Abstract:
The present invention relates to a device for detecting the raising state of lumps of dough ( 11 ) submitted to a fermentation process which is for example induced by yeast in a raising chamber and during which the volume of said lumps increases. The device includes at least one variance detector ( 21 ) which is associated with at least one of the lumps of dough placed in the raising chamber, and which generates a characteristic output signal when the thickness of the dough reaches a predetermined target value corresponding to a desired maturation degree of the dough. The variance detector ( 21 ) consists of an ultrasonic detector for measuring the propagation time of the ultrasonic signals. The detector is placed on a tripod ( 17 ) which can be arranged in the raised chamber ( 13 ) on the bottom thereof.

Description:
BACKGROUND TO THE INVENTION 
     1. Field of the Invention 
     The invention concerns a device for detecting the state of rising of lumps of dough which are subjected to a proofing or fermenting process in a proofing chamber, for example induced by yeast, in the course of which the lumps of dough experience an increase in volume. 
     2. Description of the Related Art 
     The typical bakery products such as bread or rolls, which are sold daily in large quantities by branches or retail outlets of bakery factories, in order to be able to represent that they conform to the highest possible levels of freshness and quality, are baked in the respective branch or outlet locations, whereby it is also achieved that the produced amount can be flexibly adapted to the respective demand. Herein, for example, in the production of table rolls, the process begins with lumps of dough, which are pre-produced in a roll producing equipment in large number with substantially identical weight and volume. These lumps of dough, which are already subjected to yeast in their manufacture, are, prior to the rolls can be baked in an oven, subjected to a rising step in a proofing chamber, in which the size and dough consistency required for the baking of the rolls is strived for. Herein the proofing process is so carried out, with respect to the chamber temperature and in certain cases the dwell time, that during a total proofing time of approximately 20 minutes the necessary dough size is achieved, which in typical cases represents the five fold of the volume of the fresh “green” dough lumps produced on the roll producing device before the initiation of the rapidly occurring proofing process is set in motion therein by the elevation of the temperature, after the course of which, that is as soon as the dough lumps have achieved their desired size, these should be baked immediately, in order to achieve table rolls of standardized desired quality. The most important characteristic of quality of the finished baked rolls, which is associated in the mind of consumer with the image of quality, is the size thereof, which should also be uniform among the various types of rolls. 
     In order to achieve this uniformity, it would seem to be basically suitable to employ constant uniform conditions for carrying out the proofing process, for example using a computer program controlled time-wise control of the proofing chamber temperature, combined with an indication that the proofing time has concluded as determined by the temperature profile. Through such a temperature control it is however not possible to exclude influences on the size of the proofed dough lumps, which result from variations in yeast quality and/or variations in the introduction temperatures of the “green” dough lumps, and which can lead to significant size variations of the proofed dough lumps. It is thus necessary, even when employing a uniform time controlled proofing of the dough lumps, to subject the dough lumps treated in the proofing chamber to a visual quality control before they can be introduced into the baking oven, which however demands a high level of practical experience, in particular in that respect of how in certain cases a proofing process is to be carried out up to suitable ripeness of the dough lumps. The sales persons employed in the branches, which may have only limited knowledge of the baking process, do not as a rule have this particular necessary experience. This has the consequence that often it is only after the table rolls have been baked that it can be recognized whether these satisfy the required quality characteristics. 
     SUMMARY OF THE INVENTION 
     It is thus the task of the invention to provide a device of the above described type, which makes possible a reliable, objective measurement of the respective proofing condition of the dough lumps, which correlates to their desired final size. 
     This task is inventively solved thereby, that a distance sensor operating on a contactless measurement principle is provided in association with at least one of the dough lumps provided in the proofing chamber, which at least then, when the thickness of the dough lump achieves a predetermined desired value, which is associated with the intended condition of proofing of the dough lump, produces a signal which is characteristic therefore. 
