Input device having push-keys, and image forming apparatus having the same

A push type key includes a base including a main body, a key portion having an operation surface, first and second elastic portions connecting between the main body and the key portion, and an electrical equipment substrate provided on a back side of the base. The substrate includes an operating portion acted on by the key portion when the key portion moves. The first and second elastic portions have symmetrical configurations with respect to a phantom line passing through a center of the key portion, as seen perpendicularly to the operation surface. The operating portion is disposed at a position closer to the first elastic portion than to the second elastic portion. The base is provided with a third elastic portion connecting the key portion with the main body or with the second elastic portion in a side of the second elastic portion with respect to the phantom line.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to an input device for a user to operate an apparatus. It relates to also an image forming apparatus such as a copying machine, a printer, or the like, which is equipped with the input device.

Here, an image forming apparatus is an apparatus for forming an image on recording medium with the use of an electrophotographic method, for example. As for examples of electrophotographic image forming apparatus, they include electrophotographic copying machines, electrophotographic printing machines (laser beam printer, LED printers, and the like), facsimile machines, word processors, and the like.

Some image forming apparatuses are equipped with an input device having push-keys which are to be used by a user to operate the apparatus. As a push-key is pressed by a user, a corresponding switch within the input device is turned on or off so that a control section of the image forming apparatus detects the pressed key, and carries out a process which corresponds to the pressed key.

Generally speaking, an input device having push-keys has: a base member having key portions which a user touches; and an electric circuit board having portions (switches or the likes) on which the keys act. It is structured so that the base member is laid upon the electric circuit board. The base member is molded of resin, in one-piece. The key portions of the base member are in connection to a main portion of the base member through branch-like elastic portions. The input device is structured so that as a user presses one of the key portions, the elastic portions deform relative to the main portion of the base member, allowing thereby the key portion to act on the switch or the like on the electric circuit board (Japanese Laid-open Patent Application No. 2008-299444).

There is also known an input device having such keys that can be illuminated to inform a user of the state of an apparatus, degree of progression of an on-going operation, and/or the like. Its electrical circuit board is provided with light emitting elements such as LEDs. It is structured so that the keys are illuminated with the LEDs or the like from within the keys (Japanese Laid-open Patent Application No. 2004-281210).

By the way, in order to make the luminous keys better in visibility while they are illuminated, it is desired to position a light emitting element such as an LED directly below the portion of the luminous key, which is to be illuminated. Further, for the reason related to design, many input devices are structured so that the area of the key, which is to be illuminated, coincides with the center portion of the key.

In the case of an input device structured as described above, a light emitting element is disposed directly below the center portion of the key. Therefore, the switch which is to be pressed by the pressure applying portion of the key cannot be placed directly below the center portion of the key. Thus, the key feels inferior in tactility.

As described above, in the case of an input device structured so that a “switch or the like, to which pressure is applied by the key” cannot be placed directly below the center portion of the key, there is an issue that the key is inferior in tactility. By the way, even if an apparatus does not employ luminous keys, as long as it is structured so that its portion to which pressure is applied by the key cannot be positioned directly below the center portion of the key, it suffers from the same issue as the abovementioned input devices for an image forming apparatus.

SUMMARY OF THE INVENTION

The present invention was made in consideration of the above-described issue. Thus, the primary object of the present invention is to provide an input device having push-keys which feel better to a user in tactility as the user presses the keys than a conventional input device. It is also to provide an image forming apparatus having the input device.

According to an aspect of the present invention, there is provided an inputting device having a push type key, said inputting device comprising a base member including a main body portion, a key portion having an operation surface to be pushed by an operator, a first elastic portion and a second elastic portion which connect between said main body portion and said key portion; and an electrical equipment substrate provided on a back side of said base member, said electrical equipment substrate including an operating portion acted on by said key portion when said key portion moves; wherein said first and second elastic portions have symmetrical configurations with respect to a phantom line passing through a central portion of said key portion, as seen in a direction perpendicular to said operation surface, wherein said operating portion is disposed at a position closer to said first elastic portion than to said second elastic portion, and wherein said base member is provided with a third elastic portion connecting said key portion with said main body portion or with said second elastic portion in a side of said second elastic portion with respect to the phantom line.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a few of the preferable embodiments of the present invention are described in detail. However, the measurements, materials, and shapes of the structural components of the input devices and image forming apparatuses in the following embodiments of the present invention, and their positional relationship among them, are not intended to limit the present invention in scope, unless specifically noted. They are to be modified as necessary according to the structure of the apparatus to which the present invention is applied, and also, various conditions under which the apparatuses are operated.

