JPH1125340A - Dew condensation preventing device for window glass surface of automatic vending machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress energy consumption by detecting whether there is a condition for generating dew condensation on the store outside surface of an window glass through which commodities in the store are to be looked or not, and only at the time of detecting the condition for the generation of dew condensation, controlling a window glass heating heater to a heating operation state. SOLUTION: In an automatic vending machine constituted so as to look commodities in a store through an window glass, a dew condensation detection means 402 detecting a condition for generating dew condensation or the generation of dew condensation actually on the window glass transmits the detected information to a main control device 401. The device 401 outputs a command to a vending means 407 to turn the glass heating heater 408 to a driving state and the means 407 receiving the command turns a switch 409 to a conductive state and the heater 408 starts heating. When the means 402 detects a condition indicating no fear of dew condensation, the means 407 interrupts the switch 409 to stop heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing dew condensation on a glass surface of a vending machine.

[0002]

2. Description of the Related Art An automatic vending machine, in which a product sample is displayed at a place different from an actual product, so that a product actually sold without using the product sample can be seen by a customer through a transparent glass window. There is a vending machine. In such vending machines, especially cold products such as juice are cooled in the refrigerator, but with cooling, the outside air is cooled through the window glass, and condensation forms on the glass surface. You will not be able to see it.

[0003] For this reason, the window glass is made of heat insulating glass to prevent dew condensation by preventing heat exchange with the outside air. Further, a transparent conductor is sandwiched between the window glasses having a multilayer structure. It has been practiced to prevent the dew condensation by applying a current to a conductor to generate heat (Japanese Utility Model Laid-Open No. 61-189377).

[0004] Regarding the above-mentioned electric conductor, which generates an electric current by flowing an electric current to prevent dew condensation, the electric conductor (fog-prevention heater) is provided regardless of the state of the outside air and the season. The current was constantly flowing and heating was continued.

[0005] In order to cool the inside of the vending machine and to heat the window surface on the other hand, not only power for heating is consumed but also this heat is transferred to the inside of the vending machine to reduce the cooling capacity. It was also. As described above, the energy for heating and the further energy accompanying the decrease in the cooling capacity consume power unnecessarily, which is not preferable from the viewpoint of energy saving.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to heat a window glass surface only when heating is required in accordance with the state of the outside air, thereby suppressing energy consumption. Is what you do.

[0007]

This problem is solved by the following means.

(1) First invention A window glass through which a product in a storage can be seen through, and a product cooling means for cooling the product in the storage,
A glass heating means for heating the window glass, and a dew condensation preventing device for a window glass surface of a vending machine comprising:
A dew-condensation condition detecting means for detecting whether or not dew condensation occurs on the surface of the window glass outside of the storage; and a control means for controlling a heating operation state of the glass heating means, wherein the dew-condition detection is performed. When the means detects the condition of the occurrence of dew condensation, the glass heating means is controlled to the heating operation state, and when the means does not detect the condition, the glass heating means is controlled to the non-heating operation state. A dew condensation preventing device for a window glass surface of a vending machine, comprising: a control unit.

(2) Second invention In the apparatus for preventing dew condensation on the surface of a window glass of a vending machine according to the first invention, the storage is divided into a plurality of compartments by hot walls for partitioning the interior of the vending machine. Is divided into a plurality of sections corresponding to the plurality of sections, and the control means controls a heating operation state for each of the sections of the glass heating means. Device to prevent condensation on window glass.

(3) Third invention In the apparatus for preventing dew condensation on a window glass surface of a vending machine according to the first or second invention, the dew condensation condition detecting means is attached to a surface of the window glass on the outside of the storage. An apparatus for preventing dew condensation on a window glass surface of a vending machine, comprising a dew sensor.

(4) Fourth invention In the device for preventing dew condensation on a window glass surface of a vending machine according to the first or second invention, the dew condensation condition detecting means detects the humidity of air outside the storage. A temperature sensor for detecting the temperature of the air outside the storage; and a humidity sensor and a humidity and a temperature detected by the temperature sensor when the air reaches a saturation state when cooled to the temperature of the window glass surface. Computing means for computing whether or not
A device for preventing dew condensation on the surface of a window glass of a vending machine, characterized by comprising:

(5) Fifth invention In the apparatus for preventing dew condensation on the surface of a window glass of a vending machine according to a fourth invention, the air whose humidity and temperature are detected by the humidity sensor and the temperature sensor are the same as those of the window glass. An apparatus for preventing dew condensation on a window glass surface of a vending machine, characterized in that the air is near the surface on the outside of the storage.

