CN118003385A - Food slicer with optical blade evaluation - Google Patents

Abstract

A slicer for slicing a food product includes a slicer body, a slicer knife mounted for rotation relative to the slicer body, the slicer knife having a peripheral cutting edge, and an associated knife drive motor. A food carriage is mounted to the slicer body for reciprocal movement back and forth across the cutting region of the slicer knife. The blade evaluation system includes at least one imaging device positioned and configured for imaging the peripheral cutting edge.

Description

Food slicer with optical blade evaluation

Technical Field

The present application relates generally to food slicers for slicing bulk food products and, more particularly, to food slicers including imaging devices for blade evaluation.

Background

A common reciprocating food slicer has a rotatable circular or disc-shaped slicing blade (slicer knife), an adjustable ranging plate for determining the thickness of the slice, and a carriage for supporting the food item as it moves back and forth past the cutting edge of the knife during slicing. The carriage may be coupled to a drive motor to drive the carriage back and forth during an automatic slicing operation performed by a controller of the microtome. The distance measuring plate is arranged along the edge of the knife towards the front of the slicing stroke and can be moved laterally with respect to the knife to determine the thickness of the slice to be cut. These microtomes are commonly used in restaurants, grocery stores, and the like.

Such slicers have cutters that need to be ground frequently to maintain good slicing performance. Knife sharpeners are typically included in or integrated into the machine to allow an operator to sharpen the microtome blade.

It is difficult for an operator to objectively determine if the microtome blade needs to be sharpened. It is obvious to experienced operators that the knife dulls because the slicing effect of the machine does not reach its level. But when the operator makes such a determination, it is theoretically too late. It is also difficult to objectively determine when the sharpening process has ended sufficiently and properly. To overcome these difficulties, many operators will either overwear or under-wear. Excessive sharpening typically occurs to ensure proper performance throughout, but typically significantly shortens the life of the tool. The undersharpening typically occurs because frequent sharpening is not performed properly (operator error or sharpener failure), or the operator is unaware that sharpening is desired.

Attempts to solve this problem have focused on trying to predict when sharpening is needed (by calculating the number of revolutions of the cutter, product pallet travel, or time) or by measuring the load on the machine (in particular motor current). It has also been theorized how to automate the sharpening process. For example, U.S. patent No. 8,220,383 (incorporated herein by reference in its entirety) discloses a sharpener with timed sharpening operation wherein a slicer operating parameter (e.g., slicing stroke) may be monitored and a sharpening annunciator (e.g., light element) triggered when the operating parameter reaches a certain level (e.g., a set threshold number of slicing strokes).

One disadvantage of predictive methods is that they are not very accurate. The prediction based on time, number of passes or number of tool revolutions ignores one large variable of tool wear, namely the type of product being sliced and the speed at which the product is sliced.

One disadvantage of the load measuring method is that the load on the motor cannot be accurately measured in a way that provides good data on the efficiency of the tool. The load on the cutter motor is determined by the sharpness of the cutter, how hard the operator is pushing and the type of product being sliced. Since this method cannot predict or measure the other two variables, it is difficult to obtain good data. Even though this data may be collected and is the only variable directly related to the sharpness of the tool, the tool needs to become very dull to determine that performance degradation has occurred.

Furthermore, the previous solutions suffer from the following additional conditions: knife sharpener misalignment, whetstone wear, knife sharpener failure to fully sharpen the edge, tool damage or chipping.

It is desirable to provide a microtome that can adequately determine one or more of the sharpness of the knife, whether the knife needs to be sharpened, whether sharpening has been completed, and/or whether the knife has good/acceptable quality (or needs to be replaced).

Disclosure of Invention

In one aspect, a food slicer for slicing a food product includes: a slicer body, a slicer knife, a food carriage, and a knife edge evaluation system; a microtome blade mounted for rotation relative to the microtome body, the microtome blade having an outer edge cutting edge and an associated blade drive motor; a food carriage is mounted to the slicer body for reciprocating back and forth across a cutting region of the slicer knife; the blade evaluation system includes at least one imaging device positioned and configured for imaging the peripheral cutting edge.

In some implementations, the imaging device includes a camera that captures an image of the outer edge cutting edge, and the edge evaluation system further includes a controller for evaluating the image, wherein the edge evaluation system is configured to evaluate the image to determine a condition of the outer edge cutting edge that indicates that the microtome blade needs sharpening.

In some implementations, the imaging device includes a digital camera that captures an image of the outer edge cutting edge, and the edge evaluation system further includes a display device on which the image may be displayed.

