NUM> is completely assembled, thus implementing secure coupling between the outer door <NUM> and the door liner <NUM>.

The structure and the process of fabricating the panel assembly <NUM> will be described in detail later.

As shown in <FIG> and <FIG>, a right refrigerating compartment door <NUM> of the refrigerator according to an embodiment includes a main door <NUM>, which is hingedly coupled to the cabinet <NUM> and has therein a central opening, and a sub door <NUM>, fitted in the opening in the main door <NUM> and hingedly coupled thereto.

In the refrigerator according to the previous embodiment, the main door and the sub door are the same size when viewed from the front, and the sub door overlaps the main door when the sub door is closed.

In contrast, in the refrigerator according to this embodiment, the sub door <NUM> is configured to have a smaller size than that of the main door <NUM>, and is fitted into the opening <NUM> in the main door <NUM> when the sub door <NUM> is closed.

Specifically, in the previous embodiment, the sub door <NUM> is exposed to the front of the main door <NUM> when the sub door <NUM> is closed with respect to the main door <NUM>. In the second embodiment, the sub door <NUM> is fitted in the main door <NUM> when the sub door <NUM> is closed with respect to the main door <NUM>. The former may be referred to as an outside type sub door, and the latter may be referred to as an inside type sub door.

Likewise in this embodiment, the main door <NUM> may simply be the cabinet. In this case, the sub door <NUM> may be considered to be a door for opening and closing the storage compartment <NUM>.

As shown in <FIG>, the main door <NUM> may be provided at the center thereof with an opening <NUM>, and may be provided at the rear surface thereof with a sub storage compartment <NUM>. In other words, the main door <NUM> may be provided with an opening <NUM> into which the sub door <NUM> is fitted and the opening <NUM> for allowing access to the sub storage compartment <NUM>. A stepped portion is defined between the two openings <NUM> and <NUM>. In other words, the opening <NUM> for allowing access to the sub storage compartment <NUM> may be positioned inside the opening <NUM> in the radial direction into which the sub door <NUM> is fitted.

When the sub door <NUM> is opened, it is possible to access the sub storage compartment <NUM> through the opening <NUM> in the main door <NUM>. That is to say, the sub storage compartment <NUM> may be accessed by opening only the sub door <NUM>, without having to open the main door <NUM>.

As shown in <FIG>, a plurality of mounting protrusions <NUM> for mounting a plurality of baskets (not shown) may be provided at rear regions of the inner surfaces of the opening <NUM> in the main door <NUM>. The plurality of baskets may be two or three baskets, which are vertically spaced apart from each other by predetermined distances. Accordingly, a user can access the sub storage compartment <NUM> by opening the sub door <NUM> while leaving the main door <NUM> closed, as shown in <FIG>.

The sub door <NUM> is internally provided with a panel assembly <NUM> that selectively becomes transparent. Although the panel assembly may be constituted by a single panel, the panel assembly is preferably constituted by a plurality of panels as described hereinafter. The panel assembly <NUM> may be selectively changed into a see-through panel assembly, and as such, a user can see the internal space behind the door through the panel assembly <NUM>.

More specifically, the sub storage compartment <NUM> is visible through the panel assembly provided at the opening <NUM> of the sub door <NUM> and the opening <NUM> provided in the main door <NUM>. It is possible to see the interior of the sub storage compartment <NUM> even in the state in which the sub door <NUM> is closed, and it is possible to easily perceive where a specific object is positioned in the sub storage compartment <NUM>. Thereafter, a user can easily take a desired object out of the sub storage compartment <NUM> by opening the sub door <NUM>.

For example, assuming that <NUM> similar objects are stored in the sub storage compartment <NUM> in a <NUM> x <NUM> matrix, a somewhat long period of time may be required to open the sub door <NUM>, find a desired specific object among the <NUM> similar objects and take the desired object out of the sub storage compartment <NUM>. However, in the case where the <NUM> similar objects are visible from the outside, there is no need to take time to find and select the specific object. Specifically, since a user has already seen the position of the specific object, the user can quickly take out the specific object after merely opening the sub door <NUM>. Therefore, it is possible to minimize the loss of cold air and to improve the user's convenience.

Hereinafter, the structure of the sub door <NUM> will be described in detail with reference to <FIG> and <FIG>.

The sub door <NUM> according to this embodiment includes a door frame <NUM> having a central opening <NUM>.

The door frame <NUM> may include an inner frame <NUM> constituting the marginal region of the rear side of the sub door <NUM>, and a door liner <NUM>, coupled to the inner frame <NUM> to constitute the marginal region of the rear surface of the sub door <NUM>.

Unlike the first embodiment, the inner frame <NUM> and the door liner <NUM> may be integrally formed with portions corresponding to cap decorations provided at the upper and lower ends thereof without providing separate cap decorations.

Supports <NUM> may be respectively disposed between upper ends of the inner frame <NUM> and the door liner <NUM> and between the lower ends of the inner frame <NUM> and the door liner <NUM>.

An upper hinge bracket <NUM> and a lower hinge bracket <NUM> may be respectively coupled to one side of the upper support <NUM> and one side of the lower support <NUM>. Sub door hinges may be respectively coupled to the upper hinge bracket <NUM> and the lower hinge bracket <NUM>.

Unlike the construction shown in the drawings, the cap decorations may be respectively coupled to upper ends and lower ends of the inner frame <NUM> and the door liner <NUM>, and upper and lower hinges (not shown) may be directly coupled to the cap decorations.

The door liner <NUM> may be provided at the rear surface thereof with a groove in which a gasket <NUM> is fitted. When the sub door <NUM> is closed with respect to the main door <NUM>, the gasket <NUM> serves to seal the clearance between the sub door <NUM> and the main door <NUM>, thus preventing the leakage of cold air. Specifically, the gasket <NUM> may be disposed at the position between the two openings <NUM> and <NUM>.

As shown in <FIG> and <FIG>, the panel assembly <NUM> of the sub door <NUM> according to an embodiment is coupled to the front surface of the sub door <NUM>. Specifically, the panel assembly <NUM> may be coupled to the inner frame <NUM> from the front.

The panel assembly <NUM> may be identical or similar to the panel assembly of the previous embodiment. However, the front panel <NUM> of the panel assembly <NUM> according to this embodiment is distinguished from the first embodiment in that the front panel <NUM> is not covered at the marginal area thereof with the outer door <NUM> but is coupled to the front surface of the inner frame <NUM> having the opening.

In the previous embodiment, the marginal region of the front surface of the sub door <NUM> is constituted by the outer door <NUM> and the central region of the front surface of the sub door <NUM> is constituted by the front panel <NUM>. According to this embodiment, the front surface of the sub door <NUM> is preferably constituted by the front panel <NUM>. In other words, the marginal region and the central region of the front surface of the sub door <NUM> are preferably constituted by the front panel <NUM>.

To this end, the front panel <NUM> is preferably configured to be larger than the plurality of thermal insulation panels <NUM> and <NUM>. That is, the front panel <NUM> preferably not only covers the entire area of the thermal insulation panels but also extends outward beyond the boundary of the entire area.

The plurality of thermal insulation panels <NUM> and <NUM> may be fitted on the inner surface of the opening in the inner frame <NUM>, that is, on the inner surface of the opening <NUM>, and the rear surface of the second thermal insulation panel <NUM> may be supported by the door liner <NUM>.

A rectangular spacer rod <NUM> may be interposed between the front panel <NUM> and the first thermal insulation panel <NUM> so as to maintain a predetermined spacing therebetween.

A handle may be coupled to the left side of the inner frame <NUM> and the door liner <NUM>, which are coupled to each other.

For the purpose of coupling between the inner frame <NUM> and the handle <NUM>, the left side surface of the inner frame <NUM> may be provided with a pair of catch ribs <NUM>, which engage with a pair of fitting ribs <NUM> vertically formed on the right side surface of the handle <NUM>.

The pair of catch ribs <NUM> may be configured in such a manner as to laterally project from the left side surface of the inner frame <NUM> and then be respectively bent forward and rearward.

