Abstract:
The function expanding method for a display device comprises: a step of preparing a plurality of types of function expanding modules; a step of selecting a function expanding module or modules from the plurality of types of function expanding modules; and a step of stacking the selected single or plurality of function expanding module(s) to a rear part of the display device at will, and connecting the module(s) by using expanding connector(s).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a function expanding method for a display device which displays conditions of an external apparatus that is controlled by a programmable controller. The programmable controller is a so-called programmable logic controller, a PLC, a sequencer, or the like, and it is referred to as a PLC hereinafter. 
     2. Description of the Related Art 
     PLCs are used for controlling external apparatuses such as factory equipment. As an HMI (human-machine interface) of a control system, a display device can display conditions of an external apparatus controlled by the PLC and can operate the external apparatus as well. An operation component (HMI component) for operating the external apparatus is displayed on the display device. A user operates the external apparatus through operating the operation component displayed on the display device. An example of such display device is a programmable display device, which is used by being installed at a place where a control board and the like are placed. 
     The industrial usage of this type of display device has been expanded dramatically, and such display device has been used by being installed at places where there are drastic changes in environmental temperatures and at scenes of cold districts and the like. The display device includes a type which comprises a touch panel for allowing a direct operation of the operation component that is displayed on a display screen, and a type which comprises no touch panel so that the operation component on the display screen cannot be touch-operated with fingers and the like directly. Further, the display device is normally fitted into a display device attachment opening of a control board (not shown) from a front of the display device main body so as to be engaged with an outer periphery of the display device attachment opening to be fixedly mounted to the opening. 
     While such device is required to comprise various functions in accordance with the expansion of its usage, usage of small-sized and inexpensive display devices has been expanding. 
     However, when the display device is small, it is difficult to mount various required functions to that single device. Thus, small-sized display devices corresponding to each required function are fabricated in the actual circumstances. Because of that, the manufacturing cost becomes increased. Further, the required functions may change at the scene, so that it is not easy to follow the changes. In such case, it becomes necessary to prepare many types of small-sized display devices, for example, thereby increasing the cost as well as the time and effort further. 
     Even if various types of slots and connectors are attached to a rear part of the small-sized display device and function expanding modules are mounted to those slots and connectors so as to expand the functions of the small-sized display device, the number of function expanding modules placed thereto is restricted because the area of the rear part is small. Further, when the function expanding modules are placed in other parts than the rear part of the small-sized display device, the advantage of the small-sized device as being small in size, becomes spoiled. 
     Japanese Unexamined Patent Publication H11-215217 discloses a technique which makes it possible to mount a plurality of types of option apparatuses (function expanding modules) to a casing of a portable information terminal device simultaneously, and makes it possible to operate any of the arbitrary option apparatuses that are mounted to an option apparatus mount mechanism through operations of a touch panel of a display device. 
     Japanese Unexamined Patent Publication 2003-018678 discloses a technique which makes it possible to select function expanding modules that can collect prescribed monitor data among a plurality of types of function expanding modules which can collect different monitor data from each other except specific monitor data, and makes it possible to connect those selected modules detachably and to be capable of performing data communication with each other. 
     SUMMARY OF THE INVENTION 
     The main object of the present invention therefore is to provide a function expanding method for a display device, which can expand the functions at will while maintaining the advantage of the display device as being small in size. 
     In order to achieve the foregoing object, the function expanding method of the present invention is a method for expanding functions of a display device that is provided with an internal circuit to be capable of being used even by itself for displaying a condition of an external apparatus that is controlled by a programmable controller. 
     The present invention is a function expanding method for expanding functions of a display device that is provided with an internal circuit to be capable of being used even by itself for displaying a condition of an external apparatus that is controlled by a programmable controller. The method comprises: 
     a first step of preparing a plurality of types of function expanding modules, each of which comprises a built-in function expanding circuit for the display device; 
     a second step of selecting a function expanding module from the plurality of types of function expanding modules prepared in advance; and 
     a third step of stacking the selected function expanding module to a rear part of the display device, and electrically connecting the display device and the internal circuit of the function expanding module to expand the functions of the display device. 
