JPH0344709B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a heat-retaining device that maintains a light source of a color reading device at an optimal temperature for lighting.

<Prior art and its drawbacks> Various devices have been proposed that scan a document while sequentially lighting up red, green, and blue fluorescent lights to read the colors of the document, but the fluorescent lights used in these devices As shown in the characteristic graph in Figure 5, the luminescent characteristics of the lamp change drastically with temperature, so in order to obtain highly accurate readings when used in facsimile machines, etc., it must be kept at its optimum temperature of around 50°C. must be activated. Therefore, conventionally, a heater 2 is mounted on the surface of the fluorescent lamp 20, as shown in a perspective view in FIG.
1 and a temperature sensor 22 were installed to control the temperature of each of the three fluorescent lamps separately. Therefore,
Not only does the control circuit become complicated, but the power required to maintain heat increases, and it is very difficult to maintain the three-color fluorescent lamps in the same state at all times, so the balance of light emission tends to shift. In addition, since the above-mentioned measures have to be taken for the fluorescent lamp, which is a consumable part, there is a drawback that the cost becomes high. Furthermore, when the fluorescent lamp is turned on, the fluorescent lamp itself generates heat,
There is no device equipped with a means for regulating the drive of the heater in this lighting state, resulting in problems such as overheating of the fluorescent lamp and overload of the power supply circuit.

<Objective of the Invention> In order to solve the above-mentioned drawbacks, this invention controls three color fluorescent lamps simultaneously with one temperature control system, simplifies the circuit configuration, maintains the light emission balance, reduces costs, and improves the fluorescent lamp. It is an object of the present invention to provide a light source warming device for a color reading device that enables prevention of overheating and overloading of a power supply circuit.

<Configuration of the Invention> The present invention includes a cover for covering three-color fluorescent lamps, a heater and a temperature sensor disposed within the cover,
a comparator for comparing the detected value of the temperature sensor with a reference value corresponding to around the optimum temperature of the fluorescent lamp; The heater control unit outputs a heater-on signal only when the heater is not lit, and controls the heating of the heater so that the detected value matches the reference value.

<Embodiment> FIG. 1 is a structural diagram of a main part of a color reading device which is an embodiment of the present invention. Document table 8 which is a glass plate
A document 9 is set on top. This manuscript table 8
is driven by a pulse motor 17 (see FIG. 2) during operation. A light source device A is installed below and close to the document table 8 . This light source device A includes a metal cover 1, a glass top plate 2, red, green, and blue fluorescent lamps 3, 4, 5, heaters 6a, 6b, and a temperature sensor 7.
It consists of A metal cover 1 opens upward, and a glass top plate 2 closes the opening.
Furthermore, an optical path slit 1a is provided on the bottom surface of the cover 1. Fluorescent lights 3, 4, and 5 are installed inside the cover 1 and illuminate the original 9 through the glass top plate 2 and the original table 8. Heaters 6a, 6b and temperature sensor 7 are installed inside cover 1. The cover 7 is grounded, and the ground side terminals of the fluorescent lamps 3, 4, and 5 are connected to the cover 1. In addition, fluorescent lamp 3,
The reflected light from the original 9 illuminated by slits 1 and 4
a. Light enters the image sensor 12 via the reflecting mirror 10 and the lens 11.

FIG. 2 is a block diagram of the above embodiment. The inverting input terminal of the comparator COM is supplied with the temperature detection voltage Vtemp set by the temperature sensor 7 and resistor R1, and the non-inverting input terminal is supplied with resistors R2, R3 and R4.
The reference voltage Vth set in is supplied. Resistor R4 is connected in parallel to resistor R3 by closing analog switch AS. The temperature sensor 7 is a Cds whose resistance value decreases as the temperature rises.
It is element. Therefore, the temperature detection voltage Vtemp increases as the temperature rises. The comparator COM outputs an output signal HON' when the temperature detection voltage Vtemp is lower than the reference voltage Vth. Here, the reference voltage Vth when resistor R4 is connected in parallel with resistor R3 is
Assuming Vth1, Vth1=1.5V, which is equal to the temperature detection voltage Vtemp when the temperature inside the cover 1 is 40°C. Also, if the reference voltage Vth when resistor R4 is not connected to resistor R3 is Vth2, then Vth2=
2V, which is equal to the temperature detection voltage Vtemp when the temperature inside the cover 1 is 50°C. Therefore the comparator
COM outputs HON' when the temperature inside cover 1 is below 40℃ when analog switch AS is closed.
Cover 1 when analog switch AS is open
Outputs HON' when the internal temperature is below 50℃. The output HON' of the comparator COM is input to the control circuit 13 and gates G1 and G2 of a heater control section to be described later. Note that 50°C is the optimal temperature for lighting a fluorescent lamp, and 40°C is an initial temperature set based on the expectation that the temperature inside the fluorescent lamp will rise faster than the temperature inside the cover during initial heating, which will be described later. This is the temperature for heating control.