In order to match the catch ribs <NUM>, the pair of fitting ribs <NUM> may be configured to be laterally projected from the right side surface of the handle <NUM> and then be respectively bent forward and rearward.

As a consequence of coupling between the inner frame <NUM> and the door liner <NUM>, a predetermined space <NUM> is defined in the marginal portion of the sub door <NUM>. The space <NUM> may also be defined by coupling the cap decorations to the inner frame <NUM> and the door liner <NUM>. In other words, the space <NUM> is defined in the upper and lower marginal portions and both lateral side portions of the sub door <NUM>. The space may be referred to as a filling space that is filled with a thermal insulation material.

Accordingly, the marginal portion of the sub door <NUM> may be thermally insulated by the thermal insulation material, and the central portion of the sub door <NUM> may be thermally insulated by the panel assembly <NUM>.

The region of the front panel <NUM> that is positioned outside the thermal insulation panel in the radial direction may be in close contact with the inner frame <NUM>. The region of the front panel <NUM> may also be in close contact with the cap decorations. The latter is the case where the upper and lower portions of the inner frame are constituted by separate cap decorations.

After the handle <NUM> is coupled to the inner frame <NUM>, the cap decorations may be coupled to the inner frame <NUM> if necessary. Subsequently, the panel assembly <NUM> may come into close contact with the inner frame <NUM> from the front. At this point, the inner frame <NUM> and the panel assembly <NUM> may be temporarily coupled to each other by disposing a piece of transparent adhesive tape or a transparent adhesive therebetween. Specifically, the transparent adhesive tape may be disposed between the inner frame <NUM> and the rear surface of the marginal region of the front panel <NUM> (i.e. the marginal region positioned outside the thermal insulation panel in the radial direction).

After the panel assembly <NUM> is temporarily coupled to the inner frame <NUM>, the door liner <NUM> may be coupled to the inner frame <NUM> from the rear position of the inner frame <NUM>. Thereafter, the space <NUM> is filled with a foamed material, with the result that the panel assembly <NUM> is closely coupled to the door frame <NUM>.

Hereinafter, the structure and the process of fabricating the panel assembly will be described with reference to <FIG>.

<FIG> is a schematic view of the panel assembly <NUM> according to an embodiment.

The front panel <NUM> is the same size as the thermal insulation panels <NUM> and <NUM>.

The front panel <NUM> is preferably made of thermally hardened glass that is enhanced in strength by being heated to about <NUM> to <NUM>.

In the thermal hardening process, the glass may be heated above the glass-transition temperature (Tg) and may then be rapidly cooled so as to create compression stress due to the difference in shrinkage between the inner portion and the outer portion of the glass.

The depth of the compression stress in the thermal hardening process is about <NUM>% of the overall thickness of the glass.

The rear surface of the front panel <NUM> may be vapor-deposited with metal, such as titanium or nickel, so as to create a deposited layer <NUM>. When the lighting device in the storage compartment is activated, the deposited layer <NUM> may allow the light emitted from the lighting device to be transmitted to the outside through the front panel <NUM>, thus making the interior of the storage compartment visible. Meanwhile, when the lighting device is deactivated, the deposited layer shields the interior of the storage compartment, thus making the interior of the storage compartment invisible. Of course, the front panel <NUM> may be made of glass, or may be provided thereon with a color coating layer.

Accordingly, it is preferable that the front panel <NUM> be converted into a see-through panel when light is transmitted therethrough and be converted into an opaque panel when light is not transmitted therethrough. It is further preferable that the front panel <NUM> enable light to be elegantly transmitted therethrough, unlike general window glass. Thanks to this effect, the atmosphere of the room in which the refrigerator is positioned may be made more elegant.

The first thermal insulation panel <NUM> and the second thermal insulation panel <NUM> are preferably made of chemically strengthened glass that was produced by soaking the glass in electrolyte solution at the glass transition temperature or higher.

In the chemical strengthening process, when glass in an electrolyte solution containing molten salt, such as KNO<NUM>, is heated to a temperature below the glass transition temperature, some of the sodium ions on the glass are replaced with potassium ions, thus creating compression stress caused by the difference between the ionic radii.

In the chemical strengthening process, the depth of compression stress may be about <NUM> to <NUM>% of the overall thickness of the glass.

The rear surface of the first thermal insulation panel <NUM> may be provided with a low-emissivity coating layer <NUM> for reducing radiative heat transfer to the inside of the storage compartment.

Glass equipped with such a low-emissivity coating layer <NUM> is referred to as a low-ε glass. The low-emissivity coating layer <NUM> is typically created by depositing the surface of glass with silver or the like through sputtering.

A vacuum space may be defined between the first thermal insulation panel <NUM> and the second thermal insulation panel <NUM>. To this end, the first thermal insulation panel <NUM> includes a hole <NUM> through which vacuum pumping is executed.

The hole <NUM> is plugged with a plug <NUM>. The plug <NUM> is inserted into the hole <NUM> so as to plug the hole <NUM> after completion of the vacuum pumping.

The process of coupling the first thermal insulation panel <NUM> and the second thermal insulation panel <NUM> and forming the vacuum space therebetween will now be described.

Frit glass <NUM> is first dispensed onto the marginal area of the second thermal insulation panel <NUM>. Frit glass <NUM> is a glass raw material composed of glass powder having a melting point of about <NUM>-<NUM>, a binder, and the like. The frit glass <NUM> has a melting point lower than the first and second thermal insulation panels <NUM> and <NUM>.

After the frit glass <NUM> is arranged along the marginal area of the front surface of the second thermal insulation panel <NUM>, the first thermal insulation panel <NUM> is placed thereon. Thereafter, the frit glass <NUM> is melted and then solidified, thus coupling the first and second thermal insulation panels to each other.

Prior to placing the first thermal insulation panel <NUM> after the frit glass <NUM> is arranged, a plurality of spacers <NUM> are arranged on the second thermal insulation panel <NUM>.

Since there is a limit to which the thickness and strength of the thermal insulation panel, which is made of glass, can be increased, the plurality of spacers <NUM> serves to support the center area of the thermal insulation panel so as to prevent the center area from drooping.

The spacers <NUM> may be made of stainless steel, glass, plastic, or the like. The spacers <NUM> are preferably made of a material capable of supporting the first thermal insulation panel <NUM> and the second thermal insulation panel <NUM> in the state of maintaining a predetermined spacing therebetween and of almost completely eliminating conductive heat transfer.

After the first thermal insulation panel <NUM> is coupled to the second thermal insulation panel <NUM>, vacuum pumping is executed through the hole <NUM> to create a vacuum between the first thermal insulation panel <NUM> and the second thermal insulation panel <NUM>.

After the vacuum pumping, the hole <NUM> is plugged with the plug <NUM>. The plug <NUM> may be covered by frit glass <NUM>. In this case, the plug <NUM> may not protrude from the surface of the first thermal insulation panel <NUM>, and the frit glass <NUM> may be slightly convex from the surface of the first thermal insulation panel <NUM>.

The frit glass <NUM> may have a lower melting point than the frit glass <NUM> disposed between the first and second thermal insulation panels <NUM> and <NUM>.

After the operation of coupling the first and second thermal insulation panels <NUM> and <NUM> to each other and of performing the vacuum pumping and the sealing is complted, the rectangular spacer rod <NUM> having a predetermined thickness is placed on the front surface of the first thermal insulation panel <NUM>, and the front panel <NUM> is attached thereto.

The spacer rod <NUM>, the first thermal insulation panel <NUM> and the front panel <NUM> are attached to each other by means of a transparent adhesive applied therebetween.

As shown in <FIG>, the panel assembly <NUM>, which has been prepared in this way, is disposed between the outer door <NUM> and the door liner <NUM>, and the outer door <NUM> and the door liner <NUM> are coupled to each other, thus completing fabrication of the sub door <NUM>.