     The inventive device is based on the fact that the volume increase, which the dough lump experiences through the proofing process, seen from its center of gravity, leads to a dimensional enlargement in every direction, so that by measurement of the distance or separation of a surface point or area of the dough lump from the position at which the sensor is situated, a very reliable determination of the volume of the dough lump, or its proofing ripeness condition, is made possible. Starting with an absolute measurement of the starting distance as reference value, and with the progressive measurement of the reduction of this separation, the volume of the dough lump is determinable with sufficient precision, so that from such a distance measurement a sufficiently precise indication with respect to the ripeness of the dough lump can be determined. 
     By means of the invention the objective determination of the condition of ripeness of the monitored dough lump is made possible in a simple manner, and therewith also that of other dough lumps identical to this dough lump. The inventive device makes possible at the same time an automatic monitoring of the proofing process and in certain cases also permits, depending upon the instantaneously detected volume of the dough lumps, to control the proofing process by influencing the proofing chamber temperature in such a manner, so that the condition of ripeness necessary for the subsequent baking process of the dough lumps is achieved after the expiration of a pre-determined time span. The inventive device is suitable for avoiding inaccurate determinations of the condition of ripeness of the dough lumps and therewith makes possible the rational production of baked wares in a branch or chain operation. 
     In a preferred design of the inventive device the distance sensor thereof is arranged and oriented in such a manner that it measures the height of the dough lump, in the central area thereof, over the sheet or support, which is useful as a measuring value for the reason that it is determinable in relation to a fixed pre-determined reference value, namely the distance of the support for the dough lumps to the distance sensor, which is pre-determined by the construction specifications of the proofing chamber. Further, the vertical thickness of a dough lump during the proofing process, even in the case that this is smaller than the largest horizontal cross-section, will change a greater amount than measurable by a “horizontal” distance measurement of the horizontal radius of the dough lump, since the vertical thickness change is comprised of the sum of the distance change from the center point of the dough lump to the support plus the change in the vertical separation from the dough lump upper surface to the center point of the dough lump. 
     A suitable distance sensor to be realized for the inventive device could for example be in the manner of a distance measuring and adjusting system of an auto-focus camera, or an optoelectronic distance measuring device, which however because of the required optical imaging of the target or measurement object is associated with a substantial space requirement, which would be acceptable only in the case of a fixed installation in a chamber with high capacity. 
     In a preferred design of the inventive device the distance sensor is thus designed as an ultrasonic sensor, which works on the principle of the elapsed travel time measurement of the ultrasonic signal. A distance sensor of this type only requires a small amount of space and can be installed without complication between two support surfaces for dough lumps within a proofing chamber, so that sufficient space for the monitored dough lump still remains below the sensor. 
     In accordance therewith the distance sensor can be provided on a framework which can be set up on the floor inside a conventional proofing chamber, preferably a three legged framework, and insofar is suitable as a retrofit component for existing proofing cabinets. 
     As distance sensor a light interruption device is also suitable, in which a light beam is interrupted as soon as at least one of the dough lumps achieves a height that is characteristic for a desired degree of ripeness. 
     A light interruption device is preferably fixedly installed in the proofing cabinet, wherein the light source and the light detector can be built into the proofing cabinet walls preferably in such a manner, that the light detector is height adjustable, wherein the height adjustability can be realized in simple manner thereby, that the light source is height adjustable and a receiver line is provided fixed in the chamber, comprised of a number of light detectors arranged in small vertical separation from each other, or a single receiver with receiver surface extending in the vertical direction, as well as a gate or aperture which is adjustable in height to a pre-determined distance above the floor which carries the dough lumps. 
     In a preferred design of such a light detector the detector light beam is so arranged that it crosses over multiple dough lumps, for example a centrally oriented row of dough lumps, whereby even in the case of a minor irregular arrangement of the dough lumps the probability is increased that the light detector is interrupted at the correct point in time, even when the light detector-light beam does not precisely cross over the central plane of some of the individual dough lumps. 