This control circuit 13 is connected to a heater control section 14 which will be described later.
A red fluorescent lamp lighting signal (hereinafter referred to as RFLON), a green fluorescent lamp lighting signal (hereinafter referred to as GFLON), and a blue fluorescent lamp lighting signal (hereinafter referred to as BFLON) are sent to the gate G4 and the fluorescent lamp control unit 15. A start signal (hereinafter referred to as PENA) that instructs the pulse motor control section 16 that controls the pulse motor 17, the gate G2 of the heater control section 14 (described later), and the inverter INV to start reading is output. Also,
Motor drive signals CW and CCW specifying the rotational direction of the motor 17 are output to the pulse motor control section 16. The analog switch AS is turned on and off by the signal ACIN of the control circuit 13.

These signals are controlled and output as follows. First, when the power is turned on, ACIN is first output, and when HON' is output from the comparator COM,
Output RFLON, GFLON, BFLON. After that, when HON′ turns off, ACIN, RFLON,
Turn off all GFLON and BFLON. PENA is output when a certain period of time T elapses after ACIN is turned off, or when HON' is turned off again. RFLON, GFLON, BFLON when reading starts
are alternately output in pulse form.

The heater control unit 14 controls the gates G1, G2, G
It consists of a judgment circuit 14a made up of G3, G4 and an inverter INV, and a heater heating circuit 14b.
The gate G1 is an AND gate, and inputs HON' and the inverter INV. Gate G4 is a Noah gate, RFLON,
GFLON and BFLON are input. The output of this gate G4 is input to gate G2.

The gate G2 is an AND gate, and the outputs of the gate G4, HON', and PENA are inputted thereto.
The outputs of the gates G1 and G2 are supplied to the gate G3. The gate G3 is an OR gate, and outputs a heater heating signal HON to the heating circuit 14b when the output of the gate G1 or G2 is "H".

The gate G1 is PENA during initial heating.
When is not output and HON' is output, the gate G2 outputs "H", and the gate G2 outputs HON' after PENA is output, and
Outputs “H” when RFLON, GFLON, and BFLON are not output. This heater control section 1
4 and the control circuit 13 correspond to the heater control section of the present invention.

FIG. 3 is a timing chart of each signal in the above embodiment. When the power is turned on, the control circuit 13
outputs ACIN (see Figure 2) and sets the reference voltage Vth
is set to Vth1 (=1.5V). Therefore the comparator
COM until the temperature inside cover 1 reaches 40℃
Outputs HON′. According to this HON', the control section 13 outputs RFLON, GFLON, and BFLON. These outputs turn on the heaters 6a, 6b and also turn on the fluorescent lamps 3, 4, 5. This is because the emitted heat of the fluorescent lamps 3, 4, and 5 is also used for initial heating to improve the heating rate. When the temperature inside the cover 1 reaches 40℃ and HON' is no longer output, the control circuit 13 outputs ACIN, RFLON,
Stops output of GFLON and BFLON. Since ACIN stops, the reference voltage Vth is set to Vth (=2V), and HON' is output again. This HON' causes the heater 6 to continue heating. As shown in the figure, even though the temperature inside cover 1 is 40℃, the temperature inside the tubes of fluorescent lamps 3, 4, and 5 has already reached 50℃, which is the optimum lighting temperature, due to the emitted heat. This is because the fluorescent lights 3, 4, and 5 are turned off and the heater 6 is used to raise the temperature inside the cover 1 to 50°C.
PENA is output and starts reading the original when a certain period of time T (one minute in this embodiment) has elapsed after the temperature inside the cover reached 40°C, or when the temperature inside the cover reached 50°C. This fixed period of time T starts after the temperature inside the cover 1 reaches 40°C, and then the heaters 6a and 6b
The temperature is set to the time required for the cover 1 to be heated to a temperature that does not interfere with lighting the fluorescent lamp inside the cover 1.