(6) Sixth invention In the apparatus for preventing dew condensation on the surface of a window glass of a vending machine according to the fourth or fifth invention, the calculating means approximates the boundary of the saturated state with a straight line of temperature and humidity. An apparatus for preventing dew condensation on a window glass surface of a vending machine.

(7) Seventh invention In the apparatus for preventing dew condensation on the surface of a window glass of a vending machine according to the first or second invention, the dew condensation condition detecting means includes a time measuring means and a date and time when the dew condensation condition occurs throughout the year. And a dew-condensation condition occurrence date and time table containing the dew-condensation condition. The dew-condensation condition is detected with reference to the dew-condition occurrence date and time table based on the date and time measured by the clocking means. Device to prevent condensation on window glass of vending machines.

(8) Eighth invention In the apparatus for preventing dew condensation on a window glass surface of a vending machine according to the first or second invention, the commodity cooling device comprises: a temperature sensor in the storage for detecting a temperature in the storage; An outside air temperature sensor for detecting the temperature of the outside air, wherein the dew condensation condition detecting means is configured to detect a difference between the inside temperature detected by the inside temperature sensor and the outside air temperature detected by the outside air temperature sensor. A dew-condensing condition on a window glass surface of a vending machine, wherein the device is under a dew-condensing condition when is greater than or equal to a predetermined value set in advance.

(9) Ninth invention In the apparatus for preventing dew condensation on the surface of a window glass of a vending machine according to any one of the second to eighth inventions, the vending machine further heats the product in the storage. Product heating means for performing, when the product heating means is operating,
An apparatus for preventing dew condensation on a window glass surface of a vending machine, wherein the glass heating means does not operate.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) With regard to the invention of claim 1, the dew condensation preventing device on the window glass surface of the vending machine of the present invention is used for cooling the window glass that can see through the goods in the storage and the goods in the storage. Commodity cooling means, a glass heating means for heating the window glass, a dew condensation condition detecting means for detecting whether or not the dew condensation occurs on the surface outside the storage of the window glass, and a control means The control means controls the glass heating means to a heating operation state when the dew condensation condition detecting means detects that the dew condensation occurs, and does not detect that the dew condensation condition exists. At this time, the glass heating means is controlled to a non-heating operation state. Therefore, the glass heating means is operated for heating only when dew condensation actually occurs, and the heating operation is not performed when no dew condensation occurs, so that power is not wastefully consumed.

(2) According to the second aspect of the present invention, in the vending machine according to the second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the storage is further provided with a hot wall for partitioning the inside of the vending machine. The glass heating means is divided into a plurality of sections corresponding to the plurality of sections, and the control means performs a heating operation state for each of the sections of the glass heating means. Control.

[0019] Therefore, since the glass heating means is operated to heat only the storage which is actually cooled and where dew condensation may occur, energy consumption can be suppressed.

(3) According to the third aspect of the present invention, a dew condensation preventing device for a window glass surface of a vending machine according to the present invention has a dew condensation condition detecting means in addition to the configuration of the first or second aspect of the present invention. And a dew condensation sensor attached to the surface of the window glass on the outside of the storage. For this reason,
It is possible to directly detect a state in which dew condensation occurs, and to perform accurate control.

(4) According to the invention of claim 4, the apparatus for preventing dew condensation on the surface of a window glass of a vending machine according to the present invention is characterized in that, in addition to the constitution of the invention of claim 1 or 2, the dew condensation condition detecting means is provided. , A humidity sensor that detects the humidity of the air outside the storage, a temperature sensor that detects the temperature of the air outside the storage, and the humidity and temperature of the air detected by the humidity sensor and the temperature sensor up to the temperature of the window glass surface. Calculating means for calculating whether or not a saturated state is reached when cooled.

Therefore, there is no need to provide a dew condensation sensor that hinders the customer from looking inside the storage as in the third aspect of the present invention.