The panel assembly <NUM> may be attached to the front surface of the inner frame <NUM> using a transparent adhesive. At this point, the first and second thermal insulation panels <NUM> and <NUM> are disposed in the opening in the inner frame <NUM>, and the marginal area of the front panel <NUM> is attached to the front surface of the inner frame <NUM>.

The thermal insulation panel is composed of a plurality of glass panels, which are provided therebetween with the space for hindering heat transfer therebetween. Furthermore, since the glass panels are made of low-emissivity coating glass, it is possible to minimize heat transmitted through the panel assembly <NUM>.

<FIG> is a graph illustrating the variation in temperatur of two thermal insulation panels when a vacuum insulation space is created between the two thermal insulation panels using vacuum-pumping technology. <FIG> is a graph illustrating the variation in temperature of two thermal insulation panels when a vacuum insulation space is created between the two thermal insulation panels using vacuum-chamber technology.

In the vacuum-pumping technology shown in <FIG>, when the frit glass <NUM> is heated for welding in a heating apparatus, the frit glass <NUM> may be heated to about <NUM>.

The welding operation is indicated by character "A" in <FIG>. In the welding operation, the frit glass <NUM> is heated to about <NUM> from the ambient temperature, i.e. <NUM>, for about <NUM> minutes. The heating temperature is set to be the melting point of the frit glass <NUM> or higher, and may be heated to a temperature range of <NUM>-<NUM> depending on the kind of frit glass.

The welding operation is maintained at about <NUM> for about <NUM> minutes, and the temperature is then lowered to about <NUM> for about <NUM> minutes.

The operation of creating the vacuum and sealing, which is indicated by character "B", may be performed at about <NUM><NUM>.

The operation of creating the vacuum and sealing may be performed for about <NUM> hours with maintenance of the temperature is maintained at about <NUM>.

The operation of creating the vacuum and sealing is performed in such a way as to connect a pipe of a vacuum-pumping device to the hole <NUM> so as to execute vacuum pumping, plug the hole <NUM> with the plug <NUM>, and seal the hole by welding the frit glass <NUM>.

The temperature of <NUM> is determined in consideration of the melting point of the frit glass <NUM>, and the operation of creating the vacuum and sealing may be carried out at a temperature range of <NUM>-<NUM> depending on the kind of frit glass <NUM>.

The pipe of the vacuum-pumping device may be cut after vacuum pumping such that the end portion of the pipe fitted in the hole <NUM> serves as the plug <NUM>.

Subsequently, the spacer rod <NUM> is placed on the front surface of the first thermal insulation panel <NUM>, and the front panel <NUM> is attached to the spacer rod <NUM> using a transparent adhesive.

The outer circumferential surfaces of the first thermal insulation panel <NUM>, the frit glass <NUM>, the second thermal insulation panel <NUM>, the spacer rod <NUM> and the front panel <NUM> may be sealed using a sealant.

Thereafter, in the operation indicated by character "C" in <FIG>, the components may be cooled to <NUM> from <NUM> in about <NUM> hours, thus completing fabrication of the panel assembly <NUM>.

Meanwhile, the vacuum chamber technology illustrated in <FIG>, which is configured to fabricate the panel assembly in a vacuum chamber, includes (<NUM>) a vacuum heating operation, (<NUM>) a vacuum welding operation, (<NUM>) a first cooling operation, (<NUM>) a capping operation, and (<NUM>) a second cooling operation.

In the vacuum heating operation (<NUM>), the frit glass <NUM> is dispensed to the marginal area of the first thermal insulation panel <NUM> disposed in a vacuum chamber, and the plurality of spacers <NUM> are arranged thereon. The second thermal insulation panel <NUM> is placed thereon. The air in the vacuum chamber is removed to create a vacuum in the chamber. Subsequently, the vacuum chamber is heated to about <NUM> in about <NUM> minutes to raise the internal temperature in the vacuum chamber.

In the vacuum welding operation (<NUM>), the internal temperature in the vacuum chamber is maintained at about <NUM> for <NUM> minutes such that the frit glass <NUM> is melted so as to weld the second thermal insulation panel <NUM> to the first thermal insulation panel <NUM>.

In the first cooling operation (<NUM>), the resulting components are cooled to about <NUM> from about <NUM> in <NUM> hour.

In the capping operation (<NUM>), the hole <NUM> is plugged with the plug <NUM>, and the clearance between the hole <NUM> and the plug <NUM> is completely sealed with the frit glass <NUM>.

In the second cooling operation (<NUM>), the resulting components are gradually cooled to the ambient temperature from about <NUM> for about <NUM> hours, thus completing the fabrication of the panel assembly <NUM>.

A comparison between the two technologies for creating a vacuum will now be made below.

Although the vacuum-pumping technology is easily applied to the present invention because the technology has generally been used in creating vacuums, the technology has a disadvantage of leaving a cut end of a pipe after the creation of the vacuum. Hence, the hole must be formed at a position that is invisible from the outside of the sub door.

Since the panel assembly according to the embodiments of the present invention is made of transparent glass, it should be noted that the cut end must be invisible. Accordingly, the positioning of the hole is extremely restrictive, and it may be required to provide an additional part for shielding the hole.

In the vacuum chamber technology, since the work of assembling the components is carried out in a vacuum chamber, the vacuum chamber must be sufficiently large to accommodate both the front panel and the thermal insulation panel.

Meanwhile, since the assembly work is carried out in the vacuum chamber, the cut pipe is not left in the hole after completion of the assembly, and the hole may be easily sealed. However, since the hole must be still formed in the transparent thermal insulation panel, it may be required to provide an additional part for shielding the hole.

The vacuum space of the panel assembly <NUM> and <NUM> provides a remarkable effect in terms of thermal insulation performance. However, the panel assembly may make fabrication difficult, and may make the design thereof unpleasant due to the presence of the hole. Accordingly, an inert gas space, which is filled with argon or the like, may be provided in place of the vacuum space. Inert gas has better thermal insulation performance than air. For this reason, it is possible to provide space between the front panel and the thermal insulation panel and between thermal insulation panels, and to fill the spaces with inert gas so as to ensure thermal insulation performance.

As described above, the main door or the sub door according to the embodiments may be selectively converted into a see-through door. Specifically, upon the input of specific command from a user, the main door or the sub door may be converted into a see-through door.

The conversion into a see-through door of a refrigerator according to claim <NUM> is implemented by activating the lighting device <NUM> disposed in the storage compartment. Upon activation of the lighting device <NUM> in the storage compartment, the storage compartment becomes bright. Accordingly, the light in the storage compartment is transmitted to the outside through the door, whereby the interior of the storage compartment becomes visible through the door from the outside.

The refrigerator according to to claim <NUM> includes a sensor for detecting user input for the conversion to a see-through door.

The sensor <NUM> is a sensor for detecting sound waves propagating through a medium. The user input is detected by identifying sound waves, detected by the sensor, as a certain pattern of sound waves.

This indicates that the sensor <NUM> can detect the occurrence of a vibration even when the position at which the sound waves are generated is spaced apart from the position at which the sound waves are detected, as long as the medium is continuous. In other words, considering the entire surface area of the refrigerator door, this indicates that the distance between the sound wave generation position and the sound wave detecting position can be maximally increased as long as the continuity of the medium of the refrigerator door is maintained.

The sound wave generating position may be considered to be the position at which the user input for conversion into a see-through door is applied, and the sound wave detecting position may be considered to be the position at which the user input is detected by the sensor. Therefore, by adoption of the sensor for detecting sound waves, the position and manner in which the user input is applied may be variously changed regardless of what the posture a user assumes or whether a user is holding objects with both hands.

By virtue of the adoption of the sound wave sensor, a user can apply input to the front surface of the door at any position. In this regard, considering the characteristics of sound waves, the same continuous medium is preferably provided between the position at which a specific vibration input is applied and the position at which the vibration input is detected. In other words, it is preferable that sound waves, which are generated by user knock input applied at a certain position, be transmitted to a predetermined position through a consistent medium for detection.