     The above-described display device includes not only a display device with a touch panel but also a display device without a display panel. 
     The internal circuit and the like of the function expanding module is loaded on a substrate, or the entire or a part of the function extending module is surrounded by a case, and an extending connector is attached to the case. 
     With the function expanding method of the present invention, the function expanding modules corresponding to the expanding functions of the display device are prepared in advance. Thus, it is possible to select the function expanding module that corresponds to a change in the usage of the display device, addition of a function, or the like. Then, by stacking the selected function expanding module to the rear part of the display device, the circuit for expanding the function of the function expanding module can be electrically connected to the internal circuit of the display device so as to expand the functions of the display device. In that case, when the display device is a small-sized device, the functions of the display device can be expanded at will without spoiling the advantage thereof as being small in size. 
     Preferably, the first step prepares: a display device that comprises an expanding connector provided at its rear part; a plurality of types of bezels, each of which comprises on its front side an opening that is capable of housing the display device, as well as operation keys, an output-side expanding connector at a bottom part of the opening, and an input-side expanding connector on a rear part side; and a plurality of types of function expanding modules, each of which comprises an expanding connector on its back side. 
     Preferably, the second step selects a single bezel from the plurality of types of bezels, and selects a single function expanding module (a specific function expanding module) from the plurality of types of function expanding modules. 
     Preferably, the third step houses the display device in the opening of the selected bezel and connects the output-side expanding connector of the bezel to the expanding connector of the display device and, further, loads the selected specific function expanding module on the rear part of the bezel and connects the input-side expanding connector at the rear part of the bezel to the expanding module of the specific function expanding module. 
     A display device unit according to the present invention comprises a display device that is provided with an internal circuit to be capable of being used even by itself, and 
     a plurality of function expanding modules, each of which comprises an internal circuit for expanding functions of the display device, wherein: 
     the display device and the plurality of function expanding module respectively comprises an expanding connector for electrically connecting the respective internal circuits by being mechanically connected to each other, under a state where each of the function expanding modules is stacked in a rear part of the display device; and 
     the display device can be used by itself under a state where the modules are not being stacked, and the functions of the display device can be expanded by the internal circuits of the function expanding modules when the display device and respective internal circuits of each of the function expanding modules are connected through both of the expanding connectors under a state where the modules are loaded by being stacked. 
     Even if the display device is small so that the area of the rear part thereof is small, there is no restriction set in the display device unit of the present invention regarding the number of function expanding modules to be placed, since the function expanding modules are stacked to be loaded on the rear part of the display device. Further, when the display device is small, the functions of the display device can be expanded without spoiling the advantage of the display device as being small in size. 
     A preferable form of the present invention is that the above-described function expanding module is a bezel that comprises an opening for housing the display device detachably and comprises operation keys, and that the above-described bezel allows operations of the display device mounted to the opening through the operation keys. 
     With this form, display of the display screen can be control-operated through the operation keys of the bezel whether there is a touch panel on the display screen of the display device or not. Particularly, when hand operations cannot be performed easily because the display screen is small since it is a small-sized display device, the operation keys of the above-described bezel are convenient since the keys allow the user to operate the display control easily. 
     A preferable form of the present invention is that the above-described bezel is capable of loading another function module on its rear part. 
     This form makes it possible to stack another function expanding module on the rear part of the bezel easily. 
     A preferable form of the present invention is that the above-described display device can be housed in openings of different types of bezels. 
     With this form, different types of bezels can be used for the display device. Therefore, it becomes possible to expand the functions of the display device in more various ways by using the bezels having different arrangements of the operations keys, for example. 
     A preferable form of the present invention is that the above-described function expanding module is a module that comprises a plurality of expanding functions. 
     This form is convenient since it can suppress an increase in the number of provided function expanding modules for expanding the usage of the display device further, through providing the plurality of function expanding modules to a singe function expanding module. 