(5) According to the fifth aspect of the present invention, in the vending machine of the present invention, the dew condensation preventing device for a window glass surface further includes two sensors near the window glass in addition to the configuration of the fourth aspect. Therefore, it is possible to more accurately detect the dew condensation condition.

(6) The invention according to claim 6 is a device for preventing dew condensation on the surface of a window glass of a vending machine according to the present invention, in addition to the structure of claim 4 or 5, further comprising: Since the boundary is determined by approximating the boundary with a straight line of the temperature and the humidity, the calculation can be performed more easily.

(7) According to the seventh aspect of the present invention, in the vending machine of the present invention, the dew condensation preventing device on the surface of the window glass has the structure of the first or second aspect of the present invention. It has a timekeeping means and a dew condensation condition occurrence date and time table containing the date and time when the dew condition occurs throughout the year, and refers to the dew condition occurrence date and time table based on the date and time measured by the timekeeping means to determine the dew condition. To detect. Therefore, maintenance is easy because no sensor for the outside air temperature or the like is used.

(8) According to the invention of claim 8, the apparatus for preventing dew condensation on the surface of a window glass of a vending machine according to the present invention, in addition to the structure of the invention of claim 1 or 2, further comprises: It has an internal temperature sensor for detecting the temperature in the storage, and an external air temperature sensor for detecting the temperature of the external air, and the dew condensation condition detecting means detects the internal temperature detected by the internal temperature sensor and the external air temperature. When the difference from the outside air temperature detected by the temperature sensor is equal to or more than a predetermined value, it is determined that the dew condensation condition exists. Since the outside air temperature sensor and the internal temperature sensor of the cooling device of the conventional vending machine can be used as they are, the cost can be reduced.

(9) According to the ninth aspect of the present invention, the apparatus for preventing dew condensation on the surface of a window glass of a vending machine according to the present invention further includes, in addition to the configuration of any of the second to ninth aspects, A product heating unit for heating the product in the storage is provided, and the glass heating unit does not perform a heating operation when the product heating unit is operating. For this reason, since no heating is performed on the window glass of the storage in which dew condensation does not occur, there is no wasteful energy consumption.

[0028]

【Example】

Embodiment 1 FIG. 1 is a front view of a vending machine according to one embodiment of the present invention, and FIG. 2 is a sectional side view of the same.

Reference numeral 1 denotes a vending machine main body. Numeral 2 denotes an internal partition hot wall provided inside the storage of the vending machine. In the example of this figure, three internal heat insulating partition walls 2 form four sections, from the first internal part 3 to the fourth internal part 6. , Is divided into. Goods sold by the vending machine are stored in the first to fourth warehouses.

Reference numeral 7 denotes a dew condensation condition detecting means, which is installed at a location where the dew condensation condition can be detected most appropriately. The location shown in FIG. 1 is merely an example, and an appropriate installation location differs depending on the principle of detecting the dew condensation condition, the structure of the vending machine, and the like. In addition, the number is not limited to one as shown in FIG.

The front side (customer side) of the storage is constituted by a transparent window glass 8 so that the customer can see the goods inside.

The storage is provided with a heating device or a cooling device so that heating or cooling can be independently performed for each of the storages, and the heating and cooling are switched according to a change in season or a product to be sold. Can be

When the storage is cooled in summer or the like,
The outside air is cooled through the window glass, which becomes dewed and adheres to the surface of the window glass to make the inside invisible, so that this window glass usually employs a heat insulating structure and a means for heating the surface of the window glass. . FIG. 3 shows a cross-sectional structure of such a window glass. By arranging the two glass plates 9 and 10 with a space therebetween, heat transfer is suppressed, and further, by providing a glass heating means 11, for example, a transparent film-shaped heater inside the outer glass plate 9, The glass plate 9 is heated to prevent dew condensation.

[0034] The glass heating means 11 is provided from the first chamber to the fourth chamber.
When any part of the refrigerator is cooled, it can be heated independently.

FIG. 4 is a block diagram showing an outline of control according to the embodiment of the present invention.