The sensor <NUM> may include a microphone for measuring sound waves substantially transmitted through a medium. Although the medium of the front panel is different from air, sound waves may be efficiently transmitted to a point very far away because of the inherent property of sound waves.

For example, when a person puts his/her ear to a train rail, the person can perceive that there is a running train at a location very far away. This indicates that sound waves are efficiently transmitted a long distance through the train rail, which serves as a medium.

Of course, vibrations of the medium itself rather than sound waves generated by a user knock input may be generated.

However, vibrations of a medium are transmitted through the surface of the medium. That is, the vibrations may be referred to as transverse waves. Accordingly, as the distance between the input position and the detection position in the same medium is increased, the damping width is increased. In contrast, the damping width of sound waves is very small. Accordingly, considering the size of a refrigerator, it is considered more efficient to detect sound waves transmitted through the inside of the medium rather than vibrations transmitted through the surface of the medium.

The sensor for detecting sound waves is intended to detect the transmission of sound waves through the front panel itself. Accordingly, it is possible to obviate the mounting of an additional device, such as a touch panel, to the front panel. This indicates that it is possible to eliminate disadvantages, such as increased cost and complexity and decreased durability, attributable to the addition of a touch panel. Furthermore, this indicates that the knock input area can be substantially extended over the entire area of the front panel.

As described above, the front panel according to this embodiment is preferably constituted as a medium through which a sound wave caused by user input is transmitted. In other words, it is preferable that user input be applied to the front panel, which is exposed from the front face of the door, and that the sound wave transmitted through the front panel be detected by the sensor. The sensor includes a sensor device, particularly a microphone, for detecting the transmission of sound waves through a medium.

When a microphone is used as the sensor device, the sound waves transmitted through the front panel are transmitted to the microphone through the air, which serves as another medium. Accordingly, it may be critical to shield the sound wave transmitting space, located between the front panel and the microphone, from the outside. This is because external noise may be input to the microphone if the space is not shielded. Accordingly, it is critical to keep the microphone module, including the microphone, in close contact with the front panel and to maintain such close contact, as will be described later. Furthermore, it is also critical to continuously apply a force to a support member for supporting the microphone in the contact direction. That is, the support member may also be caused to closely contact the front panel.

Accordingly, the input position can be spaced apart from the detecting position by virtue of transmission through the front panel even if no additional touch panel is provided. Particularly, the damping of sound waves transmitted through a medium is comparatively very small, whereby the spacing distance can be more efficiently increased.

In the embodiments of the present invention, it is preferable that the knock input from a user be applied to the center area of the door, which is convertible into a see-thorough area, and that the sensor for detecting the user input be provided at the marginal area of the door, which is not convertible into a see-through area. Of course, the point to which the knock input is applied and the point at which the vibration is detected are preferably positioned on a single front panel constituted by a continuous medium. Discontinuity of the medium means that variation in the detection value may be higher depending on the position at which knock input is generated even when the same vibration input is applied. Hence, the detection accuracy is inevitably decreased.

Furthermore, this indicates that the danger of determining that input applied to a medium other than the front panel is a normal knock input can be reduced. In other words, this indicates that a malfunction whereby an impact applied not to the front panel but to another portion of a refrigerator, is recognized as normal knock input can be remarkably decreased. This is because the cabinet of a refrigerator is typically constituted by a medium different from that of the front panel.

For this reason, it is strongly preferable that the knock input application point and the knock input detection point be positioned on a single front panel as in the embodiments of the present invention.

The impact applied to other portions of the refrigerator may be the vibration of the refrigerator itself. Any portion of the refrigerator may vibrate due to various causes, such as the vibrations caused by driving of the refrigeration cycle or vibrations caused by external force applied to the refrigerator. At this time, the vibrations of the refrigerator may be transmitted through the front panel, thus influencing the sensor. In other words, when an intensive vibration is generated, the front panel itself inevitably vibrates, even if the two media are different from each other. Accordingly, there may be a circumstance whereby, when vibrations of the medium itself are detected, the vibrations of the refrigerator itself are falsely recognized as normal knock input.

However, it is known that the damping width of sound waves through different, i.e. discontinuous, media is increased. Accordingly, sound waves generated by an impact applied not to the front panel but to another portion of the refrigerator may be sufficiently dampened while being transmitted through the different media. Therefore, when the knock input is recognized by detecting sound waves, the malfunctions caused by impacts or vibrations applied to portions other than the front panel can be remarkably reduced. Specifically, in the case where the microphone for detecting sound waves is used, since the microphone is less sensitive to the vibration of the refrigerator itself, errors whereby the vibration of the refrigerator itself is recognized as normal knock input can be remarkably reduced.

As shown in <FIG>, the refrigerator according to claim <NUM> includes the sensor <NUM> for detecting user input for conversion into the see-through door, a main controller <NUM> and the lighting device <NUM>.

The sensor <NUM> may be provided on the front surface of the door, for example, the front panel <NUM> or <NUM> of the sub door <NUM> or <NUM>, so as to detect the knock input by a user. In other words, the sensor <NUM> may be provided on the front panel so as to detect the knock input that is applied thereto by a user.

When the normal input for conversion into a see-through door is correctly applied by a user, the main controller <NUM> activates the lighting device <NUM>. As a result, the interior of the storage compartment is brightened, whereby the door is converted into a see-through door.

Specifically, the sensor <NUM> may include a second device for detecting input for conversion into the see-through door. In particular, the sensor <NUM> may include a microphone <NUM> as a sensor device for detecting sound waves. In other words, the sensor <NUM> preferably includes the microphone <NUM>, which is configured to detect sound waves transmitted through the inside of a medium rather than detecting the vibration of the medium itself.

The microphone <NUM> may detect not only sound waves caused by a user's knock signal but also sound waves caused by external noise. The latter kind of sound wave or vibration may be referred to simply as "noise". Accordingly, it is necessary to mechanically prevent such noise from being input to the microphone <NUM>.

To this end, the microphone <NUM> is preferably in close contact with the medium. In particular, the microphone <NUM> is preferably in close contact with the front panel <NUM> or <NUM>. Accordingly, a mounting member or support member for causing the microphone <NUM> to closely contact the front panel is required. The concrete embodiments of the member will be described later.

The main controller <NUM> may be considered a main microcomputer adapted to perform general control of a refrigerator, that is, a controller for controlling the driving of a compressor or various fans.

The refrigerator is typically provided with a door switch <NUM>. Therefore, it is possible to determine whether or not the refrigerator door is opened based on the door switch <NUM>. When the door is opened, the door switch <NUM> is switched to the ON state so as to activate the lighting device <NUM> in the storage compartment. When the door is closed, the door switch is switched to the OFF state, whereby the lighting device <NUM> in the storage compartment is deactivated. The ON state and OFF state of the door switch may be reversed with each other. The operation of the door switch <NUM> and the lighting device <NUM> may be implemented independently from the controller <NUM>. Of course, it will also be possible for the controller <NUM> to determine whether the door is open or closed by virtue of the door switch <NUM>, to thus control the lighting device <NUM> depending on the determination.

In this embodiment, the process of controlling the door switch <NUM>, the main controller <NUM> and the lighting device <NUM> may be performed in two ways. The lighting device <NUM> may include a main lighting device <NUM> and a sub lighting device <NUM>.

An operational example in which the main door itself is converted into a see-through door is first described.

For the conversion into a see-through door, the main controller <NUM> operates the lighting device <NUM>, in particular, the main lighting device <NUM>. The conversion into a see-through door is preferably implemented under the assumption that the main door is in a closed state. Accordingly, in response to the determination of input of the normal knock signal, the main controller <NUM> preferably controls the main lighting device <NUM> to operate even if the door switch <NUM> is in an ON state (the door is closed). The main controller <NUM> may control the operation of the main lighting device <NUM> in accordance with the algorithm for conversion into a see-through door as long as the door is not opened. For example, the main controller <NUM> may control the main lighting device such that the brightness of the lighting device is gradually increased. Furthermore, it is possible to control the main lighting device such that the main lighting device stops after the main lighting device has been operating for a predetermined period of time. In other words, it is possible to control the main lighting device so that it turns off after a predetermined period of time has elapsed.