     In one embodiment of the distance measuring device as a light detector device, it is particularly advantageous when a laser is employed as a light source, which emits a strongly bundled parallel light beam of small cross-section and high light intensity without requirement for specialized optical elements and/or apertures, which in an advantageous embodiment of the invention can be divided by means of a simple beam splitter into multiple partial light beams of preferably approximately the same intensity, which can be utilized for monitoring of dough lumps in multiple planes of a proofing chamber or even for monitoring of dough lumps in multiple proofing chambers, which are positioned in spatially fixed coordinates within a larger proofing facility, in which the employment of a laser can be more economical than an arrangement of light detectors which have respectively one individual light source of simple design. 
     The reliability of recognition of the interruption of a light interruption device in accordance with a further embodiment of the invention is thereby improved, in that at least one scatter-light detector is provided, preferably in a device above the sensor plane defined by the light interruption device, wherein the scatter-light detector produces a signal, when the light shutter interrupting areas of a dough lump are illuminated by the light interruption device light beam and thereby scatter light, which is easy to construct by means of a simple imaging system uniformly monitoring the dough lumps, and which by using a light detector can be utilized for producing a confirmation signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Further details of the inventive device can be found in the following description of exemplary embodiments thereof as illustrated by the drawings. There is shown: 
     FIG. 1 a schematic simplified step diagram of a proofing cabinet, which is outfitted with an inventive distance measuring device; 
     FIG. 2 a  and  2   b  a suitable ultrasonic type distance sensor for use in a proofing chamber according to FIG. 1; 
     FIG. 3 a schematic simplified representation of the light interruption device, which can be used as measuring device in the proofing chamber according to FIG. 1; 
     FIG. 4 a schematic representation of a beam splitter device, by means of which the output light beam of a laser can be distributed to plurality of light interruption devices. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the proofing chambers indicated overall with reference number  10  in FIG. 1 there are dough lumps  11 , for example for table rolls, which can be subjected to a proofing process, before they can be finally baked in a baking oven (not shown) immediately after completion of the proofing process. 
     By means of this proofing process the dough lumps  11 , which undergo a substantial increase in volume during the proofing process, are to be brought to the suitable consistency of the dough for baking, which brings about once again further volume increase up to the final size of the finished rolls. 
     Herein the dough lumps  11  rest on proofing sheets  12 , which are easily slideable in the sideways guide rails  14 , which facilitates the easy introduction of the dough lumps into the proofing chamber  13  of the proofing cabinet and the removal thereof. These proofing sheets  12  which have an approximately square carrying surface  16  are provided respectively in the same spatial separation h from each other, which for the purposes of explanation will be presumed herein to be approximately 70 mm, wherein it is presumed that the intended thickness d s  of the dough lumps  11  as a result of the proofing process, is to have a vertical final thickness of approximately 50 mm. In the design presumed for the proofing cabinet  10  used in this explanation, 6 proofing sheets  12  are provided, on which batches of respectively 25 dough lumps  11  can be deposited. 
     The proofing cabinet  10  is provided with a hot air convection heating device (not shown), by means of which the temperature produced in the proofing chamber  13  is adjustable and can be changed or varied to conform to a product-optimal temperature curve, over which the proofing process is controllable, wherein various temperature curves can be pre-selected and be run by control programs. 
     For monitoring the proofing process, which results in an increase in volume of the dough lumps, a distance sensor indicated overall with  21  is provided, by means of which the vertical thickness d in the central area of a selected dough lump  11  is determinable, which is monitored as criteria for the degree of ripeness of the dough lumps  11  subjected to the proofing process. As soon as the dough lump has achieved the pre-determined intended thickness d s , the distance sensor  21  produces an electrical output signal characteristic therefore, which serves as an indicator signal signifying that the dough lumps have achieved their condition of readiness for baking and, on the other hand, as control signal for reducing the temperature in the proofing chamber  13 , in order to stop the proofing process. 