Reference numeral 401 denotes a main controller for controlling the operation of the entire vending machine; 402, a dew-condensation condition detecting means for detecting whether or not dew condensation is occurring on the window glass 8; Reference numeral 403 denotes a money processing means for identifying the money inserted by the customer, accepting the money, and paying necessary change.

A display / setting unit 404 has a display function for displaying the state of the vending machine for a customer or a vending machine maintenance person, and a setting function for inputting the setting conditions of the vending machine. Have. Reference numeral 405 denotes a dip switch for setting whether to cool or heat the inside of the refrigerator. Reference numeral 406 denotes a keyboard for inputting a product price, a sales time, and other numerical values, both of which perform the above-described setting functions. It is.

Reference numeral 407 denotes a selling unit which controls the dropping of a product selected by the customer and the like, and turns on / off the power of the glass heating unit 11 as described later. 40
Reference numeral 8 denotes a heater constituting the glass heating means 11, and power is supplied to the heater 408 through a switch 409 operated by the selling means. Although three switches 409 are shown in FIG.
Are operated independently.

A power supply 410 supplies power to the heater 408.

With the above configuration, this embodiment operates as follows.

When the dew condensation condition detecting means 402 detects a condition in which dew condensation occurs on the window glass 8 or that dew condensation actually occurs, this information is transmitted to the main controller 401.

Main controller 401 issues a command to vending means 407 to put glass heating means 11 into an operating state.
9 is turned on, and the glass heating means 11 starts generating heat.

At this time, if the product is set in a state where the product is being heated in any of the refrigerators, there is no danger of dew condensation. Therefore, the glass heating means 11 corresponding to this is heated. I will not do it.

When the dew condensation condition detecting means 402 detects that there is no risk of dew condensation or no dew condensation, the selling means 407 operates the switch 409 to the cut-off state through the same route as above, and the heating is stopped. Stopped.

By the above operation, electricity is supplied to the glass heating means 11 only when dew condensation occurs or when conditions for dew condensation on the window glass occur, so that not only energy is not wasted but also glass heating means is not wastefully consumed. It is possible to prevent a decrease in cooling capacity in the refrigerator due to the heat generated by the means 11 being transmitted into the refrigerator, and to prevent waste of energy due to this.

The following embodiments can be given depending on the mode of the dew condensation condition detecting means 402.

[Embodiment 2] In this embodiment, a dew condensation sensor is used as the dew condensation condition detecting means, and it is attached to the surface of the window glass on the outside of the storage. At this time, it is preferable to select a location that does not block the line of sight to the interior of the storage and that best represents the dew condensation state on the entire surface of the window glass.

In FIG. 5, the dew sensor utilizes the fact that the resistance value changes due to dew. The condensation sensor R8 has a bridge formed by the resistors R5, R6, and R7, and amplifies the potential difference between the points a and b by an operational amplifier. Since the operational amplifier OP is subjected to positive feedback by R2, the power supply voltage (8 V or 5 V) is applied to the output OUT.
Or 0V is output. Zener diode ZD, capacitor C and resistor R9 are for obtaining a voltage for the bridge.

The output OUT indicates whether condensation actually occurs or not.

Embodiment 3 When the air is cooled and the contained water vapor reaches the saturation temperature or less, the water vapor contained therein cannot exist in the form of water vapor, and this water vapor forms water droplets and forms dew. . Further, the amount of water contained in the saturated air varies depending on the temperature.

In this embodiment, the dew condensation condition is detected using this principle.

A temperature sensor and a humidity sensor for detecting the temperature and humidity of the air there are provided outside the storage.

When the air at the point where the sensor is provided reaches the window glass surface, it is cooled by the heat transfer from the storage. The extent to which air is cooled is affected by the temperature of the window glass surface, and the temperature of the window glass surface is determined by the thermal gradient between the outside air temperature and the temperature inside the storage, and the amount of saturated steam Since is a function of temperature, it is determined whether or not dew condensation takes place in consideration of these factors, and therefore, whether or not the glass heating means 11 is heated.

The graph of FIG. 6 is obtained by approximating the boundary of whether to heat the glass heating means by a linear relationship between humidity and temperature. If the above detection result is above this line,
When it is determined that dew is formed on the surface of the window glass, the glass heating means 11 is energized.

The dew condensation condition can be determined more accurately when the humidity and temperature are detected closer to the surface of the window glass.

