An encapsulated endoscope in which exposure amount is controlled at the light source side, and a MOS image sensor is not required to mount a vertical scanning circuit for electronic shutter which is to provide an exposure amount control function. Therefore, since a vertical scanning circuit for electronic shutter is not mounted, the sensor area can be made smaller so that size of the interior of the encapsulated endoscope can be reduced.

This application claims benefit of Japanese Patent Application No. 2005-313961 filed in Japan on Oct. 28, 2005, the contents of which are incorporated by this reference.

BACKGROUND OF THE INVENTION

The present invention relates to an encapsulated endoscope.

It is generally known to provide a vertical scanning circuit for electronic shutter as a means for controlling exposure amount in solid-state imaging apparatus that are used in various imaging apparatus. The construction and method of controlling exposure amount will be described below of a prior-art solid-state imaging apparatus (area sensor) disclosed in Japanese Patent Application Laid-Open Hei-5-227489.FIG. 1is a block diagram of an overall construction of area sensor40as disclosed in the above publication. The area sensor40includes: a pixel section13having a plurality of pixels two-dimensionally disposed in rows and columns; a vertical scanning circuit15(hereinafter referred to as read vertical scanning circuit) for selecting a row of the pixel signals of the pixel section13to be read and sequentially switching the selected row; a vertical scanning line16for connecting between the pixel section13and the read vertical scanning circuit15; a vertical scanning circuit42(hereinafter referred to as electronic shutter vertical scanning circuit) for resetting charge signals accumulated at the pixels; a vertical scanning line16′ for connecting between the pixel section13and the electronic shutter vertical scanning circuit42; a vertical signal line17onto which the pixel signals of the rows to be read, selected at the read vertical scanning circuit15are outputted; a horizontal read circuit14for sequentially outputting the signals outputted onto the vertical signal line17; and an operation control section19for controlling operation of the area sensor40.

The pixel section13consists of a light-receiving pixel region11and a light-blocked pixel region12. The read vertical scanning circuit15is provided to the left of the pixel section13while the electronic shutter vertical scanning circuit42is provided to the right of the pixel section13.

FIG. 2is a timing chart for explaining an exposure amount control operation when light is continuously irradiated onto the area sensor40. Supposing that the scanning direction of the read vertical scanning circuit15and the electronic shutter vertical scanning circuit42of the area sensor40is from the upper portion to the lower portion of the pixel section13, the signals accumulated at the pixels are reset once between n-th and (n+1)-th frames as shown in the timing chart of the reset signal output and pixel region output ofFIG. 2, and pixel signals accumulated again after the resetting are read out. The exposure time (exposure time1, exposure time2) for thus read pixel signals is time from the resetting to the readout, i.e., the time difference between the reset timing of a-th row and the read timing of a-th row.

Such exposure time then is proportional to the number of rows occurring between the row (b-th row in the illustrated example) where pixel signals are being reset by the electronic shutter scanning circuit42at a point in time t1when pixel signals (a-th row in the illustrated example) are read out by the read scanning circuit15and the row (a-th row) where the pixel signals are being read out by the read scanning circuit15. The exposure time, therefore, is controlled by changing such number of rows.

In addition, of imaging apparatus for taking images of a dark part for example in the body cavity, there is a method of controlling exposure amount by controlling an emission of light source.FIG. 3shows an encapsulated endoscope where such exposure amount control method is used as disclosed in Japanese Patent Application Laid-Open 2005-552.

As shown inFIG. 3, an encapsulated endoscope2disclosed in the above publication has an outward appearance of a capsule-type tablet form. It includes a case3for example of a resin formed into a capsule having a substantially oval longitudinal section. A front portion of case3is formed of a transparent member3a. At the interior of the case3, the encapsulated endoscope2has its main portion where the following members are disposed. In particular, disposed in a front portion facing the transparent member3aare: a light source6for example of LED for illuminating an object to be taken such as a digestive organ within the body cavity; an observation optical system8(hereinafter referred to as objective lens) for forming an optical image of the object illuminated by the light source6; and an area sensor40consisting for example of CCD or CMOS sensor for taking an image through the objective lens8and effecting predetermined photoelectric conversion processing to generate image signals. Disposed from there toward the back are: a light source drive control section5receiving output from the area sensor40for controlling light amount or light-emitting time of and driving the light source6; a drive control/signal processing unit9having a drive control circuit and signal processing circuit of the area sensor40; a communication unit10receiving image signals outputted from the drive control/signal processing unit9to transmit/output the same to a predetermined receiving/record ing apparatus (not shown) provided at the outside of the body cavity for example with using a wireless communication; and a power supply4consisting of power supply batteries4aand4b.