     Examples of the expanding functions are a power supply function, a serial communication function, an I/O function, an Ethernet (registered trademark) function. These functions can be used alone or in combination. 
     It is possible with the present invention to load the function expanding modules at a small rear part while having no restriction in the number of the function expanding modules to be placed without spoiling the advantage of the display device as being small in size. Therefore, the functions of the display device can be expanded effectively. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects of the present invention will become clear from the following description of the preferred embodiments and the appended claims. Those skilled in the art will appreciate that there are many other advantages of the present invention possible by embodying the present invention. 
         FIG. 1A  is a perspective view taken from the front of a small-sized display device according to embodiments of the present invention; 
         FIG. 1B  is a perspective view taken from the back of the display device; 
         FIG. 1C  is a circuit block diagram of the display device; 
         FIG. 2A  is a perspective view taken from the front of a first bezel; 
         FIG. 2B  is a perspective view taken from the back of the first bezel; 
         FIG. 2C  is a circuit block diagram of the first bezel; 
         FIG. 3A  is a perspective view taken from the front of a second bezel; 
         FIG. 3B  is a perspective view taken from the back of the second bezel; 
         FIG. 3C  is a circuit block diagram of the second bezel; 
         FIG. 4A  is a perspective view taken from the front of a first function expanding module; 
         FIG. 4B  is a perspective view taken from the back of the first function expanding module; 
         FIG. 4C  is a circuit block diagram of the first function expanding module; 
         FIG. 5A  is a perspective view taken from the front of a fourth function expanding module; 
         FIG. 5B  is a perspective view taken from the back of the fourth function expanding module; 
         FIG. 5C  is a circuit block diagram of the first function expanding module; 
         FIG. 5D  is a circuit block diagram of a fifth function expanding module; 
         FIG. 5E  is a circuit block diagram of a sixth function expanding module; 
         FIG. 6  is an illustration showing a combined example of the small-sized display device, the first bezel, the second bezel, a third function expanding module, and the fourth function expanding module; 
         FIG. 7  is an illustration of a mechanism that corresponds to the combined example shown in  FIG. 6 ; and 
         FIG. 8  is an illustration of a mechanism that corresponds to another combined example that is different from the example shown in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferred embodiments of the present invention will be described hereinafter by referring to the accompanying drawings. 
     By referring to  FIG. 1A-FIG .  1 C, a display device used in a control system will be described.  FIG. 1A  is a perspective view taken from the front of the display device,  FIG. 1B  is a perspective view taken from the back of the display device, and  FIG. 1C  is a circuit block diagram of the display device. 
     A display device  1  has a rectangular shape when viewed from the front, and comprises a display screen  2  on its front side. The display device  1  comprises a plurality of function keys  4  which are arranged in parallel beneath the display screen  2 , and comprises an expanding connector  6  on its back side. When operation components are displayed on the display device  1 , an operation-part pin can be focused through operating the function keys  4 . 
     The display device  1  is a programmable display device that can be used as a monitor control display device functioning as an HMI of the control system. The display device  1  comprises a CPU  8 , a memory  10 , a display part  12 , an input part  14 , a communication interface  16 , a function expansion interface  18 , and a DC/DC converter  19  in terms of circuit. The expanding connector  6  is illustrated in  FIG. 1C  for better understanding. The memory  10  is constituted with a RAM, a ROM, a flash ROM, a VRAM, or the like. 
     In the display device  1 , the CPU  8  is capable of displaying/controlling the state of an external apparatus in accordance with a display control program stored in the memory  10 , through communicating with a programmable logic controller (PLC) that controls the external apparatus via the communication interface  16 . 
     The display device  1  uses a touch panel for the input part  14 . A user grasps the state and the like of a control-target external apparatus based on the display on the display screen of the display part  12 . The user can input a control instruction and the like for the external apparatus by operating the touch panel. 