In the case where the door is opened while conversion into a see-through door is maintained, the algorithm may be overridden by the normal control algorithm for the main lighting device <NUM>. In other words, control may be performed such that the main lighting device <NUM> is always operated while the main door is opened. Of course, it may also be controlled such that an alarm is generated and the main lighting device <NUM> is turned off when the door has remained in an open state for an excessively long period of time.

An operational example in which not the main door but the sub door is converted into a see-through door will now be described. In this example, the sub lighting device <NUM> for making the interior of the sub storage compartment bright is preferably provided, in addition to the main lighting device <NUM> for making the storage compartment bright.

Although not shown in the drawings, the sub lighting device <NUM> may include an LED module mounted on one or both inner sides of the opening <NUM> or <NUM> of the main door <NUM> to illuminate the sub storage compartment. The LED module may be constituted by an elongated circuit board and a plurality of LEDs arranged on the circuit board at predetermined intervals.

The LED module is preferably mounted in a groove formed in both inner sides of the opening in the main door <NUM> and is preferably covered by a transparent cover so as to protect the LED module and prevent the entry of moisture or pollutants.

In response to the determination of input of the normal knock signal, the main controller <NUM> may activate the sub lighting device <NUM> to convert the sub door into a see-through door. At this time, the sub lighting device <NUM> is preferably controlled to be operated for a predetermined period of time. If a predetermined time has not elapsed when the sub door is opened by a user, the sub lighting device <NUM> may be controlled to be continuously activated.

If a predetermined time has not elapsed, a user cannot open the main door. In this case, there is no need to maintain the conversion of the sub door into a see-through door. Accordingly, when it is determined that the main door has been opened through the door switch while the sub door is in the state of having been converted into a see-through door, the operation of the sub lighting device <NUM> is preferably controlled to be stopped.

Consequently, unnecessary operation of the lighting device <NUM> may be reduced through control of the relationship between the main controller <NUM>, the lighting device <NUM> and the door switch <NUM>.

The main controller <NUM> determines whether a normal signal for conversion into a see-through door has been input, based on the signal input through the sensor <NUM>.

The main controller <NUM> determines whether the input signal is a normal signal or noise. In this case, an overload may be applied to the main controller <NUM>, and the effect of noise inherent in the signal line itself may be further increased owing to the distance between the sensor <NUM> and the main controller <NUM>.

As described above, the sensor <NUM> is preferably provided on the front panel <NUM> or <NUM>. In most cases, the main controller <NUM> is provided on the cabinet <NUM> rather than the door. Hence, the distance between the sensor <NUM> and the main controller <NUM> is increased, which means that the length of the signal line is increased. This indicates that the normal signal for conversion into a see-through door may be contaminated by the noise inherent in the signal line and before being input to the main controller <NUM>. Therefore, the recognition rate of the signal for conversion into a see-through door is inevitably deteriorated. In particular, in the case where the sensor includes a microphone as a sensor device, it is common for the signal output through the microphone to be on the order of mV whereas the signal input to the main controller <NUM> must be on the order of of V. Hence, it is undesirable for the main controller <NUM> to determine whether the signal is a normal signal for conversion into a see-through door because of the physical difference in magnitude of the signals.

In particular, refrigerators are electronic appliances that consume high voltage and high current. Accordingly, the amount of electrical noises generated by refrigerators is relatively high. This means that the signal on the order of mV, output through the microphone, is more easily affected by such electrical noise.

In order to solve this problem, according to this embodiment, the sensor <NUM> for detecting input for conversion into a see-through door is modularized. In this regard, the modularized sensor is referred to as a sensor module.

The sensor module or knock sensor module, which is denoted by the numeral "<NUM>", may include the microphone <NUM>, as the sensor device, and a modular microcomputer <NUM>. As described above, the microphone <NUM> is a sensor device for detecting a knock on signal, and the modular microcomputer <NUM> serves to determine whether the signal detected by the microphone <NUM> is a knock on signal.

For example, the modular microcomputer <NUM> determines whether the input signal is a normal knock on signal. When the input signal is determined to be a normal knock on signal, the modular microcomputer <NUM> may send to the main controller <NUM> a signal indicating that normal knock on input has been applied. When the input signal is determined not to be a normal knock on signal, the modular microcomputer <NUM> may not send the signal. For example, when the input signal is determined to be a normal knock on signal by the modular microcomputer <NUM>, the modular microcomputer <NUM> may send a signal of 5V to the main controller <NUM>. In the other case, the modular microcomputer <NUM> may send a signal of 0V to the main controller <NUM>. The latter is considered to be the case where no signal is sent to the main controller <NUM>.

Since the main controller <NUM> receives a signal that indicates only that normal knock on signal has been input, the main controller <NUM> does not perform any additional determination. Consequently, it is possible to minimize the effect of noise inherent in the signal line between the main controller <NUM> and the modular microcomputer <NUM>. In the same way as above, the modular microcomputer <NUM> may determine whether a normal knock on signal has been input based on a signal which is input through the modularized microphone and which contains minimal noise. Accordingly, an accurate recognition rate may be realized.

The knock sensor module or sensor module <NUM> may include a filter <NUM>. The filter <NUM> serves to eliminate noise from the signal received from the microphone <NUM>. Specifically, the filter <NUM> may be a noise filter. The filtered signals are preferably amplified through an amplifier. Therefore, the sensor module <NUM> preferably further include an amplifier <NUM> for amplifying the filtered signal and transmitting the amplified signal to the modular microcomputer <NUM>. Specifically, the amplifier <NUM> may be an operational amplifier.

The sensor module <NUM> preferably includes the filter <NUM>, the amplifier <NUM> and the modular microcomputer <NUM> mounted on a single PCB, and the microphone <NUM> preferably extends from the PCB by means of a signal line. The structure by which the microphone <NUM> is mounted or secured will be described later.

Hereinafter, the microphone or microphone module as the sensor device is described in detail with reference to <FIG>.

As shown in <FIG>, a microphone <NUM> is preferably embodied as the microphone module <NUM>. In other words, the microphone <NUM> for directly detecting sound waves is preferably provided in the state of being received in a receptor <NUM>. Accordingly, the microphone <NUM> and the microphone receptor <NUM> may be collectively referred to as the microphone <NUM> or the microphone module <NUM>.

The microphone <NUM> may be configured to have a circular plate having a predetermined thickness. The microphone <NUM> is received in the microphone receptor <NUM>, and the movement of the microphone <NUM> is thus restricted by the internal structure of the microphone receptor <NUM>. In other words, the microphone <NUM> is preferably supported such that the microphone <NUM> floats in the microphone receptor <NUM>.

The microphone receptor <NUM> is preferably made of a rubber material. Basically, the microphone <NUM> is closely fitted in the microphone receptor <NUM>. The microphone receptor <NUM> may be provided at the top and bottom thereof with openings <NUM> and <NUM>, each of which may have a circular shape.

One side of the microphone <NUM> is considered to function as a sound wave receiver 511a for receiving sound waves. The sound wave receiver 511a may be oriented to face one of the openings in the microphone receptor <NUM>. For the convenience of illustration, the sound wave receiver 511a is illustrated as facing the lower opening <NUM>.

A signal line <NUM> is connected to the other side of the microphone <NUM>. The signal line <NUM> may be connected to the PCB of the knock sensor module through the opening <NUM>, as described above.

A predetermined space is preferably defined between the lower opening <NUM> and the sound wave receiver 511a. The predetermined space is preferably sealed. To this end, the predetermined space is preferably sealed by causing the lower opening <NUM> to closely contact the medium, i.e. the front panel <NUM> or <NUM>.

The predetermined space <NUM> may also be isolated from the upper opening <NUM> by the close contact between the microphone <NUM> and the microphone receptor <NUM>.