Of thus constructed encapsulated endoscope2, the light source drive control section5determines light emitting conditions (emitting light amount and/or emitting time) of the light source6based on the output signals of the area sensor40and drives the light source6based on the determined light emitting conditions using the drive signals from the drive control/signal processing unit9.

FIG. 4shows drive timing (timing of light source drive current) of the light source6and the drive timing (timing of pixel region output) of the area sensor40. In a dark part such as in the body cavity, light does not enter the area sensor40unless the light source6is caused to emit. In other words, the emitting time of the light source6is the exposure time of the area sensor40. Accordingly, the exposure amount of the area sensor40can be controlled by controlling the light emitting conditions of the light source6.

In the case where MOS imaging device is mounted on an encapsulated endoscope and the exposure amount is controlled at the light source, an electronic shutter function provided at an ordinary MOS imaging device is unnecessary because the interior of the body cavity is dark. On the other hand, there is a limit on the length and/or thickness of an encapsulated endoscope, since the encapsulated endoscope is to take images at the interior of the body cavity. For this reason, size reduction of MOS imaging device is a necessity when downsizing of the encapsulated endoscope is considered.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an encapsulated endoscope capable of further downsizing with mounting MOS imaging device having a suitable structure.

In a first aspect of the invention, there is provided an encapsulated endoscope including: MOS imaging device having a pixel section of a plurality of pixels disposed two-dimensionally in rows and columns, each pixel with a photodiode and MOS transistor where a signal from the photodiode is amplified and outputted as a pixel signal, a sole and exclusive vertical scanning section for generating row select signals to select pixels of the pixel section by rows and to cause each pixel signal to be outputted to a plurality of vertical signal lines provided for each column, and a horizontal scanning circuit for causing selective outputting of each pixel signal outputted onto the plurality of vertical signal lines; an illumination light source section; a light source control section for controlling light emitting amount or emitting time of the illumination light source section; and a drive control/signal processing unit for controlling the light source control section to illuminate an object by said illumination light source section during a predetermined time and causing the pixel signals of said MOS imaging device to be outputted thereafter.

In a second aspect of the invention, the pixel section in the encapsulated endoscope according to the first aspect comprises a rectangular region with its center at a position corresponding to a substantial center of the MOS imaging device as a light-receiving pixel region, and a region surrounding the light-receiving pixel region as a light-blocked pixel region.

In a third aspect of the invention, the vertical scanning section in the encapsulated endoscope according to the first or second aspect has a first vertical scanning unit corresponding to odd rows of the pixel section and a second vertical scanning unit corresponding to even rows of the pixel section, the first vertical scanning unit and the second vertical scanning unit being disposed at regions opposing each other with the pixel section between them.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A description will be given below of some embodiments with reference to the drawings. A first embodiment of the encapsulated endoscope according to the present invention will now be described.FIG. 5is a block diagram schematically showing construction of the electrical circuit of an encapsulated endoscope2according to the first embodiment, where like or corresponding components as in the prior-art encapsulated endoscope2shown inFIG. 3are denoted by like reference numerals. The construction and drive operation of the encapsulated endoscope according to the first embodiment shown inFIG. 5are substantially identical to the construction and drive operation of the prior-art encapsulated endoscope shown inFIG. 3, and MOS image sensor1is suitably used as the area sensor therein. Further, since exposure amount thereof is controlled at the light source side, an exposure amount control at MOS image sensor1is not to be effected.

FIG. 6is a block diagram schematically showing construction of MOS image sensor1to be mounted on the encapsulated endoscope according to the first embodiment, where like or corresponding components as in the prior-art area sensor shown inFIG. 1are denoted by like reference numerals. The MOS image sensor1includes: a pixel section13having a plurality of pixels two-dimensionally disposed in rows and columns, each pixel containing a photodiode for effecting photoelectric conversion and an amplifying MOS transistor where the optically produced charge generated at the photodiode is changed to voltage and amplified to be outputted; a read vertical scanning section15for selecting rows to be read out of the pixel signals of the pixel section13and sequentially switching the rows to be selected; a vertical scanning line16connecting between the pixel section13and the read vertical scanning section15; a vertical signal line17to which the pixel signals of the read rows, selected at the read vertical scanning section15are outputted; a horizontal read circuit14for sequentially outputting the signals outputted onto the vertical signal line17; and an operation control section19for controlling operation of MOS image sensor1. The pixel section13consists of a light-receiving pixel region11and a light-blocked pixel region12, and the vertical scanning section15is provided to the left of the pixel section13.

Since exposure amount of the encapsulated endoscope2according to the first embodiment shown inFIG. 5is controlled at the light source side, MOS image sensor1is not required to mount a vertical scanning circuit for electronic shutter which is to provide an exposure amount control function. Accordingly, due to the fact that a vertical scanning circuit for electronic shutter is not mounted, the sensor area can be made smaller as compared to the prior-art MOS image sensor so that size of the interior of the encapsulated endoscope can be reduced.