First, referring toFIGS. 1-7(b), an image forming apparatus in a first embodiment of the present invention is described.

By the way, electrophotographic image forming apparatuses in the following embodiments of the present invention are electrophotographic full-color image forming apparatuses, in which four process cartridges are removably installable. However, the following embodiments are not intended to limit the present invention in the number of process cartridges which the apparatuses employ for the formation of a full-color image. That is, the number is set as necessary. For example, when the apparatuses are used for forming a monochromatic image, the number of process cartridge which the apparatuses employ is one.

Further, the image forming apparatus in each of the following embodiments which will be described hereafter is a printer. However, these embodiments are not intended to limit the present invention in the type of image forming apparatus to which the present invention is applicable. That is, the present invention is also applicable to other image forming apparatuses than printers. For example, the present invention is applicable to copying machines, facsimileing machines, and multifunction machines capable of performing functions of two or more of the abovementioned machines.

(General Structure of Image Forming Apparatus)

To begin with, an image forming apparatus1to which the present invention is applicable is described about its general structure.FIG. 1is an external perspective view of the image forming apparatus1in this embodiment.FIG. 2is a schematic sectional view of the image forming apparatus1in this embodiment.

This image forming apparatus1is a full-color laser printer based on four primary colors. It forms a color image on a sheet S of recording medium with the use of an electrophotographic process. It has an image forming portion structured as follows. That is, it employs a process cartridge system. It is structured so that process cartridges (which hereafter may be referred to simply as cartridges) are removably installable in its main assembly2.

Here, regarding the orientation of the image forming apparatus1, the side having a door3is referred to as “front” side, and the opposite side from the front side is referred to as “rear” (back) side. Further, the right side of the image forming apparatus1as seen from the front side is referred to as “drive” side, whereas the left side is referred to as “non-drive” side.

In the main assembly2of the image forming apparatus1, four cartridges, more specifically, first to fourth cartridges PY, PM, PC and PK are removably mountable in such a manner that they horizontally align. It is structured so that as the door3is opened, a cartridge tray24can be pulled out frontward from the main assembly2through an opening30of the apparatus main assembly2to replace the cartridges PY, PM, PC and PK. To the first to fourth cartridges (PY, PM, PC and PK), rotational driving force is transmitted from a driving force output portion (unshown) of the main assembly2. Further, to each of the first to fourth cartridges (PY, PM, PC and PK), bias voltages (charge bias, development bias, and the like) are supplied from the bias voltage sources (unshown) of the main assembly2.

Each of the first to fourth cartridges (PY, PM, PC and PK) has its own electrophotographic image forming system. The four cartridges are similar in structure, although they are different in the color of the developer (which hereafter may be referred to as toner) they use. The first cartridge PY contains yellow (Y) toner. It forms a yellow (Y) toner image on the peripheral surface of a photosensitive drum40. The second cartridge PM contains magenta (M) toner. It forms a magenta (M) toner image on the peripheral surface of the photosensitive drum40. The third cartridge PC contains cyan (C) toner. It forms a cyan (C) toner image on the peripheral surface of the photosensitive drum40. The fourth cartridge PK contains black (K) toner. It forms a black (K) toner image on the peripheral surface of the photosensitive drum40.

Above the combination of the first to fourth cartridges (PY, PM, PC and PK), a laser scanner unit LS is provided as an exposing means. This laser scanner unit LS outputs a beam Z of laser light while modulating the beam Z according to the information of the image to be formed. As the beam Z of laser light is outputted, it projects through an exposure window of the cartridge P, and scans (exposes) the peripheral surface of the photosensitive drum40.

