Sheet feeder with a light sensor

Abstract

A sheet feeder includes a housing, a cover and a sensing device. The cover is mounted on the housing, and the sensing device is disposed between the housing and the cover. The sensing device includes a light sensor and a reflecting mirror. The light sensor is mounted on the inside surface of the cover, and the reflecting mirror is mounted on the housing opposite the light sensor. As a signal light is being emitted from the light-emitting unit of the light sensor, the signal light is reflected from the reflecting mirror or a document and received by the receiving unit of the light sensor. The reflected signal light will then be transformed to a signal voltage which, according to its value, indicates the using status of the sheet feeder, such as ‘without document’, ‘document present’ or ‘cover open’, such that the number of the sensors on the sheet feeder can be reduced and the manufacturing costs can be lessened.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a sheet feeder structure. The sheet feeder is mounted on a scanning device to provide an automatic document feeding function. More particularly, the sheet feeder comprises a housing and a cover and the housing is functioning in conjunction with the cover, and a sensing device is disposed between the cover and the housing. The intensity of the signal light emitted and received by the sensing device indicates the operational status of the sheet feeder, namely, whether or not a document is present or whether the cover is open or closed.

2. Description of the Prior Art

The scanning device is used to scan images. The scanning is executed via the relative motion of an optical mechanism mounted in the scanning device and a to-be-scanned document. A sheet feeder is usually used to feed to-be-scanned documents the relative motion.

As shown in FIG. 1, a sheet-feeding scanner 10 is combined with a sheet feeder 12, such that the optical mechanism (not shown in the figure) in the sheet feeder 12 is capable of scanning images when to-be-scanned documents are fed in.

As shown in FIG. 2, a flatbed scanner 20 is combined with a sheet feeder 22. The sheet feeder 22 is capable of feeding to-be-scanned documents by the optical mechanism in the scanner 20.

FIG. 3 is a schematic view showing the structure of a sheet feeder 30, which is similar to the structure of the two aforementioned sheet feeders. The sheet feeder 30 has a housing 32 and a cover 34. The housing 32 has an internal combination structure comprising a plurality of rollers and transmission belts (or gears). Automatic pickup and feeding of to-be-scanned documents are executed via the roller combination. The cover 34 is joined with the housing 32 pivotally and can be opened or closed against the housing 32.

In a typical sheet feeder, a cover sensor 36 is disposed between the cover 34 and the housing 32 to detect whether the cover 34 is open. When the cover 34 is open, the automatic document feeding function of the sheet feeder 30 is suspended. A light sensor 38 is also disposed between the cover 34 and the housing 32 to detect whether there is any to-be-scanned document in the feeding passage of the sheet feeder 30. If no document is in the feeding passage, the automatic document feeding function is suspended.

In addition to the sensor to detect the open/closed status of the cover 34, a sheet feeder 30 with the aforementioned structure requires another independent sensor to detect whether any to-be-scanned document is in the feeding passage. Any additional structures would increase the number of parts used, which in turn would increase the cost of the production.

SUMMARY OF THE INVENTION

The present invention provides a structure of a sheet feeder which has a sensor and a reflecting mirror mounted between the housing and the cover of the sheet feeder. The sensor detects the open/closed status of the cover and detects the presence of a document in the feeding passage via the interaction of the sensor and reflecting mirror.

More particularly, a light sensor is mounted on the inside surface of the cover and a reflecting mirror is mounted on the housing opposite to the light sensor and forms a non-parallel configuration with the light sensor. Through this non-parallel configuration, the open/closed status of the cover is readily detected. A signal light is emitted by a light-emitting unit of the light sensor, reflected by the reflecting mirror and at last received by a receiving unit of the light sensor. The signal light received by the light sensor is then transformed to different signal voltage values, which would, in result, indicate the different operational statuses of the sheet feeder.

The following is a preferred embodiment of the present invention described based on the objective, functional and structural configuration thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a sheet-feeding scanner;

FIG. 2 is a perspective view of a combined set of a flatbed scanner and a sheet feeder;

FIG. 3 is a schematic view showing a structure of a prior art sheet feeder;

FIG. 4 is a schematic view showing the structure of the present invention;

FIG. 5 is a schematic view showing the using status without documents to be scanned;

FIG. 6 is a schematic view showing the using status with documents to be scanned;

FIG. 7 is a schematic view showing that the cover of the present invention is opened; and

FIG. 8 is a schematic view showing the structure of another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 4 is a schematic view showing the structure of a sheet feeder 40. The sheet feeder 40 is capable of working together with a sheet-feeding scanner or a flatbed scanner. The sheet feeder 40 has a plurality of rollers and transmission devices inside (not shown in the figure).

The sheet feeder 40 includes a housing 42 and a cover 44, and most of the aforementioned rollers and transmission devices are mounted in the housing 42. The cover 44 is joined with the housing 42 pivotally and can be opened or closed against the housing 42.

