WO2018210162A1

WO2018210162A1 - Coarse feed device and microtome having same

Info

Publication number: WO2018210162A1
Application number: PCT/CN2018/086037
Authority: WO
Inventors: Zheguang Fan; Chonglu Wang
Original assignee: Leica Microsystems Ltd., Shanghai
Priority date: 2017-05-18
Filing date: 2018-05-08
Publication date: 2018-11-22
Also published as: CN108956192A

Abstract

A coarse feed device and a microtome having the same are provided. The coarse feed device includes: a power input unit (10) having an adjustable position; a power output unit (20) disposed in a first fixed position; an idle gear unit (30) disposed between the power input unit (10) and the power output unit (20), and configured to couple the power input unit (10) to the power output unit (20); and a switching unit (40) configured to switch the power input unit (10) between a first position and a second position. The power output unit (20) includes: a first output gear (201) disposed in the first fixed position; and a second output gear (202) fixed to the first output gear (201), and coaxially disposed with the first output gear (202), in which a tooth number of the second output gear (202) is less than a tooth number of the first output gear (201). When the power input unit (10) is located in the first position, the power input unit (10) is coupled to the first output gear (201) via the idle gear unit (30); when the power input unit (10) is located in the second position, the power input unit (10) is coupled to the second output gear (202) via the idle gear unit (30).

Description

COARSE FEED DEVICE AND MICROTOME HAVING SAME

TECHNICAL FIELD

The present invention relates to a field of microtechnique, more particularly to a coarse feed device and a microtome having the same.

BACKGROUND

A microtome is used to cut a specimen into slices. These slices are then placed on a cover glass, processed properly and further examined by a microscope.

In the current microtome, a cutting unit is driven by rotating a hand wheel. The microtome particularly has a first hand wheel and a second hand wheel. The first hand wheel is used to transmit the specimen to be cut to a cutting member of the cutting unit by a coarse feed, and the second hand wheel is used to move the specimen by a fine feed, so as to cut the specimen. The first hand wheel is connected with a coarse feed mechanism, and the first hand wheel is operated to drive the specimen to move forwards and backwards. When a new specimen is mounted, the specimen is driven to move forwards until being adjacent to the cutting unit. When the cutting operation is finished, the specimen is driven to move backwards. In the forward and backward movements of the specimen, the coarse feed mechanism has the same transmission ratio.

However, in fact, the user needs to drive the specimen to move forwards slowly and to move backwards quickly, so as to improve the work efficiency while ensuring the quality of work. Thus, when the user operates the first hand wheel with a same speed, the coarse feed mechanism of the current microtome cannot achieve above effects.

Chinese patent application No. CN102401750B relates to a microtome. The microtome has a first shaft which is fixed and can be driven by a hand wheel. A first gear is anti-torsionally arranged on the first shaft. In addition, the microtome also is provided with a second shaft. A second gear is anti-torsionally arranged on the second shaft. The first gear and the second gear are connected with each other by a transmission unit. Therefore, the second shaft can be driven by the first shaft. In a first transmission position of the transmission unit, the first shaft and the second shaft can be driven in the same direction and in a second transmission position of the transmission unit, the first shaft and the second shaft can be driven in opposite rotation directions. Thus, the coarse feed of specimen can be obtained by a clockwise or anticlockwise rotation of the hand wheel, without large changes of the microtome.

Chinese patent application No. CN104416609A relates to a microtome. The microtome includes: a first shaft arranged in a fixed position and capable of being driven to rotate by a hand wheel; a first gear wheel non-rotatably mounted on the first shaft for rotation with the first shaft; a second shaft arranged in another fixed position; a second gear wheel non-rotatably mounted on the second shaft for rotation with the second shaft; a transmission unit via which the first gear wheel and the second gear wheel are coupled to each other so that the second shaft can be driven to rotate by rotation of the first shaft; and a shift unit for pivotably shifting the transmission unit between a first position and a second position. The first shaft and the second shaft are rotatable in the same direction when the transmission unit is in the first position, and the first shaft and the second shaft are rotatable in opposite directions when the transmission unit is in the second position. Thus, the coarse feed of specimen can be obtained by a clockwise or anticlockwise rotation of the hand wheel, without large changes of the microtome.