Below the combination of the first to fourth cartridges (PY, PM, PC and PK), an intermediary transfer unit11is disposed as a transferring member. The intermediary transfer unit11has a driver roller13, a turn roller17, and a tension roller15. It has also a flexible transfer belt12, which is suspended by the abovementioned three rollers13,17and15.

The photosensitive drum40of each of the first to fourth cartridges (PY, PM, PC and PK) is in contact with the upwardly facing portion of the outwardly facing surface of the transfer belt12. The area of contact between the photosensitive drum40and transfer belt12is a primary transfer portion. On the inward side of the loop which the transfer belt12forms, four primary transfer rollers16are disposed so that they oppose the four photosensitive drums40one for one.

Against the turn roller17, a secondary transfer roller14is kept pressed with the presence of the transfer belt12between the two rollers17and14. The area of contact between the transfer belt12and secondary transfer roller14is a secondary transfer portion.

Below the intermediary transfer unit11, a sheet feeding-conveying unit18is disposed. This sheet feeding-conveying unit18has a sheet feeding-conveying tray19in which sheets S of recording medium are stored in layers, and a sheet feeding-conveying roller20which feeds the sheets S from the sheet feeding-conveying tray19into the main assembly2, one by one, and conveys each sheet S further into the main assembly2.

Referring toFIG. 2, in the top-left portion of the main assembly2, a fixation unit21and a discharge unit22are disposed. A part of the top surface of the main assembly2is utilized as a delivery tray23. As each sheet S of recording medium is conveyed through the abovementioned fixation unit21, the toner image on the sheet S is fixed to the sheet S by a fixing means, with which the fixation unit21is provided. Then, the sheet S is discharged by the discharge unit22into the abovementioned delivery tray23.

Next, the operation carried out by the image forming apparatus1structured as described above to form a full-color image is described.

The photosensitive drum40in each of the first to fourth cartridges (PY, PM, PC and PK) is rotationally driven at a preset speed (direction indicated by an arrow mark inFIG. 2; counterclockwise direction). The transfer belt12is rotationally driven so that it moves in the same direction (direction indicated by arrow mark C inFIG. 2) in the area of contact between photosensitive drum40and transfer belt12at a speed which corresponds to the speed of the photosensitive drum40.

The laser scanner unit LS scans (exposes) the peripheral surface of each photosensitive drum40with the beam Z of laser light it emits while modulating the beam Z with image formation signals which correspond to monochromatic images into which the image to be formed was separated. Consequently, an electrostatic latent image, which reflects the image formation signals, is effected on the peripheral surface of the photosensitive drum40. Then, the latent image is developed by a development roller42, which is in a developing device41and is rotationally driven at a preset speed.

Through an electrophotographic image formation process such as the above-described one, a yellow (Y) toner image, which corresponds to the yellow component of the full-color image to be formed, is formed on the peripheral surface of the photosensitive drum40in the first cartridge PY. This toner image is transferred (primary transfer) onto the transfer belt12.

Similarly, on the photosensitive drum40of the second cartridge PM, a magenta (M) toner image which corresponds to the magenta (M) component of the full-color image to be formed, is formed. This toner image is transferred (primary transfer) onto the transfer belt12, in a manner to be layered upon the yellow (Y) toner image which has just been transferred onto the transfer belt12.

Similarly, on the photosensitive drum40of the third cartridge PC, a cyan (C) toner image which corresponds to the cyan (C) component of the full-color image to be formed, is formed. This toner image is transferred (primary transfer) onto the transfer belt12, in a manner to be layered upon the yellow (Y) and magenta (M) toner images, which have just been transferred onto the transfer belt12.

Similarly, on the photosensitive drum40of the fourth cartridge PK, a black (K) toner image which corresponds to the black (K) component of the full-color image to be formed, is formed. This toner image is transferred (primary transfer) onto the transfer belt12, in a manner to be layered upon the yellow (Y), magenta (M), and cyan (C) toner images, which have just been transferred onto the transfer belt12.

Consequently, an unfixed full-color toner image is synthetically formed of yellow (Y), magenta (M), cyan (C), and black (K) monochromatic images, on the transfer belt12.