     There is a type of display device  1 , which has no touch panel. The display part  12  is constituted with a liquid crystal display. When a touch panel is used as the input part  14 , the touch panel is arranged on the display screen of the display part  12 . Through applying a pressure (touching) the touch panel with a point of a stylus or a fingertip, a signal in accordance with a coordinate value right under the pressed point can be transferred to the CPU  8 . The display part  12  has an area that is about the same or slightly smaller than an effective touch area of the touch panel, in which a large number of liquid crystal pixels are arranged crosswise in matrix. 
     The CPU  8  monitors operations inputted from the touch panel. The CPU  8  can control various kinds of external apparatuses in accordance with the operations of the user inputted to the touch panel that serves as the input part  14 . 
     In a case where a plurality of buttons are displayed in the display device  1 , no touch panel may be provided. Since there is no touch panel in such case, it is not possible to perform selecting (focusing) operation with direct and physical touch of fingers and the like. Therefore, the display device  1  can accept the user operations through utilizing the function keys as the operation keys that can be physically operated with fingers and the like. Further, the display device  1  can accept operations through operation keys of bezels B 1  and B 2  which will be described later. 
     Illustrations and explanations of a backlight circuit, other circuits, various input/output ports, and the like for the liquid crystal display of the display device  1  are omitted. 
     A first bezel B 1  as a first function expanding module will be described by referring to  FIG. 2A-FIG .  2 C.  FIG. 2A  is a perspective view taken from the front of the first bezel B 1 ,  FIG. 2B  is a perspective view taken from the back of the first bezel B 1 , and  FIG. 2C  is a circuit block diagram of the first bezel B 1 . 
     The first bezel B 1  comprises an opening  20  for detachably housing the display device  1 . The first bezel B 1  comprises operation keys  22 . An output-side expanding connector  24  is provided at a bottom part of the opening  20 . An input-side expanding connector  26  is provided at a rear part of the first bezel B 1 . The display device  1  is not illustrated in  FIG. 2A  and  FIG. 2B . 
     As the operation keys for selecting (focusing) the buttons pasted on the display screen of the display device  1 , the operation keys  22  are constituted with a total of eight keys, i.e. four arrow keys to scroll the aforementioned buttons on the screen in directions of the arrows, an “Enter” key, an “Esc” key, a “Menu” key, and a “CLR” key. 
     Each of the arrow keys is used to move the focus on the buttons in the vertical and horizontal directions, and the “Enter” key is operated for finalizing the focus. Explanations of the keys marked with English abbreviations such as “ESC”, “Menu”, and “CLR” are omitted. 
     The first bezel B 1  comprises a key input logic block  28  loaded inside thereof. Through operations of the arrow keys, and “Esc”, “Menu”, “CLR”, “Enter” keys in the first bezel B 1 , the key input logic block  28  outputs operation signals that correspond to the operations to the output-side expanding connector  24 . 
     In the first bezel B 1 , when a function expanding signal is supplied from another function expanding module to the other connector, i.e. the input-side expanding connector  26 , the supplied function expanding signal is transmitted to the output-side expanding connector  24 . A detailed explanation of the key-input logic block  28  will be omitted. 
     A second bezel B 2  as a second function expanding module will be described by referring to  FIG. 3A-FIG .  3 C.  FIG. 3A  is a perspective view taken from the front of the second bezel B 2 ,  FIG. 3B  is a perspective view taken from the back of the second bezel B 2 , and  FIG. 3C  is a circuit block diagram of the second bezel B 2 . 
     The second bezel B 2  comprises an opening  30  for detachably housing the display device, and operation keys  32 . An output-side expanding connector  34  is provided at a bottom part of the opening  30 . An input-side expanding connector  36  is provided at a rear part of the second bezel B 2 . The operation keys  32  are constituted with a total of twenty keys, i.e. four arrow keys to scroll the aforementioned buttons on the screen in directions of the arrows, an “Esc” key, a “Menu” key, a “CLR” key, an “Enter” key, numeral value keys, a decimal point key, and the like. 
