EP0057729A1

EP0057729A1 - Heating state indicator for heat cooking oven using multicolor fluorescent

Info

Publication number: EP0057729A1
Application number: EP81902251A
Authority: EP
Inventors: Takashi Niwa
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1980-08-19
Filing date: 1981-08-17
Publication date: 1982-08-18
Also published as: KR850000429Y1; CA1183908A; EP0057729A4; WO1982000703A1; AU535857B2; KR830006632A; JPS5740007U; AU7456081A

Abstract

In this heat cooking oven, a cooking mode indicator (15) indicates heat or microwave cooking mode, a temperature scale indicator (23) indicates the set cooking temperature, a temperature indicator (24) indicates the present cooking temperature, and a time indicator (16) indicates the cooking time. The variety of information is indicated in multiple colors in one multicolor fluorescent display tube to be easier to see and read without error in a microwave heat cooking oven having a heater.

Description

TECHNICAL FIELD

This invention relates to means for displaying the heating condition of a heating cooking apparatus such as a microwave oven.

BACKGROUND ART

With the progress of the semiconductor technology, many microcomputer-applied products are now being made in the field of domestic appliances, too. The field of heating apparatus is also not an exception, and many microcomputer-applied products have appeared in this field so far. On the other hand, however, the procedure for manipulation of such an apparatus seems to become more complex. In the field of domestic appliances, ease of manipulation and clear visibility of display are especially required.
In an apparatus such as a so-called composite oven which is an integral combination of a microwave oven and an ordinary oven, it is necessary to apply the output power level and cooking time as input information in the case of cooking with the microwave oven and to apply the oven internal temperature and time as input information in the case of cooking with the ordinary oven. In the practical use of such an apparatus, it seems that many of the users have had the feeling of perplexity in spite of the digital display of the heating condition. That is, when a single display tube is used to display both of the temperature and the time, the user is unable to see the temperature when the display tube is-displaying the time. This applies also to the converse case.
Although both of the temperature and the time can be simultaneously displayed by providing two display tubes, this results in various problems including an increase in the cost and a large space occupied by the display part.
Referring to Fig. 1, microwave generated from a magnetron 1 is guided by a waveguide 2 to be absorbed by a foodstuff placed in a heating cavity 3. An electric heater 4 is provided in the heating cavity 3 to heat the interior of the heating cavity 3 for oven cooking. On the other hand, a fluorescent display tube has a structure as shown in Figs. 2A and 2B, and thermions emitted from a cathode 5 are accelerated by a positive voltage applied across grids 6 and anodes 7 to stimulate and cause fluorescence of a fluorescent paint 8 coated on the anodes 7. The voltage is selectively applied across the grids 6 and the anodes 7 so as to display desired figures, characters, symbols and graphics.
Fig. 3 shows an example of a control panel in which two fluorescent display tubes are used. One of the fluorescent display tubes 9 includes a cooking mode display part 10 and a time display part 11, and the other fluorescent display tube 13 provides a temperature display part 14. Because of the provision of two fluorescent display tubes, the control part has been complex resulting in poor controllability.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a heating cooking apparatus in which a single multicolored fluorescent display tube is employed to clearly visibly display both of the temperature and the time and which is satisfactorily controllable.
An embodiment of the present invention will be described hereinunder with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a partly cut-away, front elevation view of a composite microwave oven.
Figs. 2A and 2B are a sectional view and a partly sectional, perspective view showing the structure of a prior art fluorescent display tube.
Fig. 3 is a front elevation view of part of a control part of a heating apparatus using a plurality of fluorescent display tubes.
Fig. 4 is a connection diagram of individual segments of a multicolored fluorescent display tube in an embodiment of the heating cooking apparatus of the present invention.
Fig. 5 is a display pattern diagram of the multicolored fluorescent display tube.
Fig. 6 is a diagram showing the temperature display part and its light emission timing.
Fig. 7 is a circuit diagram of one embodiment of the heating cooking apparatus of the present invention.
Fig. 8 is a display pattern diagram showing another structure of the multicolored display tube.
Fig. 9 is a circuit diagram of another embodiment of the present invention.
Fig. 10 is a diagram showing the relation between the anode voltage and the luminance of the fluorescent display tube.
Fig. 11 is a display pattern diagram of the multicolored fluorescent display tube when the color is changed for each of the heating parameters.
Fig. 12 is an external perspective view of the composite microwave oven.