Meanwhile, the sheet feeding-conveying roller20begins to be driven with preset timing, whereby the sheets S stored in layers in the sheet feeding: conveying tray19begin to be fed into the main assembly2, while being separated one by one, and to be guided into the secondary transfer nip, which is the area of contact between the secondary transfer roller14and transfer belt12, to be conveyed through the nip.

While each sheet S of recording medium is conveyed through the secondary transfer nip, the four toner images which are different in color and are layered on the transfer belt12are transferred together onto the sheet S as if they are peeled away from the transfer belt12.

Next, an input device (input device having push-keys) is described about its structure. Referring toFIG. 1, the main assembly2of the image forming apparatus1is provided with an input device A through which the image forming apparatus1receives inputs from a user. The input device A is disposed so that its top surface is exposed upward. In this embodiment, the input device A is an integral part of a top cover80of the main assembly2.

The input device A is provided with a display74, and keys51,52b,52cand53dwhich are operable by a user. Among the four keys, the key51can be illuminated from its inward side. It is for a user to connect the image forming apparatus1to a wireless LAN, or disconnect the image forming apparatus1from the wireless LAN. That is, as the key51is pressed once by a user, not only is the image forming apparatus1connected to the wireless LAN, but also, the key51is illuminated to confirm that the image forming apparatus1is in connection to the wireless LAN. On the other hand, as the key51is pressed while the key51is luminous, the key51stops being luminous, and the image forming apparatus1becomes disconnected from the wireless LAN. Disconnecting the image forming apparatus1from the wireless LAN reduces the image forming apparatus1in electric power consumption.

Referring to parts (a) and (b) ofFIG. 3and parts (a) and (b) ofFIG. 4, the input device A is an assembly of an input key member50(base member), and an electric circuit board70on which the input key member50is layered. The entirety of the input key member50(base member) is molded in one-piece, of a resinous substance. It has a main portion50h, and key portions51,52b,52cand52dhaving an area to be pressed by a user. Each key portion51,52b,52cand52dis connected to the main portion50hwith elastic portions, as will be described later. The circuit electric board70is provided with switches (on which key portions act)71a-71f, four of which correspond to the key portions51,52b,52cand52d, respectively, and a light emitting element72for illuminating the luminous key portion51. The switches71a-71fare sensors that detect whether or not the corresponding key portions51,52b,52cand52dhave just been pressed. One of these switches, more specifically, the switch71a, corresponds to the luminous key portion51. The switch71bcorresponds to the key portion52b. The switch71ccorresponds to the key portion52c. The switch71dcorresponds to the key portion52d. The switches71eand71fcorrespond to a multifunction input key60. As any of these keys is pressed by a user, the input device A informs the control portion (unshown) which input key has just been pressed. Then, the control portion presents the information related to the pressed key on a display74. Further, it displays on the display74, information regarding whether or not the image forming apparatus1is in connection to the wireless LAN, in response to whether or not the light emitting element72is on (whether or not switch71ais on). With use of the input device A, a user can conversationally choose various functions of the image forming apparatus1.

Referring to part (a) ofFIG. 5, the main portion50hof the input key portion member50(base member) is connected to the luminous key portion51and non-luminous key portions52b-52dby elastic portions57a1,57a2-57d. That is, the main portion50h, key portions52b-52d, and elastic portions57a-57dare integral parts of a one-piece component. All the key portions except for the luminous key portion51are connected to the main portion50hby two elastic portions. More specifically, the key portion52bis connected to the main portion50hby two elastic portions57b. The key portion52cis connected to the main portion50hby two elastic portions57c. The key portion52dis connected to the main portion50hby two elastic portions57d. To the main portion50h, the base portion of each elastic portion is connected. As a key portion is pressed, the corresponding elastic portions elastically deform, allowing the key to move relative to the main portion50hto press on the corresponding switch.