In order to prevent the hermetical space from being damaged by the imbalance, a protrusion <NUM> is preferably provided along the periphery of the lower opening <NUM>. Specifically, even if the distribution of force that acts on the microphone receptor <NUM> to cause the microphone receptor to closely contact the medium subsequently becomes imbalanced, the hermetical space is effectively maintained by the elastic deformation of the protrusion <NUM>.

Accordingly, one side of the hermetical space is closed by the medium. Consequently, the air in the hermetical space is vibrated by sound waves transmitted through the inside of the medium, and sound waves generated by the vibration may be input to the microphone <NUM>.

By virtue of the hermetical sealing, it is possible to block or suppress the infiltration of external noise or vibrations into the predetermined space. Therefore, the erroneous determination of knock on input or malfunctions attributable to external noise may be remarkably reduced, and the recognition rate of knock on input may be improved. In other words, when a knock on input is applied, the accuracy of the determination of whether a knock on input was applied may be greatly improved.

Hereinafter, the structure for mounting the sensor for detecting input for conversion into a see-through door will be described in detail. In particular, the structure for mounting the sensor will be described in detail under the assumption that the sensor is embodied as the microphone module <NUM> shown in <FIG>. For the convenience of illustration, the signal line <NUM> is not shown in <FIG>.

An example of the structure for mounting the microphone module <NUM> is first described with reference to <FIG>.

According to this embodiment, the front panel <NUM> may constitute the central area of the door or the sub door, and the door frame <NUM> may constitute the marginal area of the door or sub door.

Specifically, <FIG> illustrates a partially broken away perspective view and an enlarged view of the structure for mounting the microphone module <NUM> on the sub door. For the convenience of illustration, the door liner <NUM> is omitted in <FIG>.

According to this embodiment, the microphone module <NUM> is preferably mounted on the front panel <NUM> in a close-contact manner.

As shown in the drawings, the marginal area of the front panel <NUM> is covered by the door frame <NUM>, in particular, the outer door <NUM>. The microphone module <NUM> is disposed between the outer door <NUM> and the front panel <NUM>. The microphone module <NUM> is preferably in close contact with the front panel <NUM>.

Specifically, in order to mount the microphone module <NUM> to the front panel <NUM> in close-contact manner, a support member <NUM> is preferably provided. The support member <NUM> may be disposed between the outer door <NUM> and the front panel <NUM>. Furthermore, the support member <NUM> may be disposed between the outer door <NUM> and the door decoration <NUM>.

Accordingly, both the microphone module <NUM> and the support member <NUM> may be positioned outside the opening <NUM> in the radial direction for the conversion into a see-through door. Therefore, the microphone module <NUM> and the support member <NUM> may not be visibly exposed to the front of the door even upon conversion into a see-through door. In addition, since the microphone module <NUM> and the support member <NUM> are prevented from being visibly exposed to the outside through the see-through door, the design of the door becomes elegant and neat.

Specifically, the support member <NUM> preferably includes an elastic element <NUM>. The elastic element <NUM> is preferably configured to exert an elastic force in the direction of causing close contact of the microphone module <NUM>. Therefore, it is preferable that the support member <NUM> always be biased toward the microphone module <NUM>.

The support member <NUM> may include a fulcrum <NUM>, a first extension <NUM> extending in one direction from the fulcrum <NUM>, and a second extension <NUM> extending in the opposite direction from the fulcrum <NUM>. The fulcrum <NUM> may be interposed between the outer door <NUM> and the door decoration <NUM>.

The first extension <NUM> may be provided with a holder <NUM>. The holder <NUM> may be positioned at the end of the first extension <NUM>. The holder <NUM> may be provided with the microphone module <NUM> held therein.

The elastic element <NUM> may be disposed between the second extension <NUM> and the door decoration <NUM> so as to exert an elastic force on the second extension <NUM>, thus biasing the second extension <NUM> forward. The elastic force is converted into an elastic force that pushes the first extension <NUM> rearward like a seesaw, which is in turn converted through the holder <NUM> into a force that causes the microphone module <NUM> to closely contact the front panel <NUM>. Consequently, the elastic force from the elastic element is continuously applied to the microphone module <NUM> so as to cause the microphone module <NUM> to closely contact the front panel <NUM>.

If the sub door <NUM> is configured so as not to include the door decoration <NUM> and the inner frame <NUM>, the support member <NUM> will be disposed between the outer door <NUM> and the door liner <NUM>. Accordingly, the support member <NUM> may be positioned outside the opening in the door frame <NUM> in the radial direction.

The elastic element <NUM> may be a coil spring. The second extension <NUM> may be provided on the rear surface thereof with a protrusion <NUM> for supporting the elastic element <NUM>.

Specifically, the elastic element <NUM> may be compressed a predetermined amount at the time of assembly so as to exert an elastic force that pushes the second extension <NUM>.

Since the elastic element <NUM> biases the second extension <NUM>, the first extension <NUM>, which is positioned at the opposite side with respect to the fulcrum <NUM>, biasedly pushes the microphone module <NUM>, whereby the microphone module <NUM> is caused to closely contact the front panel <NUM>. In other words, it is possible to continuously maintain the state in which the microphone module <NUM> is in close contact with the front surface of the front panel <NUM>.

Therefore, the microphone module <NUM> can efficiently recognize that a user is tapping the front panel <NUM>.

Hereinafter, another embodiment of the structure for mounting the microphone module <NUM> will be described with reference to <FIG> and <FIG>.

As in the above embodiment, the microphone module <NUM> is preferably mounted so as to closely contact the front panel. In addition, the microphone module <NUM> is mounted on the door frame such that the microphone module <NUM> does not interfere with the see-through door.

The structure for mounting the microphone module according to this embodiment may be applied to the door shown in <FIG>. In other words, this structure may be applied to the case where the front panel <NUM> defines the entire appearance of the front surface of the door.

Specifically, this structure may be applied to a door in which the thermal insulation panel is fitted in the opening and the rear marginal area of the front panel is in close contact with the door frame.

As described above, the door frame <NUM> may include the inner frame <NUM>. The inner frame <NUM> may be integrally formed with cap decorations <NUM>, or the cap decorations <NUM> may be respectively coupled to the upper and lower ends of the inner frame <NUM>.

Referring to <FIG> and <FIG>, the structure in which the microphone module <NUM> is mounted by means of the cap decorations <NUM> is shown.

More specifically, the cap decoration <NUM> may be provided at the front region thereof with a through hole <NUM> through which the microphone module <NUM> passes. The microphone module <NUM> may closely contact the front panel <NUM> through the through hole <NUM>.

For the purpose of close contact of the microphone module <NUM>, a support member <NUM> is provided. The cap decoration <NUM> may be preferably provided with a seat portion <NUM> in which the support member <NUM> is stably received.

The microphone module <NUM> is at least partially received in a holder <NUM>. Accordingly, it is possible to cause the microphone module <NUM> to closely contact the front panel and to maintain that state by pushing out the holder <NUM> toward the front panel <NUM>. Therefore, the support member <NUM> preferably includes an elastic element <NUM> for biasedly supporting the holder <NUM> and exerting an elastic force to the holder <NUM>.

The holder <NUM> may be provided with a slit or slot 561a through which the signal line <NUM> shown in <FIG> is led out. Specifically, the microphone module <NUM> may be received in the holder <NUM>, and the signal line <NUM>, for transmitting the signal input to the microphone module <NUM> to the outside, may extend to the outside from the holder <NUM> through the slit or slot 561a.

When the holder itself is made of a flexible material, the signal line <NUM> may be fitted in the slit or slot 561a, and may thus be stably supported thereby.

The support member <NUM> may include a holder receptor <NUM> for receiving the holder <NUM>. The elastic element <NUM> may be disposed between the holder <NUM> and the holder receptor <NUM>. Therefore, the holder <NUM> is always biased forward with respect to the holder receptor <NUM>.

The holder receptor <NUM> may be seated in the seat portion <NUM> such that the holder receptor <NUM> is always pushed forward. Specifically, the support member <NUM> including the holder receptor <NUM> may be securely seated in place in the seat portion <NUM>, and, as such, a force for supporting the support member <NUM> forward may be applied to the support member <NUM> by itself.