A sensing device 50 is mounted between the cover 44 and the housing 42. The sensing device 50 includes a light sensor 52 and a reflecting mirror 54. The light sensor could be, for example, an infrared sensor, a LED sensor and etc. The light sensor 52 has a light-emitting unit 522 and a receiving unit 524, which are mounted on the inside surface of the cover 44 and can be positioned side by side.

The reflecting mirror 54 is mounted on the housing 42 opposite the light sensor 52. The reflecting mirror 54 is finely adjusted such that the reflecting mirror 54 forms an angle in a non-parallel position opposite the light sensor 52.

FIG. 5 shows that there is no to-be-scanned document in the feeding passage between the cover 44 and the housing 42. A signal light is emitted from the light-emitting unit 522 and reflected from the reflecting mirror 54, and then received by the receiving unit 524. Since the reflecting mirror 54 has a high reflectivity, the receiving unit 524 receives a reflected signal light of a high intensity. The received signal light intensity is then transformed to a signal voltage of a high voltage value V1.

FIG. 6 shows that there is a to-be-scanned document 62 in the feeding passage 60. A signal light is emitted from the light-emitting unit 522, reflected from the to-be-scanned document 62, and then received by the receiving unit 524. Since the signal light is reflected by the to-be-scanned document 62, which has a lower reflectivity than that of the reflecting mirror, the receiving unit 524 receives a signal light of a lower intensity. The received signal light intensity is then transformed to a signal voltage of a lower voltage value V2, and V2<V1.

FIG. 7 shows that the cover 44 is open. Only a part of the signal light emitted by the light-emitting unit is reflected from the reflecting mirror 54 and, in turn, received by the receiving unit 524. The received signal light is then transformed to a signal voltage with a value of V3, and V3<V2.

The design concept as described in the aforementioned embodiment is to utilize the changes in the intensities of the signal light received by the receiving unit 524 as the document 62 is fed to the sheet feeder, no document 62 is fed and the cover 44 is open, and to determine the operational status of the sheet feeder according to the different voltage values transformed from the different intensities of the reflected signal light. For example, V1 greater than 3V indicates that there is no to-be-scanned document 62 and the cover 44 is closed. V2 between 1.7V and 1.8V indicates that there is a to-be-scanned document 62 entering the feeding passage 60. V3 less than 1V indicate that the cover 44 is open. The present invention needs only one sensing device and can reduce the production cost effectively in comparison with existing state of art, which need two sensing devices.

In the aforementioned embodiment, the light sensor 52 is mounted on the inside surface of the cover 44, while the reflecting mirror 54 is mounted on the housing 42. FIG. 8 shows another embodiment in which the reflecting 54 is mounted on the inside surface of the cover 44, while the light sensor 52 is mounted on the housing 42. The reflecting mirror 54 and the light sensor 52 are positioned opposite each other and form a non-parallel configuration. This embodiment is carried out in the same way as the previous embodiment.

Although the present invention has been disclosed and illustrated with reference to the preferred embodiments, the principles involved can be applied for use in numerous other embodiments that will be apparent to persons skilled in the art. The present invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Claims

1. A sheet feeder with a light sensor to be mounted on an image scanning device which provides an automatic feeding function for a to-be-scanned document comprises:

A housing;

A cover mounted on said housing and opened or closed against said housing;

A feeding passage formed between said cover and housing for the to-be-scanned document;

A sensing device mounted between said housing and cover;

Said sensing device comprising a light sensor and a reflecting mirror opposite to said light sensor; said light sensor receiving signal lights of different intensities under different circumstances, such as when no said to-be-scanned document is fed, when said to-be-scanned document is fed, and when said cover is open; said signal lights of the different intensities being then transformed to different voltage values and said voltage value serving as an indication of the operational status of said sheet feeder.

2. The sheet feeder of claim 1, wherein said light sensor of said sensing device and said reflecting mirror are opposite to each other and form a non-parallel configuration.

3. The sheet feeder of claim 1, wherein said light sensor has a light-emitting unit and a receiving unit.

4. The sheet feeder of claim 3, wherein said light-emitting unit and said receiving unit are mounted on an inside surface of said cover.

5. The sheet feeder of claim 3, wherein said light-emitting unit and said receiving unit are mounted on said housing.

6. The sheet feeder of claim 1, wherein said image scanning device is a sheet-feeding scanner.

7. The sheet feeder of claim 1, wherein said image scanning device is a flatbed scanner.

8. The sheet feeder of claim 1, wherein the voltage value is defined as V1 when no said to-be-scanned document is fed, the voltage value is defined as V2 when said to-be-scanned document is fed, and the voltage value is defined as V3 when said cover is open, and V1>V2>V3.