The key portion51is connected to the main portion50hby first and second elastic portions57a1and57a2. As the key portion51is seen from the direction which is perpendicular to a control panel51P, the first and second elastic portions57a1and57a2are symmetrically shaped and positioned with reference to a hypothetical line L51which coincides with a center C51of the key portion51. In this embodiment, other elastic portions57a1,57a2-57dare also symmetrically shaped and positioned with reference to a hypothetical line which coincides with the center of the corresponding key.

Further, the surface of the input key member50(base member), which faces the electric circuit board70, is provided with pressing sections53a-53dfor pressing down the switches71a-71d. The pressing section53ais for pressing the switch71a, and the pressing section53bis for pressing the switch71b. The pressing section53cis for pressing the switch71c, and the pressing section53dis for pressing the switch71d. Also, the pressing section53eis for pressing the switch71e, and the pressing section53fis for pressing the switch71f.

Referring to parts (a) and (b) ofFIG. 4, the input key member50(base member) having keys has first positioning holes55aand55b, whereas the top cover80has positioning bosses85aand85b. As the input key member50(base member) is attached to the top cover80so that the positioning bosses85aand85bfit into the first positioning holes55aand55b, respectively, the input key member50(base member) is precisely positioned relative to the top cover80.

Further, the electrical circuit board70has second positioning holes75aand75b. As the electrical circuit board70is attached to the top cover80so that the positioning bosses85aand85bfit into the second positioning holes75aand75b, the electrical circuit board70is precisely positioned relative to the top cover80.

Referring to parts (a) and (b) ofFIG. 3, and parts (a) and (b) ofFIG. 4, the multifunction input key60is provided with a pair of rotational shafts66aand66b, and a pair of pressing sections63eand63f. Referring to part (a) ofFIG. 3, the input key member50is provided with a pair of bearings56aand56b, which correspond to the rotational shafts66aand66bof the multifunction input key60, and by which the rotational shafts66aand66bare borne, respectively. As the left or right side of the multifunction input key60is pressed, the multifunction input key60pivotally moves about the rotational shafts66aand66b, becoming thereby tilted. Consequently, the switches71eand71fon the electrical circuit board70are pressed down by the pressing sections63eor63f, respectively.

Next, the structure of the luminary (or luminous) key portion51is described in detail. Part (a) ofFIG. 5is a top view of the input key member50, and part (b) ofFIG. 5is a sectional view of the input key member50. Part (a) ofFIG. 5shows the pressing section53a, switch71a, and light emitting element72, which are contoured by broken lines.

The center portion of the luminary key portion51is provided with a round transparent area B, which is formed of transparent resin. On the other hand, other portions (main portion50h, key portions51,52b,52c,52d) of the input key member50(base member) than the center portion of the luminary key portion51are formed of opaque resin. The transparent area B is formed as an integral part of the input key member50(base member), which is molded in one-piece. In this embodiment, the material for the transparent area B of the input key member50(base member) is PS (Polyester), whereas the material for the other portions (opaque portions) of the input key member50(base member) is ABS (Acrylonitrile Butadiene, Styrene).

The light emitting element72on the electric circuit board70is directly below the transparent area B of the luminary key portion51. More specifically, the light emitting element72is positioned so that in terms of the direction perpendicular to the control panel51P, the center of the light emitting element72aligns with the center of the center C51of luminary key portion51. Therefore, the switch71aand pressing section53a, which correspond to the luminary key portion51, cannot be positioned directly below the luminary key portion51. That is, as the luminary key portion51is seen from the direction perpendicular to the control panel51P, the light emitting element72is positioned closer to the center C51of the luminary key portion51than the switch71a(on which pressing section53aacts). Therefore, the switch71aand pressing section53a, which correspond to the luminary key portion51, are positioned so that they are offset leftward relative to the light emitting element72, as shown in part (a) ofFIG. 5. Also as the luminary key portion51is seen from the direction perpendicular to the control panel51P, the switch71a(on which pressing section53aacts) is positioned so that it is closer to the first elastic portion57a1than the second elastic portion57a2.