However, these patent applications both have the problem mentioned above, i.e., the coarse feed mechanism has the same transmission ratio in the forward and backward movements of the specimen. Therefore, the current microtome further needs to be improved.

SUMMARY

The present invention seeks to solve at least one of technical problems existing in the related art to at least some extent. Accordingly, embodiments of the present invention provide a coarse feed device, used for a microtome, and the coarse feed device has different transmission ratios in forward and backward movements of a specimen. Thus, a user may drive the specimen to move forwards slowly and to move backwards quickly, without increasing an operating speed.

Embodiments of the present invention further provide a microtome, including the coarse feed device according to above embodiments of the present invention.

The coarse feed device according to embodiments of the present invention includes: a power input unit having an adjustable position; a power output unit disposed in a first fixed position; an idle gear unit disposed between the power input unit and the power output unit, and configured to couple the power input unit to the power output unit; and a switching unit configured to switch the power input unit between a first position and a second position, in which the power output unit includes: a first output gear disposed in the first fixed position; and a second output gear fixed to the first output gear, and coaxially disposed with the first output gear, in which a tooth number of the second output gear is less than a tooth number of the first output gear. When the power input unit is located in the first position, the power input unit is coupled to the first output gear via the idle gear unit; when the power input unit is located in the second position, the power input unit is coupled to the second output gear via the idle gear unit.

In the coarse feed device according to embodiments, the power input unit may be switched between the first position and the second position. In the first position, the power input unit is coupled to the first output gear, and in the second position, the power input unit is coupled to the second output gear. The tooth number of the first output gear is larger than the tooth number of the second output gear. Thus, the coarse feed device according to embodiments of the present invention has different transmission ratios, such that the user may select different transmission ratios according to actual needs during the coarse feed. For example, a smaller transmission ratio may be selected during a forward movement of the specimen, and a larger transmission ratio may be selected during a backward movement of the specimen.

Additionally, the coarse feed device according to embodiments of the present invention may further include following additional features.

In some embodiments of the present invention, the power input unit includes: a driving wheel having an adjustable position; and a driving gear fixed to the driving wheel and coaxially disposed with the driving wheel. When the power input unit is located in the first position, the driving gear is coupled to the first output gear via the idle gear unit; when the power input unit is located in the second position, the driving gear is coupled to the second output gear via the idle gear unit.

In some embodiments of the present invention, the idle gear unit includes: a first idle gear disposed in a second fixed position and meshed with the first output gear; and a second idle gear disposed in a third fixed position and meshed with the second output gear.

In some embodiments of the present invention, a tooth number of the first idle gear is larger than a tooth number of the second idle gear.

In some embodiments of the present invention, when the power input unit is located in the first position, the driving gear is meshed with the first idle gear so as to be coupled to the first output gear, when the power input unit is located in the second position, the driving gear is meshed with the second idle gear so as to be coupled to the second output gear.

In some embodiments of the present invention, the switching unit includes: a rocker having a first end connected to a center of the driving gear, and a second end pivotably fixed; and an elastic element having a first end connected with the rocker, and a second end fixedly disposed.

In some embodiments of the present invention, a junction point of the rocker and the first end of the elastic element is adjacent to the second end of the rocker.

In some embodiments of the present invention, the elastic element is configured to hold the power input unit in the first position or the second position when the power input unit is switched to the first position or the second position, and to provide a pretension force when the power input unit is being switched.

In some embodiments of the present invention, the elastic element is configured as a spring.

In some embodiments of the present invention, the coarse feed device further includes an actuator disposed at an edge of the driving wheel, in which an actuating force is input via the actuator, so that the power input unit is switched between the first position and the second position.