Second Embodiment

A second embodiment of the invention will now be described.FIG. 7Ais a block diagram schematically showing construction of the electrical circuit of an encapsulated endoscope2according to the second embodiment, where like or corresponding components as in the encapsulated endoscope according to the first embodiment shown inFIG. 5are denoted by like reference numerals. The construction and drive operation of the encapsulated endoscope according to the second embodiment is identical to the construction and drive operation of the encapsulated endoscope according to the first embodiment shown inFIG. 5.FIG. 7Bshows a front view as seen from the object side of the encapsulated endoscope2according to the second embodiment shown inFIG. 7A, where the center of MOS image sensor1is denoted by numeral31, the center of the light-receiving pixel region11of the pixel section13by32, the central axis of the encapsulated endoscope2by20, and the center of the objective lens8by28. It should be noted thatFIG. 7Bis a schematic representation of MOS image sensor1.

As can be seen formFIG. 7B, a substantial coincidence in disposition is achieved of the central axis20of the encapsulated endoscope2, center31of MOS image sensor, center32of the light-receiving pixel region of the pixel section13, and center28of the objective lens8.

FIG. 8is a block diagram showing construction of MOS image sensor1to be mounted on the encapsulated endoscope according to the second embodiment. Although the fundamental construction of MOS image sensor according to the second embodiment is identical to the MOS image sensor1according to the first embodiment shown inFIG. 6, there is a difference in that a light-blocked pixel region12aon the side opposite to the side on which the vertical scanning section15of the pixel section13is located is made wider as compared to a light-blocked pixel region12bon the vertical scanning section15side, thereby a substantial coincidence is achieved of the center31of MOS image sensor1and the center32of the light-receiving pixel region11.

The shape of the objective lens8in the encapsulated endoscope is a factor in determining the shape of the encapsulated endoscope2. To reduce the size of the encapsulated endoscope2, it is desirable that the objective lens8be disposed within the capsule case3as shown inFIG. 7Bso that the center28of the objective lens8and the central axis20of the encapsulated endoscope2substantially coincide. For this reason, MOS image sensor1as shown inFIG. 8is disposed in the encapsulated endoscope2so that the center31thereof and the central axis20of the encapsulated endoscope2substantially coincide, so as to result the construction of the encapsulated endoscope where a substantial coincidence is achieved of the center31of MOS image sensor1, the center32of light-receiving pixel region11, the central axis20of the encapsulated endoscope2, and the center28of the objective lens8. It is thereby possible to effectively use the space at the interior of the encapsulated endoscope, and a further downsizing of the encapsulated endoscope is feasible.

Also from the viewpoint of packaging, since the center31of MOS image sensor1and the center32of light-receiving pixel region11substantially coincide, an extra space is not required in the positioning of MOS image sensor1with respect to the observation optical system. A further downsizing of the encapsulated endoscope is thereby possible.

Third Embodiment

A third embodiment of the invention will now be described.FIG. 9is a block diagram showing construction of MOS image sensor1to be mounted on an encapsulated endoscope2according to the third embodiment. The MOS image sensor1according to the third embodiment includes: a pixel section13having a plurality of pixels two-dimensionally disposed in rows and columns: a first vertical scanning unit23for selecting odd rows to be read of the pixel signals of the pixel section13and for sequentially switching the row to be selected; a first vertical scanning line24for connecting between the pixel section13and the first vertical scanning unit23; a second vertical scanning unit22for selecting even rows to be read of the pixel signals of the pixel section13and for sequentially switching the row to be selected; a second vertical scanning line21for connecting between the pixel section13and the second vertical scanning unit22; a vertical signal line17onto which the pixel signals of the row to be read, selected at the first vertical scanning unit23and the second vertical scanning unit22are outputted; a horizontal read circuit14for sequentially outputting the signals outputted onto the vertical signal line17; and an operation control unit19for controlling operation of MOS image sensor1.

The pixel section13consists of a light-receiving pixel region11and a light-blocked pixel region12. The first vertical scanning unit23is provided to the left side of the pixel section13while the second vertical scanning unit22is provided to the right side of the pixel section13. Since exposure amount is controlled at the light source side, a vertical scanning circuit for electronic shutter is not mounted. Further, it is constructed so as to achieve coincidence of the center31of MOS image sensor1and the center32of light-receiving pixel region11. It should be noted that the first and second vertical scanning units22,23constitute a vertical scanning section.