Further, the luminary key portion51is supported not only by the first and second elastic portions57a1and57a2, but also, by an elastic portion58a(third elastic portion), which is the hatched portion in the drawing. Here, the first and second elastic portions57a1,57a2, and the elastic portions57b-57dwhich support the input keys52b-52d, are shaped and positioned so that they are symmetrical with reference to either a vertical line which coincides with the center of the corresponding key, or a horizontal line which coincides with center of the corresponding key. In comparison, there is no elastic portion which is shaped and positioned to be symmetrical with reference to a vertical or horizontal line which coincides with the center of the corresponding key. In this embodiment, the third elastic portion58ais positioned to connect the key portion51to the second elastic portion57a2. However, it may be positioned to connect the key portion51to the main portion50h. When all is said and done, the input key member50(base member) is provided with the third elastic portion58a, which connects the key portion51to the main portion50hor the second elastic portion57a2. Further, the third elastic portion58ais on the second elastic portion57a2side of the hypothetical line L51.

Here, it is desired that the length L2of the third elastic portion58ais less than the length L1of the first elastic portion57a1(57a2). The provision of the third elastic portion58a(which preferably satisfies inequality: L1>L2) increases in rigidity, the elastic portion (on second elastic portion57a2side) which is on the opposite side from the pressing section53a. Therefore, it is possible to prevent the problem that as the third elastic portion58ais made to press on the switch71aby the pressing of the key portion51, the key portion51tilts.

Part (b) ofFIG. 5is a sectional view of the luminary key portion51and its adjacencies. The luminary key portion51is provided with a bumping portion59, which is on the opposite portion of the luminary key portion51from the pressing section53a, with reference to the transparent area B of the luminary key portion51. Thus, it is possible to prevent the problem that as the luminary key portion51is pressed hard by a user, the switch71ais damaged.

At this time, what occurs to the input device A in this embodiment as the luminary key portion51is pressed is described with reference to a comparative example of an input device. Part (a) ofFIG. 6is a top view of the comparative example of input key member50, and part (b) ofFIG. 6is a sectional view of the comparative example of input key member50. In the case of the comparative example of input key member50, it is only the first and second elastic portions57a1and57a2that supports the luminary key portion51(third elastic portion58ais not provided). Part (a) ofFIG. 7is a sectional view of the luminary key portion51and its adjacencies in the comparative example of input device A, when the luminary key portion51is being pressed. Part (b) ofFIG. 7is a sectional view of the luminary key portion51and its adjacencies in the input device A in this embodiment when the luminary key portion51is being pressed.

In the case of the comparative example of input device A shown in part (a) ofFIG. 7, as a user presses on the luminary key portion51, the pressing section53acomes into contact with a part of the switch71a, and the luminary key portion51is made to pivotally move (tilt) about the point of contact between the pressing section53aand switch71a. Thus, it is possible that the amount by which force is applied to the switch71aby the pressing section53aof the luminary key portion51will be insufficient, and therefore, the switch71awill not respond. In the case of the comparative example of input device A, therefore, unless the luminary key portion51is pressed harder (deeper) than the nonluminous key portions52b-52d, the pressing section53adoes not press the switch71ahard enough to activate the switch71a. Thus, a user might feel that the luminary key portion51is inferior in tactility.

On the other hand, in this embodiment, the luminous key portion51is supported by the third elastic portion58ain addition to the first and second elastic portions57a1and57a2. Therefore, the input key member50is higher in rigidity across the area which is on the opposite side (right side in parts (a) and (b) ofFIG. 5of the luminary key portion51from the pressing section53a. Therefore, as a user presses down the luminary key portion51, the pressing section53apresses on the top surface of the switch71ain the roughly vertical direction. Therefore, the luminary key portion51remains the same (excellent) in tactility, because the luminary key portion51descends with the top surface of the luminary key portion51remaining parallel to the electric circuit board70.

As described above, according to this embodiment, it is possible to place the light emitting element72directly below the transparent area B of the luminary key portion51. Therefore, it is possible to make the luminary key portion51better in terms of how it looks when it is illuminated. Further, the input key member50is provided with the third elastic portion58awhich is asymmetrical in shape and positioning, in addition to multiple elastic portions by which the luminary key portion51is supported in a conventional input key member. It is possible to provide an input device which is classier in tactility (usability) than a conventional one, without the cost increase attributable to the need for additional components.