In some embodiments of the present invention, when the power input unit is switched between the first position and the second position, the driving wheel revolves around the second end of the rocker and also rotates around a center of the driving wheel under action of the actuator.

In some embodiments of the present invention, the actuator is configured as a handle and is manually operated.

The microtome according to embodiments of the present invention includes: a specimen chuck configured to clamp a specimen; a transmission mechanism connected with the specimen chuck and configured to drive the specimen chuck to move; a conveyor belt having a first end connected with the transmission mechanism; and a coarse feed device according to above embodiments of the present invention, in which a power output unit of the coarse feed device is connected to a second end of the conveyor belt.

Significant effects of the microtome according to embodiments of the present invention are the same with those of the coarse feed device according to embodiments of the present invention, and thus will not be described in detail herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic view of a coarse feed device according to embodiments of the present invention, in which a power input unit of the coarse feed device is located in a first position.

Fig. 2 is a schematic view of a coarse feed device according to embodiments of the present invention, in which a power input unit of the coarse feed device is located in a second position.

Fig. 3 is a schematic view of a microtome according to embodiments of the present invention.

DETAILED DESCRIPTION

Reference will be made in detail to embodiments of the present invention. The embodiments described herein with reference to drawings are explanatory, illustrative, and used to generally understand the present invention. The embodiments shall not be construed to limit the present invention. The same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions.

Fig. 1 and Fig. 2 show a coarse feed device 1 used for a microtome according to embodiments of the present invention. Fig. 3 shows a microtome 1000 according to embodiments of the present invention. It will be understood by those skilled in the related that a feed of the microtome 1000 includes a coarse feed and a fine feed, and the present invention just relates to the coarse feed of the microtome 1000. Compared with the fine feed, the coarse feed has a higher feed rate and a larger feed amount.

The coarse feed device 1 according to embodiments of the present invention includes: a power input unit 10, a power output unit 20, an idle gear unit 30 and a switching unit 40. The power input unit 10 has an adjustable position, i.e., the power input unit 10 is not disposed in a fixed position. The power output unit 20 is disposed in a first fixed position. The idle gear unit 30 is disposed between the power input unit 10 and the power output unit 20, and configured to couple the power input unit 10 to the power output unit 20. The switching unit 40 is configured to switch the power input unit 10 between the first position and the second position. It should be noted that the first fixed position is not particularly limited herein, but intended to indicate that a position of the power output unit 20 is fixed.

Furthermore, the power output unit 20 includes: a first output gear 201 and a second output gear 202. The first output gear 201 is disposed in the first fixed position. The second output gear 202 is fixed to the first output gear 201, and coaxially disposed with the first output gear 201, i.e. a center of the first output gear 201 and a center of the second output gear 202 lie in a same axis. Moreover, a tooth number of the second output gear 202 is less than a tooth number of the first output gear 20, i.e. a radius of the second output gear 202 is less than a radius of the first output gear 201.

In embodiments of the present invention, when the power input unit 10 is located in the first position, the power input unit 10 is coupled to the first output gear 201 via the idle gear unit 30; when the power input unit 10 is located in the second position, the power input unit 10 is coupled to the second output gear 202 via the idle gear unit 30. Herein, it should be noted that “two members coupled to each other” means that the two members are linked. That is, when one of the two members coupled to each other rotates, the other one of the two members coupled to each other will rotate therewith.

In the coarse feed device 1 according to embodiments of the present invention, the power input unit 10 may be switched between the first position and the second position. In the first position, the power input unit 10 is coupled to the first output gear 201, and in the second position, the power input unit 10 is coupled to the second output gear 202. Further, the tooth number of the first output gear 201 is larger than the tooth number of the second output gear 202. Thus, the coarse feed device 1 according to embodiments of the present invention may provide different transmission ratios, and the user may select different transmission ratios according to actual needs during the coarse feed, i.e. switching the power input unit 10 to the first position or the second position. For example, in a forward movement of the specimen, the user may switch the power input unit 10 to the second position to select a small transmission ratio, and in a backward movement of the specimen, the user may switch the power input unit 10 to the first position to select a large transmission ratio, thus improving a work efficiency while ensuring a quality of work.