After the temperature inside cover 1 reaches 50℃, comparator COM outputs to keep the temperature inside cover 1 at 50℃.
HON' is turned on and off, and based on this, the judgment circuit 14a of the heater control section 14 turns on and off HON and controls the heaters 6a and 6b. By this,
The temperature inside the cover 1 is maintained at 50°C. however,
As mentioned above, when any of the fluorescent lamps is on, HON will not turn on even if HON' is on.
This is because the inside of the fluorescent lamp tube and the inside of the cover 1 are kept warm by the emitted heat of the fluorescent lamp, so that the heaters 6a and 6b are not energized to reduce the burden on the power source.

Figure 4 A shows that the temperature inside cover 1 is 40 when the power is turned on.
This is a timing chart when the temperature is above ℃ and below 50℃. ACIN is turned on at the same time as the power is turned on, but since Vtemp has already exceeded 1.5V
HON′ is not output and ACIN is immediately turned off.
Therefore, Vth is set to Vth2 (= 2V) and cover 1
The ratio comparator COM continues until the temperature inside reaches 50℃.
Outputs HON′. At this time, the control circuit 13
Outputs RFLON, GFLON, and BFLON with the same pulse as when reading. Temperature inside cover 1 is 50℃
When HON' is no longer output, PENA is output from the control circuit 13. FIG. 4B is a timing chart when the temperature inside the cover 1 is 50° C. or higher when the power is turned on. As soon as the power is turned on
ACIN is turned on, but since Vtemp has already exceeded 2V, HON' is not output, and ACIN is immediately turned off, and PENA is output from the control circuit 13. After that, it will move on to normal heat retention control.

As described above, according to this embodiment, by covering the three fluorescent lamps with one cover, temperature control can be performed with one control system, so the circuit configuration is
This simplifies wiring and provides the following effects.

1: During initial heating, the heater and fluorescent lamp are turned on at the same time, so the heating speed is fast and the electric power of the heater can be reduced.

2: The temperature inside the cover corresponding to the reference voltage is the optimum temperature for turning on the fluorescent lamp (50°C) and the temperature for turning off the fluorescent lamp that was turned on during initial heating (40°C).
Since it is set in two stages, it is possible to prevent the fluorescent lamp from overheating during initial heating.

3: When the device is operating and the fluorescent lamp is on, the heater will not turn on even if the temperature inside the cover is lower than 50℃, so this prevents overheating inside the fluorescent lamp and overloading the power circuit. I can do it.

<Effects of the Invention> As described above, according to the present invention, three colors of fluorescent lamps can be controlled simultaneously within one cover using one temperature control system, which simplifies the circuit configuration and wiring.
It becomes possible to maintain the light emission balance and reduce the cost of the device main body and consumable parts. It also has the advantage of preventing overheating of the fluorescent lamp and overloading of the power supply circuit.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of the main parts of a color reading device according to an embodiment of the present invention, FIG. 2 is a block diagram of the above embodiment, FIG. 3 is a timing chart of each signal of the above embodiment, and FIG. B is a timing chart when the temperature inside the cover 1 is 40° C. or more and less than 50° C. when the power is turned on, and when the temperature inside the cover 1 is 50° C. or more when the power is turned on, respectively. FIG. 5 is a graph showing the temperature characteristics of a fluorescent lamp for color reading, and FIG. 6 is an external view of a conventional fluorescent lamp for color reading. A... Light source device, 1... Cover, 2... Glass top plate, 3, 4, 5... Fluorescent lamp, 6a, 6b...
Heater, 7... Temperature sensor, 13... Control circuit,
14... Heater control section, 15... Fluorescent lamp control section,
COM……Comparator.

Claims (1)

[Scope of Claims] 1. A document having three colored fluorescent lamps of red, green and blue, and a document placed on a document table made of a transparent plate such as glass is exposed to a small amount of light from the three colored fluorescent lamps. A color reading device that reads the color of a document by sequentially irradiating it at intervals of time includes a cover that covers the three color fluorescent lights, a heater and a temperature sensor installed in the cover, and a detection of the temperature sensor. a comparator for comparing the value with a reference value corresponding to the vicinity of the optimal temperature of the fluorescent lamp; and a state in which the detected value in this comparator is lower than the reference value and none of the three color fluorescent lamps are lit. A light source heat-retaining device for a color reading device, comprising: a heater control section that outputs a heater-on signal only when the heater is turned on, and controls heating of the heater so that the detected value matches the reference value.