     This distance sensor  21 , now explained in greater detail by reference to FIG. 2 a  and  2   b,  is in constructed the represented special exemplary embodiment as an ultrasonic sensor, which is mounted on a carrying framework  17  in the manner of a three legged round table in the central area of the “table top”  18 . The ultrasonic sensor includes an ultrasonic transmitter  22  seated in a flat cell  19 , which is seated in a central borehole of the table top  18 , and an immediately adjacent ultrasonic receiver  23 , wherein the ultrasonic sensor  22  is so constructed and arranged, that the central axis  24  of its lobe-shaped emission field indicated with dashed lines in FIG. 2 b  is directed vertically downwards, when the distance sensor  21  with its three leg design  17  is seated upon the proofing sheet  12  carrying the dough lump  11  to be monitored. The receiver  23  is so designed and positioned, that it can receive “direct” ultrasonic transmission emitted slightly sideways from the emitter and reflected from the dough lump  11 , so that a measurement of the distance of a central area of the upper surface of the dough lump  11  from the ultrasonic emitter  22 , and therewith the known separation of the ultrasonic sender  22  from the carrying surface  16  of its framework  17 , and also the thickness of the dough lump  11 , can be determined in the following manner: 
     If the emitter  22  is caused to emit ultrasound, then there occurs immediately thereafter in response to the direct emission received “along the shortest path”, which is radiated out sideways, a starting signal of the receiver  23 , which initiates the activation of a timing pulse counter (not shown), which counts the number of counting pulses produced for example with the frequency of 1 MHz, until the ultrasonic radiation reflected following reception by the measuring object, the dough lump  11 , produces in the receiver a higher level then the starting signal, the occurrence of which terminates the timing pulse counting. The count of the time counter is then a very precise measurement representing the travel time of the ultrasonic radiation from emitter  22  to dough lump  11  and from this to the receiver  23 , and can be converted by a measurement operation driving, essentially schematically indicated, electronic control unit  26  into the thickness d of the dough lump. In this mode of operation of the distance sensor  21 , which can be calibrated in simple manner by making a reference measurement without a dough lump  11 , that is, measurement of the distance from the sensor  21  to the proofing sheet  16 , the measurement of the thickness of the dough lump with a precision of 0.3 to 0.5 mm is easily achieved, which is sufficient for monitoring the thickness of the dough lumps. By means of a time-wise repetition of such a measuring cycle, for example in time intervals of 10 to 20 seconds, a quasi continuous monitoring of the proofing process is possible, so that based on the value of the continuously determined values of the thickness of the dough lump  11  the process control can be influenced—“corrected”—by means of the electronic control unit  26  in such a manner, for example by temperature changes in the proofing chamber  13 , so that the proofing process after the expiration of the defined process time results in the desired degree of ripeness overall of the dough lumps  11 . 
     As already mentioned, the distance sensor  21  which can be introduced into the proofing cabinet  10  is suitable in particular for a retrofitting of existing proofing cabinets, for which it is essentially only necessary to provide electrical lines for the supply of electricity for the distance sensor and for relaying signals to the electronic control unit  26 . It is also understood that a distance sensor  21  of the above mentioned type can be permanently installed as a measuring device as original equipment in a proofing cabinet  10 . 
     In an alternative design to the ultrasonic sensor, which is suitable in particular for a permanent installation in a proofing cabinet  10 , the distance sensor is a light interruption device  21 ′ indicated essentially schematically in FIG. 1, for the explanation of the details of which reference can be made to the discussion of FIGS. 3 and 4. 