BEST MODE FOR CARRYING OUT THE INVENTION

Fig. 4 shows a connection pattern of a single multicolored fluorescent display tube 12 which includes therein a cooking mode display part 15, a time display part 16, a temperature display part 24 and a temperature . scale display part 23. In the multicolored fluorescent display tube 12 above described, a fluorescent paint whose fluorescent color is green is coated on characters "Hi" 19 (a display indicating a high microwave output), "Lo" 20 (a display indicating a low microwave output), "GRILL" 21 (cooking by a heater subsequent to cooking with a high microwave output), and segments of individual digits, and a fluorescent paint whose color is red is coated on characters "OVEN" 22 (cooking by the heater) and segments of the temperature scale display part 23 and temperature display part 24. The cathode of "OVEN" 22 and the cathode of the temperature scale display part 23 are connected within the display tube. Therefore, when the "OVEN" mode is selected, the "OVEN" display part 22 and the temperature scale display part 23 emit light simultaneously so that the purpose of demanding the temperature input can also be attained.
When now a positive voltage is applied to the multicolored fluorescent display tube 12 through a terminal 0₇ and a terminal R₄ connected to a grid 24-a, "OVEN" 22 luminesces in red. On the other hand, when the positive voltage is applied through the terminal 0₇ and a terminal R₃ connected .to a grid 24-b, "YEAST 120" luminesces in red. Similarly, by sequentially energizing through terminals R₂ and O₇, terminals R₁ and O₇, and terminals R_φ and O₇ at a high speed, the human eye recognizes as if all of the "OVEN" display 22 and the temperature scale display part 23 are luminant as shown in Fig. 5. The temperature display segments are controlled by signal conductors extending from terminals R₇- R₁₀ and signal conductors extending from terminals R₃- R_φ. Fig. 6 shows the timing chart of output voltage levels at the terminals R_O- R₃ and terminals ^R ₇- R₁₀ when "200°C" is displayed. The fluorescent paint whose color is red is also coated on the anode segments of the temperature scale. Fig. 7 shows one form of an electrical circuit used for the practice of the present invention.
A microcomputer 25 controls this systems. Current supply to the electric heater 4 is controlled by a triac 26 which is turned on-off by an output terminal R₅ of the microcomputer 25 and an electronic circuit 27. For controlling the internal temperature of the heating cavity 3, a thermistor 28, output terminals R₁₁- R₁₅ of the microcomputer 25, a D-A converter 29 and a comparator 30 sense the temperature, and, on the basis thereof, the microcomputer 25 judges as to whether or not its output should appear at the terminal R₅.
On the other hand, excitation of the magnetron 1 is controlled by turning on and off the primary side of a high-voltage transformer 32 by an output terminal R₆ of the microcomputer 25 and an electronic circuit 31. As soon as the primary side is closed, a high voltage is induced in the secondary side thereby exciting the magnetron 1. When the heater 4 is selected as the heating source, the temperature scale luminescens in red. No luminescence occurs when the magnetron 1 is selected. The grid voltage for a multicolored fluorescent display tube 33 is sequentially supplied from terminals R₃- R of the microcomputer 25, and the anode voltage is supplied in parallel from terminals 0₀- 0₇.
When a temperature key 35 is depressed after selection of "OVEN" by a cooking mode key 34, the number of times of depression or the duration of depression is counted to display the set temperature. After depression of a time key 36, a start key 37 is depressed. The signal output from the microcomputer 25 is controlled so that, with the rise of the internal temperature of the oven, the segments corresponding to the present internal temperature make flashing, and, thus, both of the set temperature and the present temperature are displayed on the same temperature display part. Alternatively, for the display of the set temperature, the segments corresponding to that temperature only are turned on or make flashing so as to display the oven internal temperature in the form of a bar.
Fig. 8 illustrates that a status part indicating the cooking condition is additionally disposed above the time display part. The color of light emitted from that part differs from those of the other display parts and differs also from that of the figure display part. Fig. 9 shows a circuit for driving the fluorescent display tube above described. Output voltages from terminals R₁₆- R₂₀ and terminals 0₈- O₁₁ are raised by drivers 39 and 40 before being applied to the multicolored fluorescent display tube. This is because the luminous efficacy differs depending on fluorescent paints as shown in Fig. 10, and it is therefore necessary to increase the luminance of a paint having a poor luminous efficacy. Fig. 11 shows another example in which the display parts emit different colors corresponding to the heating parameters. For example, "Hi" and "Lo" indicating the cooking condition under microwave heating as well as the cooking time display figures emit green light, while "OVEN" and "GRILL" indicating the cooking condition under heating with the heater as well as the temperature display part emit red light, so that the cooking condition can be identified at a glance.

INDUSTRIAL APPLICABILITY

As described hereinbefore, according to the present invention, a single multicolored fluorescent display tube is employed to display in plural colors the cooking condition under microwave heating, the cooking condition under heating with the heater, the time setting and the temperature setting. Therefore, the present invention can provide a heating cooking apparatus in which the display is clearly visible and can be read without any error and which is free from mal- handling.

Claims

1. A heating cooking apparatus comprising a plurality of heating means for cooking an object to be heated by heating the same, a control part controlling these heating means, input means for applying to said control part a plurality of data including selection of the heating means, heating temperature and heating time, and a multicolored display tube capable of simultaneously displaying said plural data applied from said input means.

2. A heating cooking apparatus according to Claim 1, wherein said multicolored display tube displays different colors corresponding to the plural heating means respectively.

3. A heating cooking apparatus according to Claim 1, wherein, when the heating means requiring temperature display is selected, the color displaying that mode is the same as that of the temperature display.

4. A heating cooking apparatus according to Claim 1, wherein the voltage applied across the grids and the anodes of said multicolored display tube is changed for each of the emitted colors.

5. A heating cooking apparatus according to Claim 1, wherein the heating time is digitally displayed, and the heating temperature is analogly displayed in a bar form.