In some embodiments of the present invention, the power input unit 10 includes: a driving wheel 101 and a driving gear 102. The driving wheel 101 also has an adjustable position, i.e. a position of the driving wheel 101 is not fixed. The driving gear 102 is fixed to the driving wheel 101, and is coaxially disposed with the driving wheel 101, i.e. a position of the driving gear 102 is also adjustable, and a center of the driving gear 102 and a center of the driving wheel 101 lie in a same axis. When the power input unit 10 is located in the first position, the driving gear 102 is coupled to the first output gear 201 via the idle gear unit 30, such that when the driving gear 102 rotates, the first output gear 201 will rotate along with the driving gear 102 to output power. When the power input unit 10 is located in the second position, the driving gear 102 is coupled to the second output gear 202 via the idle gear unit 30, such that when the driving gear 102 rotates, the second output gear 202 will rotate along with the driving gear 102 to output power.

Furthermore, the idle gear unit 30 includes: a first idle gear 301 and the second idle gear 302. The first idle gear 301 is disposed in a second fixed position and is meshed with the first output gear 201. The second idle gear 302 is disposed in a third fixed position and is meshed with the second output gear 202. It should be noted that the second fixed position and the third fixed position are similar to the first fixed position, i.e. not particularly limited herein, but intended to indicate that positions of the first idle gear 301 and the second idle gear 302 are fixed respectively.

In a specific embodiment shown in Figs. 1 and 2, a tooth number of the first idle gear 301 is larger than a tooth number of the second idle gear 302, i.e. a radius of the first idle gear 301 is larger than a radius of the second idle gear 302. However, it will be understood by those skilled in the related that the tooth number of the first idle gear 301 may also be equal to the tooth number of the second idle gear 302, or even less than the tooth number of the second idle gear 302, which is not limited herein.

As shown in Fig. 1, when the power input unit 10 is located in the first position, the driving gear 102 is meshed with the first idle gear 301, and the first idle gear 301 is meshed with the first output gear 201, so that the driving gear 102 is coupled to the first output gear 201. In this case, a power transmission path of the coarse feed device 1 travels from the driving gear 102 to the first idle gear 301, and further to the first output gear 201 from the first idle gear 301.

As shown in Fig. 2, when the power input unit 10 is located in the second position, the driving gear 102 is meshed with the second idle gear 302, and the second idle gear 302 is meshed with the second output gear 202, so that the driving gear 102 is coupled to the second output gear 202. In this case, the power transmission path of the coarse feed device 1 travels from the driving gear 102 to the second idle gear 302, and further to the second output gear 202 from the second idle gear 302.

Since the tooth number of the first idle gear 301 is larger than the tooth number of the second idle gear 302, and the tooth number of the first output gear 201 is larger than the tooth number of the second output gear 202, the coarse feed device 1 has a larger transmission ratio when the power input unit 10 is located in the first position, and the coarse feed device 1 has a smaller transmission ratio when the power input unit 10 is located in the second position. That is, the coarse feed device 1 according to embodiments of the present invention may provide different transmission ratios.

Thus, the second position shown in Fig. 2 is more suitable for the user to slowly move the specimen forwards until the specimen is adjacent to a cutting member, so as to perform a cutting operation. The first position shown in Fig. 1 is more suitable for the user to quickly move the specimen backwards after the cutting operation is finished, so as to withdraw the specimen.

In some embodiments of the present invention, the switching unit 40 includes: a rocker 401 and an elastic element 402. A first end 4011 of the rocker 401 is connected to a center of the driving gear 102, and a second end 4012 of the rocker 401 is pivotably fixed, i.e. pivotably disposed in a fixed position. As shown in Fig. 2, the second end 4012 of the rocker 401 is provided with a pivot hole 4014, and a pivot shaft (not shown) may be disposed in the pivot hole 4014 so as to pivotably fix the second end 4012 of the rocker 401 to a certain member (not limited herein) in the microtome 1000. A first end of the elastic element 402 is connected with the rocker 401, and a second end of the elastic element 402 is fixedly disposed, i.e. disposed in a fixed position.