[Embodiment 4] In this embodiment, the measurement result for controlling the cooling device is used as it is by using the outside temperature sensor and the inside temperature sensor provided in the cooling device of the vending machine. .

When the difference between the outside air temperature and the inside temperature is equal to or more than a predetermined value, it is determined that the condition for dew condensation is present, and the glass heating means 11 is energized.

FIGS. 7 and 8 show that when the temperature in the refrigerator changes,
And a graph showing whether or not to heat the glass heating means when the outside air temperature changes.

In this embodiment, there is no need to newly provide a sensor for detection, and therefore, there is an advantage that the cost can be reduced.

[Embodiment 5] The present embodiment utilizes the fact that dew condensation is greatly affected by the season and time zone.

The humidity is extremely high during the rainy season and during the summer throughout the year, so that dew condensation tends to occur. The same is true during the afternoon and evening.

In this embodiment, a day and a time zone in which dew condensation is likely to occur are statistically summarized to create a dew condensation occurrence date and time table.
It is stored in the storage device of the dew condensation condition detecting means. In the present embodiment, the date and time are read from a clock device (clock), and the result is referred to as the output of the dew-condensation condition detecting means with reference to the dew-deposition condition in the above-mentioned dew-condensation occurrence date and time table corresponding to the read date and time.

[0063]

According to the first aspect of the present invention, in a conventional vending machine cooling device, cooling is performed in a refrigerator and the window is heated on the other hand. The situation that this heat was also transmitted to the inside of the refrigerator and reduced the cooling capacity was revised, and unnecessary heating energy was eliminated, thereby reducing the cooling capacity. To play.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the glass heating means is operated to heat only the storage which is actually cooled and there is a possibility of dew condensation. An effect that can be suppressed is exerted.

The third aspect of the present invention provides the first or second aspect.
In addition to the effects of the invention, the effect that dew condensation is occurring can be directly detected and accurate control can be performed.

The invention of claim 4 is the invention of claim 1 or claim 2.
In addition to the effect of the invention of the third aspect, there is an effect that there is no need to provide a dew condensation sensor that hinders the customer from looking inside the storage as in the invention of the third aspect.

According to the fifth aspect of the invention, in addition to the effect of the fourth aspect of the invention, since two sensors are installed near the window glass, more accurate detection of the dew condensation condition can be performed. Is played.

The invention of claim 6 is the invention of claim 4 or claim 5.
In addition to the effects of the invention, the calculation means determines the boundary of the saturated state by approximating the boundary with a straight line of temperature and humidity, so that the calculation can be performed more easily.

The seventh aspect of the present invention is the first or second aspect.
In addition to the effects of the invention, the present invention has an effect that maintenance is easy because a sensor for the outside air temperature or the like is not used.

The invention of claim 8 is the invention of claim 1 or claim 2.
In addition to the effects of the invention, the present invention has an effect that the temperature can be reduced because the outside air temperature sensor and the internal temperature sensor of the cooling device of the conventional vending machine can be used as they are.

The ninth aspect of the present invention is the second or eighth aspect.
In addition to the effects of the invention, when the product heating means is operating, the glass heating means does not perform the heating operation, so that the window glass of the storage where dew condensation does not occur is not heated, so that there is no wasteful energy consumption. To play.

[Brief description of the drawings]

FIG. 1 is a front view of a vending machine according to one embodiment of the present invention.

FIG. 2 is a side sectional view of the vending machine of FIG. 1, which is one embodiment of the present invention.

FIG. 3 is a sectional view of a window glass of a vending machine according to one embodiment of the present invention.

FIG. 4 is a block diagram showing an outline of control of a vending machine according to one embodiment of the present invention.

FIG. 5 is an example of a circuit diagram of a dew condition detecting unit using a dew sensor in the embodiment of the present invention.

FIG. 6 is a graph in which the boundary of whether to heat the glass heating means is approximated by a linear relationship between humidity and temperature.

FIG. 7 is a graph showing whether or not the glass heating means is heated when the temperature in the refrigerator changes.