To this end, a cover may be provided so as to cover the seat portion <NUM>. The cover <NUM> may be a hinge cover <NUM> for covering the sub door hinge <NUM> mounted on the cap decoration <NUM>. In other words, because the hinge cover <NUM> is coupled to the cap decoration <NUM>, the support member <NUM> may be supported by the hinge cover <NUM> and may thus be pushed forward.

Specifically, the cover <NUM> may be coupled to the cap decoration <NUM> by means of hook elements <NUM>. At this point, the cover <NUM> may be provided with a protrusion or rib <NUM> so as to push the support member <NUM> forward.

Accordingly, the protrusion or rib <NUM> may serve to push the whole support member <NUM> forward and to maintain the pushed state of the support member <NUM>. In addition, the elastic element <NUM> biases the holder <NUM> forward. As a result, the microphone module <NUM> may be maintained in the state of being in close contact with the front panel <NUM>. In this embodiment, the microphone module <NUM> may, of course, come into close contact with the rear surface of the front panel <NUM> through the through hole <NUM>.

The shape of the through hole <NUM> is preferably configured to mate with the shape of the holder <NUM>. Consequently, since it is possible to prevent the holder <NUM> from being displaced in the through hole <NUM>, the tight contact force of the microphone module <NUM> can be efficiently maintained.

The PCB of the knock sensor module <NUM> may be mounted on the lower surface of the cover <NUM>. In other words, the cap decoration <NUM> may be provided with a space required to mount the sub door hinge <NUM> and the PCB. The signal line of the sensor or sensor module <NUM> may extend to the inside of the cabinet <NUM> or the main door through the through hole <NUM> and is connected to the main controller <NUM>.

Although the sensor module <NUM> may be mounted at any position on the marginal area of the door or the sub door, the knock sensor module <NUM> will be preferably mounted on the upper cap decoration in order to satisfactorily dispose the signal line.

Hereinafter, a further embodiment of the structure for mounting the microphone module <NUM> will be described with reference to <FIG>.

As in the above embodiments, this embodiment also suggests the structure for mounting the microphone module <NUM> using the door frame, in particular, the cap decoration <NUM>.

The cap decoration <NUM> may include a through hole <NUM> formed therein. The microphone module <NUM> may pass through the through hole <NUM> and may closely contact the rear surface of the front panel <NUM>.

The microphone module <NUM> is received in the holder <NUM>, which is configured to be identical or similar to that in the above embodiments. The holder <NUM> may constantly push the microphone module <NUM> toward the front panel, thus constantly causing the microphone module <NUM> to closely contact the front panel.

Since the holder <NUM> may also be made of a flexible material, the holder <NUM> may be flexibly restored toward the front panel in the state of being compressed.

To this end, a holder mount <NUM> may be provided in the rear of the through hole <NUM>. The holder <NUM> may be pushed into and mounted in the holder mount <NUM> while containing the microphone module <NUM> therein. At this point, the through hole <NUM> may be configured to have a larger dimension than the holder <NUM> in the direction in which the holder is mounted. Specifically, when the holder <NUM> is pushed from the left side toward the right side to be mounted, as shown in <FIG>, the through hole <NUM> preferably has a horizontal width greater than the horizontal width of the holder <NUM>. Of course, the through hole <NUM> is preferably configured to have a vertical width corresponding to the vertical width of the holder <NUM> such that the upper and lower surfaces of the holder <NUM> are tightly fitted in the through hole <NUM>.

Specifically, a predetermined space may be defined between the holder mount <NUM> and the through hole <NUM>, and the holder <NUM> may be fitted in the predetermined space <NUM>. More specifically, the width of the predetermined space in the forward and rearward direction is decreased as the holder <NUM> is inserted into the predetermined space. In other words, when the holder <NUM> is fully inserted into the space, the holder <NUM> is compressed forward and rearward. Accordingly, the holder <NUM> tends to flexibly return to its original state, thus generating a force that pushes the microphone module <NUM> forward.

The holder <NUM>, which has been inserted, may be held in position. As described above, the cover <NUM> may be a cover for covering the cap decoration <NUM>, or may be a hinge cover for covering the sub door hinge <NUM>. The cover <NUM> may also be coupled to the cap decoration <NUM> by means of the hook elements <NUM>.

The cover <NUM> may be provided on the lower surface thereof with a protrusion or rib <NUM> that protrudes downward. When the cover <NUM> is coupled to the cap decoration <NUM>, the protrusion or rib <NUM> pushes the holder <NUM>. In other words, the protrusion or rib <NUM> pushes the holder <NUM> in the direction in which the holder <NUM> is inserted into the through hole <NUM>.

Consequently, the holder <NUM> may always be maintained in the compressed state in the holder mount <NUM>, and may be securely held regardless of vibrations or movement of the door. Therefore, the microphone module <NUM> may closely contact the front panel <NUM>, and the close contact state may be continuously maintained.

<FIG> is a conceptual diagram illustrating the position on the see-through door on which the microphone module is mounted and the area on the see-through door to which a user knock input is applied. In the case where the main door or the sub door is constructed to be converted into a see-through door, the door has the opening <NUM> for defining the see-through door. In other words, the storage compartment or the sub storage compartment becomes visible from the outside through the area radially inside the opening.

In the front surface of the door, the area inside the opening and at least part of the area outside the opening are defined by the front panel, as mentioned above. In the front surface of the outside type door, the area inside the opening and at least part of the area outside the opening are defined by the front panel, and the marginal area of the door is defined by the door frame, as mentioned above. In the inside type door, the entire front surface of the door is defined by the front panel.

Accordingly, the area to which a user knock input is applied may be basically the entire area defined by the front surface of the front panel. However, a user may unconsciously apply the knock input to the area that is converted into a see-through door. The area that is substantially converted into a see-through door is considered as the area radially inside the opening <NUM> or <NUM>. Therefore, the entire rectangular area defined by the opening <NUM> or <NUM> may be defined as the area on which a user applies the knock input.

Since this knock input area is a see-through area, the microphone module is preferably mounted on an area other than the see-through area. Of course, the microphone module mounting area may be considered as an extension of the area of the front panel.

Accordingly, the mounting point of the microphone module is preferably positioned at the area radially outside the opening <NUM> or <NUM>. As shown in <FIG>, the microphone module is preferably mounted at a predetermined area S surrounding the opening <NUM> or <NUM>.

Since the predetermined area S is not the see-through area, a user cannot easily see the microphone module from the front of the door even though the microphone module is in close contact with the front panel. Accordingly, the area to which the knock input can be applied may be efficiently expanded, and the distance between the knock input area and the microphone module mounting area can be sufficiently increased.

In order to sufficiently prevent the microphone module from being visibly exposed from the front surface of the door, the rear surface of the predetermined area S may be provided with a printed layer. In other words, the area of the rear surface of the front panel according to the predetermined area S may be formed with a printed layer. However, since the outside type door is constructed such that the predetermined area S is covered by the door frame or the outer door, the printed layer may be omitted.

As described above, the user input for conversion into a see-through door may be tapping on the front surface of the door, and the tapping may be detected by the sensor device, in particular, the microphone.

So many environmental factors that apply vibrations to the front surface of the door may be present. The front surface of the door may be vibrated by impacts caused by opening and closing of the door, intensive external noise, or the like. The input caused by these environmental factors may be determined to be a normal knock signal.

Accordingly, the sensor module enables a number of taps on the front surface of the door by a user to be determined as normal knock input. Specifically, the action whereby a user taps on the front surface of the door multiple times at a predetermined time intervals may be determined as normal knock input.

By way of example, the action whereby a user taps on the front surface of the door twice within a predetermined period of time may be determined as normal knock input. Considering a user's general knock pattern, it will be appreciated that the interval between the first knock and the second knock is about <NUM> or less. Since one second is <NUM>, the action whereby the first knock and the second knock occur at an interval shorter than <NUM> second may be determined to be normal knock input.