It should be noted that the first fixed position, the second fixed position, the third fixed position, the fixed position in which the second end 4012 of the rocker 401 is disposed and the fixed position in which the second end of the elastic element 402 is disposed may be located at a same member or different members, which is not limited herein.

Further, the elastic element 402 is configured to hold the power input unit 10 in the first position or the second position when the power input unit 10 is switched to the first position or the second position, so that it is ensured that the power input unit 10 may stably transmit power in the first position and the second position. In addition, the elastic element 402 is further configured to provide a pretension force when the power input unit 10 is being switched, so that a state of the power input unit 10 may be changed easily without using a large force, and thus it is convenient to switch the power input unit 10 between the first position and the second position.

Further, as shown in Fig. 2, a junction point 4013 of the rocker 401 and an upper end (serving as an example of the first end) of the elastic element 402 is adjacent to the second end 4012 of the rocker 401. Thus, it is convenient for the elastic element 402 to hold the power input unit 10 in the first position or the second position, and to provide the pretension force when the power input unit 10 is being switched. In some embodiments of the present invention, the elastic element 402 is configured as a spring.

In some embodiments of the present invention, as shown in Fig. 3, the coarse feed device 1 further includes an actuator 50. The actuator 50 is disposed at an edge of the driving wheel 101, and an actuating power is input via the actuator 50, so that the power input unit 10 may be switched between the first position and the second position. When the power input unit 10 is switched between the first position and the second position, the driving wheel 101 revolves around the second end 4012 of the rocker 401 and also rotates around a center of the driving wheel 101 under action of the actuator 50. In other words, during a switching action of the power input unit 10, the power input unit 10 has a revolution around the second end 4012 of the rocker 401 and also a rotation around its own center.

In a specific embodiment of the present invention, the actuator 50 is configured as a handle and is adapted to be manually operated, and thus the user may input the actuating power by operating the handle, such that the power input unit 10 may be switched between the first position and the second position, i.e. between feeding the specimen forwards and withdrawing the specimen backwards, thereby achieving a feeding operation and a withdrawing operation of the specimen at different transmission ratios. Preferably, the feeding operation of the specimen is achieved at a smaller transmission ratio, as shown in Fig. 2, while the withdrawing operation of the specimen is achieved at a larger transmission ratio, as shown in Fig. 1.

In some embodiments of the present invention, the actuator 50 is integrally formed with the driving wheel 101, so that a connection strength between the actuator 50 and the driving wheel 101 is improved, and it is convenient to manufacture the actuator 50 and the driving wheel 101, thus reducing a manufacturing cost.

In other embodiments of the present invention, the actuator 50 and the driving wheel 101 are detachable from each other, i.e. the actuator 50 and the driving wheel 101 are separately manufactured, and thus it is easy to maintain and replace the actuator 50 and the driving wheel 101.

A working principle of the coarse feed device 1 according to embodiments of the present invention will be described in detail with reference to Figs. 1 and 2.

As shown in Fig. 2, when the specimen needs to be fed forwards slowly, the user may manually operate the actuator 50 to apply an actuating force on the power input unit 10 towards the second position, and also, the elastic element 402 applies a pretension force on the power input unit 10, so that the power input unit 10 may be switched to the second position under action of the actuating force and the pretension force. After the power input unit 10 is switched to the second position, the elastic element 402 holds the power input unit 10 in the second position, and the power input unit 10 continues rotating clockwise under action of the actuating force, so as to drive the second idle gear 302 meshed with the power input unit 10 to rotate counterclockwise. Then, the second idle gear 302 further drives the second output gear 202 meshed with the second idle gear 302 to rotate clockwise. Thus, the power is output by the second output gear 202 at a smaller transmission ratio, and the second output gear 202 is further connected with other transmission mechanisms of the microtome 1000, so as to drive the specimen to move forwards until being adjacent to the cutting member.