FIG. 8 is a graph showing whether the glass heating means is heated when the outside air temperature changes.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 vending machine 2 internal compartment hot wall 3 first internal compartment 4 second internal compartment 5 third internal compartment 6 fourth internal compartment 7 dew condensation condition detecting means 8 window glass 9 glass plate 10 glass plate 11 glass heating means 401 main Control device 402 Condensation condition detecting means 403 Money processing means 404 Display / setting means 405 Dip switch 406 Keyboard 407 Sales means 408 Heater 409 Switch 410 Power supply R1 to R7, R9 Resistance R8 Condensation sensor OP Op amp C Capacitor ZD Zener diode

Claims (9)

[Claims] 1. A window glass through which goods in a storage can be seen through, a product cooling means for cooling the goods in the storage, and a glass heating means for heating the window glass. A dew condensation prevention device for a window glass surface of a vending machine, comprising: a dew condensation condition detecting means for detecting whether or not a condition under which dew condensation occurs on the outer surface of the storage of the window glass; and a heating operation of the glass heating means. Control means for controlling the state, wherein when the dew condensation condition detecting means detects that the dew condensation condition is present, the glass heating means is controlled to a heating operation state, and the detection is not performed that the dew condensation condition is detected. And a control means for controlling the glass heating means to a non-heating operation state. A device for preventing dew condensation on the surface of a window glass of a vending machine, comprising: 2. The device for preventing dew condensation on the surface of a window glass of a vending machine according to claim 1, wherein the storage is divided into a plurality of sections by a partitioning hot wall, and the glass heating means is divided into the plurality of sections. Correspondingly divided into a plurality of sections, wherein the control means controls a heating operation state for each of the sections of the glass heating means, and prevents dew condensation on a window glass surface of a vending machine. apparatus. 3. The dew condensation preventing device for a window glass surface of a vending machine according to claim 1, wherein said dew condensation condition detecting means is constituted by a dew condensation sensor attached to a surface of said window glass on the outside of a storage. A device for preventing dew condensation on a window glass surface of a vending machine, which is characterized in that: 4. A dew condensation preventing device for a window glass surface of a vending machine according to claim 1, wherein said dew condensation condition detecting means comprises: a humidity sensor for detecting humidity of air outside said storage; A temperature sensor for detecting the temperature of the air; calculating whether or not the humidity sensor and the humidity and temperature air detected by the temperature sensor reach a saturation state when cooled to the temperature of the window glass surface; An apparatus for preventing dew condensation on the surface of a window glass of a vending machine, comprising: an arithmetic unit; 5. The apparatus for preventing dew condensation on a window glass surface of a vending machine according to claim 4, wherein the air whose humidity and temperature are detected by said humidity sensor and said temperature sensor is in the vicinity of the surface of said window glass on the outside of said storage. An apparatus for preventing dew condensation on a window glass surface of a vending machine, characterized in that the air is natural air. 6. The apparatus for preventing dew condensation on a window glass surface of a vending machine according to claim 4, wherein said calculating means approximates the boundary of said saturated state with a straight line of temperature and humidity. A device to prevent condensation on the window glass of vending machines. 7. The dew condensation preventing device for a window glass surface of a vending machine according to claim 1, wherein said dew condensation condition detecting means comprises: a time measuring means; and a dew condensation condition including a date and time when the dew condensation condition occurs throughout the year. A window glass for a vending machine, comprising: an occurrence date and time table; and detecting the dew condensation condition by referring to the dew condition occurrence date and time table based on the date and time measured by the timing means. Surface dew prevention device. 8. The device for preventing dew condensation on a window glass surface of a vending machine according to claim 1 or 2, wherein the commodity cooling device detects a temperature in a storage, and detects a temperature of outside air. An outside air temperature sensor, wherein the dew condensation condition detecting means is configured such that a difference between an inside air temperature detected by the inside air temperature sensor and an outside air temperature detected by the outside air temperature sensor is set in advance. An apparatus for preventing dew condensation on a window glass surface of a vending machine, characterized in that the apparatus is under a dew condensation condition when a certain value or more is present. 9. The apparatus for preventing dew condensation on a window glass surface of a vending machine according to any one of claims 2 to 8, wherein the vending machine further comprises a product heater for heating a product in the storage. Means for preventing condensation on the surface of a window glass of a vending machine, wherein the glass heating means does not operate when the commodity heating means is operating.