In some implementations, the imaging device includes a lens device with an associated eyepiece mounted or mountable on the microtome body.

The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

Drawings

FIG. 1 is a side view of a food slicer; and

Fig. 2 is a schematic diagram of a slicer knife edge evaluation system.

Detailed Description

Referring to fig. 1, a food slicer 50 includes a housing or base 52 and a circular, motor-driven slicing knife 54, the slicing knife 54 being mounted to the housing for rotation about an axis 55. Fig. 1 depicts a right side view of the microtome. The left side of fig. 1 is commonly referred to as the front side of the microtome (where the operator stands to slice) and the right side of fig. 1 is commonly referred to as the rear side of the microtome. The food product may be supported on a manually operable food carriage 56, which food carriage 56 moves the food product to be sliced past the cutting edge 57 of the rotary slicing knife 54. The food carriage 56 reciprocates from left to right (relative to fig. 1) along a linear path such that the lower end of the bulk food item slides along the surface of the ranging plate 70, is cut by the knife 54, and then slides along the stationary knife cover plate 72. The food carriage 56 includes a tray mounted on a tray arm 58, which tray arm 58 orients the food carriage tray at a suitable angle (generally perpendicular) to the plane of the cutting edge. The food carriage reciprocates in a slot 64 in the lower portion of the housing 52, and a handle 66 is mounted to the food carriage 56. The handle may be grasped by a user and may be used to manually move the food carriage in a manual-only mode. The carriage may also be automatically driven (e.g., by a motor drive or other prime mover) in an automatic mode. A manual assist mode may also be provided. In another implementation, the manual-only mode may be canceled such that automatic or manual assistance is the available mode for slicing. Also shown is a handle or knob 74 for adjusting the ranging plate to control the slice thickness.

The illustrated position of the food carriage 56 is the first or forward-most position relative to the slicer knife 54, typically the start position of the slicing stroke. This position is sometimes also referred to as the home position of the bracket.

The sharpening assembly 42 is mounted on the microtome. For example, a sharpening assembly similar to that described in U.S. patent 7,134,937 may be used.

Referring to fig. 2, the microtome includes an optical blade evaluation system that includes a camera 100 (or multiple cameras, or other image capture devices) and an associated controller 102. The term controller as used herein is intended to broadly encompass any circuit (e.g., solid state, application Specific Integrated Circuit (ASIC), electronic circuit, combinational logic circuit, field Programmable Gate Array (FPGA)), processor (e.g., shared, dedicated, or group-including hardware or software that execute code), or other component that performs the control functions of the machine, or any component thereof, or a combination of some or all of the above.

Camera 100 is positioned to capture an image or video of blade 57 to determine from the image/video whether the blade is sharp (e.g., controller 102 is configured to evaluate the image/video). One possible arrangement involves bringing the camera close to the theoretical parallel cutting plane of the circular cutter. For example, the viewing direction of the camera is oriented substantially coincident with a line 80, which line 80 is tangential to the circular edge of the knife. Alternative configurations may include positioning the camera to provide an image of the blade (at varying angles), an image of the tool silhouette, or an image of the blade reflection.

Due to geometrical limitations of the working distance of the camera when positioning the camera according to fig. 2, it may be necessary to use a specific lens configuration to achieve the required magnification for a given working distance. Magnification components such as macro lenses, near-field lenses or macro filters can be used to obtain good images of the blade itself, which represents a unique application of camera magnification/optics. The image magnification used may be at the edge of the microscopic range, but with a larger working distance.

The exact method of image evaluation may vary. The camera captures images/video, which the controller analyzes using standard computer vision techniques and specific object detection algorithms to obtain quantifiable objective data. The evaluation process can be done efficiently and quickly enough to process the individual images in the video stream and give real-time analysis of the tool via the video stream. These quantifiable data are then used to compare the tool to what it should look like. If the tool exceeds the set threshold, it is considered to be unsharpened.

In some embodiments, the controller may be configured to compare the captured image of the blade edge with a predetermined stored image of the sharp knife to make the determination.

In some embodiments, the controller may be configured with an image processing algorithm, such as a Canny edge detection algorithm. Standard preprocessing of the edge detection algorithm requires grayscales and then deliberately obscures the image to reduce noise. The edge detection algorithm "measures" the change in pixel intensity so that the color is not correlated. Noise reduction is also used because calculating the derivative of the original pixel intensity can lead to large fluctuations (and giving false emphasis to non-important potential edges). Smoothing the intensity variation near the edges helps the program to find the dominant edge structure more easily. The image is then further processed to represent the edges as straight lines. Hough line transforms are example algorithms that may be used. The "probabilistic" version is generally considered to be best. This step takes image data from the "image space" as data that can be manipulated and analyzed using equations and variables.