As shown in Fig. 1, when the specimen needs to be withdrawn quickly, the user may manually operate the actuator 50 to apply an actuating force on the power input unit 10 towards the first position, and also, the elastic element 402 applies a pretension force on the power input unit 10, so that the power input unit 10 is switched to the first position under action of the actuating force and the pretension force. After the power input unit 10 is switched to the first position, the elastic element 402 holds the power input unit 10 in the first position, and the power input unit 10 continues rotating counterclockwise under action of the actuating force, so as to drive the first idle gear 301 meshed with the power input unit 10 to rotate clockwise. Then, the first idle gear 301 further drives the first output gear 201 meshed with the first idle gear 301 to rotate counterclockwise. Thus, the power is output by the first output gear 201 at a larger transmission ratio, and the first output gear 201 is further connected with other transmission mechanisms of the microtome 1000, so as to drive the specimen to move backwards and gradually away from the cutting member.

Accordingly, compared with the microtome in the related art, by the coarse feed device 1 according to embodiments of the present invention, after the cutting operation of the specimen is finished, the specimen may be withdrawn quickly without operating the actuator 50 at a high speed, so that it is convenient for the user to operate, thus improving the work efficiency.

As shown in Fig. 3, the microtome 1000 according to embodiments of the present invention includes: a specimen chuck 100, a transmission mechanism 200, a conveyor belt 300 and a coarse feed device 1 according to above embodiments. The specimen chuck 100 is configured to clamp the specimen. The transmission mechanism 200 is connected with the specimen chuck 100 and configured to drive the specimen chuck 100 to move. A first end of the conveyor belt 300 is connected with the transmission mechanism 200, and a second end of the conveyor belt 300 is connected with the power output unit 20 of the coarse feed device 1, such that the power output from the coarse feed device 1 may be transmitted to the transmission mechanism 200, and thus the transmission mechanism 200 may drive the specimen chuck 100 to move forwards and backwards.

Since the coarse feed device 1 according to embodiments of the present invention has different transmission ratios during forward and backward movements of the specimen chuck 100, when using the microtome 1000 according to embodiments of the present invention, the user may move the specimen chuck 100 forwards slowly, so as to feed the specimen slowly, and move the specimen chuck 100 backwards quickly, so as to withdraw the specimen quickly. Thus, the operation efficiency is improved while the quality of operation is ensured.

In the description of the present invention, it should be understood that terms such as “center” , ” longitudinal” , ” lateral” , “length” , ” width” , ” depth” , “up” , “down” , “front” , “rear” , “left” , “right” , “vertical” , “horizontal” , “top” , “bottom” , “inner” , “outer” , ” clockwise” , “counterclockwise” , “axial” , “radial” , “circumferential” should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the present invention be constructed or operated in a particular orientation, so shall not be construed to limit the present invention.

In addition, terms such as “first” and “second” are used herein for purposes of description and are not intended to indicate or imply relative importance or significance or to imply the number of indicated technical features. Thus, the feature defined with “first” and “second” may comprise one or more of this feature. In the description of the present invention, “a plurality of” means two or more than two, unless specified otherwise.

In the present invention, unless specified or limited otherwise, the terms “mounted” , “connected” , “coupled” , “fixed” should be understood broadly, and may be, for example, fixed connections, detachable connections, or integral connections; may also be direct connections or indirect connections via intervening structures; may also be inner communications or interaction relationships of two elements, unless specified or limited otherwise, which can be understood by those skilled in the art according to specific situations.

In the present invention, unless specified or limited otherwise, a structure in which a first feature is “on” or “below” a second feature may include an embodiment in which the first feature is in direct contact with the second feature, and may also include an embodiment in which the first feature and the second feature are not in direct contact with each other, but are contacted via an additional feature formed therebetween. Furthermore, a first feature “on” , “above” or “on top of” a second feature may include an embodiment in which the first feature is right or obliquely “on” , “above” or “on top of” the second feature, or just means that the first feature is at a height higher than that of the second feature; while a first feature “below” , “under” or “on bottom of” a second feature may include an embodiment in which the first feature is right or obliquely “below, ” “under, ” or “on bottom of” the second feature, or just means that the first feature is at a height lower than that of the second feature.