     The second bezel B 2  comprises a key input logic block  38  loaded inside thereof. Through operations of the arrow keys, “Esc”, “Menu”, “CLR”, “Enter” keys, the numeral value keys, the decimal point key, and the like in the first bezel B 2 , the key input logic block  38  outputs operation signals that correspond to the operations to the output-side expanding connector  34 . 
     In the second bezel B 2 , when a function expanding signal is supplied from another function expanding module to the other connector, i.e. the input-side expanding connector  36 , the supplied function expanding signal is transmitted to the output-side expanding connector  34 . A detailed explanation of the key-input logic block  38  will be omitted. 
     A third function expanding module C 1  will be described by referring to  FIG. 4A-FIG .  4 C.  FIG. 4A  is a perspective view taken from the front of the third function expanding module C 1 ,  FIG. 4B  is a perspective view taken from the back of the third function expanding module C 1 , and  FIG. 4C  is a circuit block diagram of the third function expanding module C 1 . 
     The third function expanding module C 1  comprises an expanding connector  40  on its back side. The third function expanding module C 1  comprises a terminal block  42  and the like on its lateral side. 
     The third function expanding module C 1  comprises a DC/DC converter  44  that is build inside thereof, which is a power supply function expanding part. The DC/DC converter  44  converts a DC voltage supplied from the terminal block  42  into a prescribed DC voltage, and outputs it to the expanding connector  40 . Reference numeral  41  is an external DC voltage output power supply. 
     A fourth function expanding module C 2  will be described by referring to  FIG. 5A-FIG .  5 C.  FIG. 5A  is a perspective view taken from the front of the fourth function expanding module C 2 ,  FIG. 5B  is a perspective view taken from the back of the fourth function expanding module C 2 , and  FIG. 5C  is a circuit block diagram of the fourth function expanding module C 2 . 
     The fourth function expanding module C 2  comprises an expanding connector  46  on its back side. The fourth function expanding module C 2  comprises a DC/DC converter  48  that is a power supply function expanding part, a terminal block  50 , a serial communication part  52 , and a D-sub (D-subminiature)  54 . Other function expanding parts are a serial communication function, an I/O function, an Ethernet (registered trademark) function, and the like. 
     In such case, an I/O function part  56  and an I/O connector  58  may be provided to make a fifth function expanding module C 2 ′ as shown in  FIG. 5D . Alternatively, the serial communication part  52 , the D-sub  54  may be omitted and the I/O function part  56 , the I/O connector  58  may be added to make a sixth function expanding module C 2 ″ as in  FIG. 5E . 
       FIG. 6  is an illustration showing combination examples of the display device  1 , the first bezel B 1  as the first function expanding module, the second bezel B 2  as the second function expanding module, the third function expanding module C 1 , and the fourth function expanding module C 2 . The combination examples are as follows. 
     However, a combination of the fifth function expanding module C 2 ′ and the sixth function expanding module C 2 ″ is omitted because of the matter of explanations.
     (1) The display device  1  and the first bezel B 1     (2) The display device  1 , the first bezel B 1 , and the third function expanding module C 1     (3) The display device  1 , the first bezel B 1 , and the fourth function expanding module C 2     (4) The display device  1  and the second bezel B 2     (5) The first display device  1 , the second bezel B 2 , and the third function expanding module C 1     (6) The first display device  1 , the second bezel B 2 , and the fourth function expanding module C 2     (7) The first display device  1  and the third function expanding module C 1     (8) The display device  1  and the fourth function expanding module C 2     

     Needless to say, there are many different combinations provided based on the types of the function expanding modules. However, as way of examples, the embodiment illustrates the aforementioned eight combinations because of the matter of explanations. Note that the combinations of (1)-(8) are illustrated by using solid lines, broken lines, and alternate short and long dash lines. 
     Manufactures need to prepare the first bezel B 1 , the second bezel B 2 , the third function expanding module C 1 , the fourth function expanding module C 2 , the fifth function expanding module C 2 ′, the sixth function expanding module C 2 ″, etc. for the display device  1 . 