In some embodiments, preprocessing may be used to provide higher resolution. For example, the controller may be configured to convert to an HSV (for hue, saturation, brightness; also referred to as HSB, for hue, saturation, brightness) color space. The transition to this color space does not bring a helpful perception of the image to the human, but it can help the computer "see" possibly more important parts of the image. Edge detection operations may then be performed on the HSV color spectrum rather than the images in RGB. In another example, the controller may be configured to perform thresholding to generate a binary image. Determining a threshold of light value above the background and then converting any content exceeding the threshold to white pixels helps to get an accurate profile of content that can be determined from the image. Thresholding provides an ideal method of determining the profile of the blade if the image can be taken in a similar context and there are no distortion or reflection problems.

In some embodiments, to compare images, zeroing is performed on the frames and images. Zeroing also helps to account for manufacturing variances. Zeroing is also advantageous because over time the tool will also change size as it is progressively ground. Zeroing the image may be performed by identifying edges and mapping them to normalized geometry/equation driven vectors.

Imaging may depend to a large extent on the cleanliness of the tool. In this case cleanliness is not specifically at the hygiene level, but rather is free of debris (including dust). Machine learning can be used to analyze the edge profile/shape even if the tool is not completely clean.

In some embodiments, simpler optics may be desirable where the system evaluates the image by looking for and analyzing only the reflected light bands from the blade edge. Generally, sharper cutters reflect brighter and more consistent bands of light. A light source and a simple camera/optics arrangement (or a simpler photodiode) may be used to infer the sharpness of the tool. In this case, the controller would be configured to compare the relative light intensities at specific locations on the tool.

Once the controller determines that the knife is no longer sharp, the controller communicates this information to the operator. Such communication may be either of the LED 104 (or other light emitting element providing a visual indicator) or the audio annunciator 106, which is on for as long as the knife is not sharp, and whose status may be continuously updated. Or a display screen interface 108 (HMI) may be provided on the microtome. The system not only informs the operator when the tool needs to be worn but also when the tool has been fully worn. For example, the system may continuously analyze the blade image as sharpening proceeds and cease notifying the blade of the non-sharpening via the LED, audio annunciator, or display once the blade is determined to be sharp (e.g., the optical system evaluates the blade during sharpening and updates as the blade is resharpened).

The system may also inform the operator if the sharpener is not sharpening the knife (e.g., if the edge is not sharpened after a set duration of sharpening of the knife, the system may provide a specific output to indicate that the sharpener is not sharpening (e.g., a specific pattern of LED blinking, audio information, or visual information display on a display screen)).

In some implementations, the system can identify a chipping condition on the tool by capturing a video of the tool as the tool rotates, scanning substantially the entire tool. Also, the system may provide an output (e.g., a specific pattern of LED blinking, audio information, or visual information display on a display screen) informing the operator of the condition.

In some implementations, the system can identify if the tool is loose or misaligned and provide an output to alert the operator (e.g., a specific pattern of LED blinking, audio information, or visual information display on a display screen).

In some implementations, the system can identify if the tool is too worn and needs replacement (e.g., if the position of the blade is determined to be more than a set distance from the intended position of the blade) and provide an output informing the operator of the condition (e.g., a particular pattern of LED blinking, audio information, or visual information display on a display screen).

In some implementations, the system may be configured to display video/images of the blade edge to a service person or operator to better troubleshoot slicing problems or verify the sharpness of the knife.

In some implementations, the system may be configured as a portable/separate component from the microtome. Such a system may include an autonomous battery powered retrofit to the above features so that the system can operate as a sharpness indicator for any type of round cutter. In some implementations, such a stand-alone system may also be combined with a suitable fixture to determine the sharpness of a kitchen or other non-circular knife.

For example, microtomes utilizing the optical system described above provide various advantages, such as: the determination of the sharpness of the tool is no longer operator dependent; less time/effort is required to determine if the knife is sharp; more accurate sharpness determination; the excessive grinding of the cutter is prevented, so that the service life of the cutter is prolonged; the cutter is always kept in a sharper state, so that better slicing performance is provided; providing the ability to better troubleshoot slicing problems using images/videos of the blade edge; providing the ability to fully integrate automatic sharpening into the microtome (e.g., using an electrically powered, actuatable knife sharpener), determining when sharpening and when sharpening is completed by the system; providing the ability to determine whether the tool is misaligned or loose; providing an objective determination of blade edge/performance; providing the operator with the ability to inform the operator that the tool has exceeded its useful life (as the blade has been worn away too much); providing the operator with the ability to notify the operator that the tool has been damaged; predicting how long a tool can be used before it needs to be replaced; in the case of a stand-alone implementation, providing a unit with the ability to evaluate all the knives of all the slicers in a given delicatessen/kitchen; and/or provide the ability to evaluate non-circular tools (e.g., kitchen tools).