Reference throughout this specification to “an embodiment” , “some embodiments” , “an example” , “a specific example” or “some examples” means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In the present specification, the illustrative statement of the terms above is not necessarily referring to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples. In addition, the different embodiments or examples can be combined or united by those skilled in the related art.

Although embodiments of the present invention have been shown and described, it would be appreciated that the embodiments above are illustrative and shall not be construed to limit the present invention, changes, alternatives, variation and modifications can be made in the embodiments without departing from the scope of the present invention by those skilled in the art.

Claims

A coarse feed device, used for a microtome, comprising:

a power input unit having an adjustable position;

a power output unit disposed in a first fixed position;

an idle gear unit disposed between the power input unit and the power output unit, and configured to couple the power input unit to the power output unit; and

a switching unit configured to switch the power input unit between a first position and a second position,

wherein the power output unit comprises:

a first output gear disposed in the first fixed position; and

a second output gear fixed to the first output gear, and coaxially disposed with the first output gear, in which a tooth number of the second output gear is less than a tooth number of the first output gear,

when the power input unit is located in the first position, the power input unit is coupled to the first output gear via the idle gear unit; when the power input unit is located in the second position, the power input unit is coupled to the second output gear via the idle gear unit.
The coarse feed device according to claim 1, wherein the power input unit comprises:

a driving wheel having an adjustable position; and

a driving gear fixed to the driving wheel and coaxially disposed with the driving wheel,

when the power input unit is located in the first position, the driving gear is coupled to the first output gear via the idle gear unit; when the power input unit is located in the second position, the driving gear is coupled to the second output gear via the idle gear unit.
The coarse feed device according to claim 2, wherein the idle gear unit comprises:

a first idle gear disposed in a second fixed position and meshed with the first output gear; and

a second idle gear disposed in a third fixed position and meshed with the second output gear.
The coarse feed device according to claim 3, wherein a tooth number of the first idle gear is larger than a tooth number of the second idle gear.
The coarse feed device according to claim 3, wherein

when the power input unit is located in the first position, the driving gear is meshed with the first idle gear so as to be coupled to the first output gear,

when the power input unit is located in the second position, the driving gear is meshed with the second idle gear so as to be coupled to the second output gear.
The coarse feed device according to claim 2, wherein the switching unit comprises:

a rocker having a first end connected to a center of the driving gear, and a second end pivotably fixed; and

an elastic element having a first end connected with the rocker, and a second end fixedly disposed.
The coarse feed device according to claim 6, wherein a junction point of the rocker and the first end of the elastic element is adjacent to the second end of the rocker.
The coarse feed device according to claim 6, wherein the elastic element is configured to hold the power input unit in the first position or the second position when the power input unit is switched to the first position or the second position, and to provide a pretension force when the power input unit is being switched.
The coarse feed device according to claim 6, wherein the elastic element is configured as a spring.
The coarse feed device according to claim 6, further comprising an actuator disposed at an edge of the driving wheel, wherein an actuating force is input via the actuator, so that the power input unit is switched between the first position and the second position.
The coarse feed device according to claim 10, wherein when the power input unit is switched between the first position and the second position, the driving wheel revolves around the second end of the rocker and also rotates around a center of the driving wheel under action of the actuator.
The coarse feed device according to claim 10 or 11, wherein the actuator is configured as a handle and is manually operated.
A microtome, comprising:

a specimen chuck configured to clamp a specimen;

a transmission mechanism connected with the specimen chuck and configured to drive the specimen chuck to move;

a conveyor belt having a first end connected with the transmission mechanism; and

a coarse feed device according to any one of claims 1-12, wherein a power output unit of the coarse feed device is connected to a second end of the conveyor belt.