Accordingly, it is possible to remarkably prevent abnormal input from being determined as a normal knock signal by setting the time interval.

The intensities of users' knocks may be different from each other. Although the difference between the intensities of users' knocks may be great, it will be appreciated that the difference between users' vibration patterns is very small. Accordingly, the difference between intensities of users' knocks may be compensated for by an algorithm, and normal knock input may be efficiently recognized based on the pattern of knock input and the time interval between knocks.

In other words, this indicates that the error whereby abnormal knock input is recognized as normal knock input may be remarkably reduced.

As described above, when the knock input is determined to be normal knock input, the controller <NUM> activates the lighting device <NUM>. The controller <NUM> may control the lighting device to be turned off after the lapse of a predetermined period of time. When a user applies a second knock input before the predetermined period of time has elapsed, the controller <NUM> may control the lighting device <NUM> to be turned off. The knock input in this case may be the same as the knock on input. At this point, in order to distinguish such knock input from knock on input, only a single knock may be recognized as the knock off input.

It is, of course, preferable that the single knock input be recognized as the knock off input only when the single knock input occurs before the lapse of a predetermined period of time after the determination of knock on input.

As described above, the substantially entire front surface of the door may be used as the knock on input area by employing a sensor device such as the microphone. In other words, a wide area may be used as the knock on input area without having to provide the knock on input area with an additional sensor, such as a touch sensor or an electrostatic sensor. This means that it is possible to prevent an increase in costs attributable to the provision of a touch sensor, or an electrostatic sensor, or an additional panel including the sensor, and to improve durability. Furthermore, the door can be simply constructed.

In addition, this indicates that the knock on input can be easily applied to a wide area regardless of a user's posture or even if both hand are not free. Furthermore, the knock on input area may be defined to be substantially identical to the see-through area. Accordingly, it is possible to obviate elements that obstruct the transmission of light through the see-through area, that is, components such as a touch panel. As a result, a clearer see-through may be realized.

There may be the case where two continuous knock on inputs are applied, for example in advertently or due to children playing. While two continuous knock inputs within <NUM> of each other are determined to be normal knock input, there is a need to efficiently handle the case of three or more continuous knock inputs.

<FIG> illustrates an example of the control method at the time of the continuous generation of knock signals.

When a second knock signal is generated within <NUM> after generation of the first knock signal, the knock input is recognized as normal knock input, thus activating the lighting device. The lighting device may be basically controlled in such a manner as to be turned on, for example, for <NUM> seconds at the time of application of the normal knock input.

When the normal knock input is recognized by the application of the second knock signal, the second knock signal may be recognized as a subsequent first knock signal. Accordingly, when a third knock signal is further applied within <NUM>, the second knock signal and the third knock signal may be recognized as normal knock input. Therefore, the lighting device may be controlled to be further turned on for <NUM> seconds after recognition of the third knock signal. In other words, when the normal knock signals are continuously recognized, the ON state of the lighting device may be controlled to be continuously extended.

Accordingly, according to this embodiment, since the two normal knock inputs are recognized as the normal knock input signal, the reliability of knock input may be ensured. However, when two continuous normal knock inputs are applied due to a user playing, there may be the possibility that the lighting device is unnecessarily activated.

<FIG> illustrates another example of the control method at the time of the continuous generation of knock signals.

When the second knock signal is generated within <NUM> after generation of the first knock signal, the knock input is recognized as normal knock input, thus activating the lighting device. The lighting device may be basically controlled in such a manner as to be turned on, for example, for <NUM> seconds at the time of application of the normal knock input.

When the normal knock input is recognized by the second knock signal, the time interval between the second knock signal and the third knock signal is determined. For example, when the third knock signal is applied after a time interval of <NUM>, this may be recognized as a normal knock off signal. In other words, when the third knock signal is applied after a time interval of <NUM> since the lighting device was turned on by the second knock signal, this may be recognized as normal knock off input. However, when a third knock signal is applied within a time interval of <NUM>, the third knock signal may be ignored.

When the third knock signal is applied within the time interval of <NUM> and the fourth knock signal is further applied within the time interval of <NUM>, the fourth knock signal may be recognized as knock off input. Accordingly, the lighting device may be controlled to be turned off when the fourth knock signal is recognized. When the fifth knock signal is applied within a time interval of <NUM> after the application of the fourth knock signal, the fifth knock signal and the sixth knock signal may be recognized as normal knock on input, thus activating the lighting device again.

Accordingly, according to this embodiment, when the normal knock inputs are repeatedly applied, the lighting device may be controlled to be repeatedly turned on and off. Thanks to this control method, it is possible to reduce the time during which the lighting device is continuously turned on compared to the previous embodiment.

<FIG> illustrates a further example of the control method at the time of the continuous generation of knock signals.

According to this embodiment, when knock inputs are repeatedly applied at time intervals equal to or less than <NUM>, only the first two knock inputs are recognized as normal knock inputs. In other words, the lighting device is turned on for <NUM> seconds by the two normal knock inputs, and knock input signals which are applied while the lighting device is turned on may be ignored.

According to this embodiment, it is possible to prevent the lighting device from being activated for a longer time than necessary and to prevent the lighting device from being repeatedly turned on and off when not necessary. However, since this case does not need knock off input, the lighting device may be maintained in the state of being turned on for a predetermined time when the lighting device is turned on. Accordingly, for example, in the case of a series of actions whereby a user performs knock on input, opens the door to take out a desired object, and then closes the door within, for example, <NUM> seconds, a problem whereby the lighting device is activated for a longer time than necessary may occur.

Nevertheless, this embodiment is able to control the lighting device in a very simple and easy manner even when knock on input is repeatedly applied, and is able to prevent the deterioration of durability due to frequently turning on and off the lighting device.

Various embodiments have been described in the best mode for carrying out the invention.

Claim 1:
A refrigerator comprising:
a cabinet (<NUM>) having a storage compartment;
a lighting device (<NUM>) to illuminate an interior of the storage compartment;
a door (<NUM>) connected to the cabinet (<NUM>) and configured to open and close the storage compartment, the door (<NUM>) having an opening defined therethrough and comprising:
a panel assembly (<NUM>, <NUM>) configured to cover the opening in the door (<NUM>) and becoming transparent according to light from the light device (<NUM>) for illuminating the interior of the storage compartment (<NUM>), the panel assembly (<NUM>, <NUM>) comprising:
a front panel (<NUM>, <NUM>) that defines an outer appearance of the door (<NUM>) and through which light emitted from the lighting device (<NUM>) passes in a state in which the door (<NUM>) is closed;
a sensor (<NUM>) arranged in the door (<NUM>) and in contact with the front panel (<NUM>, <NUM>) of the panel assembly (<NUM>, <NUM>) of the door (<NUM>), the sensor (<NUM>) being configured to detect a knock input applied on the front panel (<NUM>, <NUM>); and
a controller (<NUM>) configured to determine, based on the knock input detected by the sensor (<NUM>), whether the knock input is applied on the front panel (<NUM>, <NUM>) of the panel assembly (<NUM>, <NUM>) of the door (<NUM>), and to turn on the lighting device (<NUM>) to illuminate the interior of the refrigerator when the sensor (<NUM>) detects the knock input applied on the front panel (<NUM>, <NUM>), thus making the storage compartment visible from outside the door (<NUM>) through the opening when a predetermined knock input is detected,
wherein the sensor (<NUM>) includes a sensor device module, which is disposed radially outside the opening and closely contacts the front panel (<NUM>, <NUM>),
wherein
the front panel (<NUM>, <NUM>) includes a color coating film, or is constituted by a color panel, such that the front panel (<NUM>, <NUM>) is opaque under low-intensity light conditions, and the front panel (<NUM>, <NUM>) becomes transparent under relatively high-intensity light conditions, and
the front panel (<NUM>, <NUM>) is opaque when the lighting device (<NUM>) behind the front panel (<NUM>) is deactivated, and
the front panel (<NUM>, <NUM>) is converted into a transparent panel when the lighting device (<NUM>) is activated.