     Through preparing the various types of function expanding modules in advance as described, each module can be assembled through the expanding connector as in  FIG. 7  to be supplied to a user when the user requests the combination (1) among the aforementioned combinations (1)-(8). Alternatively, when the user requests the combination (2) among the aforementioned combinations (1)-(8), each module can be assembled through the expanding connectors as in  FIG. 8  to be supplied to the user. 
       FIG. 7  shows the combination (1) among the aforementioned combinations (1)-(8). 
     This combination is of the display device  1  and the first bezel B 1 , in which the display device  1  is housed in the opening  20  of the first bezel B 1 . The display device  1  is connected to the first bezel B 1  through the expanding connectors  6  and  24  while being housed in the opening  20  of the first bezel B 1 , and operation signals of the operation keys  22  are supplied to the function expanding interface  18  of the display device  1  via the both expanding connectors  6  and  24 . In the display device  1 , the CPU  8  controls the display of the HMI component such as buttons that are displayed on the display screen of the display part  12  in accordance with the contents of the operation signals. 
     As described above, in a case of the combination of the display device  1  and the first bezel B 1 , the display device  1  is housed in the first bezel B 1  in a compact manner. At the same time, the functions of the operation keys  22  of the first bezel B 1  as the first function expanding module can be expanded. Therefore, even if the rear part area of the display device  1  is small, the function of the display device can be expanded without spoiling the advantage of the display device as being small in size. 
       FIG. 8  shows the combination (2) among the aforementioned combinations (1)-(8). This combination is of the first display device  1 , the first bezel B 1 , and the third function expanding module C 1 . In this combination, the expanding connector  6  of the display device  1  is connected to the expanding connector  24  of the first bezel B 1 , and the expanding connector  26  in the rear part of the first bezel B 1  is connected to the expanding connector  40  of the third function expanding module C 1 . With this, the operation signals of the operation keys  22  of the first bezel B 1  are supplied to the function expanding interface  18  of the display device  1  via the both expanding connectors  6  and  24 . At the same time, the DC current of the DC/DC converter  44  (12-24V DC is converted to 5V DC) of the third function expanding module C 1  is supplied to the display device  1  through the expanding connector  40  of the third function expanding module C 1 , the expanding connectors  26 ,  24  of the first bezel B 1 , and the expanding connector  6  of the display device  1 . 
     As described above, in a case of the combination of the display device  1 , the first bezel B 1 , and the third function expanding module C 1 , the display device  1  is housed in the first bezel B 1  in a compact manner. At the same time, the functions of the operation keys  22  of the first bezel B 1  as the first function expanding module and the functions of the third function expanding module C 1  can be expanded. 
     As described above, with the embodiment, it is unnecessary to provide each of the functions required for the display device on the single display device itself. In addition, it is unnecessary to fabricate the display devices that correspond to each of the required functions. Thus, the cost for manufacturing the display devices can be suppressed. Further, even if the required function changes on the actual scene, it is possible to select and assemble the function expanding modules in accordance with the change. Therefore, unlike the conventional case, it is unnecessary to prepare a large number of display devices for each function so that the cost as well as the time and effort can be decreased dramatically. Furthermore, through preparing the function expanding modules in advance, the manufactures can also follow the changes in the specification required by the users. 
     Moreover, even if the rear part area of the display device is small because it is the small-sized display device, there is no restriction set in the number of function expanding modules to be mounted. Therefore, it is possible to take a full advantage of the display device as being small in size. 
     Among the display devise, particularly in a case of a display device that is fitted into the display device attachment opening of a control board (not shown) from its front face, for example, it is fixedly mounted to the opening by being engaged with the outer periphery of the display device attachment opening. Even in such form where the display device is to be fixedly mounted, the function expanding modules can be stacked in the rear part of the display device, for example. Therefore, the display device can be used in various ways. 
     The present invention has been described in detail by referring to the most preferred embodiments. However, various combinations and modifications of the components are possible without departing from the spirit and the broad scope of the appended claims.