The automatic dishwasher is now a very common appliance, found in many homes and restaurants.  Of course, it takes some time, usually on the order of an hour, for the dishwasher to clean and dry a load of soiled dishes.  With the time pressures of modern society that means that the user of the automatic dishwasher is not going to sit around and wait for the dishwasher to complete its cycle of washing and drying its contents, but rather the user will do other chores, go to work, rest or even go to sleep, Sometime later the user or a third party, such as another member of the user's family (if the dishwasher is installed in a home) or a co-worker (if the dishwasher is installed in a restaurant), will have a need to clean further dishes and will load newly soiled dishes into the dishwasher not realizing until it is too late that the dishes in the machine are (were) clean.  But now spoiled dishes have been commingled with the previously clean dishes.  Practically speaking, that usually means that the entire load of commingled clean and soiled dishes must now be washed.  The inadvertent error of loading a few soiled dishes into a dishwasher of previously washed and dried dishes causes not only aggravation, but also wastes water and energy resources, since more loads of dishes are washed than is really necessary. 
An objective of the invention is to improve dishwashers so as to give a visual and/or an audible indication that the dishes in the dishwasher are clean or are soiled thereby saving energy, soap, water and aggravation which otherwise occurs when soiled articles are mixed with clean articles. 
These objectives are achieved as is now described.  A washing machine has a cavity which accepts soiled articles, which are placed on movable racks disposed in the cavity, and washes them in soapy water or other cleansing liquid, rinses the articles, optionally dries the articles and then holds them in the racks until removed.  A typical automatic dishwasher has two racks which can each move into and out of the cavity to facilitate unloading clean dishes from the racks and loading soiled dishes into the racks.  A water tight door, typically on the front of the machine, provides access to the washing cavity and the racks can move through the door's opening.  The machine is provided with means for sensing when the articles to be washed are placed into the machine and when they are subsequently removed.  Such a sensing means may be provided by a device for weighing, or more correctly, detecting changes in weight of the racks, including any dishes disposed in the racks. 
The machine has an on-off switch, usually part of a timing apparatus, for controlling a pump used to direct water and cleaning substances at the dishes in the washer.  The timing apparatus also controls electrically operated valves which admit fresh water into the cavity and permit the discharge of used water from the cavity as well as permit the introduction of cleaning substances into the cavity. 
A warning device or indicator is provided which has at least two positions, for example "CLEAN" and "SOILED", signifying that the cavity either contains clean dishes or is ready to receive soiled (i.e. used, dirty) dishes.  Initially, when the dishwasher is empty the warning indicator assumes its "SOILED" position indicating that the cavity is prepared to receive (or actually contains) soiled dishes.  The indicator is set to its "CLEAN" position at or near the end of a washing cycle by means of the timing apparatus.  The indicator is set back to its "SOILED" position when the racks of the washer have been unweighted, that is, the dishes have been removed from the racks, as sensed by the sensing means mentioned above. 
The warning device can be provided by a pair of Light Emitting Diodes, or other visual display devices, such as Liquid Crystal Display devices.  Preferably, however, the warning device is provided by an audible alarm or sound device such as a voice generator which would give an audible warning such as "The dishes are clean" whenever the door of the machine is opened after the completion of a washing cycle and before the dishes have been unloaded.  At other times the voice generator can say something such as "Ready to receive soiled dishes" whenever the door is opened after the clean dishes had been removed as sensed by the sensing device. 
An electronic latch is connected to the on-off switch and timing mechanism so as to set the latch when the washing cycle has completed.  The latch is also connected to the at least one sensor to reset the latch whenever the dishes are unloaded.  The set condition of the latch provides the CLEAN signal when the reset condition of the latch provides the SOILED signal.