In the above-described first embodiment, the switch71awas placed on the portion of the electric circuit board70, which is offset from the center C51of the luminary key portion51in terms of the first direction, that is, the left-right direction, in part (a) ofFIG. 5. Further, in terms of the second direction, that is, the top-bottom direction, which is perpendicular to the first direction, the switch71ais positioned so that it aligns with the center C51of the luminary key portion51. However, the first embodiment is not intended to limit the present invention in terms of the positioning of the luminary key portion51and switch71arelative to each other. For example, the switch71aand pressing section53amay be asymmetrically positioned with reference to the center C51of the luminary key portion51in terms of the left-right and/or top-bottom direction. Also in the first embodiment, a fourth elastic portion58bis provided in addition to the third elastic portion58a. Referring toFIG. 8, a center C53aof the pressing portion (center of portion to be pressed) is positioned on the bottom side of a second hypothetical line L51Y which is perpendicular to the hypothetical line L51. The third elastic portion58ais positioned on the second elastic portion57a2side of the hypothetical line L51. The fourth elastic portion58bis positioned on the opposite side of the second hypothetical line L51Y from the center C53a(center of switch71a) of the pressing section53a. Positioning an additional third elastic portion58aor the like as described above can further improve the luminary key portion51in tactility (how the luminary key portion51feels as user presses the luminary key portion51).

Also in the above-described first embodiment, the entirety of the luminary key portion51is an integral part of the input key member50(base member) which is molded in one-piece. However, the first embodiment is not intended to limit the present invention in terms of how the luminary key portion51is formed. For example, a part51P1of the luminary key portion51may be separately formed from the rest of the luminary key portion51, so that it can be removably attached to the rest. Even if the luminary key portion51is formed in this manner, the effects of the first embodiment are the same as those described above. Further, in the case of the input device A shown inFIG. 9, only the transparent area B of the part51P1of the luminary key portion51is transparent, whereas the rest of the part51P1are opaque. Further, the transparent portion of the part51P1of the luminary key portion51, and the opaque portion of the part51P1of the luminary key portion51, are molded together, of transparent resin and opaque resin, respectively, as integral parts of the part51P1of the luminary key portion51. Moreover, the part51P1of the luminary key portion51is provided with a hook-like portion51F, which engages with the hook-like portion51P2of the luminary key portion51of the input key member50(base member) when the luminary key portion51is attached to the input key member50(base member).

FIG. 10shows another embodiment of the present invention. The input key member50(base member) includes the main portion50hand a part51B of the luminary key portion51, which are molded together as integral parts of the input key member50(base member) molded in one-piece. In the case of this embodiment, however, the center portion of the part51B of the luminary key portion51is nothing but a hole H; the part51B does not have the transparent portion. A referential code51T stands for a component which makes up a part of the luminary key portion51. The component51T is formed of a transparent substance, and is shaped like a cap. It is attached to a the part51B of the luminary key portion51to complete the luminary key portion51. That is, the luminary key portion51may be a combination of the opaque part51B and transparent component51T.

In all the embodiments described above, the keys which are to be illuminated by a light emitting element were provided with the third elastic portion. Instead, however, the input device A may be structured so that the pressing portion of a key which is not illuminated by a light emitting element is positioned closer to the first elastic portion than to the second elastic portion, and the base member is provided with the elastic portion which corresponds to this key.

Further, in each of the above-described embodiments, the image forming apparatus was a printer. However, the preceding embodiments are not intended to limit the present invention in terms of an apparatus to which the present invention is applicable. That is, the present invention is also applicable to other image forming apparatuses than a printer. For example, the present invention is also applicable to a copying machine, a facsimile machine, and multifunction machine capable of performing two or more functions of the abovementioned machines. Moreover, the present invention is also applicable to a monochromatic image forming apparatus.

This application claims the benefit of Japanese Patent Applications Nos. 2015-111982 filed on Jun. 2, 2015 and 2016-078999 filed on Apr. 11, 2016, which are hereby incorporated by reference herein in their entirety.