In order to explain construction of the first and second vertical scanning units of MOS image sensor and mode of connection between the pixel section and the first and second vertical scanning units of the third embodiment, a description will be first given by way ofFIG. 10of construction of the vertical scanning section15of MOS image sensor1and connecting mode of the vertical scanning line16for connecting between the pixel section13and the vertical scanning section15in the first embodiment shown inFIG. 6. In the connecting mode of the first embodiment shown inFIG. 10, a scanning stage part of the vertical scanning section corresponding to one row of the vertical scanning section15conforms to one row of the pixel section13, where a light-receiving region corresponding to one row of the pixel section13is denoted by numeral26, and a scanning stage part of the vertical scanning section corresponding to one row is denoted by numeral25.

Of MOS image sensor1in the third embodiment shown inFIG. 9,FIG. 11shows construction of the pixel section13and the first vertical scanning unit23, the connecting mode of the first vertical scanning line24for connecting between the pixel section13and the first vertical scanning unit23, construction of the second vertical scanning unit22, and the connecting mode of the second vertical scanning line21for connecting between the pixel section13and the second vertical scanning unit22. In the third embodiment shown inFIG. 11, a scanning stage part of one row of the first vertical scanning unit23corresponds to one row of the odd rows of the pixel section13, and a scanning stage part of one row of the second vertical scanning unit22corresponds to one row of the even rows of the pixel section13. A light-receiving region corresponding to one row of the odd rows of the pixel section13is denoted by numeral26, and a scanning stage part of the first vertical scanning unit23corresponding to one row of the odd rows by27.

Of the MOS image sensor according to the third embodiment as shown inFIGS. 9 and 11, the first vertical scanning unit23for selecting odd rows and the second vertical scanning unit22for selecting even rows are disposed to the left side and to the right side, respectively, of the pixel section13. An extent of width corresponding to two rows of the pixel section13can be secured as the vertical length of each scanning stage part of the first and second vertical scanning units22,23that is necessary for scanning of one row of the pixel section13.

For this reason, as shown inFIG. 11, the horizontal length of the first vertical scanning unit23and the second vertical scanning unit22in MOS image sensor according to the third embodiment can be made shorter as compared to the vertical scanning section15in MOS image sensor according to the first embodiment shown inFIG. 10.

By suitably disposing the circuits, then, the horizontal length of the vertical scanning section15of MOS image sensor according to the first embodiment and the horizontal length combining the first vertical scanning unit23and the second vertical scanning unit22of MOS image sensor according to the third embodiment can be made substantially the same so that an area increase of MOS image sensor1may be reduced to a minimum.

By disposing MOS image sensor1according to the third embodiment having such construction into the encapsulated endoscope2according to the second embodiment2shown inFIG. 7Aso that the center31of MOS image sensor1and the central axis20of the encapsulated endoscope2substantially coincide, the encapsulated endoscope2is obtained as having construction where a substantial coincidence is achieved of the center31of MOS image sensor1, the center32of the light-receiving pixel region11, the central axis20of the encapsulated endoscope2, and the center28of the objective lens8. An effective use of the space at the interior of the encapsulated endoscope is thereby possible, and a further downsizing of the encapsulated endoscope2is feasible.

In the encapsulated endoscope according to the third embodiment, since the center31of MOS image sensor1and the center32of the light-receiving pixel region11coincide, the positioning of MOS image sensor1with respect to an observation optical system at the time of packaging can be effected without requiring an extra space. For this reason, a further downsizing of the encapsulated endoscope2is possible. Further, the degree of freedom is increased of the disposition of the light-receiving pixel region11and the light-blocked pixel region12in the case where coincidence is achieved of the center31of MOS image sensor1and the center32of the light-receiving pixel region11.

As has been described by way of the above embodiments, in accordance with the first aspect of the invention, the exposure amount control of MOS imaging device is effected by a light-source control section, and by a sole vertical scanning section, row select signals having one-to-one correspondence to each row of the pixel section are generated without providing a vertical scanning section for electronic shutter which has conventionally been disposed as a separate vertical scanning circuit for example at a position opposite to a vertical scanning section with the pixel section between them. A downsizing of the encapsulated endoscope is possible by using MOS imaging device having the sole vertical scanning section where thus generated row select signals are the signals for designating the rows to be read out of the pixel signals.

In accordance with the second aspect of the invention, since the center of the light-receiving pixel region of the pixel section and the center of MOS imaging device substantially coincide, the positioning of MOS imaging device with respect to the encapsulated endoscope can be effected without requiring an extra space, whereby a further downsizing of the encapsulated endoscope is possible. In accordance with the third aspect of the invention, since it is readily possible to achieve coincidence of the center of the light-receiving pixel region and the center of MOS imaging device, the positioning of MOS imaging device with respect to the encapsulated endoscope is easy without requiring an extra space, whereby a further downsizing of the encapsulated endoscope is possible.