It is to be clearly understood that the above description is intended by way of illustration and example only and is not to be taken by way of limitation, and that other variations and modifications are possible. For example, other blade sensing devices/systems may be implemented as an alternative to optical image sensing of the blade. The capacitive sensing system may be implemented by placing a capacitive sensor probe near the cutting edge, and a change in the radius of the edge may change the measured capacitance. As another example, a light reflecting system may be implemented in which light is reflected from the blade and a light sensor is used to determine whether the amount of light or the orientation/pattern of the light indicates a sharp or blunt blade. As another example, a refractive system may be implemented in which light is displayed and blocked primarily by the blade, and a change in the radius of the blade may result in a change in refractive characteristics, which ultimately changes the intensity of light refracted around the blade, which may be detected (e.g., using a photodiode), measured, and evaluated.

In another embodiment, the microtome may include an imaging device in the form of a built-in lens system 90 having an associated eyepiece 92 mounted to the microtome, and through which eyepiece 92 an operator or maintenance/service person may observe the condition of the cutting edge of the knife. The system may better assist the operator in determining blade condition (e.g., when sharpening, when a tool needs to be replaced).

Claims (15)

1. A food slicer for slicing a food product, comprising:

a slicer body;

a microtome blade mounted for rotation relative to the microtome body, the microtome blade having an outer edge cutting edge with an associated cutting region and an associated blade drive motor;

a food carriage mounted to the slicer body for reciprocating back and forth through the cutting region of the slicer knife;

A blade evaluation system comprising at least one imaging device positioned and configured for imaging the outer edge cutting edge.

2. The food product slicer of claim 1 wherein the imaging device includes a camera that captures an image of the outer edge cutting edge and the edge evaluation system further includes a controller for evaluating the image, wherein the edge evaluation system is configured to evaluate the image to determine a condition of the outer edge cutting edge that indicates that the slicer knife needs sharpening.

3. The food product slicer of claim 2 wherein the controller is configured to process the image to determine a profile of the outer edge cutting edge.

4. The food product slicer of claim 2 wherein the controller is configured to perform edge detection on the image.

5. The food product slicer of claim 4 wherein the controller is configured to pre-process the image prior to performing edge detection.

6. The food slicer of claim 5, wherein the preprocessing involves conversion of images into HSV space.

7. The food product slicer of claim 5 wherein the preprocessing involves application of thresholding pixels of the image.

8. The food product slicer of claim 2 wherein the controller is configured to zero the image mapped to a vector.

9. The food product slicer of claim 2 wherein the edge evaluation system is configured to provide an output to alert an operator that the slicer knife requires sharpening.

10. The food product slicer of claim 2 wherein the edge evaluation system is configured to evaluate an image of the outer edge cutting edge during tool sharpening to determine a condition of the outer edge cutting edge indicative of the slicer knife being sharp and provide an output to alert an operator of the slicer knife being sharp.

11. The food product slicer of claim 2 wherein the edge evaluation system is configured to evaluate an image of the outer edge cutting edge during tool sharpening to determine a condition indicating that the slicer tool is not being sharpened and to provide an output to alert an operator that a tool sharpener is not sharpening the slicer tool.

12. The food product slicer of claim 2 wherein the edge evaluation system is configured to evaluate an image of the outer edge cutting edge during tool sharpening to determine a condition of the outer edge cutting edge indicating that the slicer tool has reached an end of life and to provide an output to alert an operator that a slicer tool needs replacement.

13. The food product slicer of claim 2 wherein the edge evaluation system is configured to evaluate an image of the outer edge cutting edge to determine a condition of the outer edge cutting edge indicative of damage to the outer edge cutting edge and provide an output to alert an operator of the slicer knife damage.

14. A food product slicer according to claim 2 wherein the imaging means comprises lens means with an associated eyepiece mounted or mountable on the slicer body.

15. The food product slicer of claim 1 wherein the imaging device includes a digital camera that captures an image of the outer edge cutting edge and the edge evaluation system further includes a display device on which the image is displayable.