HUMIDITY MEASURING APPARATUS AND IMAGE FORMING APPARATUS

Abstract

A humidity measuring apparatus including: a humidity detecting element whose resistance value changes according to a humidity change; a resistor serially connected to the humidity detecting element; a signal output unit which outputs a clock signal to the humidity detecting element and the resistor; and a measuring unit which detects a voltage of a connecting point of the humidity detecting element and the resistor at predetermined timing from an edge of the clock signal and obtains a humidity based on the detected voltage, wherein an abnormality of the humidity detecting element is detected by detecting the voltage at timing different from the predetermined timing based on the voltage detected by the measuring unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a construction of a humidity detecting circuit used in an embodiment 1.

FIG. 2 is a block diagram illustrating a construction of the embodiment 1.

FIG. 3 is a cross sectional view illustrating a structure of the embodiment 1.

FIG. 4 is a flowchart showing processes of the embodiment 1.

FIG. 5 is a waveform diagram of a humidity detecting circuit.

FIG. 6 is a table showing a correlation between an output of the humidity detecting circuit and a humidity.

FIG. 7 is a waveform diagram of the humidity detecting circuit.

FIG. 8 is a waveform diagram of the humidity detecting circuit.

FIG. 9 is a flowchart showing processes of an embodiment 2.

FIG. 10 is a waveform diagram of a humidity detecting circuit.

FIG. 11 is a waveform diagram of the humidity detecting circuit.

FIG. 12 is a flowchart showing processes of an embodiment 3.

FIG. 13 is a waveform diagram of a humidity detecting circuit.

FIG. 14 is a diagram illustrating a schematic construction of a control system.

FIG. 15 is a waveform diagram of a humidity detecting circuit in the related art.

FIG. 16 is a waveform diagram of the humidity detecting circuit.

Claims

1. A humidity measuring apparatus comprising: a humidity detecting element whose resistance value changes according to a humidity change;a resistor serially connected to the humidity detecting element;a signal output unit which outputs a clock signal to the humidity detecting element and the resistor; anda measuring unit which detects a voltage of a connecting point of the humidity detecting element and the resistor at predetermined timing from one of a leading edge and a trailing edge of the clock signal and obtains a humidity based on the detected voltage,wherein an abnormality of the humidity detecting element is detected by detecting the voltage at timing different from the predetermined timing based on the voltage detected by the measuring unit.

2. An apparatus according to claim 1, further comprising a discriminating unit which discriminates whether or not the humidity detecting element is abnormal based on the voltage detected at the timing different from the predetermined timing.

3. An apparatus according to claim 1, wherein the voltage is detected by the measuring unit at a plurality of timing different from the predetermined timing.

4. An apparatus according to claim 2, wherein if it is determined by the discriminating unit that there is no abnormality in the humidity measuring apparatus, the humidity is obtained by the measuring unit.

5. An apparatus according to claim 3, wherein the abnormality of the humidity detecting element is detected based on a maximum value and a minimum value among the plurality of detected voltages.

6. An image forming apparatus comprising: an image forming unit which forms an image;a humidity detecting apparatus having a humidity detecting element whose resistance value changes according to a humidity change and a resistor serially connected to the humidity detecting element;a signal output unit which outputs a clock signal to the humidity detecting element and the resistor;a measuring unit which detects a voltage of a connecting point of the humidity detecting element and the resistor at predetermined timing from one of a leading edge and a trailing edge of the clock signal and obtains a humidity based on the detected voltage; anda control unit which controls the image forming unit,wherein the control unit detects an abnormality of the humidity detecting element by detecting the voltage at timing different from the predetermined timing based on the voltage detected by the measuring unit.

7. An apparatus according to claim 6, further comprising a discriminating unit which discriminates whether or not there is an abnormality of the humidity detecting element based on the voltage detected at the timing different from the predetermined timing.

8. An apparatus according to claim 6, wherein the control unit detects the voltage at a plurality of timing different from the predetermined timing.

9. An apparatus according to claim 7, wherein if it is determined by the discriminating unit that there is no abnormality in the humidity measuring apparatus, the control unit obtains the humidity by the measuring unit and sets image forming conditions of the image forming unit according to the obtained humidity.

10. An apparatus according to claim 8, wherein the abnormality of the humidity detecting element is detected based on a maximum value and a minimum value among the plurality of detected voltages.