     In the light detector device  21  a laser  29  is provided as light source, for example on the outside of the two parallel vertical cabinet walls, which produces a tightly bundled parallel light beam of small cross section and relative high light intensity, represented essentially by a central beam  31 , which is emitted in the vertical direction out of the laser  29 . This light beam  31  is redirected about 90° by means of a deflection mirror  32  in order to produce the cabinet light beam  31 ′ necessary for the light detector device and channeled into the proofing chamber  13  via a window  33  provided in the cabinet wall, as shown in the representation according to FIG. 3 in the left cabinet wall  27 , so that it passes over multiple dough lumps  11 , which are provided on the proofing sheet  12 , in defined separation therefrom and impinges on detector device  34  positioned on the opposite cabinet wall  28 , essentially schematically indicated, which produces an output signal of defined level, as long as the cabinet light beam  31 ′ is not interrupted. 
     In order to be able to adjust the vertical separation of the cabinet light beam  31 ′ from the support surface  16  of the proofing sheet, which carries the dough lumps  11  being monitored, and thereby to be able to select the size to which these dough lumps  11  should be allowed to be rise, the deflection mirror  32  via which the cabinet light beam  31 ′ is channeled into the proofing chamber  13 , is designed to be height-adjustable by means of a schematically indicated rack and pinion drive  36 . In accordance therewith the entry window  33  for the cabinet light beam  31 ′ is preferably formed to have a narrow slit shape, so that it extends over the possible adjustment range of the deflection mirror and herein the detector device  34  is adapted thereto in such a manner that its light sensitive receiver surface  37  likewise extends over the possible adjustment range of the cabinet light beam  31 ′. 
     In order to be able to utilize a laser  29 , which is capable of producing a relatively high light output, as light source for a multiplicity of dough lumps  11  when monitoring the proofing process of dough lumps  11 , which in certain cases can be provided in various proofing cabinets which are positioned with fixed  30  spatial correlation to each other within a larger facility, the beam splitter device shown overall with reference number  38  in FIG. 4 can be used, by means of which the primary output light beam  31  of the laser  29  can be divided into four chamber light beams of approximately the same intensity, which via a height adjustable deflection mirror  32  can be channeled into the respective proofing cabinets. 
     The primary output light beam  31  produced by the laser  29  impinges on a first half-silvered or partially transmissive mirror serving as a beam splitter  41  and is divided thereby into an—according to the representation in FIG.  4 —right angled redirected reflected partial light beam  42  and a transmitted partial light beam  43 , wherein these two light beams  42  and  43  have the same intensity. The partial light beam  42  reflected by the first beam splitter  41  impinges on a second beam splitter  44  designed as partially transmissive deflection mirror and is divided thereby into a transmitted partial light beam  46  and a reflected partial light beam  47 , which again have the same intensity. The partial light beam  43  which passes through the first beam splitter  41  impinges upon a third beam splitter  45  designed as partially transmissive deflection mirror and is there divided into a transmitted partial light beam  48  and a reflected partial light beam  49  of respectively the same intensity. 
     The four partial light beams  46  through  49  of same intensity can be used for forming light interruption detector devices  21  in the manner shown in FIG. 3 in four different proofing chambers. 
     For the laser  29  in the “vertical” arrangement thereof as shown in FIG. 3, that is the vertical emission direction of its primary light beam  31 , the emitted light beam  48  and the thereto parallel emitted light beam  47  traveling in the direction of the optical axis of the laser  29  can, by employment of respectively one height adjustable mirror  32 , be used directly for formation of a height adjustable light detector device  21  (FIG.  2 ). For the two other output light beams  46  and  49  there is required, for the indicated purpose, also respectively one 90° deflection mirror  51  or as the case may be  52 . 
     A useful arrangement of the light interruption detection device can also be comprised therein, that a scatter light sensor  52  is provided shown essentially in schematic manner in FIG. 1, which is provided above the first dough lump, upon which the chamber light beam of the respective light detectors can impinge, and, as soon as this dough lump reaches the light beam, part of this scatter light reaches the detector and thereby is caused to produce an electrical indicator signal.